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Cellular Processes
| Question | Answer |
|---|---|
| Compartmentalization | The process by which cells have evolved organelles, membrane-enclosed structures that perform specific functions, to increase the efficiency of cell metabolism. |
| Surface-area-to-volume ratio | Calculated by dividing a cell's surface area by the volume. Used to measure cell efficiency. |
| Fluid Mosaic Model | A model of membrane structure. |
| Membranes are composed of a double layer of what. | Phospholipids |
| Plasma membrane | Separates the eukaryotic cell's contents from the outside. |
| Cytoplasm | All the cell's contents from the plasma membrane to the nucleus. |
| Cytosol | The liquid of the cytoplasm. |
| Fatty acid tails are saturated with hydrogen, they are nonpolar or what? | Hydrophobic |
| The charged head of a phospholipid is polar or what? | Hydrophilic |
| Phospholipid bilayer | Refers to the arrangement of phospholipid bilayer in the cell membrane. |
| Central dogma | DNA makes RNA, and RNA directs protein synthesis. |
| Nucleolus | The site for ribosomal synthesis. |
| Nuclear envelope | A double membrane that surrounds the nucleus and contains pores. |
| Ribosomal subunits | Located at the outside of the nuclear envelope. |
| Nuclear lamina | Comprised of structural proteins that serve to hold the nucleus together and keep it intact. |
| Chromatin | Chromosomes in an uncondensed state. |
| Cytoskeleton | Consists of a series of fibers and filaments that are responsible for maintaining the cell's shape. |
| Three main types of protein fibers are: | Thin microfilaments, medium-sized intermediate filaments, large microtubules. |
| Microfilaments consist of twisted double strands of what protein? | Actin |
| What are microfilaments responsible for? | Muscle contraction, formation of the cleavage furrow during cell division, and movement of pseudopodia. |
| What defect in anchoring protein results in muscular dystrophy? | Dystrophin |
| Intermediate filaments | Consists of rope-like proteins and include the keratin family. |
| Microtubulues | About 25nm in diameter. Arranged in a spiral protein. |
| Centriole | A cylindrical structure in an animal cell. |
| What structures aid in locomotion or move fluids across the surface of tissue cells of animals? | Flagella and cilia |
| Protein motor molecules | Provide the force of bending and movement of both cilia and flagella. |
| 9 + 0 pattern | Derived from the fact that there are nine fused triplets of microtubules surrounding an empty space. |
| What is the length of flagella and how does it function? | Long structures that function as propellers in locomotion. |
| What is the length of cilia and how does it function? | Relatively short and work like oars. |
| 9 + 2 pattern | There are nine fused pairs of microtubules surrounding an unfused pair of microtubules. |
| Basal body | A eukaryotic cell organelle that is similar in structure to a centriole and directs microtubule assembly in cilia and flagella. |
| Peptidoglycans | Polymers of modified sugars cross-linked by short polypeptides. |
| How is a primary cell wall formed? | When plant cells secrete cellulose from their plasma membrane. |
| Many cells will secrete more celluloses and lignin to form a structurally rigid what? | Secondary cell wall |
| Plasmodesmata (singular, plasmodesma) | Cytoplasmic channels that run through adjacent plant cell walls. They are surrounded by plasma membrane and form a connection between the cytoplasm of one plant cell and another. |
| True or false. Plant cells have the ability to share cytoplasm. | True |
| Viruses | Noncellular infectious particles composed of a protein capsid and genetic material, either DNA or RNA. |
| What do viruses rely on in order to replicate themselves? | A host cell |
| Viruses reproduce themselves using what? | Lytic or lysogenic cycles |
| Prions | Infectious proteins that can cause other proteins to become harmful. |
| What is an example of a prion infection? | Mad cow disease |
| Lytic cycle | Begins when the virus infects the hose cell and injects its genetic material. |
| What is used to make copies of viral nucleic acids and direct the synthesis of viral proteins? | Host cell enzymes |
| What lands on a bacterium before viral reproduction? | A bacteriophage |
| Lysogenic cycle | The viral DNA is incorporated into the host cell's chromosome. Every time the host cell replicates, the viral material is also replicated. |
| The virus leaves the host cell when a lytic cycle is triggered. What are the triggers? | Chemicals or radiation |
| What are the membranes found within cells? | 1. Phospholipids (and other lipids plus membrane protein) 2. Lipid Bilayers |
| Amphipathic | Both hydrophobic and hydroliphic |
| True or False. Lipid bilayers are held together main by hydrophilic interactions. | False |
| What does the plasma membrane contain? | Proteins, sugars, and other lipids |
| What does the fluid mosaic model describe? | The arrangement of substances in and about lipid bilayers. |
