The development of electron microscopes has further opened our window on the cell and its organelles. What is considered a major disadvantage of the electron microscope?

The methods used to prepare the specimen kill the cells.

What type of images are obtained from scanning electron microscopy (SEM)?

Should describe the 3-D component of the specimen image.

What type of images are obtained from transmission electron microscopy (TEM)?

Should mention that this type of microscopy profiles a thin section of a specimen, resulting in various views of the cells prepared.

A major difference between prokaryotic and eukaryotic cells is the location of their DNA. Describe this difference.

In a eukaryotic cell, most of the DNA is in the nucleus, which is bounded by a double membrane. In a prokaryotic cell, the DNA is concentrated in a region that is not membrane enclosed, called a nucleoid.

Rigid structure outside the plasma membrane.

Membrane is enclosing the cytoplasm.

Bacterial chromosome:

Carries genes in the form of DNA.

Region where the cell's DNA is located (not enclosed by a membrane).

Complexes that synthesizes proteins.

Locomotion organelles of some bacteria.

Why are cells so small? Explain the relationship of surface area to volume.

Cells are small because high surface-to-volume ratio facilitates the exchange of materials between a cell and its environment. As a cell increases in size, its volume grows proportionally more than surface area.

Exchange of materials across the plasma membrane requires a high surface-to-volume ratio. How do the microvilli of intestinal cells facilitate this?

Microvilli are long, thin projections from the cell surface, which increase surface area without an appreciable increase in volume. A sufficiently high ratio of surface area to volume is important in cells that exchange materials with surroundings.

Imagine an elongated cell that measures 125 x 1 x 1 arbitrary units (cell A). Predict how the surface-to-volume ratio would compare with a cell that is 5 x 5 x 5 (cell B) and then calculate the ratio for both cells.

Cell A would have a higher surface-to-volume ratio compared to Cell B. 1 + 1 + 125 + 125 + 125 + 125 = 502 units^2 Cell A has surface area of 502 units^2 while Cell B has a surface area of 50 units^2

As the size of a cell increases, what happens to the surface area-to-volume ratio?

As a cell increases in size, its surface area grows proportionally less than its volume.

How would the surface area of a cell growing proportionally less than its volume affect traffic into and out of the cell?

In cells, the need for high ratio of surface area-to-volume needs to be sufficient for the exchange of a lot of materials with their surrounding environment. If needed materials & waste can't enter or leave the cell, it will die.

Describe the nuclear envelope.

The nuclear envelope encloses the nucleus, separating its contents from the cytoplasm.

How many layers does the nuclear envelope have?

The nuclear envelope is a double membrane, meaning that there are two lipid bilayers.

How do molecules such as mRNA pass through the nuclear envelope?

The nuclear lamina, a netlike array of protein filaments, connects the layers of the nuclear envelope. Molecules such as mRNA pass through the pores of the nuclear envelope.

What are the nuclear lamina and nuclear matrix?

The nuclear lamina is the net-like array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelope. The nuclear matrix is a framework of protein fibers extending throughout the nuclear interior.

What function do the nuclear lamina and nuclear matrix perform?

The nuclear matrix and nuclear lamina may help organize the genetic material so it functions efficiently.

Found within the nucleus are the chromosomes. They are made of chromatin. What are the two components of chromatin?

Chromatin is composed of proteins and DNA.

When do the thin chromatin fibers condense to become distinct chromosomes?

Chromatin fibers condense to become distinct chromosomes as a cell prepares to divide.

When are the nucleoli visible?

Nucleoli are visible in a non-dividing nucleus and in cells active in protein synthesis.

What organelles are assembled when the nucleoli is visible?

Within the nucleoli, proteins imported from the cytoplasm are assembled with rRNA into large and small subunits of ribosomes.

What is the function of ribosomes?

Ribosomes are the cellular components that carry out protein synthesis.

What are the two components of ribosomes?

A large subunit and a small subunit.

Suspended in the cytosol. Produces proteins that function within the cytosol.

Attached to the outside of the ER or nuclear envelope. Produces proteins for insertion into membranes, for packaging within organelles like lysosomes, or for secretion out of the cell.

List all of the structures of the endomembrane system.

Nuclear envelope, endoplasmic reticulum, golgi apparatus, lysosomes, vesicles, vacuoles, and plasma membrane.

A cavity or cisternal space. Because the ER membrane is continuous within the nuclear envelope, the space between two membranes of the envelope is continuous with this.

What are the transport vesicles?

Bud off from a region of the rough ER called transitional ER and travel to the Golgi apparatus and other destinations.

Enzymes of the smooth ER are important in the synthesis of lipids, including oils, phospholipids, and steroids.

Detoxification of drugs and poisons:

Usually involves adding hydroxyl groups to to drug molecules, making them more soluble and easier to flush from the body.

Storage of calcium ions:

In muscle cells, the smooth ER membrane pumps these from the cytosol into the ER lumen.

Why does alcohol abuse increase tolerance to other drugs such as barbiturates?

Barbiturates, alcohol, and many other drugs induce the proliferation of smooth ER and its associated detoxification enzymes, thus increasing the rate of detoxification. This increases the tolerance to drugs.

The rough ER is studded with ribosomes. As proteins are synthesizes, they are threaded into the lumen of the rough ER. Some of these proteins have carbohydrates attached to them in the ER to form glycoproteins. What does the ER do with these proteins?

After secretory proteins are formed, the ER membrane keeps them separate from proteins that are produced by free ribosomes and that will remain in the cytosol. Secretory proteins depart from the ER wrapped in the membranes of vesicles.

What is another function of the rough ER?

