Exam 2 Review 6 7 and 8
Exam 2 Review 6 7 and 8 BSC 2010
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This 10 page Study Guide was uploaded by Marla Notetaker on Saturday October 8, 2016. The Study Guide belongs to BSC 2010 at University of South Florida taught by Eric M. Sikorski in Fall 2016. Since its upload, it has received 146 views. For similar materials see Bio I - Cellular Processes in Biology at University of South Florida.
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Date Created: 10/08/16
BSC 2010 Review Sheet – Chapter 6, 7, and 8 Chapter 6 1. Describe the structural features of mitochondria and chloroplasts. How are these organelles believed to have originated? What evidence supports the endosymbiont theory? I. The Evolutionary Origins of Mitochondria and Chloroplasts Endosymbiont theory: some organism engulfed another, which consumed oxygen and because the larger one functioned better with the smaller one they created the symbiotic relationship… this is what chloroplasts and mitochondria have 2 membranes Evidence supporting this theory: o The 2 membranes ^ o Mitochondria and Chloroplasts have both its own DNA and Ribosomes o These 2 can reproduce themselves II. Mitochondria: Chemical Energy Conversion Usually cells that are very active have more mitochondria Outer membrane is smooth Inner membrane: folded cristae, which adds more surface area Intermembrane space: as the name suggests, is the space betwndn the membranes. Mitochondrial Matrix: space enclosed by the SECOND (2 ) membrane. III. Chloroplasts Thylakoids: each “disk” inside the chloroplasts Granum: stack of thylakoids Stroma: liquid inside the chloroplasts and outside the thylakoid Plastids: special organelles in plants o Amyloplast: “colorless organelle that stores starch (amylose) Roots and Tubers Potatoes o Chromoplast: gives the color of yellow and orange 2. Name the three types of cytoskeletal fibers and describe the structure and functions of each as discussed in lecture. Which two fiber(s) help in cell division, and what do they do? I. Microtubules Dimer: αtubulin AND βtubulin The amount of Dimer is what determines the length of the Microtubule Microtubule are the “rails” of the motor proteins Play part in the separation of chromosomes in cell division Centrosomes and centrioles: o Centrosome: composed of 2 centrioles placed at 90* angle from each other near the nucleus. o Centrioles: 9 triplets (groups of 3) arranged in a “circular”, “star” o Some eukaryotic cells lack centrosomes Cilia and Flagella o Elements that extend to outside of the cell for movement or transport of the cell o Flagella are longer than Cilia and while Cilia are probably multiple per cells Flagella normally is just 1 extension o Primary Cilium: Interesting enough the Cilia of most cells do not move o “9+2” pattern: the structure of the flagellum and cilium ITSELF consisting of 9 groups of duplets (2 microtubules) arranged around 3 central tubules o “9+0” pattern: basal body, which is the “anchor” of the flagellum/cilium TO the cell. It looks like centriole o Dynein: motor protein bends the flagella/cilium to move them II. Microfilaments (Actin Filaments) “Solid rods” made of double stand of actin intertwined Function: “bear tension” Cortical microfilaments: supports the shape of the cell Cortex: “outer cytoplasmic layer of a cell” Myosin: thicker than actin filaments Pseudopodia: fake feet, mostly in amoeba Cytoplasmic streaming: the circulation inside the cell III. Intermediate Filaments Are more persistent, absorb impact, elastic, persistent to tension Even if the cell dies they sometimes stay Some research believes that they anchor certain organelles 3. Many cytoskeletal functions depend upon motor proteins. What do they do? What energy drives them? Motor proteins: proteins that carry vesicles along the cytoskeleton to a certain destination They use ATP 4. What purpose does an extracellular matrix serve? Using information from lecture/textbook/lab notebook, describe the makeup of the ECM. Main components of the ECM o Glycoproteins – “covalently bonded carbohydrates” Collagen: most abundant glycoprotein in animal cells (40% of protein in human body) o “Carbohydratecontaining molecules” o Proteoglycans: some protein as a base with a lot of carbohydrates covalently bonded… this is what holds collagen o Integrins: “cell surface receptor proteins” Can communicate ECM and cytoskeleton “ECM can regulate cell’s behavior – coordination o Fibronectin: proteins in the ECM that binds it to the Integrins 5. What makes prokaryotic and eukaryotic cells different from one another? What features do ALL cells have? Basic Features of a EVERY: o Plasma membrane: cell is bounded by this phospholipid bilayer o Cytosol: “jellylike” fluid inside the cell that “suspends” all the subcellular components o Chromosomes: carry genes in form of DNA o Ribosomes: in charge of protein synthesis DNA