| T or F. Lipid bilayers serve as 3 dimensional fluids. | False |
| What maintains the asymmetry of membranes? | Lack of flip flopping. |
| Flip flopping | Rapid diffusion within layers |
| At ___ temperatures cholesterol serves to impede phospholipid fluidity. At ___ temperatures cholesterol interferes with solidification of membranes. | Higher, lower |
| Cholesterol | A kind of steroid, that is an amphiphathic lipid that is found in lipid bilayers that serves as a temperature stability buffer. |
| Where is cholesterol found? | Animal cell membranes |
| What are the functions of a membrane? | 1. Transport of substances across membranes 2. Enzymatic activity 3. Signal transduction 4. Intracellular joining 5. Cell to cell recognition 6. Attachment to the cytoskeleton and extracellular matrix |
| Glycoproteins | Proteins to which carbohydrate molecules of intermediate length have been covalently attached. |
| Where are oligosaccharides found? | On the extracellular side of the plasma membrane. |
| T or F. Oligosaccharides play important roles in cell to cell recognition. | True |
| Intact lipid bilayers are permeable to: | 1. Hydrophobic molecules 2. Small, not ionized molecules |
| Lipid bilayers are NOT permeable to: | 1. Larger, polar molecules 2. Ions, regardless the size |
| Substance transport across membranes include: | 1. Passive transport 2. Facilitated diffusion 3. Active transport |
| Three basic types of movement across membranes: | 1. Simple diffusion 2. Passive transport 3. Active transport |
| Simple diffusion | The movement of substances across lipid bilayers without the aid of membrane proteins. |
| Molecules that are capable of moving across membranes via simple diffusion: | Small, hydrophobic, non polars and water |
| Simple diffusion is driven by what? | Random movement of molecules. |
| Passive transport | Movement through the lipid bilayer with a concentration gradient. |
| Exergonic process | Movement of higher concentration gradient to lower concentration gradient. |
| Osmosis | Movement of water across selectively permeable membranes down the water concentration gradient. |
| Hypertonic | The side with higher solute concentration. Causes cells to shrink. |
| Hypotonic | The side with lower solute concentration. Causes cells to enlarge |
| Isotonic | Both sides have the same solute concentration. |
| A plant or bacterial cell placed in a hypertonic environment will show a shrinkage of its cytoplasm. What is this shrinkage called? | Plasmolysis |
| Flaccidity | Wilting |
| Substances that are not permeable through lipid bilayers may still cross via what? | Transport proteins |
| Facilitated diffusion | Movement of a substance across a membrane via employment of a transport protein. |
| Movement of substances across membranes via facilitated diffusion is movement towards what? | Equilibrium |
| Two general categories of transport across membranes are: | 1. Those that don't require an input of energy 2. Those that do require input of energy |
| Active transport | Movement of substances across membranes against their concentration gradients. |
| Endergonic process | Uses energy |
| Sodium potassium pump | Pumps sodium out of cells and potassium into cells against a concentration gradient. |
| Why does the electrochemical gradient occur? | The pump exchanges 2 potassium ions for 3 sodium ions, which results to the loss of (+) charge from the cytoplasm, thus making the cytoplasm (-) charged. There a chemical concentration gradient, but there is also an electrical charge gradient. |
| Membrane potential | The difference between the outside and inside of a cell. |
| Endocytosis | Move substances from outside of cell to inside, but neither across a membrane nor into the cytoplasm. |
| Where are substances moved into during endocytosis? | Lumens of endomembrane system members. |
| 3 types of endocytosis in animals: | Phagocytosis, pinocytosis, and receptor mediated endocytosis. |
| Phagocytosis | The engulfing of extracellular particles by wrapping pseudopodia around the particles, thus internalizing the particles into vacuoles. |
| Give an example of an organism that employs phagocytosis to "eat." | Amoebas |
| What is the advantage of endocytosis as a method of food gathering? | It minimizes the volume within which digestive enzymes must work in order to digest food. |
| Pinocytosis | A process of developing ova obtain nutrients from their surrounding nurse cells by allowing nutrients to be obtained across many internal membranes rather than being limited to crossing the plasma membrane. |
| Receptor mediated endocytosis | Involves the binding of extracellular substances to membrane associated receptors, which in turn induces the formation of vesicles. |
| Give an example of receptor mediated endocytosis. | How your cells take up blood transported cholesterol. |
| Exocytosis | The delivery of vesicles to the plasma membrane whereupon fusion occurs and lumen contents are deposited outside the cell. |
