1
Q
Compare and contrast the general characteristics of prokaryotic and eukaryotic cells, and contrast plant and animal cells.
A
- Prokaryotic cells are enclosed by a plasma membrane but have little or no internal membrane organization. They have a nuclear area rather than a membrane-enclosed nucleus. Prokaryotic cells typically have a cell wall and ribosomes, and may have propeller-like flagella.
- Eukaryotic cells have a membrane-enclosed nucleus, and their cytoplasm contains a variety of organelles; the fluid component of the cytoplasm is the cytosol.
- Plant cells differ from animal cells in that plant cells have rigid cell walls, plastids, and large vacuoles, which are important in plant growth and development.
2
Q
Describe the structure and functions of cell membranes.
A
- Amphipathic Structure: Phospholipid Bilayer, Hydrophilic and hydrophobic=amphipathic, Also contains proteins, cholesterol, glycoproteins and glycolipids
- Function: Selectively permeable (regulates movement into & out of the cell); Physical barrier; Communication; Structural support
3
Q
Describe the structure and functions of the nucleus.
A
- Structure: three regions: Nuclear envelope (double membrane)-barrier of the nucleus and contains nuclear pores that allow for exchange of material; Nucleolus-Nucleus contains one or more nucleoli and Sites of ribosome assembly and rRNA synthesis; Chromatin- Composed of DNA and protein, Present when the cell is not dividing, Scattered throughout the nucleus, Condenses to form chromosomes when the cell divides
- Function: Control center of the cell (contains genetic material DNA), gives/recieves info regarding all cellular processes, site of DNA and RNA synthesis
4
Q
Distinguish between smooth and rough endoplasmic reticulum in terms of both structure and function.
A
Structure: fluid-filled tubles for carrying substances, part of the endomembrane system; Function: manufactures, packages and distributes in transport vesicles
5
Q
Trace the path of proteins synthesized in the rough endoplasmic reticulum as they are subsquently.
A
- The Golgi complex consists of stacks of flattened membranous sacs called cisternae that process, sort, and modify proteins synthesized on the rough ER. The Golgi complex also manufactures lysosomes.
- Glycoproteins are transported from the ER to the cis face of the Golgi complex by transport vesicles, which are formed by membrane budding. The Golgi complex modifies carbohydrates and lipids that were added to proteins by the ER and packages them in vesicles.
- Glycoproteins exit the Golgi through vesicles that are formed at its trans face. The Golgi routes some proteins to the plasma membrane for export from the cell. Others are transported to lysosomes or other organelles within the cytoplasm.
6
Q
Describe the functions of lysomes and peroxisomes.
A
- Lysosomes contain enzymes that break down worn-out cell structures, bacteria, and debris taken into cells.
- Peroxisomes are important in lipid metabolism and detoxify harmful compounds such as ethanol. They produce hydrogen peroxide, but contain the enzyme catalase, which degrades this toxic compound.
7
Q
compare the functions of mitochondria and cholorplasts.
A
- Mitochondria, organelles enclosed by a double membrane, are the sites of aerobic respiration. The inner membrane is folded, forming cristae that increase its surface area.
- The cristae and the compartment enclosed by the inner membrane, the matrix, contain enzymes for the reactions of aerobic respiration. During aerobic respiration, nutrients are broken down in the presence of oxygen. Energy captured from nutrients is packaged in ATP, and carbon dioxide and water are produced as byproducts.
- Plastids are organelles that produce and store food in the cells of plants and algae.
- Chloroplasts are plastids that carry out photosynthesis.
- The inner membrane of the chloroplast encloses a fluid-filled space, the stroma.
- Grana, stacks of interconnected disclike membranous sacs called thylakoids, are suspended in the stroma.
- During photosynthesis, chlorophyll, the green pigment found in the thylakoid membranes, traps light energy. This energy is converted to chemical energy in ATP and used to synthesize carbohydrates from carbon dioxide and water.
8
Q
Describe the structure and functions of the cytoskeleton.
A
- The cytoskeleton is a dynamic internal protein fiber framework that includes microtubules, microfilaments, and intermediate filaments. The cytoskeleton provides structural support and functions in various types of cell movement, including transport of materials in the cell.