location o In Eukaryotes: in the nucleus, which is bonded by a double membrane o In Prokaryotes: in nucleoid, a space inside the cell that has no membrane Meaning of the word: o Eukaryote: “true nucleus” – Greek eu, true, and karyon, the nucleus o Prokaryote: “before nucleus” – Greek pro, before Cytoplasm o Eukaryotes: area between the nucleus and the plasma membrane with organelles membrane bounded o Prokaryotes: Do not have membrane bounded organelles 6. Why does the surface areatovolume ratio place a limit on the size of cells? (you can refer to your textbook if you missed it in class.) The smaller/the more surface area the cell is it is easier to diffuse the chemicals/molecules/compound/ whatever to the middle or wherever needed The larger and less surface area it has it takes much longer to reach the middle of the cell Page 98 7. Explain the structure and function of the nucleus as described in lecture and your textbook. Include in your answer a description of the nuclear envelope and nuclear pores. Nucleus: hold most of the genetic material of the cell o Has 2 membranes (envelope) o Pores: holes from the inside of the nucleus to the cytoplasm Pore complex: proteins that surround the opening of the pores which determines what goes in and out of the nucleus o Nuclear lamina: protein filaments within the envelope of the nucleus that maintains its shape o Nuclear Matrix: More protein fibers INSIDE the nucleus also providing shape. 8. What do ribosomes do in cells? What 2 types of macromolecules are ribosomes constructed from? What is the difference between free and bound ribosomes? Formed by ribosomal RNA and Protein Function: Synthesize protein Are not classified “organelles” because they do not have membranes Location of protein synthesis: o Free ribosomes: “suspended in the cytosol” (p.104) o Bound ribosomes: anchored in the outside of the endoplasmic reticulum 9. Where (in a cell) are the proteins made by free ribosomes found? Where are proteins made by bound ribosomes (RER) found? Free ribosomes: proteins in the cytosol Bounded ribosomes: proteins within the plasma membrane, packing for export of the cell 10. List all organelles whose membranes are considered part of the endomembrane system. What functions does the EMS serve for the cell? Nuclear envelope Lysosomes Golgi Apparatus Endoplasmic Reticulum Vesicles Vacuoles Plasma Membrane Functions: o Synthesis of protein o Transport of proteins o Metabolism o Movement of lipids o Detoxification 11. Summarize the structure and function of the RER and the Golgi apparatus. Include the role of chaperones, vesicles and any protein modifications in your answer. Rough ER o Functions: Synthesis of protein Creates membranes Golgi Apparatus o Here is where everything is packed and sent somewhere else o Flattened cisternae o It has an orientation Cis face: receives the products… (cis…on the same side – as the ER) Trans face: “ships” the products (trans… the opposite side) o “Removes some sugar monomers” o Cisternal maturation model: the Golgi apparatus moves ITSELF from cis to trans 12. Describe functions performed by the SER that were discussed in lecture. Smooth ER o It does NOT have ribosomes o The one further away from the nucleus o Functions: o Synthesis of lipids Oil Phospholipids Steroids Sex hormones (animal) Some other hormones of the adrenal glands Sex organs (testicles and ovaries) have large amounts of Smooth ER o Metabolism of Carbohydrates o Detoxification of drugs and poison Usually needs to add –OH to solubilize Tolerance: usually, in order to process the drugs and detoxify the body, the cell creates more Smooth ER with more detoxifying enzymes, which results and better “handling” of the toxin, meaning that next time more of that toxin has to be used. Smooth ER can also decrease the effect of the drug o Storage of Calcium ions In muscle cells Calcium in the cytosol is sent to the inside of the smooth ER In order to contract the muscle the ER lumen releases the calcium back to the cytosol 13. Explain the functions of lysosomes in the cell. A sac formed of membranes with “hydrolytic enzymes” Used to break down molecules. These “hydrolytic enzymes” are synthesized in the rough ER and sent to the GA Phagocytosis: eating (engulfing) of other organisms o Macrophages: present in the human body, part of the WBC Autophagy: when the cell “recycles its own material. o Tin – Sachs disease: because there is an absence or inhibition of an enzyme that digests lipids the brain has too much fat and stops working. 14. Summarize the functions of each of the 3 types of vacuoles—central, contractile, and food. Food vacuole: stored excess material in the cell Contractile vacuole: extract the unnecessary water out of the cell Central Vacuole: hold water in Cell plants and ion concentrations Chapter 7 15. How does the chemistry of phospholipids and membrane proteins determine the structure of the cell membrane (i.e. the fluid mosaic model)? Which chemical interaction (noncovalent) holds a membrane together? 