A membrane factory for the cell; it grows in place by adding membrane proteins and phospholipids to its own membrane. It expands, and portions of it are transferred in the form of transport vesicles to other components of the endomembrane system.

A lysosome is a membranous sac of hydrolytic enzymes that an animal uses to digest macromolecules.

One function of lysosomes is intracellular digestion of particles engulfed by phagocytosis. Describe this process of digestion.

Amoebas and many other protists eat by engulfing smaller organisms or food particles, a process called phagocytosis. The food vacuole formed in this way then fuses with a lysosome, whose enzymes digest the food.

Which human cells carry out phagocytosis?

Macrophages, a type of white blood cell that help defend the body by engulfing and destroying bacteria and other invaders.

A second function of lysosomes is to recycle cellular components in a process called autophagy. Describe this process.

A damaged organelle or small amount of cytosol becomes surrounded by a double membrane, and a lysosome fuses with the outer membrane of the vesicle. The lysosomal enzymes dismantle the enclosed material and the organic monomers are returned to the cytosol

Explain what occurs in lysosomes to cause Tay-Sachs disease.

A lipid-digesting enzyme is missing or inactive, and the brain becomes impaired by an accumulation of lipids in the cell. The lysosomes lack a functioning hydrolytic enzyme normally present.

Contractile vacuoles:

Pump excess water out of the cell, thereby maintaining a suitable concentration of ions and molecules inside the cell.

Central vacuoles in plants:

Develop by coalescence of smaller vacuoles, contained in mature plant cells. Cell sap is the plant cell's main repository of inorganic ions, including potassium and chloride. Plays a major part in plant growth.

What is the endosymbiont theory?

An early ancestor of eukaryotic cells engulfed an oxygen-using non-photosynthetic prokaryotic cell, and over the course of evolution, the host cell and its endosymbiont merged into a single organism.

What is the main function of the mitochondria?

The cites of cellular respiration, the metabolic process that uses oxygen to generate ATP by extracting energy from sugars, fats, and other fuels.

What is the function of the chloroplast?

Sites of photosynthesis. They convert solar energy to chemical energy by absorbing sunlight and using it to drive synthesis of organic compounds such as sugars from carbon dioxide and water.

Help

Options

focusNode

Didn't know it?
click below

Knew it?
click below

Don't Know

Remaining cards (0)

Know

retry

shuffle

restart

0:00

Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.