| Give an example of exocytosis | Secretion of protein insulin or antibodies into the blood. |
| The rate of diffusion depends on four main factors: | 1. The concentration gradient 2. The temperature (molecules moving fast or slow) 3. The charge 4. The diameter of the molecule |
| Solute | A substance dissolved in a fluid such as water. |
| Solution | The solute and its dissolving fluid. |
| What are the 2 types of active transport? | Ion pumps, cotransport |
| ____ or nerve cells transmit information in the form of electrical signals called ____. | Neurons, action potentials. |
| Potential | Electrical difference |
| At rest, nerve cells have a ___ charge on the inside relative to their exterior. | Negative |
| Hypercholesterolemia | A defect in the receptor protein responsible for binding LDLs from the blood. |
| What can cause heart attacks? | LDL buildup along arterial walls when there is a defect int he receptor protein. |
| HDL | Reduces plaques along the arterial wall. |
| First law of thermodynamics | States that energy can neither be created nor destroyed, but it can be transferred from one form to another. |
| Second law of thermodynamics | States that each energy transfer there is an increase in entropy or disorder. |
| How is free energy (G) calculated? | G=H-TS |
| What is G, H, T, S stand for in the free energy equation? | G= free energy, H= total energy, T= temperature, S= entropy |
| The ___ organized a system is, the ___ its free energy. | more, higher |
| The change in free energy for a process or reaction is expressed by: | /\G = Gfinal - Ginital |
| When /\G is ___, the reaction is ___. | negative, exergonic |
| What is the metabolic process that gives off energy and involve the breakdown of molecules? | Catabolism |
| Anabolism | The metabolic processes that require an input of energy, which involve the synthesis of new molecules. |
| Energy coupling | The energy released from exergonic reactions that can be used to fuel endergonic reactions. |
| Activation energy | The energy required to start the reaction. |
| As the temperature ___, enzymes work ___. As the temperature ___, enzymes work ___. | Increases, faster. Decreases, slower. |
| What are the characteristics of enzymes? | Sensitive to temperature, sensitive to pH, inhibited by certain chemicals, enhanced by certain chemicals |
| Endergonic coupling | The energy released from exergonic reactions used to fuel endergonic reactions. |
| ATP | A triphosphorylated nucleotide that is used as a major energy source by the cell. |
| High energy bond | The last phosphate bond. When the bond is broken, energy is released. |
| What are the components of ATP? | Ribose (5 carbon sugar), nitrogenous base adenine, and 3 phosphate groups. |
| Membrane proteins are ___ to pump materials across the membrane. | Phosphorylated |
| ___ are phosphorylated to cause movement. | Motor molecules |
| Many chemical reactions are driven through phosphorylated ___. | Intermediates |
| What is an example of endergonic reaction | Synthesis of glutamine |
| ATP is generated through a process called ___ | Respiration |
| Respiration involves capturing the energy stored in the bonds in ___ and storing that energy in the form of ___. | Glucose, ATP |
| Respiration begins with the process called ___. | Glycolysis |
| If oxygen is present, the end products of glycolysis will proceed to the ___. If oxygen is not present, the end products will undergo ___. | Krebs cycle, fermentation |
| Anaerobic | Oxygen is not required. |
| Fermentation | When oxygen is not present and pyruvate is converted to lactate or ethanol. |
| Redox reactions | Involve the transfer of electrons between molecules. |
| Oxidation | Loss of electrons. |
| Reduction | Gain of electrons |
| When something ___ electrons, it becomes more ___; thus, it has been ___. | Gains, negative, reduced |
| Why is energy a product of redox reaction? | Because the electrons are going from a state of low electronegativity to a state of high electronegativity. |
| NAD+ | A coenzyme that is involved in the redox reactions of respiration derived from a B vitamin. |
| Dehydrogenase | Enzymes that are able to transfer atoms from food molecules to NAD+. |
| What is the reduced form of NAD+? | NADH + H+ |
| What are the 3 characteristics of enzymes? | 1. Increase the rate of reaction 2. Most enzymes act specially with only one reactant to produce products. 3. Regulated from low to high activity and vice versa. |
| Cofactors | The enzyme that consists of the protein and a combination of one or more parts. |
| Apoenzyme | The polypeptide or protein and may be inactive in its original synthesized structure. |
| Proenzyme or zymogen | The inactive form of the apoenzyme. |
| Coenzyme | A cofactor that is a non-protein substance which may be organic. |
| Metal ion activator | A cofactor in which inorganic metal ions may be bonded through coordinate covalent bonds. |
| The activating role of a cofactor is to either: | Activate the protein by changing its geometric shape or by actually participating in the overall reaction. |