16. Explain membrane fluidity. What factors influence fluidity? 17. Fluidity of the membrane: Lower temperatures: oFluid until the phospholipids are TOO close together and they move very slowly (solidification) making the layer viscous – this solidification depends on the “type of lipid it is made of” oMuch more fluid if the tails (hydrophobic) portions of the phospholipids are UNsaturated (one of the legs is bended) because this “bend” separates them and allows movement Cholesterol (in animal cells): oIf temperature is HIGH… slows the movement by sticking in the middle it’s not TOO fluid oIf temperature is LOW…makes space between the phospholipids, enough for them NOT stop moving 18. Why is the plasma membrane referred to as a ‘mosaic’? How are integral and peripheral membrane proteins positioned differently in the plasma membrane? Mosaic: because of the way it looks, gives an idea of what it has in it “collage of proteins” Types of proteins: o Integral proteins: Get INTO the hydrophobic portion (tails) Transmembrane: go from SIDE TO SIDE… all the way though Usually they are bonded by α helices o Peripheral proteins: they are “leaning” on the top/bottom of the membrane Don’t directly are In the membrane but interact with the proteins that ARE in the membrane 19. Where are proteins of the cell membrane constructed? In what way are membranes ‘asymmetrical’? 20. List the functions performed by membrane proteins. Functions of the membrane proteins: o Transport o Enzymatic activity o Signal transduction: the outside of the enzyme receives a signal and passes it to the inside. o Cellcell recognition: to identify our own cells o Intercellular joining: junctions, hook cells together o Attachment of the cytoskeleton and the extracellular matrix (ECM) 21. What are cell junction proteins, and why are they important for multicellular organisms? Proteins that joins one cell to the other one… they are important because they communicate the 2 cells 22. Explain what is meant by a concentration gradient when dealing with a membrane. How does a substance’s concentration gradient influence its diffusion? How does it influence the diffusion of another substance? Diffusion: when PARTICLES move through the space, eventually to reach dynamic equilibrium Concentration gradient: move from areas of high concentration to low concentrations 23. Explain how water diffuses across membranes (i.e. osmosis). Water moves to the zone where the SOLUTE concentration is higher until the Concentration (moles/mL or whatever measurement) since the SOLUTE cannot move across the membrane 24. List the two types of membrane transport proteins and explain how each works. Explain how these proteins are ‘specific’. Channel proteins: function like a tunnel from the outside to the inside cell Carrier proteins: very selective changes the shape of the protein slightly to pass it through These both carry very specific ions and molecules 25. Explain the difference between 1° active transport and 2° active transport (cotransport). What type of transport protein is required for active transport? How is ATP important for each? Give specific examples of both types. st 1 AT: the proteins takes ONE molecule/chemical against its gradient 2 AT (cotransport): take one chemical in while other goes out oATP provides the necessary phosphate to the protein to provide the energy CARRIER proteins are the ones that perform this job + oATP creates an H proton gradient that would power the Carrier protein 26. Create a table in which you compare and contrast all the modes of passive and active transport discussed in class. Include the following: simple diffusion, facilitated diffusion, 1º active transport, 2º active transport, direction (up/down gradient), membrane protein (yes/no), specific/nonspecific, source of energy, and a specific example. 27. Describe way(s) that each of the following substances cross the plasma membrane as discussed throughout the lecture: Na+, K+, O2, CO2, water, glucose, cholesterol, and a cellsized food particle. If a transport protein is involved, what type of transport protein? Which mechanisms require an additional input of energy? Know the sodiumpotassium pump… its explained in details and with pictures on p. 135 of the USF version of the Bio I book – uses CARRIER proteins – Active Transport O and CO can dissolve easily into the membrane because they are nonpolar 2 2 Water need aquaporins to pass through membrane since its polar – CARRIER proteins – Passive Chapter 8 28. Explain the terms metabolism, catabolism, and anabolism and how they are related. Metabolism: all the chemical reactions undergoing in a living system Catabolism: breaking down (degradation) of molecules Anabolism: building up of molecules The energy broken down in catabolism can be stored for use of anabolic reactions 29. Explain the first two laws of thermodynamics and how they apply to cells. Why must cells be open systems? st 1 : energy is not created nor destroyed but transferred 2 : entropy is always increasing in the system because heat is always lost in energy transfer They HAVE to be open system because they need nutrients and get rid of waste and to do all that they also need energy. 30. What is free energy, how/what does it have to do with cellular work? How does free energy change in chemical reactions or processes? What does the SIGN of DG (negative/positive) tell you about a reaction or process? FreeEnergy Change ΔG Free energy (ΔG): energy in the that can be used to do work Enthalpy (ΔH): Heat in the system ∆ G=∆H−T ∆S o Change in Entropy (ΔS) o Temperature in Kelvin (K) o Processes with NEGATIVE ΔG are spontaneous Exergonic (exothermic): releases free energy…. ΔG is NEGATIVE…spontaneous o The more – ΔG the more work can be done Endergonic (endothermic) absorbs free energy… ΔG is POSITIVE… nonspontaneous 31. Relate the terms exergonic and endergonic to free energy change. Then explain how the total energy and the entropy change in an exergonic or an endergonic reaction or process. Apply the terms favorable/spontaneous and unfavorable/nonspontaneous. Finally, state whether stability increases/decreases for each case. Exergonic (exothermic): releases free energy…. ΔG is NEGATIVE…spontaneous o The more – ΔG the more work can be done Endergonic (endothermic) absorbs free energy… ΔG is POSITIVE… nonspontaneous The HIGHER the ΔG the more UNSTABLE the system is (p. 146) o This usually makes them change for it to LOWER the ΔG = more STABLE 32. What type of monomer is ATP? List its parts. How is its chemical energy liberated? How do cell’s use ATP to drive endergonic reactions? What other function does ATP have in cells? Is a nucleoside Adenosine Triphosphate (ATP) : basic unit of energy Components: o Sugar ribose o Adenine nitrogenous base o 3 Phosphates The hydrolysis of the phosphates release energy 33. What is an enzyme? Catalyst? How does it speed up a reaction? Enzymes are usually proteins that speed up reactions (catalysis) By lowering the Activation energy they speed it up 34. What is activation energy and how is it usually supplied to a reaction? Activation energy (E )A the amount of energy needed to break up the bond… energy that needs to get absorbed to “agitate” the bond and make it break (up lift) “Activation energy is often supplied by heat in the form of thermal energy that the reactant molecules absorb from the surrounding” (p.152) 35. What is an enzyme’s effect on free energy? By lowering the Activation Energy LESS energy is needed to start the reaction therefore more free energy is available. 36. Substrate specificity of enzymes. Enzymes are very specific because most enzymes are proteins and with proteins (amino acids) shape determines function so only a specific reactant would fit in the active site 37. What is the active site? What is meant by induced fit? Active Site: specific part of the enzyme that can accept the substrate Induced Fit: when the enzyme closes tightly around the substrate 38. How does the active site lower the activation energy? Refer to number 35 39. What can affect the activity of an enzyme (conditions, other molecules)? What can affect an enzyme? o Temperature o pH a. Effects of Temperature and pH As the temperature increases the reaction will occur faster because “substrates collide with active sites more frequently” o TOO HIGH temperature can denature the protein o Most proteins in the human body have an optimal temperature of 35 – 40*C Most have an optimal pH of about 68 o Exceptions like digestive enzymes in the stomach of pH 2 40. What are cofactors and coenzymes? How do they effect enzyme activity? Cofactors (Inorganic) Coenzymes (Organic) – vitamins They are NOT proteins that help with catalysis, extra push 41. How do competitive and noncompetitive inhibitors work? Competitive: blocks the active site Noncompetitive: blocks somewhere OTHER than the active site. oTOXINES AND POISONS are usually PERMANENT inhibitors 42. How do changes (mutations) in genes affect enzymes? A mutation can cause an alteration in amino acid sequence which can produce a faulty protein, and since most enzymes are proteins these may be affected and can perform the wrong action 43. How do cells regulate enzyme activity? By switching ON and OFF the enzyme with an Allosteric regulator that bind to the enzyme to turn it ON or OFF 44. What is meant by allosteric regulation and how can it affect activity? Refer to 43 45. What is cooperativity? Substrate bind to the enzyme and causes its shape to change so other substrates can use it 46. What is feedback inhibition? Feedback inhibition: when the final product inhibits the reactant that started the pathway
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