Normal Size Small Size show me how

Study Guide Answers

Biology

Question	Answer
The development of electron microscopes has further opened our window on the cell and its organelles. What is considered a major disadvantage of the electron microscope?	The methods used to prepare the specimen kill the cells.
What type of images are obtained from scanning electron microscopy (SEM)?	Should describe the 3-D component of the specimen image.
What type of images are obtained from transmission electron microscopy (TEM)?	Should mention that this type of microscopy profiles a thin section of a specimen, resulting in various views of the cells prepared.
In cell fractionation, whole cells are broken up in a blender, and this slurry is configured several times. Each time, smaller and smaller cell parts are isolated. Which organelles are the smallest ones isolated in this procedure?	Ribosomes.
Which two domains consist of prokaryotic cells?	Bacteria and Archaea.
A major difference between prokaryotic and eukaryotic cells is the location of their DNA. Describe this difference.	In a eukaryotic cell, most of the DNA is in the nucleus, which is bounded by a double membrane. In a prokaryotic cell, the DNA is concentrated in a region that is not membrane enclosed, called a nucleoid.
Cell wall:	Rigid structure outside the plasma membrane.
Plasma membrane:	Membrane is enclosing the cytoplasm.
Bacterial chromosome:	Carries genes in the form of DNA.
Nucleoid:	Region where the cell's DNA is located (not enclosed by a membrane).
Ribosomes:	Complexes that synthesizes proteins.
Flagella:	Locomotion organelles of some bacteria.
Why are cells so small? Explain the relationship of surface area to volume.	Cells are small because high surface-to-volume ratio facilitates the exchange of materials between a cell and its environment. As a cell increases in size, its volume grows proportionally more than surface area.
Exchange of materials across the plasma membrane requires a high surface-to-volume ratio. How do the microvilli of intestinal cells facilitate this?	Microvilli are long, thin projections from the cell surface, which increase surface area without an appreciable increase in volume. A sufficiently high ratio of surface area to volume is important in cells that exchange materials with surroundings.
Imagine an elongated cell that measures 125 x 1 x 1 arbitrary units (cell A). Predict how the surface-to-volume ratio would compare with a cell that is 5 x 5 x 5 (cell B) and then calculate the ratio for both cells.	Cell A would have a higher surface-to-volume ratio compared to Cell B. 1 + 1 + 125 + 125 + 125 + 125 = 502 units^2 Cell A has surface area of 502 units^2 while Cell B has a surface area of 50 units^2
As the size of a cell increases, what happens to the surface area-to-volume ratio?	As a cell increases in size, its surface area grows proportionally less than its volume.
How would the surface area of a cell growing proportionally less than its volume affect traffic into and out of the cell?	In cells, the need for high ratio of surface area-to-volume needs to be sufficient for the exchange of a lot of materials with their surrounding environment. If needed materials & waste can't enter or leave the cell, it will die.
Describe the nuclear envelope.	The nuclear envelope encloses the nucleus, separating its contents from the cytoplasm.
How many layers does the nuclear envelope have?	The nuclear envelope is a double membrane, meaning that there are two lipid bilayers.
How do molecules such as mRNA pass through the nuclear envelope?	The nuclear lamina, a netlike array of protein filaments, connects the layers of the nuclear envelope. Molecules such as mRNA pass through the pores of the nuclear envelope.
What are the nuclear lamina and nuclear matrix?	The nuclear lamina is the net-like array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelope. The nuclear matrix is a framework of protein fibers extending throughout the nuclear interior.
What function do the nuclear lamina and nuclear matrix perform?	The nuclear matrix and nuclear lamina may help organize the genetic material so it functions efficiently.
Found within the nucleus are the chromosomes. They are made of chromatin. What are the two components of chromatin?	Chromatin is composed of proteins and DNA.
When do the thin chromatin fibers condense to become distinct chromosomes?	Chromatin fibers condense to become distinct chromosomes as a cell prepares to divide.
When are the nucleoli visible?	Nucleoli are visible in a non-dividing nucleus and in cells active in protein synthesis.
What organelles are assembled when the nucleoli is visible?	Within the nucleoli, proteins imported from the cytoplasm are assembled with rRNA into large and small subunits of ribosomes.
What is the function of ribosomes?	Ribosomes are the cellular components that carry out protein synthesis.
What are the two components of ribosomes?	A large subunit and a small subunit.
Free ribosomes:	Suspended in the cytosol. Produces proteins that function within the cytosol.
Bound ribosomes:	Attached to the outside of the ER or nuclear envelope. Produces proteins for insertion into membranes, for packaging within organelles like lysosomes, or for secretion out of the cell.
List all of the structures of the endomembrane system.	Nuclear envelope, endoplasmic reticulum, golgi apparatus, lysosomes, vesicles, vacuoles, and plasma membrane.
What is the lumen?	A cavity or cisternal space. Because the ER membrane is continuous within the nuclear envelope, the space between two membranes of the envelope is continuous with this.
What are the transport vesicles?	Bud off from a region of the rough ER called transitional ER and travel to the Golgi apparatus and other destinations.
Synthesis of lipids:	Enzymes of the smooth ER are important in the synthesis of lipids, including oils, phospholipids, and steroids.
Detoxification of drugs and poisons:	Usually involves adding hydroxyl groups to to drug molecules, making them more soluble and easier to flush from the body.
Storage of calcium ions:	In muscle cells, the smooth ER membrane pumps these from the cytosol into the ER lumen.
Why does alcohol abuse increase tolerance to other drugs such as barbiturates?	Barbiturates, alcohol, and many other drugs induce the proliferation of smooth ER and its associated detoxification enzymes, thus increasing the rate of detoxification. This increases the tolerance to drugs.
The rough ER is studded with ribosomes. As proteins are synthesizes, they are threaded into the lumen of the rough ER. Some of these proteins have carbohydrates attached to them in the ER to form glycoproteins. What does the ER do with these proteins?	After secretory proteins are formed, the ER membrane keeps them separate from proteins that are produced by free ribosomes and that will remain in the cytosol. Secretory proteins depart from the ER wrapped in the membranes of vesicles.
What is another function of the rough ER?	A membrane factory for the cell; it grows in place by adding membrane proteins and phospholipids to its own membrane. It expands, and portions of it are transferred in the form of transport vesicles to other components of the endomembrane system.