- Microtubules are hollow cylinders assembled from subunits of the protein tubulin. In cells that are not dividing, the minus ends of microtubules are anchored in microtubule-organizing centers (MTOCs). The main MTOC of animal cells is the centrosome, which usually contains two centrioles. Each centriole has a 9 × 3 arrangement of microtubules.
- Microfilaments, or actin filaments, formed from subunits of the protein actin, are important in cell movement.
- Intermediate filaments strengthen the cytoskeleton and stabilize cell shape.
9
Q
Compare clilia and flagella, and describe their functions.
A
- Cilia and flagella are thin, movable structures that project from the cell surface and function in movement.
- Cilia: numerous, short hair-like projections made of microtubules; move materials across the cell suface thus commonly associated with goblet cells; located in the respiratory bronchi and uterine tubes, on the protist paramecium
- Flagella: long, whip-like structure made of microtubules; propels the cell; found on sperm
10
Q
Describe the function of the cell wall.
A
•Cells of most bacteria, archaea, fungi, and plant cells are surrounded by a cell wall made mainly of carbohydrates. Plant cells secrete cellulose and other polysaccharides that form rigid cell walls.
11
Q
Compare the structures and functions of tight junctions, desmosomes, gap junctions, and plasmodesmata.
A
- Tight junctions seal membranes of adjacent animal cells together, preventing substances from moving through the spaces between the cells.
- Gap junctions, composed of the protein connexin, form channels that allow communication between the cytoplasm of adjacent animal cells.
- Plasmodesmata are channels connecting adjacent plant cells. Openings in the cell walls allow the plasma membranes and cytosol to be continuous; certain molecules and ions can pass from cell to cell.
12
Q
Evaluate the importance of membranes to the homeostasis of the cell, emphasizing their various functions.
A
- The plasma membrane physically separates the interior of the cell from the extracellular environment, receives information about changes in the environment, regulates the passage of materials into and out of the cell, and communicates with other cells.
- Biological membranes form compartments within eukaryotic cells that allow a variety of separate functions. Membranes participate in and serve as surfaces for biochemical reactions.
13
Q
Explain how the properties of the lipid bilayer govern many properties of the cell membrane (ie understand the chemical lipid bilayer structure.)
A
•The lipid bilayer is a fluid mosaic model, meaning the cell membrane consists of a fluid bilayer of pospholipid molecules in which the proteins are embedded or otherwise associated. they move like icebergs in a sea. Mostly consists phospholipids but cholesterol, glycolipids., and different type of proteins.
14
Q
Describe how membrane proteins associate within the lipid bilayer, and discuss the types, functions and importance of membrane proteins.
A
- Proteins determine most of the membrane’s specific functions
- types are peripheral and integral. Peripheral proteins is bound to the surface, NOT embedded in the lipid bilayer. Integral proteins penetrate the hydrophobic core. The majority of integral proteins are transmembrane proteins tat span the membrane
- 6 major functions: Transport, enzymatic activity, signal transductions, cell-cell recognition, intercellular joining, and attachment to cytoskeleton and extracellular matrix.
15
Q
Describe the components of a solution.
A
A solution is a homogeneous mixture of two or more components. Components are a solvent, dissolving medium, and a solute, what is being dissolved.
16
Q
Contrast the processes of passive and active transport, including simple diffusion, osmosis, facilitated diffusion, carrier-mediated active transport and bulk transport. How might temperature play a role in these processes?
A
- Passive transport is when substances are moved down their concentration gradient across the membrane without any energy input from the cell.
- Active transport is when a cell is required to input energy (ATP) to transport substances across the membrane.
- Passive transport: Simple diffusion (unassisted movement of solutes across the cell membrane from high to low concentration), facilitated diffusion (passive transport aided by proteins, carrier or channel proteins), and osmosis (the diffusion of WATER across a selectively permeable membrane.
- Active transport: solute pumping (a protein carrier is powered by ATP to move a substance against its concentration or electrical gradient, that is from low to high) and vesicular or “bulk” transport ( moves substances into or out of cells without their actually crossing the plasma membrane, packages in vesicles and requires ATP).