| Active site | Where the reaction takes place and contains a specific geometric shape. |
| Substrate | The molecule where the reaction is acted upon. |
| What are the 3 enzymes discovered before the naming system of enzymes? | Pepsin, trypsin, chymotrypsin |
| The latest systematic nomenclature system for enzymes | The International Enzyme Commission (IEC) |
| Cellular respiration | The process of oxidizing food molecules, like glucose, to carbon dioxide and water. |
| Mitochondria | Membrane-enclosed organelles distributed through the cytosol of most eukaryotic cells. Their main function is the conversion of potential energy of food molecules into ATP. |
| What can a number of mitochondria do in the cell? | Increase by their fission, decrease by their fusing together |
| What consists of the outer membrane? | Many complexes of integral membrane proteins that form channels through which a variety of molecules and ions move in and out of the mitochondrion. |
| The inner membrane contains 5 complexes (in order) of integral membrane proteins called: | NADH dehydrogenase, succinate dehydrogenase, cytochrome c reductase, cytochrome c oxidase, ATP synthase |
| What does the matrix contain? | A complex mixture of soluble enzymes that catalyze the respiration of pyretic acid and other small organic molecules. |
| The electrons of NADH and FADH2 are transferred where? | The electron transport chain |
| The electron transport chain consists of 3 complexes (in order): | NADH dehydrogenase, cytochrome c reductase, cytochrome c oxidase |
| What are the 2 freely-diffusible molecules shuttle electrons from one complex to the next? | Ubiquinone, cytochrome c |
| Where does stoichiometric production of ATP occur? | One step in the citric acid cycle yielding 2 ATPs for each glucose molecule, at two steps in glycolysis yielding 2 ATPs for each glucose molecule. |
| What are the 2 common types of fermentation? | Lactic acid fermentation and alcohol fermentation |
| When does lactic acid fermentation occur? | When the oxygen supplied by the lungs to blood system cannot get there fast enough to keep up with the muscles' needs. |
| It is the presence of this that makes yogurt sour and our muscles sore after working out the next morning. | Lactic acid |
| Alcohol fermentation is done by ___. | Yeast |
| What is one "waste" product of alcohol fermentation besides CO2? | Ethanol |
| Autotrophs | Organisms that can synthesize their own food. |
| Heterotrophs | Organisms that must take in food from outside sources. |
| Van Helmont | His research involved the conversion of abiotic material to biotic materials (plant tissues). |
| Joseph Priestly | Performed photosynthesis experiments. |
| Igenhousz | Plants give off oxygen in the presence of light. In the dark, plants give off some CO2. |
| C.B. van Neil | Worked with bacteria that used sulfur compounds as their food source. |
| Ruben and Kamen (1941) | Used an isotope of oxygen to prove van Neil correct. |
| Robin Hill (1930s) | Found that 2 separate types of reactions took place within chloroplasts. |
| What are the 2 types of reactions that took place within chloroplasts? | Split water to release oxygen gas (O2) and required light, the other was light dependent and fixed hydrogen to carbon dioxide (CO2) to make glucose. |
| Arnon (1954) | Chloroplasts deprived of CO2 could make ATP, O2, NADPH + H+, and O2 in the presence of light. |
| Photolysis | Splitting of water by light to produce O2. |
| Photosynthesis | The process of converting light energy to chemical energy and storing it in bonds of sugar. |
| Photosynthesis takes place where? | Chloroplast |
| Why does chlorophyll appear green? | Because it absorbs red and blue light. The green light is NOT absorbed that reaches the eyes. |
| The red and blue light can/cannot be used to do photosynthesis. The green light can/cannot do photosynthesis. | Can, cannot |
| Light reaction occurs in the ___ membrane and converts light energy to ___ energy. | Thylakoid, chemical |
| The chemical structure of a chlorophyll molecule is ___, which consists of several fused rings of carbon and nitrogen with magnesium ion in the center. | Porphyrin ring |
| Where does the dark reaction of photosynthesis occur? | Stroma |
| Calvin cycle | A cycle involved in dark reaction in which CO2 and energy from ATP are used to form sugar. |
| When do plants stop doing photosynthesis? | When CO2 reaches a low level during hot, dry weather, the plant lessens the amount of weather that evaporates by keeping their stomates closed. |
| How do C4 plants stay green and keep growing in hot, dry weather? | They have special enzyme that turn very low CO2 levels into oxaloacetate, which contain 4 carbons. |
| CAM plants | These plants incorporate the CO2 into various organic compounds. In the datum, when the light reaction is occurring and ATP is available, they take CO2 from organic compounds and put it into the Calvin cycle. |
| Example of CAM plants | Cacti, pineapple |
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