What is a lysosome?	A lysosome is a membranous sac of hydrolytic enzymes that an animal uses to digest macromolecules.
What is the pH range inside a lysosome?	Acidic
One function of lysosomes is intracellular digestion of particles engulfed by phagocytosis. Describe this process of digestion.	Amoebas and many other protists eat by engulfing smaller organisms or food particles, a process called phagocytosis. The food vacuole formed in this way then fuses with a lysosome, whose enzymes digest the food.
Which human cells carry out phagocytosis?	Macrophages, a type of white blood cell that help defend the body by engulfing and destroying bacteria and other invaders.
A second function of lysosomes is to recycle cellular components in a process called autophagy. Describe this process.	A damaged organelle or small amount of cytosol becomes surrounded by a double membrane, and a lysosome fuses with the outer membrane of the vesicle. The lysosomal enzymes dismantle the enclosed material and the organic monomers are returned to the cytosol
Explain what occurs in lysosomes to cause Tay-Sachs disease.	A lipid-digesting enzyme is missing or inactive, and the brain becomes impaired by an accumulation of lipids in the cell. The lysosomes lack a functioning hydrolytic enzyme normally present.
Food vacuole:	Formed by phagocytosis.
Contractile vacuoles:	Pump excess water out of the cell, thereby maintaining a suitable concentration of ions and molecules inside the cell.
Central vacuoles in plants:	Develop by coalescence of smaller vacuoles, contained in mature plant cells. Cell sap is the plant cell's main repository of inorganic ions, including potassium and chloride. Plays a major part in plant growth.
What is the endosymbiont theory?	An early ancestor of eukaryotic cells engulfed an oxygen-using non-photosynthetic prokaryotic cell, and over the course of evolution, the host cell and its endosymbiont merged into a single organism.
What is the main function of the mitochondria?	The cites of cellular respiration, the metabolic process that uses oxygen to generate ATP by extracting energy from sugars, fats, and other fuels.
What is the function of the chloroplast?	Sites of photosynthesis. They convert solar energy to chemical energy by absorbing sunlight and using it to drive synthesis of organic compounds such as sugars from carbon dioxide and water.
Why is the inner membrane of the mitochondria highly folded?	The cristae give a large surface area, thus enhancing the productivity of cellular respiration.
What role do all the individual thylakoids membranes serve?	Increase the surface area and thus the function of the chloroplast.
Explain the roles played by peroxisomes.	Contain enzymes that remove hydrogen atoms from various substrates and transfer them to oxygen, thus producing hydrogen peroxide as a by-product.
Use peroxisomes as an example to explain the value of compartmentalization in cells.	The enzymes that produce H2O2 and those that dispose of this toxic compound are sequestered away from other cellular components that could be damaged.
What is cytoskeleton?	A network of fibers extending throughout the cytoplasm.
There are three main types of fibers that make up the cytoskeleton. Name them.	Microtubules, microfilaments, and intermediate filaments.
What are three functions of the cytoskeleton?	Maintenance of cell shape, mechanical support, and cell motility both of the cell as a whole and more limited movement of parts of the cell.
Microtubules are hollow rods made of a globular protein called tubulin. Each tubulin protein is a dimer of two subunits. These are easily assembled and disassembled. Describe several functions of microtubules.	Maintenance of cell shape, cell motility, chromosome movement in cell division, and organelle movement.
Animal cells have a centrosome that contains a pair of centricles. Plant cells do not have centrioles. What is believed to be the role of centrioles?	Also known as "microtubule-organizing center"; the centrioles function as compression-resisting girders of the cytoskeleton.
Compare cilia and flagella.	Both microtubule-containing extensions that project from some cells. Share a common structure, each having a group of microtubules sheathed to an extension of the plasma membrane.
What is the function of the primary cilium?	To act as a signal-receiving "antenna" for the cell.
How do motor proteins called dyneins cause movement of cilia?	Responsible for the bending and movements of the organelle.
What is the role of ATP in the movement of dyneins?	Performs a complex cycle of movement caused by changes in the shape of the protein, with ATP providing the energy for these changes.
What are the motor proteins that move the microfilaments?	Myosin
Give two functions of intermediate filaments.	Reinforcing the shape of the cell and fixing the position of certain organelles.
What are the three functions of the cell wall?	Protects the plant cell, maintains its shape, and prevents excessive uptake of water.
What is the composition of the cell wall?	The basic design consists of microfibrils made o the polysaccharide cellulose.
What is the relatively thin and flexible wall secreted first by a plant cell?	Primary cell wall.
What is the middle lamella and what is it made of?	A thin layer of sticky polysaccharides called pectins.
Where is the middle lamilla found?	Between the primary walls of adjacent cells.
Describe the deposition of a secondary cell wall.	Often deposited in several laminated layers, has a strong and durable matrix that affords the cell protection and support.
What are the intercellular junctions between plant cells?	Plasmodesmata.
What can pass through the plasmodesmata?	Cytosol passes through and joins the internal chemical environments of adjacent cells.
Tight junctions:	Establish a barrier that prevents leakage of extracellular fluid across a layer of epithelial cells.
Desmosomes:	Function like rivets, fastening cells together into strong sheets.
Gap junction	Provide cytoplasmic channels from one cell to an adjacent cell; similar to the function of plasmodesmata in plant cells.
List the following structure from largest to smallest: proton pump, nuclear pore, cyt C, ribosomes.	Nuclear pore, ribosome, proton pump, cyt C
Considering the structures of a nucleosome and of RNA polymerase, speculate about what must happen before RNA polymerase can transcribe the DNA that is wrapped around the histone proteins of a nucleosome.	The DNA is wrapped around 8 histones that make up the nucleosome. Because the enzyme, RNA polymerase, is responsible for making messenger RNA from a sequence of DNA, the DNA will have to unwrap or move away from the histones. RNA can attach to DNA.
Find another myosin motor protein walking on a microfilament. What organelle is being moved by the myosin protein?	Mitochondrion or vesicle.
Passive transport:	Transport of small molecules that does not require energy. It may involve transport proteins.
Active transport:	Transport of small molecules that does require energy and a transport protein.
Bulk transport:	Transport of large molecules that requires energy and folding in or out of the cell membrane.
