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Biology Chapter 4
| Question | Answer |
|---|---|
| What is the smallest unit that can carry out all activities we associate with life? | Cells |
| How do cells stay alive in the lab for many years? | When provided with essential nutrients and an appropriate environment |
| Most prokaryotes and many protists and fungi consist of a _________________. | Single cell |
| Cells are the building blocks of complex _________________ organisms. | Multicellular |
| What is cell theory? | The scientific theory that the cell is the basic unit of life, of which all living thing are composed, and that all cells are derived from preexisting cells |
| Many cells are _________________ and can be measured in ____________________. | Macroscopic, mms |
| Careful study of shared cell characteristics help us trace the ____________________ of various organisms and furnish powerful evidence that all organisms alive today had a common origin. | Evolutionary history |
| The organization and functions of all cells are ___________________. | Similar |
| What is the plasma membrane? | The selectively permeable surface membrane that encloses the cell contents and through which all materials entering or leaving the cell must pass |
| How can a pathogen be considered a nonliving thing? | It needs something else to survive, like a leach. It is a parasite. |
| Do viruses exhibit all the characteristics of life? | No |
| What are things that a virus cannot do that a bacteria cell can do that makes it nonliving? | Reproduce, and they don't have functioning organelles within themselves, although they do have genes |
| Why doesn't a virus grow outside of the host? | Because it couldn't function without the host |
| Why do cells have to be small? | There needs to be more surface area in relation to its volume, and because the cells are small, the distances molecules travel within the cell are short, making molecules rapidly available for cell activities |
| Why is cell's volume to surface area important? | It helps to regulate its internal environment |
| What is metabolism? | All the reactions within the cell to create energy |
| Who was responsible for observing the first cell? | Leewenhoek. He would first look at fibers |
| What was did he observe under the microscope that make him think that something was living? | Movement, later discovered to be bacteria |
| What did Robert Hooke discover? | Cell theory |
| What are organelles? | One of the specialized structures within the cell, such as the mitochondria, Golgi complex, ribosomes, or contractile vacuole; many organelles are membrane-enclosed |
| Which statement is the third addition to the cell theory by August Weismann? | All cells come from pre-existing cells |
| Why is it important for a cell to keep its surface to volume ratio low? | To provide more surface area for the exchange of nutrients |
| What did Robert Hooke discover in 1665 when he used his own made light microscope? | Cells |
| What components does a plant cell have that an animal cell does not? | Cell walls, plastids, and very large vacuoles |
| True or false: A few specialized algae and animal cells are large enough to be seen with the naked eye. | True |
| Cell size and share are adapted to its _____________________. | Function |
| How does the cell theory contribute to our understanding of the evolution of life? | Because cells, the basic units of life, only come from pre-existing cells, it follows that their lineage extends to very ancient times |
| Could a cell function if it were not closed by a selective barrier ex. plasma membrane? | No, because membrane barriers are required to maintain the appropriate internal chemical environments for cellular functions |
| What molecule is used for information storage in all cells? | DNA is used for information storage in all cells |
| What convenient form of chemical energy is used by all cells? | ATP is one convenient form of chemical energy used by all cells |
| Why is the relationship between surface area and volume of a cell important in determining cell size limits? | Small surface areas relative to large internal volumes proven/restrict the movement of materials into, out of, and throughout the cells |
| What do biologists use to study cell structure? | A microscope |
| What are light microscopes used to study? | They are used to study strained or living cells |
| True or false: a nucleoid has no membrane around it. | True |
| Why is the light microscope referred to as a compound microscope? | Because it has several lenses |
| How does a light microscope work? | Light passes through the specimen being observed and through the lenses. Light is then refracted (bent) by the lenses, magnifying the image |
| What are the two features of a microscope that determine how clearly a small object can be viewed ? | Magnification and resolution |
| What is magnification? | The ratio of the size of an image as seen with a microscope to its actual size |
| What is resolution? | The ability of a microscope to show fine detail, defined as the minimum distance between two points at which they are seen as separate images |
| What does resolution depend on? | The quality of the lenses and the wavelength of the illuminating light |
| What is resolving power? | The ability of a microscope to show the detail, defined as the minimum distance between two points at which they are seen as separate images |
| What is an antibody? | a specific protein that recognizes and binds to specific antigens; produced by plasma cells (immunoglobulin) |