17
Q
Which molecules will move across the membrane freely? Which utilize facilitated diffusion? Active transport?
A
- Simple diffusion through cells membrane would be nonpolar molecules like oxygen and carbon dioxide.
- Facilitated diffusion are used for specific ion or polar molecules.
- Active transport like a sodium-potassium pump (exchanges sodium inside the cell for potassium outside) or proton pump (pumps an hydrogen ion outside the membrane).
18
Q
Be able to solve problems involving osmosis and diffusion: for example, predict whether cells will swell or shrink under various tonic conditions (iso- vs. hyper- vs hypotonic). Reference your lab experiments for practical application.
A
- Isotonic is the same solute. Hypertonic is more solute. And hypotonic is less solute.
- If the solution is hypertonic compared to the cell, the cell would shrink. If the solution is hypotonic compared to the cell the animal cell would burst or provide turgor pressure in plant cells.
19
Q
Use key terminology to describe transport processes (ie the tonicity of the solution versus that of the cell; concentration gradient and pressure gradient (osmotic pressure))
A
- Tonicity of a solution is the ability of a sourrounding solution to cause a cell to gain or lose weight.
- Net movement of water from hypotonic environment to hyertonic enviroment.
- Osmoic pressure (the tendency of a solution to pull water into it) is directly related the concentration of solutes in the solution. The higher the solute concentration the greater the osmotic pressure and the greater the tendency of water to move into the solution.
20
Q
Describe the sodium-potassium pump, proton pumps, and cotransport.
A
- Sodium-potassium pump actively carries sodium oins out of and potassium oin into the cell for transmission of nerve cell impulses.
- Proton pump is an active pump that uses ATP to transport protons (hydrogen ions) across membranes causing an electrochemical gradient that can be used in other processes.
- Cotransport is the transport of two solutes occurs when a membrane protein enables the “downhill” diffusion of one solute to drive the “uphill” transport of the other.
21
Q
Compare endocytosis and exocytosis transprot mechanisms.
A
- Exycytosis “out of the cell”: moves substances out of the cells by fusing a vesicle full of product with the plasma membrane
- Endocytosis “into the cell”: engulfing extracellular substances by enclosing them in a vesicle. Types: phagocytosis (cellular eating), pinocytosis (cellular drinking”), and receptor mediated endocytosis (receptor proteins bind with a ligands whcih are then internalized in a vesicle)
22
Q
Describe metabolism–anadolism vs. catabolism (what are other words we have used for these processes?)
A
- Metabolism is the sum of all chemical reactions that enable an organism to carry out its activities.
- Catabolic reaction (catabolism) is when larger molecules are broken down to smaller molecules; break bonds. AKA exergonic reaction, diffusion, cell respiration.
- Anabolic reactions (anabolism) is when reactions where larger molecules are synthesized from smaller molecules; makes bonds. AKA endergonic reaction, photosynthesis
23
Q
Define energy and use examples to contrast potential energy and kinetic energy.
A
- Energy is the capacity to do work
- Kinetic energy is the energy in motion. Heat/thermal energy is KE associated with the random movement of atoms and molecules
- Potential energy energy of position, stored energy. Chemical energy is PE of a chemical bond.
24
Q
State the first and second laws of thermodynamics, and discuss the implications of these laws as they relate to organisms.
A
- The first law of thermodynamics is that energy of the universe is constant. Energy cannot be created or destroyed, only transformed. AKA law of conservation of energy. Every change in energy releases heat. Heat is energy in an unusable form.
- The second law of thermodynamics is that every energy transfer or transformation increases the entropy of the universe. In Biological systems, energy flows in one direction with the sun providing new energy and energy existing as heat. The loss of usable energy in the form of heat makes the universe more disordered. A process is spontaneous if it increases the entropy of the universe.
25
Discuss how changes in free energy in a reaction are related to changes in entropy and enthalpy (ie understand the relationship between the three terms)
* Free energy (ΔG) is energy free to do "useful" work when temperature and pressure are uniform, as in a living cell.
* Entropy (ΔS) is the change in a system's entropy
* Enthalpy (ΔH) the total chemical potential energy of a system.