Phospholipids are amphipathic. Explain what this means.	The phospholipid has both a hydrophilic region and a hydrophobic region.
The currently accepted model of the plasma membrane is the fluid mosaic model. Describe this model.	The membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids.
What is meant by membrane fluidity?	A membrane is held together primarily by hydrophobic interactions, which are much weaker than covalent bonds. Most of the lipids and some of the proteins can shift about laterally in the plane of the membrane.
How does decreasing temperature affect membrane fluidity?	The membrane remains fluid until finally the phospholipids settle into a closely packed arrangement and the membrane solidifies. The temperature a membrane solidifies depends on the types of lipids its made of.
How does phospholipids with unsaturated hydrocarbon tails affect membrane fluidity?	The membrane remains fluid to a lower temperature if it is rich in phospholipids with unsaturated hydrocarbon tails. Because of kinks in the tails where double bonds are located, unsaturated tails cannot pack together as closely as saturated tails.
How does cholesterol affect membrane fluidity?	At relatively high temperatures---at 37 degrees Celsius, the body temperature of humans, for example---this makes the membrane less fluid by restraining phospholipid movement.
How does increasing the number of saturated hydrocarbon tails affect membrane fluidity?	They pack together, increasing the membrane viscosity and decreasing fluidity.
Integral proteins:	Penetrate the hydrophobic interior of the lipid bilayer.
Peripheral proteins:	Appendages loosely bound to the surface of the membrane, often exposed parts of integral proteins.
Transport:	A protein that spans the membrane may provide a hydrophilic channel across the membrane that is selective for a particular solute. Others shuttle a substance from one side to the other by changing shape. Some hydrolyze ATP as energy.
Enzymatic activity:	A protein built into the membrane may be an enzyme with its active site exposed to substances in the adjacent solution. In some cases, several enzymes in a membrane are organized as a team that carries out sequential steps of a metabolic pathway.
Signal transduction:	A membrane protein (receptor) may have a binding site with a specific shape that fits the shape of a chemical messenger, such as a hormone. The external messenger (signaling moleceule) may cause the protein to change shape, to relay message inside cell.
Cell-cell recognition:	Some glycoproteins serve as identification tags that are specifically recognized by membrane proteins of other cells.
Intercellular joining:	Membrane proteins of adjacent cells may hook together in various kinds of junctions, such as gap junctions or tight junctions.
Attachment to cytoskeleton:	Microfilaments or other elements of the cytoskeleton may be non-covalently bound to membrane proteins, a function that helps maintain cell shape and stabilizes the location of certain membrane proteins.
Attachment to ECM:	Proteins that can bind to ECM molecules can coordinate extracellular and intracellular changes.
Membrane carbohydrates are important in cell-cell recognition. What are two examples of this?	The sorting of cells into tissues and organs in an animal embryo, and the rejection of foreign cells by the immune system.
Distinguish between glycolipids and glycoproteins.	Carbohydrates bonded to lipids; membrane covalently. Carbohydrates bonded to proteins; membrane covalently.
Glycolipids:	Cell recognition.
Glycoproteins:	Cell recognition.
Integral proteins:	Various including cell recognition and signal transduction.
Peripheral proteins:	Various including cell recognition and signal transduction.
Cholesterol:	Fluidity buffer.
Phospholipids:	Forms bilayers that create boundaries for cells or some cell organelles.
ECM fibers:	Supportive and interactive meshwork around animal cells.
Cytoskeleton microfilaments:	Mechanical, transport, and signaling.
Integtins:	Connects the cytoskeleton to the extracellular matrix.
The outside membrane of a vesicle becomes the ______ of the cell membrane.	continuous with the inside
Distinguish between channel proteins and carrier proteins.	Channel proteins function by having a hydrophilic channel that certain molecules or atomic ions use as a tunnel through the membranes. Carrier proteins hold on to their passengers and change shape in a way that shuttles them across the membrane.
Are transport proteins specific?	Yes. A transport protein is specific for the substance it translocates, allowing only a certain substance to cross the membrane.
Peter Agre received the Nobel Prize in 2003 for the discovery of aquaporins. What are they?	Channel proteins that facilitate the passage of water molecules through the membranes of certain cells.
What is the method of transport for CO2?	Simple diffusion.
What is the method of transport for glucose?	Transport proteins.
What is the method of transport of H+?	Transport proteins.
What is the method of transport for O2?	Simple diffusion.
What is the method of transport for H2O?	Simple diffusion and protein channels (aquaporins).
Diffusion:	The movement of molecules of any substance so that they spread out evenly into the available space.
Concentration gradient:	The region along with the density of a chemical substance increases or decreases.
Passive transport:	Diffusion of a substance across a biological membrane; cell does not have to expend energy to make it happen.
Osmosis:	The diffusion of water across a selectively permeable membrane.
Isotonic:	A solution with the same concentration of solutes as the cell it surrounds. There will be no net movement of water across the plasma membrane. In an isotonic environment, the volume of the animal cell is stable.
Hypertonic:	A solution with more solutes than the cell it surrounds. The cell will lose water, shrivel, and probably die.
Hypotonic:	A solution with less solutes than the cell it surrounds. The cell will swell and lyse (burst) unless it has a supportive structure like a cell wall.
Turgid:	Very firm.
Flaccid:	Limp.
Plasmolysis:	Phenomenon during which the plant cell shrivels, and its plasma membrane pulls away from the wall.
How does the diffusion of one solute affect the diffusion of the second solute?	Each substance diffuses down its own concentration gradient.
Why does the red blood cell burst when placed in a hypotonic solution, but the plant cell does not?	Plant cells have a cell wall and animal cells do not. Plant cells are turgid and generally healthiest in a hypotonic environment.
What is facilitated diffusion?	The phenomenon during which polar molecules and ions impeded by the lipid bilayer of the membrane diffuse passively with the help of transport proteins that span the membrane. Moving down concentration gradient.
Describe active transport.	Type of membrane traffic during which the cell must expend energy.
What type of transport proteins are involved in active transport, and what is the role of ATP in the process?	Carrier proteins are involved. ATP supplies the energy for most active transport.