| What is an electron microscope? | A microscope capable of producing high-resolution, highly magnified images through the use of an electron beam rather than light. |
| What are transmission electron microscopes? | TEMs are microscopes that produce images of thin sections |
| What are scanning electron microscopes? | SEMs are microscopes that produce images of surfaces |
| What is ultrastructure? | The fine detail of a cell, generally only observable by use of an electron microscope |
| What is cell fractionation? | The technique used to separate the components of cells by subjecting the to centrifugal force |
| What is a centrifuge? | A device used to separate cells or their components by subjecting them to centrifugal force |
| What is differential centrifugation? | Separation of cell particles according to their mass, size or density. In differential centrifugation, the supernatant is spun at successively higher revolutions per minute |
| What is density gradient centrifugation? | Procedure where cell components are placed in a layer top of a density gradient usually a sucrose solution and water Cell structures migrate during centrifugation forming a band in the gradient where their own density equals the sucrose solution |
| What is a nuclear area? | Region of a prokaryotic cell that contains DNA; not enclosed by a membrane, also called nucleoid |
| What are cell walls? | The structure outside the plasma membrane of certain cells; may contain cellulose (plant cells) chitin (fungal cells), peptidoglycan and or lipopolysacharaide (bacterial cells) |
| What is flagella? | A long whiplike structure extending from certain cells and used in locomotion. Eukaryote have two central single microtbules surrounded by nine double microtubules prokaryotes flagella have filaments rotated by special structures |
| What are ribosomes? | Organelles that are part of the protein synthesis of both prokaryotic and eukaryotic cells, consists of a large and smaller subunit, each composed of rRNA and ribosomal proteins |
| What is the cytoplasm? | The plasma membrane and cell contents with the exception of the nucleus |
| What is the nucleoplasm? | The contents of the cell nucleus |
| What is cytosol? | The fluid component of the cytoplasm in which the organelles are suspended |
| What is a nuclear envelope? | The double membrane system that encloses the cell nucleus of eukaryotes |
| What are nuclear pores? | Structures in the nuclear envelope that allow passage of of certain materials between the cell nucleus and the cytoplasm |
| What is mRNA? | RNA that specifies the amino acid sequence of a protein, transcribed from DNA |
| What is chromatin? | The complex of DNA and protein that makes up eukaryotic chromosomes |
| What are chromosomes? | Structures in the cell nucleus that consists of chromatin and contain the genes |
| What is the endomembrane system (internal membrane system)? | The group of membranous structures in eukaryotic cells that interact through direct connections by vesicles; includes endoplasmic reticulum, outer membrane of the nuclear envelope, golgi complex, lysosomes, and the plasma membrane |
| What is critical in determining a cell's size? | The ratio of the plasma membrane (surface area) to the cell's volume. |
| Why do scientists use cell fractionation? | For purifying organelles as well as genetic methods to gain information about the function of cell structures |
| Describe prokaryotic cells. | Prokaryotic cells are enclosed by a plasma membrane but have little or no internal membrane organization. They have a nuclear area instead of a nucleus. Prokaryotic cells typically have a cell wall and ribosomes and propellar flagella. |
| Describe eukaryotic cells. | Eukaryotic cells ahve a membrane enclosed nucleus, and their cytoplasm contains a variety of organelles, the fluid component of the cytoplasm is the cytosol |
| How do plant cells differ than animal cells? | Plant cells have rigid cell walls, plastids, and large vauoles, which are important in plant growth and development |
| Describe 3 functions of cell membranes. | 1. Membranes divide the eukaryotic cell into compartments to conduct specialized activities & organize metabolic reactions. Small vesicles transport material between compartments 2. Energy storage& conversion 3. work surfaces for chem reactions |
| What is the nucleus bounded by? | Nuclear envelope |
| What does DNA associate with in order to form chromatin? | Protein |
| Through what, and how does DNA transcribe its information? | Through mRNA molecules, which enter the cytoplasm to provide information for protein synthesis by ribosomes. |
| What is the site of RNA synthesis? | The nucleolus, which is located in the nucleus and is the site of RNA synthesis and ribosome assembly |
| Describe smooth ER. | It is the site of lipid synthesis, calcium storage, and detoxiyfiying enzymes |
| Describe rough ER. | It is studded along its outer surface with ribosomes that manufacture polypeptides |
| Where can polypeptides that are synthesized on rough ER be moved to? | The ER lumen, where they assembled into proteins and modified by the addition of carbs and lipids. |
| What part of the golgi complex processes, sorts, and modifies proteins synthesized on the rough ER? | The stacks of flattened membranous sacs called cisternae |
| Describe the 1st 3 steps of protein synthesis via rough ER. | 1) mRNA transcribed copied moves from nucleus to ribosome the rough ER 2)polypeptides synthesized on ribosome 3)proteins assembled carb component added to ER lumen |
| Describe the last 4 steps of protein synthesis via rough ER. | 4)transport vessicles move glycoprotein to golgi cisface 5)glycoprotein further modified in golgi 6)glycoproteins packaged in transport vesicle in trans face 7)glycoprotein transported to plasma membrane 8)contents released from cell |
| What is the function of a lysosome? | They contain digestive enzymes that break down worn-out cell structures, bacteria, and debris taken into cells |
| What pH does a lysosome maintain? | A pH of 5 |
| How are primary lysosomes formed? | They are formed by budding from the Golgi complex |
| Where are the hydrolytic enzymes of lysosomes formed? | In the rough ER |
| How do lysosomes work? | The primary lysosome fuses their membrane with vesicle that contain material to be digested. Then the secondary lysosome, which contains powerful enzymes, come in contact with ingested molecules and degrade them into their components. |
| What is the function of a vacuole? | They store materials, water, wastes and maintain hydrostatic pressure in plant cells. |
| What is the function of peroxisomes? | It is involved in lipid metabolism and detoxifies harmful compounds such as ethanol. They produce hydrogen peroxide and contains the enzyme catalase, which degrades the toxic compound |
| What increases the surface area of mitochondria? | Cristae |
| What part of the mitochondria contains enzymes for aerobic respiration? | Cristae and the matrix |
| Explain aerobic respiration. | Nutrients are broken down in the presence of oxygen . Energy is captured from nutrients in packaged ATP, and carbon dioxide and water are produced as byproducts |
| What organelle produces and stores food in the cells of plants and algae? | Plastids |
| Chloroplasts are ______________ that carries out photosynthesis. | Plastids |
| What two membranes enclose the chloroplast? | Stroma and Thylakoid |
| What is the function of the inner membrane of the chloroplast stroma? | It contains enzymes that produce carbs from carbon dioxide and water, using the energy trapped from sunlight |
| What is present in the thykaloid membrane of the chloroplast? | Chlorophyll |
| What do plastids develop from? | Proplastids |
| How are chloroplasts produced? | When pro plastids are stimulated by exposure to light |
| What contains pigments that give certain flowers and fruits their characteristic colors which attract animals to pollinate them? | Chromoplasts |
| What are the unpigmented plastids that include amyloplasts, which store starch in the cells of many seeds roots and tubers? | Leukoplasts |
| What is the function of the cytoskeleton? | It's a dense network of protein fibers that gives cells strength, shape, and the ability to move. It also functions in cell division and transport of materials within the cell |
| What are the three filaments that make up the cytoskeleton? | Microtubules, microfilaments, and intermediate filaments |
| Which of the three filaments are more stable? | Intermediate |
| What is the thickest filament of the cytoskeleton? | Microtubules |
| Other than structure support, what is another function of a microtubule? | It is involved in the movement of chromosomes during cell division, and they serve as tracks for intracellular movement |
| What are the two forms of tubulin proteins that microtubules consist of? | A-tubulin and B-tubulin |
| What do the monomers a-tubulin and b-tubulin combine to form? | A dimer |
| How are microtubules disassembled? | Through the removal of dimers |
| True or false: microtubules have polarity. | True |
| What is the function of structural MAPs? | They regulate microtubules assembly |
| What is the function of motor MAPs? | They use ATP to produce movement |
| Which motor protein moves organelles towards to plus end of a microtubule? | Kinesin |
| Which motor protein moves organelles towards to minus end of the microtubule? | Dynein |
| Which of the two protein movements are considered as regrade transport? | Dynein |
| What is the name of the adapter protein that line dyne to the microtubule and the organelle? | Dynactin |
| What needs to happen in order for microtubules to act as a structural framework or to participate in movement? | They must be anchored in regions called microtubule-organizing centers (MTOCs) |
| What is the main MTOC of animal cells? | Centrosomes |
| Cell theory states, in part, that all cells come from other cells, true or false? | True |
| True of false: organelles within a eukaryotic cell are not membrane-bound. | False |
| True or false: When a cell's plasma membrane is too small in comparison to the cell volume, the faster particles are able to pass through the membrane. | False |
| True or false: Magnification is the capacity to distinguish fine detail in an image | False |
| True or false: A eukaryotic cell has a membrane-enclosed nucleus. | True |
| True or false: A bacterial cell can be motile with the help of flagellum. | True |
| True or false: A cell membrane can permit the movement of particles across it, converting potential energy into useable, chemical energy. | True |
| True or false: The two concentric membranse of the nuclear envelope come together to form nuclear pores, which are the larges and most complex assembly of proteins in most eukaryotic cells. | True |
| True or false: The rough endoplasmic reticulum is the primary site for the synthesis of phospholipids and choloesterol needed to make cell membranes. | False |
| True or false: The trans face of a Golgi stack is farthest from a cell's plasma membrane. | False |