* Gibb's Free energy (ΔG)=ΔH-TΔS. Where ΔG predicts whether a particular chemical reaction will release free energy (be spontaneous), or require an input of energy (be non-spontaneous). ΔH (change in potential energy) predicts if a reaction will be hotter or colder. ΔS (change in entropy) predicts if a system will have more or less disorder.
26
Distinguish between exergonic and endergonic reactions, and give examples of how they may be coupled.
* Exergonic (downhill) reaction is a reaction in which the bonds in the products have less free energy than the bonds in the reactants. ΔG is negative (reactants have more free energy than the products)
* Endergonic (uphill reaction is a reaction in which the bond in the products have more free energy than the reactants. ΔG is positive (reactants have less free energy)
* Energy coupling us exergonic process to drive an endergonic. Usually mediated by ATP
27
Discuss the types of work performed by a cell.
* Chemical which is endergonic reactions, require free energy, ei synthesis of polymers from monomers.
* Transport is pumping of substance against a concentration gradient
* Mechanical which would be beating of cilia, muscle contraction, or movement of DNA
28
Explain the chemical stucture of ATP. Discuss the central role of ATP in the overall energy metabolism of the cell. How does ATP perform work?
* ATP (adenosine triphosphate) is a chemical compound (nucleotide) that packages energy. Composed: ribose (a sugar), adenine (a nitrogenous base), and three phosphate groups.
* ATP is the energy used my cells to do work with the energy within the phosphate groups.
* Reaction 1 the hydrolysis of ATP bonds lower free energy ("releases free energy") therby making it exergonic.
* Reaction 2 the bonds of the reactants have lower free energy and thus "absorbs/requires" energy (increase free energy) to form the product, making it nonspontaneous endergonic reaction.
29
Is ATP able to be regenerated?
•yes it turns into ADP to be recycled and reformed by adding a phosphate group to the ADP creating ATP.
30
Explain how an enzyme lowers the required energy of activation for a reaction. What is activation energy? What is an ezyme-substrate complex and what is its importance?
* Enzymes are biological catalysts by speeding up the rates of chemical reactions by lowering the activation energy. A chemical agent that speeds up a reation without being consumed by the reaction.
* They are organic catalysts generally made of proteins.
* Substrate is the reactant an enzyme acts on. The combination of enzyme and substrate is called enzyme-substrate complex.
* Enzymes make the substrate molecule less stable and increase the chance of an effective collision.
31
Describe the specific ways in which ezymes are regulated (ie How does temperature, pH, ect. affect enzyme function?). Reference your lab experiments for practical application.
* Factors afffecting enzymes function would be temperature, pH, cofactors, and inhibitors.
* Optimum temperature has the greatest turnover rate. To cold and the enzyme slows down where to hot it denatures the enzyme
* Optimum pH where the enzyme works best. Proteins are held together by ionic interactions that are affected by changing the pH of the solution that surrounds them.
32
What are cofactors and coenzymes? Reversible vs. irreversible inhibition? Competitive and non competitive inhibitors?
•Cofactors are non-protein molecules (eg metal atoms) necessary for enzyme function. Coenzymes is a non-protein organic cofactor (eg vitamins)
Inhibitors reduce the effectiveness of the enzymes. •Reversible inhibition forms a weak chemical bonds with enzyme thus can restore function (Competitive inhibitions and Noncompetitive inhibition). Irreversible inhibition is permanent inactivation of enzymes through forming stable bonds or denaturations.
•Competitive inhibition is the when the inhibitor competes with normal substrate for binding to active site
•Noncompetitive inhibition is when the inhibitor binds to sites other than the active sites.
33
Understand redox reactions and the use of H+ and electron transfer.
* Redox reactions, AKA oxidation-reduction reactions, is a chemical reactions that trasfer electrons between reactants.
* In cellular respiration, the fuel (glucose) is oxidized to CO2, and O2 is reduced to H2O.
* Oxidization is happening through out the process and the reduction doesn't happen until the last step of electron transport chain.
34
Understand FADH2 and NADH and how they relate to oxidation and reduction.