What is membrane potential?	The voltage across a membrane, which ranges from about -50 to -200 millivolts (mV).
What side of the membrane is positive?	The minus sign indicates that the inside of the cell is negative relative to the outside.
What are the two forces that drive the diffusion of ions across the membrane?	A chemical force (the ion's concentration gradient) and an electrical force (the effect of the membrane potential on the ion's movement).
What is the combination of the two forces that drive diffusion of ions across the membrane called?	Electrochemical gradient.
What is cotransport?	The coupling of the "downhill" transport of one substance to the "uphill" transport of another substance against its own concentration gradient.
How is the understanding of cotransport used to treat diarrhea?	Patients are given a solution to drink containing a high concentration of salt and glucose. The solutes are taken up by sodium-glucose cotransporters on the surface of intestinal cells and passed through the cells into the blood.
Exocytosis:	The cellular secretion of biological molecules by fusion of vesicles containing them with the plasma membrane. Many secretory cells used this mechanism to export products.
Endocytosis:	Cellular uptake of biological molecules and particulate matter via formation of vesicles from the plasma membrane.
Receptor-mediated endocytosis:	The movement of specific molecules into a cell by the inward budding of vesicles containing proteins with receptor sites specific to the molecules being taken in; enables a cell to acquire bulk quantities of specific substances.
Phagocytosis:	A type of endocytosis in which large particulate substances or small organisms are taken up by a cell. It is carried out by some protists and certain immune cells of animals.
Pintocytosis:	A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes. Cells "gulp" droplets of extracellular fluid into tiny vesicles.
What is the key feature of receptor-mediated endocytosis:	Specific receptors on the cell membrane that bind to specific substances that may be in low concentration in the extracellular fluid.
Which reactions release energy?	Catabolic.
Which reactions consume energy?	Anabolic.
Which reactions build up larger molecules?	Anabolic.
Which reactions break down molecules?	Catabolic.
Which reactions are considered "uphill"?	Anabolic.
Which type of reaction is photosynthesis?	Anabolic.
Which type of reaction is cellular respiration?	Catabolic.
In living systems, which reactions require enzymes to catalyze them?	Anabolic, catabolic.
Energy is the capacity to cause change, do work, or move matter against opposing forces. It exists in various forms. Contrast kinetic energy with potential energy.	Kinetic energy is associates with the relative motion of objects, whereas potential energy refers to an object not presently moving; it is the energy that matter possesses because of its location or structure.
Which type of energy does water behind a damn have? A mole of glucose?	Potential energy for both. More specifically, glucose has chemical energy, a term used by biologists to refer to the potential energy available for release in a chemical reaction.
According to the first law of thermodynamics, what can and cannot happen to energy?	Energy can be transferred and transformed, but it cannot be created or destroyed.
The second law of thermodynamics states that every energy transfer or transformation increases the entropy of the universe. Some call this the "you always lose rule". What always happens in each energy transfer that makes this an apt expression?	Some energy is converted to thermal energy and released as heat, becoming unavailable to do work. A consequence of the loss of usable energy as heat to the surroundings is that each energy transfer or transformation makes the universe more disordered.
What is meant by a spontaneous process?	Occurs without an overall input of energy; a process that is energetically favorable.
What is free energy?	The portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell.
What is the symbol for free energy?	The letter G.
Once we know the value of △G for a reaction we can use it to predict whether it will be spontaneous. For an exergonic reaction, is △G negative or positive?	Proceeds with the net release of energy. Because the chemical mixture loses free energy, △G is negative for an exergonic reaction.
Is cellular respiration an endergonic or an exergonic reaction?	Exergonic reaction.
What is the △G for the exergonic reaction in cellular respiration?	△G = -686 kcal/mol.
Is photosynthesis endergonic or exergonic?	Endergonic reaction.
What is the energy source that drives the endergonic reaction of photosynthesis?	Plants get the required energy to make a mole of glucose from the environment by capturing light energy from the sun and converting its energy into chemical energy. The △G for the reaction: △G = +686 kcal/mol.
If energy is released, △G must be positive/negative.	△G is negative.
Explain why the light bulb goes off when the system is at equilibrium.	If the △G is negative, water flowing downhill would be a spontaneous reaction turning a turbine that drives a generator providing electricity to a light bulb.
Chemical work:	The pushing of endergonic reactions that would not occur spontaneously, such as the synthesis of polymers from monomers.
Transport work:	The pumping of substances across membranes against the direction of spontaneous movement, possible examples include the sodium-potassium pump and proton pump.
Mechanical work:	The beating of cilia, the contraction of muscle cells, and the movement of chromosomes during cellular respiration.
What is energy coupling?	In cellular metabolism, this is the use of energy released from an exergonic reaction to drive an endergonic reaction.
By what process will break an ATP bond?	Hydrolysis.
Explain the name ATP by listing all the molecules that make it up.	ATP, (Adenosine triphosphate), contains the sugar ribose, with the nitrogenous base adenine and a chain of three phosphate groups bonded to it.
1. When the terminal phosphate bond is broken, a molecule of inorganic phosphate Pi is formed, and energy is ______.	released
2. ATP --> ADP + Pi, △G =	-7.3 kcal/mol (-30.5 kJ/mol).
3. Is this reaction endergonic or exergonic?	Exergonic.
In many cellular reactions, a phosphate group is transferred from ATP to some other molecule in order to make the second molecule less stable. What term is now used to describe the second molecule?	Phosphorylated intermediate.
If you could not regenerate ATP by phosphorylating ADP, how much ATP would you need to consume each day?	Humans would use up nearly their body weight in ATP each day.
What is a catalyst?	A chemical agent that selectively increases the rate of a reaction without being consumed by the reaction.
What is activation energy (EA)?	The amount of energy that reactants must absorb before a chemical reaction will start; also called free energy of activation.
What effect does an enzyme have on EA?	An enzyme catalyzes a reaction by lowering the EA barrier.
Enzyme:	A macromolecule serving as a catalyst, a chemical agent that increases the rate of a reaction without being consumed by the reaction. Most enzymes are proteins.