| True or false: When lysosomes cannot break down enzymes, their malfunction can become the root cause of a human disorder such as Tay-Sachs disease. | True |
| Chloroplasts within plant cells use green pigment exclusively to absorb the sun's energy for fueling photosynthesis. | False |
| True or false: Cells use cilia to move liquids and particles over the cell surface. | True |
| What is the most fundamental feature that enables the cell to function as a distinct entity, separate from its environment? | Plasma membrane |
| What is not found in a prokaryotic cell? | Nucleus |
| What are some examples of things that can pass through a nuclear pore? | Ribosome subunit, ribosomal protein, messenger RNA, and water |
| What is the sequence of glycoprotein processing in eukaryotic cells? | 1) rough ER 2)transport vesicle 3)cis face of Golgi 4) trans face of Golgi |
| What does every pant cell require in order to carry out its life functions? | Mitochondria and ribosomes |
| Describe microtubules. | They have constant diameters, but vary in length |
| Describe integrins. | They are rceptor proteins, they help organize the cytoskeleton, they are important in cell signaling, and they are located in the plasma membrane |
| Why does a eukaryotic cell need both membranous organelles and fibrous cytoskeletal components? | Membranous organelles provide the cell with compartments with unique environments. Fibrous cytoskeletal components provide for structure and movement |
| What is one of the functions of smooth ER? | To produce lipids |
| Why is it important for a cell to keep its surface to volume ratio low? | To provide more surface area for the exchange of nutrients |
| What did Robert Hooke discover in 1665 when he used his own made light microscope? | Cells |
| What components does a plant cell have that an animal cell does not? | Cell walls, plastids, and large vacuoles |
| What component of a cell differentiates between its internal and external environment? | Plasma membrane |
| What type of fibers help our bicep muscles contract (e.g., aerobic respiration? | Actin |
| What organelle releases specialized enzymes to initiate apoptosis? | Mitochondria |
| If ribosomes on the rough ER manufactures proteins, which organelle modifies those proteins? | Golgi complex |
| What cellular structure is found in prokaryotic cells, plant cells, and animal cells? | Ribosomes |
| What do chloroplasts and mitochondria have in common? | They both produce energy |
| Some components of the cytoskeleton in all cells are thought to have originated from what type of organism? | Bacteria |
| The wood that is formed as a sapling matures into a tree is due to the development of what? | Secondary cell walls |
| The cellulose structure of cell walls help provide plants with what? | Structure |
| Nuclear pores within the nuclear membrane are made up of thousands of what type of organic molecule? | Proteins |
| What is evidence that all living cells have a common origin? | The basic similarities in cell structure and chemistry |
| Why is it advantageous for cells to be small? | A small cell has a small volume relative to surface area, thereby increasing efficient transport |
| What does the process of differential centrifugation achieve? | It separates components of the cell that have different densities |
| The ratio of the size of the image seen with the microscope to the actual size of the object is called? | Magnification |
| You want to determine the location of a specific protein in a cell using a colored stain. What is the best technique for this purpose? | Fluorescence microscopy |
| How does the scanning electron microscope differ from the transmission electron microscope? | The SEM gives a three dimensional image of the object being studied |
| What is one cellular characteristic found in all prokaryotic and eukaryotic cells? | Plasma membrane |
| If a toxin such as bacterial toxin destroys ribosomes, what cellular activity will be affected first? | A protein synthesis |
| DNA is associated with certain proteins, forming a complex called? | Chromatin |
| What does the nucleolus within the nucleus synthesize? | Ribosomal RNA |
| DNA must transcribe its information into what kind of molecule before leaving the nucleus and entering the cytoplasm? | mRNA |
| What enzyme in the ER lumen catalyze the efficient folding of proteins into proper conformations? | Molecular chaperones |
| Proteins made on ribosomes may be further modified within which organelle? | Golgi complex |
| What two organelles are both responsible for converting energy into forms that an be used by cells? | Mitochondria and chloroplasts |
| What cellular structure is unique to plant cells and some photosynthetic fungi? | Chloroplasts |
| A glyco protein destined for secretion from the cell would move through eh Golgi complex in which sequence? | cis face, medial region, trans face |
| What organelle is considered to be a sorting, processing and packaging center? | Golgi complex |
| What is the role of a centrosome? | It plays a part in cell division |
| What are some facts about centrioles? | They are thought to play a role in microtubule assembly, they are present in most animal cells but not most plant cells, they are duplicated before cell division, and they are found in teh centrosome |
| What is the microtubule arrangement of a flagellum or cilium? | 9+2 arrangement |
| What protects a cell and may help keep other cells at a distance? | Glycocalyx |
| What is found between the primary walls of adjacent cells for cells to adhere tightly to one another? | Middle lamella |
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