* The cellular respiration builds FADH2 and NADH by oxidizing the glucose and reducing the FADH2 and NADH
* FADH2 and NADH is built through out cellular respiration to allow the last step of the electron transfer chain to work. They are oxidized in this step to allow for the oxygen to be reduced to make water.
35
Be able to define phosphorylation, dehydrogenation and decarboxylation.
* Phosphorylation is when a phosphate group is transferred from ATP to glucose, the bonds of glucose break and it is rearranged through a series of 3 steps.
* Dehydrogenation is a form of oxidation in which hydrogen atoms are removed from a molecule.
* Decarbozylation is a reaction in which a molecule CO2 is removed from a carboxyl group of an organic acid.
36
Know the structure and function of the mitochondria--what is it's job and it's structure (matrix, cristae, PHOSPHOLIPID BILAYER)
* Structure: double membrane with two compartments (outer and inner); membranes made of phospholipid bilayer; space between outer and inner membranes is called the intermembrane space; inner membrane consists of crustal (folds) and matrix (space).
* Function is aerobic respiration
37
Define anabolism and catabolism and understand which is endergonic and which is exergonic--how are these processes related to cellular respiration?
* Catabolic reaction (catabolism) is when larger molecules are broken down to smaller molecules; break bonds. AKA exergonic reaction, diffusion, cell respiration.
* Anabolic reactions (anabolism) is when reactions where larger molecules are synthesized from smaller molecules; makes bonds. AKA endergonic
* The whole process is to take glucose through catabolic reactions then to turn around and use anabolic reactions to create ATP.
38
Write the reaction of aerobic respiration (the molecular formula indicating reactants and products)
•C6H12O6 + 6 O2 --->6 CO2 + 6 H2O + Energy (36-38 ATP)
39
Indicate where, in the overall formula of aerobic respiration, which reactant becomes oxidized and which product becomes reduced.
•In cellular respiration, the fuel (such as glucose) is oxidized to CO2, and O2 is reduced to H2O
40
List and give an overview of the four stages of aerobic respiration — know the broad steps, reactants (what we begin each stage with) and products for EACH STAGE.
* Glycolysis ("splitting of sugar"): harvests chemical energy by oxidizing glucose to pyruvate; occurs whether or not oxygen is present; Sugar molecule is prepared with ATP since sugar is a stable molecule it has to be invested with energy to start the process; Once 2 ATP is used to change the DHAP and G3-P is created then turned into Pyruvic acid; no O2 is required; products are 2 pyruvate molecules, 2 NADH, and 4 ATP made, 2 ATP invested
* Formation of acetyl-coenzyme A: oxygen is required to get into the mitochondria (without fermentation could happen in the cytosol), reaction begins with 2 pyruvate; Oxidation of pyruvate to acetyl CoA; products created by this step is 2 NADH and 2 CO2 molecules; the NAD+ is reduced to NADH
* The citric Acid cycle (tricarboxylic acid cycle - TCA) or Krebs Cycle- the acetyl CoA combines with oxaloacetate forming citrate (6-C), next 7 steps back to oxaloacete thus making a cycle;oxygen is required to enter the mitochondria, reaction begins with 2 Acetyl CoA and Oxaloacetate (4 carbon molecule) from the continuous cycle; Products are 4 CO2, 2 ATP, 6 NADH, and 2 FADH2; No ATP invested; Net yield of energy per glucose is 6 NADH, 2 ATP, and 2 FADH2.
* The electron transport chain (ETC): coupled to ATP synthesis (oxidative phosphorylation); now the NADH and FADH2 account for most of the nergy extracted from food; NADH and FADH2 donate electrons to the electron transport chain; oxygen is required, reactaion begins with NADH, FADH2, O2, ADP, H+; Products are H2O, ATP, NAD+, FAD; Net yield of energy is 34-36 ATP.
41
Indicate where each stage of aerobic respiration takes place in a eukaryotic cell.
* Glycolysis: This process is completed in the cytosol,
* Formation of acetyl-coenzyme A: Location in the mitochondria matrix
* The citric Acid cycle: Location is in the mitochondria matrix,
* The electron transport chain (ETC): located in the mitochondria inner membrane (cristae) and intermembrane space
42
Understand the electron transport chain, define chemiosmosis, and explain how a gradient of protons is established across the inner mitochondrial membrane.