Substrate:	The reactant on which an enzyme works.
Active site:	Typically, a pocket or groove on the surface of the enzyme where the substrate binds and catalysis occurs.
Products:	A material resulting from a chemical reaction.
What is meant by induced fit?	The slight change in shape of the active site of an enzyme so that it binds more snugly to the substrate.
Explain how protein structure is involved in enzyme specificity.	Enzymes are proteins, and proteins are macromolecules with unique three-dimensional configurations. The specificity of an enzyme results from its shape, which is a consequence of its amino acid sequence.
How do enzymes lower activation energy in reactions involving two or more reactants?	The active site provides a template on which the substrates can come together in the proper orientation for a reaction to occur between them.
How do enzymes lower activation energy as the active site of an enzyme clutches the bound substrate?	The enzyme may stretch the substrate molecules toward their transition-state form, stressing and bending critical chemical bonds that must be broken during the reaction.
How do enzymes lower activation energy with the active site?	The active site may also provide a microenvironment that is more conductive to a particular type of reaction than the solution itself would be without the enzyme.
How do enzymes lower activation energy with amino acids in active site?	Amino acids in the active site may directly participate in the chemical reaction.
Initial concentration of substrate:	The more substrate molecules that are available, the more frequently they access the active sites of the enzyme molecules.
pH:	With some exceptions, the optimal pH values for most enzymes fall in the range of pH 6-8.
Temperature:	Up to a point, the rate of an enzymatic reaction increases with increasing temperatures, partly because substrates collide with active sites more frequently when molecules move rapidly. Above the temperature, the speed of the enzymatic reaction drops.
Recall that enzymes are globular proteins. Why can extremes of pH or very high temperatures affect enzyme activity?	The 3-D structures of proteins are sensitive to their environments. As a consequence, each enzyme works better under some conditions than other conditions, because these optimal conditions favor the most active shape for their enzyme molecule.
Name a human enzyme that functions well in pH 2. Where is it found?	Pepsin, a digestive enzyme, is found in the human stomach.
Distinguish between cofactors and coenzymes.	A cofactor is any non-protein molecule that is required for the proper functioning of an enzyme. A coenzyme is an organic molecule serving as a cofactor.
Competitive inhibitors:	Substances that reduce the activity of an enzyme by entering the active site in place of the substrate, whose structure it mimics.
Noncompetitive inhibitors:	Substances that reduce the activity of an enzyme by binding to a location away from the active site,
What is allosteric regulation?	The binding of a regulatory molecule to a protein at one site that affects the function of the protein at a different site.
How is allosteric regulation somewhat like noncompetitive inhibition? How might it be different?	The noncompetitive inhibition in that it may inhibit enzyme activity, but different in that it may also stimulate enzyme activity.
Explain the difference between an allosteric activator and an allosteric inhibitor.	The binding of an activator to a regulatory site stabilizes the shape that has functional active sites, whereas the binding of an inhibitor stabilizes the inactive form of the enzyme.
Although it is not an enzyme, hemoglobin shows cooperativity in binding O2. Use O2 binding in fish hemoglobin to explain cooperativity.	Hemoglobin is made up of four subunits, each of which has an oxygen-binding site. The binding of an oxygen molecule to one binding site increases the affinity for oxygen of the remaining binding sites.
Explain the difference between fermentation and aerobic respiration.	Fermentation is a partial degradation of sugars or other organic fuel that occurs without the use of oxygen. Aerobic respiration consumes oxygen as a reactant along with the organic fuel.
Summarize the catabolic degradation of food by aerobic respiration.	Organic compounds (food) with the addition of oxygen are broken down into carbon dioxide, water, and energy.
The breakdown of glucose is linked to cellular work by a chemical driveshaft known as ______	cellular respiration.
Both cellular respiration and photosynthesis are redox reactions. In redox reactions, pay attention to the flow of electrons. What is the difference between oxidation and reduction?	In a redox reaction, the loss of electrons from one substance is called oxidation, and the addition of electrons to another substance is known as reduction.
Xe- + Y ---> X + Ye-	Redox reaction.
Xe-	Reducing agent.
Y	Oxidizing agent.
When compounds lose electrons, they ____ energy; when compounds gain electrons, they ____ energy.	lose; gain
In cellular respiration, electrons are not transferred directly from glucose to oxygen. Following this movement of hydrogens allows you to follow the flow of electrons. What electron carrier is hydrogen transferred to first?	NAD+
NAD+ is a coenzyme. What are coenzymes?	An organic molecule serving as a cofactor. Most vitamins function as coenzymes in metabolic reactions.
Describe what happens when NAD+ is reduced. What enzyme type is involved?	The enzymatic transfer of 2 electrons and 1 proton (H+) from an organic molecule in food to NAD+ reduces the NAD+ to NADH; the second proton (H+) is released. The enzyme is involved in dehydrogenase.
NAD+	Oxidized; lower energy.
NADH	Reduced; higher energy.
What is the function of the electron transport chain in cellular respiration?	Shuttles electrons down a series of redox reactions that release energy used to make ATP.
Electron transport involves a series of electron carriers, mostly proteins. Where are these carrier molecules found in eukaryotic cells?	Within the inner membrane of the mitochondria.
Which strongly electronegative atom, pulling electrons down the electron transport chain, is the final electron acceptor?	Oxygen.
Three types of phosphorylation (adding a phosphate) are covered and two of these occur in cellular respiration. Explain how the electron transport chain is utilized in oxidative phosphorylation.	This mode of ATP synthesis is powered by the redox reactions of the electron-transport chain. The energy released in each step provides the energy to maintain the chemiosmotic gradient that powers the ATP synthase complex.
What is the meaning of glycolysis?	A series of reactions that ultimately splits glucose into pyruvate.
What occurs in the glycolysis step of cellular respiration?	Occurs in almost all living cells, serving as the starting point for fermentation or cellular respiration.
The starting product of glycolysis is the six-carbon sugar ____ and the ending products are two ____-carbon molecules of ____.	glucose, three, pyruvate.
Where does glycolysis occur in the cell?	Occurs in the cytosol of the cell.