* ETC: chain of proteins and other molecules; electrons are transferred from NADH and FADH2 to the electron transport chain, electron pass through proteins including cytochromes that alternate reduced/oxidized states as they accept and donate electrons
* each component of the chain becomes reduced when it accepts electrons from is "uphill" neighbor, which has lower affinity for electrons; it then returns to oxidized form as it passes electrons to "downhill", more electronegative neighbor.
* Electrons drop in free energy as they go down the chain and are finally passed to O2 forming H2O; O2 is the final electron acceptro in aerobic respiration.
* Electron transfer in ETC causes proteins to pump H+ from the mitochondrial matrix to the intermembrane space; stores energy as proton-motive force (H+ gradient created by ETC across the membrane)
* Chemiosmosis is the use of energy in a H+ gradient to drive cellular work.
43
Describe the process by which the proton gradient drives ATP synthesis in chemiosmosis
* Electron transfer in ETC causes proteins to pump H+ from the mitochondrial matrix to the intermembrane space; stores energy as proton-motive force (H+ gradient created by ETC across the membrane)
* H+ move back across the membrane down their concentration gradient, through a special protein called ATP synthase;
44
Describe ATP synthase and its importance.
* ATP synthase (on the matrix side) contains 3 catalytic sites where ADP and Pi can bind; ATP synthase uses the exergonic flow of H+ to drive phosphorylation of ADP.
* Through this synthase it allows for up to 34-36 ATP to be synthesis through.
45
Add up the energy captured (as ATP, NADH, and FADH2) in each stage of aerobic respiration
* Glycolysis: net yield of energy per glucose 2 ATP and 2 NADH.
* Formation of acetyl-coenzyme A: 2 NADH
* The citric Acid cycle: 2 ATP, 6 NADH, and 2 FADH2
* The electron transport chain (ETC): 34-36 ATP
46
Summarize (briefly) how the products of protein and lipid catabolism enter the same metabolic pathway that oxidizes glucose.
* Protein: amino acids are metabolized by reactions in which the amino group (-NH2) is first removed (a process called deamination); the remaining carbon chain is metabolized and eventually used as a reactant in one of the aerobic respiration steps (ie amino acid alanine undergoes deamination to become pyruvate which enters aerobic respiration as the end product of glycolysis)
* Lipids/Fats: digested to glycerol (used in glycolysis) and fatty acids (used in generating acetyle); gram of fat produces more than twice as much ATP as a gram of carbohydrate; lipids are rich in energy because they are highly reduced (lots of hydrogens and few oxygen atom)
47
Compare and contrast aerobic to anaerobic respiration and fermentation, including the mechanism of ATP formation, the final electron acceptor, and the end products.
* Compare: use glycolysis (net 2 ATP) to oxidize glucose; NAD+ is the oxidizing agent during glycolysis
* Contrast: Aerobic-final electron acceptor is O2, produce 32 ATP per glucose; Fermentation-final electron acceptors is an an organic molecule (pyruvate or acetaldehyde), also produces 2 ATP per glucose.
48
Where does anaerobic respiration take place in the cell?
•Begins in the cytosol and the rest in the mitochondria
49
Why don't humans utilize fermentation pathway more readily (ie how efficient is it?)
•Fermentation is very inefficient. To perfom the same amount of work, a cell engaged in fermentation must consume up to 20 times more glucose per second than a cell using aerobic respiration.
50
How does a selectively permeable membrane affect not only the cell as a whole, but also cellular reactions such as respiration - ie connect diffusion, facilitated diffusion, active transport, etc. to what we are studying with our ETC and cristae membrane in cell respiration!
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51
How do endergonic and exergonic processes we spoke about in chapter 7 ultimately relate to the formation of ATP energy?
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52
What is the importance of enzymes and coenzymes? -how are dehydrogenase, NADH, FADH2 important in our reactions?
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53
Have a strong understanding of redox reactions - respiration is essentially a series of exidation/reduction reactions.
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Biology 211
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