Is oxygen required for glycolysis?	No, oxygen is not required.
How many NADHs are formed in the citric acid cycle?	3 from each pyruvate.
How many total carbons are lost as pyruvate is oxidized in the citric acid cycle?	3.
The carbons are lost in the citric acid cycle in which molecule?	Carbon dioxide.
How many FADH2 are formed in the citric acid cycle?	1 per pyruvate molecule.
How many ATPs are formed in the citric acid cycle?	1 per pyruvate molecule.
How many times does the citric acid cycle occur for each molecule of glucose?	2.
The step that converts pyruvate to acetyl CoA occurs twice per glucose. This oxidation of pyruvate accounts or two additional reduced ____ molecules and two molecules of CO2.	NADH.
Explain what has happened to the six carbons found in the original glucose molecule.	There are a total of six molecules of CO2 released containing the six carbons in the original glucose molecule. Two molecules are released from the conversion of pyruvate to acetyl CoA and four molecules are released from the citric acid cycle.
As the citric acid cycle is completed what compound is regenerated?	Citrate.
Little ATP has been produced. Where is most of the energy at this point in cellular respiration?	NADH and FADH2.
Oxidative phosphorylation involves two components:	The electron transport chain and ATP synthesis.
Each member of the electron transport chain is lower in ____ than the proceeding member of the chain but higher in ____.	free energy, electronegativity.
The molecule at zero free energy, which is ____, is the lowest of all the molecules in free energy and the highest in electronegativity.	oxygen.
Explain why oxygen is considered the ultimate electron acceptor.	Oxygen is extremely electronegative.
Oxygen stabilizes the electrons by combining with two hydrogen ions to form what compound?	H2O.
What are the two electron carrier molecules that feed electrons into the electron transport system?	NADH and FADH2.
What is the role of the electron transport chain in forming the H+ gradient across the inner mitochondrial membrane?	Move H+ across the inner mitochondrial membrane, creating a proton gradient. This gradient powers ATP synthase to make ATP.
Relate chemiosmosis to the process of oxidative phosphorylation.	Refers to the energy-coupling mechanism that uses energy stored in the form of a hydrogen ion gradient across a membrane to drive cellular work, such as the synthesis of ATP.
Relate proton-motive force to the process of oxidative phosphorylation.	Refers to the potential energy stored in the form of a proton electrochemical gradient, generated by the pumping of hydrogen ion (H+) across a biological membrane during chemiosmosis.
Why is the total count about 30 or 32 ATP molecules rather than a specific number?	The exact ATP yield from glucose breakdown varied due to inefficiencies in energy transfer, different electron shuttles, and other cellular uses of the proton gradient.
Fermentation allows the production of ATP without using either ____ or any ____	oxygen, electron transport chain.
For aerobic respiration to continue, the cell must be supplied with oxygen---the ultimate electron acceptor. What is the electron acceptor in fermentation?	NAD+.
Alcohol fermentation starts with glucose and yields ethanol. Explain this process, and be sure to describe how NAD+ is recycled.	Pyruvate is converted to ethanol in two steps. First, pyruvate loses carbon dioxide and becomes acetadehyde. Then, acetaldehyde is reduced by NADH to form ethanol, which regenerates NAD+ from glycolysis to continue.
Lactic acid fermentation starts with glucose and yields lactate. Explain this process and be sure to describe how NAD+ is recycled.	Pyruvate is directly reduced by NADH to form lactate without releasing CO2. This regenerates NAD+ for glycolysis.
Track coaches used to think that lactic acid accumulated in the muscles, so he had them job to get more oxygen to the muscles to reduce soreness. What is currently known about lactate production and muscle soreness?	Lactate production improves performance during exercise. After production, lactate is quickly shuttled to other tissues for oxidation or to the liver and kidneys for production of glucose or glycogen. Muscle soreness caused by trauma to cells.
Why is pyruvate a key juncture in metabolism?	The end product of glycolysis, pyruvate, represents a fork in the catabolic pathways of glucose oxidation. In a facultative anaerobe, capable of both aerobic cellular respiration and fermentation, pyruvate is committed to one of those two pathways.
Glycolysis is thought to have evolved very early in the evolution of life on Earth. Provide two pieces of evidence that justify this hypothesis.	Glycolysis is the most widespread metabolic pathway among Earth's organisms suggests that it evolved very early in the history of life. The cytosolic location of glycolysis also implies great antiquity.
What three organic macromolecules are often utilized to make ATP by cellular respiration?	Proteins, carbohydrates, and fats are utilized to make ATP by cellular respiration.
Starch:	The polymer is hydrolyzed to glucose which is broken down in cells by glycolysis and the citric acid cycle.
Glycogen:	The polymer is hydrolyzed to glucose which is broken down in cells by glycolysis and the citric acid cycle.
Proteins:	The polymer is hydrolyzed to amino acids, their amino groups are removed, and enzymes convert them to intermediates of glycolysis and the citric acid cycle.
Fats:	The polymer is hydrolyzed to glycerol and fatty acids. Glycerol is converted to glyceraldehyde 3-P and enters glycolysis. Fatty acids are broken into 2 carbon fragments by beta oxidation and enter the citric acid cycle as acetyl CoA.
Explain the energy usage in catabolic reactions of cellular respiration.	Funnel electrons from many kinds of organic molecules into cellular respiration. Many carbohydrates can enter glycolysis, most often after conversion to glucose. Amino acids of proteins must be deaminated before being oxidized. Etc.
Explain the energy usage in anabolic reactions of cellular respiration.	Can use energy and small molecules from food directly or build other substances using intermediates of glycolysis or the citric acid cycle.
Explain how AMP stimulates cellular respiration, whereas ATP and citrate inhibit it.	Cellular respiration speeds up when ATP levels drop and slows down when ATP is abundant. The enzyme phosphofructokinase regulates this process: it is activated by AMP and inhibited by ATP and citrate.
Phosphofructokinase is an allosteric enzyme that catalyzes an important step in glycolysis. Explain how this step is a control point in cellular respiration.	As ATP and citrate accumulate, they inhibit phosphofructokinase, slowing glycolysis and reducing acetyl group supply to the citric acid cycle. When ATP is used up and AMP levels rise, the enzyme is reactivated. This regulation helps coordinate glycolysis.
What molecule is the "pacemaker" of cellular respiration?	Phosphofructokinase or pfk.

Created by: UkiyosDomain

Popular Biology sets

Genetics: Monohybrid, Dihybrid, & Non-Mendelian

Unit 2- Requirements of Life

Evidence of Evolution

"Know" box contains:
Time elapsed:
Retries: