Chapter 6, Chapter 5: bioenergetics, Quiz 4, Beckers World of the Cell: chapter 3, Cell Biology Beckers World of the Cell Chapter 5
Glyoxysomes play an important role in the germination of fat-storing seeds and are considered to be specialized
A) peroxisomes*. . B) lysosomes. C) vacuoles. D) centrioles. E) ribosomes.
10) Based on the following amino acid sequence, which region(s) is/are hydrophobic? 1[K-K-N-Q] - 2[A-G-G-V] - 3[Y-C-S-R] - 4[H-E-C-Y] A) region 2 B) region 4 C) region 1 D) region 3 E) both regions 1 and 3
A) region 2 (region 2: Alanin, Glycin, Valin: group A)
If the surface area of a cell increases by a factor of 100, the volume of that cell will
A) remain the same. B) increase by a factor of 100. C) increase by a factor of 1000. * D) increase by a factor of 10. E) decrease by a factor of 100.
32) Trans fats
A) resemble saturated fatty acids in shape. B) are present in small amounts in meat and dairy products. C) are unsaturated fatty acids. D) are associated with an increased risk of heart disease. E) all of the above
Which sequence reflects the locations that a secretory protein will visit on its way from its production to its secretion outside the cell?
A) rough ER, secretory vesicle, Golgi complex, ER vesicle B) rough ER, Golgi complex, smooth ER, ER vesicle C) nucleus, Golgi complex, rough or smooth ER, secretory vesicle D) smooth ER, rough ER, Golgi complex, secretory vesicle E) rough ER, ER vesicle, Golgi complex, secretory vesicle*
20) Fibrous proteins have extensive ________ structure, which allows them to be highly ordered and repetitive.
A) secondarya (f.ex. keratin, collage, elastin)
In which of the following properties are the archaea more like eukaryotes than the bacteria?
A) size B) microtubules and microfilaments C) translation initiation* D) mode of cell division E) both translation initiation and mode of cell division
The main role of the central vacuole in plant cells is to
A) store glycogen for seed growth. B) synthesize and store proteins. C) digest trapped food particles. D) catalyze photorespiration in association with chloroplasts. E) maintain turgor pressure in plant tissue.*
Which of the following processes would be most likely to occur in the Golgi complex?
A) synthesis of steroids B) production and packaging of lipids C) glycosylation of proteins* D) synthesis of DNA E) detoxification of drugs
The major structural elements of the cytoskeleton are
A) the extracellular matrix and the cell wall. B) microtubules, microfilaments, and intermediate filaments.* C) the cytoplasm and cytosol. D) cleavage furrows and G-actin. E) proteoglycans and cellulose microfibrils.
Km
Michaelis--Menten plot
Bioluminescence
Production of light. Another way that cells use energy, light is produced by a number of bioluminescent organisms such as fireflies and is generated by the reaction of ATP with specific luminescent compounds. Usually pale blue, yellow or green. This is useful to study specific proteins inside cells
________ is a mechanism of lowering the activation energy barrier in some reactions, as with the detoxification of hydrogen peroxide.
Quantum tunneling
Entropy
measure of the disorder or randomness of the particles that make of a system (measurement of movement of particles in a spontaneous reaction)
glycolsis
metabolic process that breaks down carbohydrates and sugars through a series of reactions to either pyruvic acid or lactic acid and releases energy for the body in the form of ATP
Two specific coenzymes we need to obtain from our diet are niacin and ________, as our bodies cannot synthesize them.
riboflavin
Which of the following does accurately describe the Lineweaver—Burk plot? A) It is a double-reciprocal plot. B) The y intercept is equal to 1/Vmax. C) The x intercept is -1/Km. D) It is a linear plot. E) Its slope is the same as the Eadie—Hofstee plot.
E. Its slope is the same as the Eadie-Hofstee plot
The cytosol is best described as the
A) fluid within the nucleus. B) three-dimensional array of interconnected filaments. C) semifluid substance in which organelles are suspended. * D) internal contents of organelles. E) area of the cell not occupied by the nucleus.
A competitive inhibitor will affect the ________ of an enzymatic reaction. A) Km B) Vmax C) S D) P E) both choices A and B
A. Km
The equation v = Vmax [S]/(Km + [S]) is part of which of the following plots? A) Michaelis—Menten B) Lineweaver—Burk C) Eadie—Hofstee D) both choices A and B E) none of the above
A. Michaelis-Menten
The type of inhibitor that binds to the enzyme (E) but not to the enzyme-substrate (ES) complex is a(n) ________ inhibitor. A) competitive B) noncompetitive C) uncompetitive D) coenzyme E) mixed-type
A. competitive
An organism that is labeled a cryophile is capable of A) growth at 4°C. B) growth in hydrothermal vents. C) synthesizing liquid nitrogen. D) producing large quantities of liquid hydrogen. E) both choices C and D
A. growth at 4 °C.
Homeotherms
Animals that regulate their body temperature independent of the environment. Voodo
A noncompetitive inhibitor will affect the ________ of an enzymatic reaction. A) Km B) Vmax C) S D) P E) both choices A and B
B. Vmax
31) Which of the following is not a polymer of numerous monomer units?
E) lipids (nucleic acids are linear polymers of nucleotides)
The induced-fit model A) was proposed by Hans Buchner. B) involves a conformational change in the shape of the enzyme. C) is also called the lock-and-key model. D) states that enzyme-substrate interactions are rigid. E) proposes that very strong covalent bonds are formed upon substrate binding.
B. involves a conformational change in the shape of the enzyme.
Saturation can be defined as A) denaturation of an enzyme. B) the inability to increase reaction velocity beyond a finite upper limit. C) inhibition of enzyme function by blocking the active site. D) the substrate concentration at which velocity reaches one-half maximum velocity. E) a characteristic of all uncatalyzed reactions.
B. the inability to increase reaction velocity beyond a finite upper limit.
27) Which of the following is true of fatty acids?
C) Saturated fatty acids have no double bonds between carbons. (correct:) (a: laurate = saturated, no double bonds) (b: 16 - 18 carbons) (d: a bend or kink) (e: two caron units)
24) Which of the following is not true of phospholipids?
C) Sphingolipids are the predominant phospholipid in membranes.
11) Which of the following is an example of a defensive protein? A) keratin B) cell surface receptor C) antibody D) myosin E) hormone
C) antibody
An enzyme influences the structure of which of the following? A) substrate B) product C) transition state D) cofactor E) intermediate
C. transition state
Energy
The capacity to cause specific physical or chemical changes.
Free Energy
The portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system.Dependent on the free energies of the products and reactants.ΔG=G products-G reactants Δ H is positive for endo and negative for exo reactions
equilibrium constant K'eq
The position of equilibrium for any give chemical reaction. The reactant and product concentrations at equilibrium K(eq) = {[C][D]}/{[A][B]}
System
The restricted portion of the universe that is being considered at any given moment . Can be opened or closed
Second law of thermodynamics
a rule that states that every energy transfer or transformation increases the entropy (disorder) of the universe; unstoppable trend toward randomization of the universe as a whole. No process or reaction disobeys this law
Closed system
a system in which no matter is allowed to enter or leave
________ is the class of enzymes able to convert a substrate to its mirror image.
Isomerases
double-reciprocal
Lineweaver--Burk
when the size of a cell increases, the surface area/volume ratio
decreases
lignin is an important component in
plant cell walls
Nonprotein catalysts are known as ________.
ribozymes
the cytosol is best describes as
semifluid substance in which organelles are suspended
viruses are important in the study of cell biology because
they cause disease and are used as model organisms to study molecular biology and genetics
Autotroph
...
Mechanical Work
Changes in the location or orientation of a cell or sub cellular structure. Involves a physical change in the position of orientation of a cell or some part of the cell. Example: movement of a cell with respect to its environment
30) Which of the following is a terpene?
D) dolichol (vitamin A is built upp by terpene)
________ are a class of enzymes responsible for the movement of functional groups from one molecule to another
Transferases
photoautotroph
Use solar to produce carbon compounds from CO2 during photosynthesis
prosthetic group
Zinc
heterotroph
...
The size range of most plant and animal cells is
A) 1-10 nm. B) 1-5 μm. C) 10-50 μm* . D) 0.1-0.5 mm. E) 50-100 mm.
Prokaryotes have ________ ribosomes with ________ and ________ subunits, whereas eukaryotes have ________ ribosomes with ________ and ________ subunits.
A) 80S, 50S, 30S; 100S, 60S, 40S B) 100S, 60S, 50S; 90S, 60S, 40S C) 70S, 50S, 30S; 80S, 60S, 40S* D) 70S, 40S, 30S; 80S, 50S, 30S E) 80S, 60S, 40S; 70S, 50S, 30S
9) Which of the following statements is not true of the amino acids?
A) All amino acids exist in two stereoisomeric forms.
Viruses are composed of
A) DNA and protein. B) only protein. C) RNA and lipid. D) nucleic acid, protein, and sometimes lipid.* E) only nucleic acid.
28) Which of the following is true of glycolipids?
A) Glycolipids are usually found on the exterior surface of the plasma membrane. (correct:) (b: containing a carbohydrate group) (c: laurate is a fatty acid) (d: 1 to 6 sugarunits) (e: d-glucose and d-galactose)
21) Which of the following is true of transfer RNA?
A) It is responsible for the correct positioning of amino acids in a polypeptide.
Which of the following is true of plant cells?
A) Plant cells may contain chloroplasts.* B) Plant cells are always much larger than animal cells. C) Chromosomes are found only in plant cells. D) Only plant cells have a cell membrane. E) The plant cell has no cell wall.
Which of the following is a true statement regarding lysosomes?
A) The lysosome may mature from a late endosome.* B) The lysosome may function in glycosylation. C) The contents of the lysosome originate in the smooth ER. D) The lysosome functions in export packaging. E) None of these are correct.
Which of the following would be attributed to a peroxisomal dysfunction?
A) accumulation of N-acetylglucosamine phosphotransferase B) accumulation of ganglioside GM2 C) accumulation of very long chain fatty acids* D) accumulation of glucocerebroside E) accumulation of complex sugars
The methanobacteria, halobacteria, and sulfobacteria are included in which domain?
A) bacteria B) protista C) blue-green algae D) archaea* E) eukarya
Which of the following is characteristic of eukaryotic cells?
A) binary fission B) membrane-bounded nucleus* C) peptidoglycan cell wall D) 70S ribosomes E) smaller than 5 μm in diameter
The extracellular matrix outside the plasma membrane of animal cells is typically composed of
A) collagen and proteoglycans.* B) lipids. C) cellulose. D) peptidoglycan. E) collagen, proteoglycans, lipids, and peptidoglycan.
29) Which of the following is not a steroid?
A) epinephrine
A(n) ________ is composed of tetrameric protofilaments.
A) extracellular matrix B) microtubule C) bacteriophage D) microfilament E) intermediate filament*
Eukaryotic cells are believed to have arisen
A) from a symbiotic relationship between primitive nucleated cells and bacterial cells.* B) from the fusion of multiple archaeal cells into a larger, more complex cell. C) independently from prokaryotic cells. D) by mutations that lead to changes in plasma membranes, leading to internal membrane-bound organelles. E) independently from prokaryotic cells by mutations that lead to changes in plasma membranes, leading to internal membrane-bound organelles.
13) To which of the following classes of sugars does glucose belong?
A) hexose (hexa = 6)
The hallmark feature of peroxisomal diseases is the accumulation of
A) hydrolases. B) very long chain fatty acids.* C) peroxidases. D) ATP. E) pigments.
5) The primary structure of a protein
A) is simply the order of amino acids from one end of the protein to another. B) is the linear sequence of amino acids that are linked together by peptide bonds. C) is important both genetically and structurally. D) is important for determining the secondary and tertiary structure of a protein. E) all of the above
14) Which of the following is a disaccharide?
A) lactose (lactose = galactose + glucose)
The smooth endoplasmic reticulum functions in synthesis of
A) lipids.* B) polysaccharides. C) proteins. D) DNA. E) lipids, polysaccharides, proteins, and DNA.
The chromoplast is an organelle associated with
A) oxidation of sugars. B) synthesis of secretory proteins. C) plant pigment storage.* D) ribosome production in primitive plants. E) storage of chromium.
26) Which of the following is not one of the six classes of lipids?
A) pectins (pectin = polysaccharid)
Prions are
A) the site of protein synthesis in prokaryotic cells. B) simple viruses composed of protein. C) primitive protein particles that are believed to be an ancient precursor of living cells. D) infectious circular RNA molecules that replicate in host cells. E) infectious misfolded proteins that cause normal protein molecules to misfold.*
1) Which of the following is a nonpolar (hydrophobic) amino acid?
A) valine (valine is nonpolar and hydrophobic)
Which of the following variables is part of the Michaelis—Menten equation? A) kcat B) Km C) Vmax D) [S] E) v
A. kcat
According to the EC system, which is not one of the major groups of enzymes? A) proteases B) hydrolases C) oxidoreductases D) transferases E) ligaseS
A. proteases
Of the following, which is used to inhibit specific enzymes in the treatment of many bacterial and viral diseases? A) substrate analogues B) noncompetitive inhibitors C) intercalating agents D) nitrous oxide E) X-rays
A. substrate analogues
The equation A-PO4 + B → A + B-PO4 would be catalyzed by which of the following classes of enzymes? A) transferases B) oxidoreductases C) hydrolases D) ligases E) isomerases
A. transferases
Which of the following is an example of a prosthetic group? A) a zinc ion B) a glycine residue C) a polypeptide chain D) a nickel catalyst E) carboxypeptidase A
A. zinc ion
Heat
An increase in Temperature that is useful to warm-blooded animals. Voodoo lily is a plant that is dependent of metabolic heat to extend its growing season and attract pollinators.
Phototroph
An organism that relies on photons to excite electrons within pigments in membranes. .
23) Which of the following is true of purines?
B) Purines have a double-ringed structure. (purines: adenin and guanine have two rings) (pyrimidines: thymine, cytosine, uracil have one ring)
17) The chemical nature of each amino acid is determined by which of the following groups?
B) R
2) Which of the following does not represent the correct pairing of the three-letter abbreviation with the one-letter abbreviation of an amino acid?
B) arg-A (arginine = R) (arginin blir arrrrrrrrg:-)
25) The term amphipathic describes the characteristic of some molecules that have________.
B) both a polar and a nonpolar region
12) Cellulose belongs to which of the following groups of macromolecules?
B) carbohydrates
7) Which of the following is not correctly matched?
B) enzymatic protein - collagen (collagen is a structural protein)
19) Which of the following is a purine? A) cytosine B) guanine C) thymine D) cysteine E) uracil
B) guanine (purine: adenine and guanine) (pyrimidines: thymine, uracil, cytosine) (cysteine = amino acid)
22) Which of the following is not a base used in DNA replication? A) guanine B) uracil C) cytosine D) thymine E) adenine
B) uracil (uracil replaces thymine in RNA)
An allosteric inhibitor A) increases the rate of substrate binding. B) binds and activates the high-affinity state of the enzymes. C) is identical to the active site. D) binds at the regulatory site. E) is converted to an activator by the enzyme.
B. binds and activates the high-affinity state of the enzymes
An enzyme A) decreases the rate of a reaction. B) binds substrates in a manner that facilitates the formation of product. C) changes the position of the equilibrium of the reaction. D) does not change the rate at which the equilibrium is achieved. E) is always a prot
B. binds substrates in a manner that facilitates the formation of product.
A sick person often has a fever, which can inhibit the growth of bacteria because A) bacteria reproduce more rapidly at higher body temperature. B) enzymes do not function as well at temperatures other than the optimal temperature. C) the higher temperature increases the activity of lyases. D) sweating removes prosthetic groups from biological enzymes. E) fever blocks synthesis of proteins in the bacterial nucleus.
B. enzymes do not function as well at temperatures other than the optimal temperature
6) The amino acid referred to as the "helix breaker" (because it lacks the hydrogen atom needed for hydrogen bonding) is
C) proline. (because its R group is covalently bonded to the amino nitrogen group, which therefore lacks the hydrogen atom nedded for hydrogenbonding, it's rarely found in an alpha-helix)
4) Disulfide bonds are often found to stabilize which of the following levels of protein structure?
C) tertiary (two cysteines)
A linear relationship between Vmax and enzyme concentration would be expected when A) [S] << Km. B) [S] >> Km. C) [S] = Km. D) both choices A and B E) both choices B and C
C. [S] = Km
The site on an enzyme that will bind the substrate is called the A) prosthetic group. B) catalyst. C) active site. D) metastable site. E) activation site.
C. active site
A competitive inhibitor A) binds at a site other than the active site. B) irreversibly binds and inactivates the enzyme. C) cannot be processed by the enzyme. D) does not inhibit enzyme activity but does lower substrate concentration. E) binds to and inactivates the substrate.
C. cannot be processed by the enzyme.
Which of the following is an enzyme? A) iron B) histidine C) carboxypeptidase A D) ATP E) N-acetylmuramic acid
C. carboxypeptidase A
A noncompetitive inhibitor will A) bind to free enzyme. B) bind to free product. C) decrease Vmax. D) decrease Km. E) both choices A and C
C. decrease Vmax
The equation AB + H2O → A + B would be catalyzed by which of the following classes of enzymes? A) oxidoreductases B) transferases C) hydrolases D) ligases E) isomerases
C. hydrolases
The active site for carboxypeptidase A) contains amino acids that are contiguous to one another along the primary sequence of the protein. B) uses iron as the prosthetic group. C) involves only 6 out of a total of 307 amino acids. D) contains a glutamate residue at position 69. E) is formed by the interaction of two polypeptide chains.
C. involves only 6 out of a total of 307 amino acids
Which of the following is/are means whereby a catalyst can lower the activation energy of a reaction? A) decreasing the number of reactive molecules B) altering the temperature within the cell to one appropriate for reactions to proceed C) quantum tunneling D) inefficient collisions E) permanently binding substrates
C. quantum tunneling
An enzyme is active in the stomach of an animal but quickly loses its activity when it leaves the stomach. This example illustrates that enzymes are A) specific to the organs in which they are produced. B) inactivated by movement. C) sensitive to changes in pH. D) inactivated by inhibitors in the small intestine. E) consumed by the quantities of substrate in the small intestine.
C. sensitive to changes in pH.
Synthetic Work
Changes in chemical bonds, and important work in ever cell at all times is the work of biosynthesis which results in the formation of new chemical bonds and the synthesis of new molecules. This work is required to maintain existing cellular structures, due to most components of the cell are in constant turnover. Almost all of the energy that cells require for biosynthetic work is used to make energy rich organic molecules from simpler starting materials and incorporated into macromolecules.
________ inhibitors bind reversibly at the active site of an enzyme.
Competitive
16) Which of the following is not a characteristic of DNA?
E) contains ribose
15) Which of the following is not a polysaccharide?
D) extensin (extinsin = protein in cellwall)
3) Which of the following three-letter symbols represents an amino acid that is polar and uncharged?
D) gln (gln / Q = glutamine, group B)
18) The nucleoside triphosphate molecules in DNA are linked together in the 5'→3' by a(n) ________ bridge.
D) phosphodiester (phosphodiester)
33) Lipid rafts are
D) regions of the membrane that are high in sphingolipids, which facilitate communication with the external environment of the cell.
8) Hydrogen bonding is most important in stabilizing the ________ structure of many proteins.
D) secondary (secondary structure)
All of the following are examples of irreversible enzyme inhibitors except A) herbicides. B) pesticides. C) monoamine oxidase inhibitors. D) aspirin. E) natural poisons.
D. aspirin
The Michaelis constant A) can be determined using the Lineweaver—Burk plot. B) is equal to twice the Vmax. C) is equal to the substrate concentration at Vmax/2. D) both choices A and C E) choices A, B, and C
D. both choices A and C
Why is the Lineweaver—Burk plot important in enzyme kinetics? A) It is a single-reciprocal plot. B) It illustrates enzyme specificity. C) It reveals the presence of prosthetic groups in enzymes. D) It makes it easier to determine Vmax. E) It is nonlinear.
D. it makes it easier to determine Vmax.
An example of an irreversible inhibitor is A) a competitive inhibitor. B) acetylcholinesterase. C) a noncompetitive inhibitor. D) penicillin. E) isoleucine.
D. penicillin
ribozymes
DNA
Covalent modification A) can activate an enzyme. B) affects the activity of an enzyme by adding or removing a chemical group. C) can involve the addition of phosphate groups. D) produces modifications that can sometimes be reversed. E) all of the above.
E. all of the above
Substrate activation may involve A) a change in enzyme conformation induced by substrate binding. B) accepting protons from the enzyme. C) formation of temporary covalent bonds. D) donation of protons to the enzyme. E) all of the above
E. all of the above
Mixed type inhibitors will affect the ________ of an enzymatic reaction. A) Km B) Vmax C) S D) P E) both choices A and B
E. both choices A and B
In the Eadie—Hofstee plot, A) the x axis shows substrate concentration. B) the y intercept is Vmax. C) the slope can be used to determine Km. D) the y axis shows v/[S]. E) both choices C and D
E. both choices C and D
Which of the following is not true of the enzyme-substrate interaction? A) Many enzymes are extremely specific regarding a substrate. B) Many enzymes cannot recognize a stereoisomer of their substrate. C) Some enzymes accept any of a whole group of substrates. D) Carboxypeptidase recognizes any of the amino acids from the carboxyl end of a polypeptide. E) Cells are often able to carry out metabolic activity with only a handful of enzymes.
E. cells are often able to carry out metabolic activity with only a handful of enzymes.
The work of James B. Sumner was to A) discover ribozymes. B) prove that enzymes were carbohydrates. C) isolate the insulin hormone. D) originate the term ferments to describe enzymes. E) crystallize urease, the first enzyme isolated.
E. crystallize urease, the first enzyme isolated.
All of the following are associated with substation activation except A) bond distortion. B) proton transfer. C) electron transfer. D) intramolecular hydrogen bonding. E) neutron transfer.
E. neutron transfer
Enzyme regulation may occur by several methods. Which of the following is not a means of enzyme regulation? A) substrate-level phosphorylation B) feedback inhibition C) allosteric regulation D) covalent modification E) saturation
E. saturation
Which of the following best describes a metastable state? A) This state is composed of the difference in activation energy of a catalyzed versus an uncatalyzed reaction. B) The metastable state is formed by transient complexes with the substrate. C) The metastable state is created by the prosthetic group of the enzyme. D) This state changes the position of the equilibrium but not the rate. E) The metastable state is a state of the substrate in which the reaction can proceed but typically requires a catalyst.
E. the metastable state is a state of substrate in which the reaction can proceed but typically requires a catalyst.
As new enzymes are discovered, the EC system for naming enzymes is to be used. The names are to be based on which of the following criteria? A) the name of the substrate B) a description of substrate function C) an indication of the size of the substrate D) the six major classes of enzyme function E) the size of the enzyme
E. the size of the enzyme
All of the following are examples of ribozymes or ribozyme activity except A) peptidyl transferase. B) autocatalytic RNAs. C) ribonuclease P. D) intron removal from pre-rRNA. E) zymogen.
E. zymogen
Work
In biological systems, work is the use of energy to drive any process other than feat flow. Example muscle contraction for chemical expediture
Chemoheterotroph
Ingest and use chemical compounds such as carbohydrates, fats, and proteins to provide both energy and carbon for cellular needs
Electrical Work
Moving Ions across a membrane against an electrochemical Gradient. The change of difference is known as electrical potential or membrane potential.
Concentration Work
Moving molecules across a membrane against a concentration gradient. The purpose is either to accumulate substances within a cell or organelle or to remove potentially toxic by-products of cellular activity
________ inhibitors bind the enzyme at a location other than the active site but still interfere with product formation.
Noncompetitive
Chemotroph
Organism that uses organic compounds or inorganic substances, such as iron, nitrate, ammonia, or sulfur, as sources of energy.This is done by oxidizing chemical bonds in molecules
Needed kinds of needed work in a cell
Synthetic work Mechanical work Concentration work Electrical work
Surroundings
The foundry of the system such as a glass beaker or membrane.
Thermodynamic Spontaneity
a measure of whether a reaction can occur, but says nothing about whether the reaction actually will occur. Reactions with a negative free energy change are thermodynamically spontaneous.
Open system
a system that can exchange both matter and energy with its surroundings
Inhibitors of enzymes can be either reversible or irreversible. The most common reversible inhibitors are competitive or noncompetitive. Based on what you know about enzyme inhibitors, can you determine the type of inhibition discussed in these examples? a. Diisopropyl fluorophosphate binds to acetylcholinesterase and permanently inactivates the enzyme. Paralysis results. b. An inhibitor binds to the active site of an enzyme but disassociates and leaves the enzyme active. c. A toxin binds to an enzyme. The enzyme then binds the substrate. No product is produced. The toxin may disassociate and allow for product formation. d. Vitamin K is a coenzyme involved in blood clotting. An anticoagulant drug binds at the site of vitamin K and prevents clotting. Clotting resumes after the drug has been discontinued. e. Aspirin binds to prostaglandin synthetase and permanently stops its ability to produce prostaglandin.
a. irreversible b. competitive c. noncompetitive d. competitive e. irreversible
Enzyme activity may be regulated by several means. Can you identify the mode of regulation for each of the following examples? a. When glucose is converted to glucose-6-phosphate by hexokinase, the accumulation of glucose-6-phosphate inhibits the reaction. b. A foreign substance is added to the reaction in part a above. This substance binds to hexokinase and prevents its ability to catalyze the reaction. c. An inactive form of an enzyme becomes active after being phosphorylated. d. Pepsinogen becomes pepsin after being released into the lumen of the stomach. e. In a series of enzymatic reactions, it is found that the product of the last reaction inhibits the first enzyme in the series of reactions.
a. substrate-level regulation b. inhibition c. covalent modification d. proteolytic cleavage e. allosteric regulation or feedback inhibition
The ________ is the minimum energy required before two molecules can be successful in producing a reaction
activation energy
The site on an enzyme that is designated for the substrate bind is called the ________.
active site
Carbon dioxide reduction
addition of hydrogen to carbon dioxide to form organic molecules. Occurs in the light independent reactions of photosynthesis
Chemoautotroph
an organism that derives energy from the oxidation of inorganic compounds, such as hydrogen sulfide (H2S) or H2 gas or organic ions for energy and synthesize all their organic compounds from CO2
Bioenergetics
applied thermodynamics, The application of thermodynamic principles to reactions and processes in the biological world.
Changes in free energy for the oxidation and synthesis of glucose
cell respiration vs photosynthesis
Thermodynamics
changes in heat and other forms of energy and processes that convert energy from one form to another. Concerns the laws governing the energy transactions that accompany most physical processes and all chemical reactions
which of the following organelles is not generally found in animal cells
chloroplasts
Δ G processes
decrease in free energy ( less than 0 is increase in entropy all process or reactions that occur spontaneously will result in a decrease in the free energy content of the system ( -)
induced-fit model
distortion of substrate and enzyme
feedback inhibition
end-product inhibition
which of the following is least likely to be part of a cell membrane
enzymes
Enthalpy change (ΔH)
favorable in negative values
Entropy change (ΔS)
favorable reactions are indicated by positive value
communication between animal cells is facilitated by
gap junctions
photoheterotroph
harvest solar energy to power cellular activities but rely on intake of organic molecules for their carbon needs
________ is the turnover number for a given enzyme.
kcat
viroids differ from viruses in that they
lack capsid proteins
dynamic steady state in open system
maintain energy in and entry out. example in humans we need to eat to provide us with energy to use then release of energy
The ________ velocity of an enzymatic reaction is the velocity at substrate concentration.
maximum
Vmax
maximum velocity
mitochondria are thought to have evolved from ancient bacteria. which characteristics of a free-living bacteria have mitochondria lost over time?
motility
viruses are composed o f
nucleic acid, protein, and sometimes lipids
Methane oxidation
occurs in complex arrays of intracellular membranes; oxidized to methanol and then to formaldehyde which can be assimilated into cell material
isothermal
of a process or change taking place at constant temperature
Jumping Reaction
once our system is at equilibrium we can count up the number of beans in each chamber and express the results in a ration. Keq=beans in chamber 2 / chamber 1
which of the following organelles has only a single bilayer membrane around it
peroxisome
State
pressure, temperature or volume that is held constant at a specified value
A nonprotein component of an enzyme that is usually a metal ion or small organic molecule is called a(n) ________.
prosthetic group
kuru is a transmissible degenerative disease of the central nervous system caused by
protein
covalent modification
protein kinases
Enthalpy
represented by the symbol H for heat and is related to the internal energy by E by a term that combines both pressure and volume H=E + PV H is dependent of both E and PV because changes in heat content following a process or reaction can affect the tool energy as well as pressure and volume.For biological reactions both are considered zero. ΔH = ΔE + ΔPV= ΔE
Km/Vmax
slope of Michaelis--Menten plot
-1/Km
slope of the Eadie--Hofstee plot
Azidothymidine (AZT) is a(n) ________ used in the treatment of AIDS and targets the enzyme reverse transcriptase.
substrate analogue
[S]
substrate concentration
Glucose oxidation
the central reaction in energy metabolism. moves spontaneously. no energy required. C6H12O6 +6O2 --> 6CO2 +6 H2O +energy
Internal energy
total energy stored within a system. Represented by symbol E. We are not usually concerned with the actual value of E for a who system because value can't be measured directly. However it is possible to measure the change in internal energy We cannot measure the internal energy in a system, we can only determine the change in internal energy, E, that accompanies a change in the system. The change in internal energy that accompanies the transfer of heat, q, or work, w, into or out of a system can be calculated using the following equation: Note the value of heat and work as they are transferred into or out of a system. Reduces E Increases E q < 0 (q negative), heat lost q > 0 (q positive), heat gained w < 0 (w negative), work done by system w > 0 (w positive), work done on system
proteolytic modification
trypsin
kcat
turnover number
a function of the smooth endoplasmic reticulum is the synthesis of
vitamins and lipids
Coupled reactions
when the energy released by an exergonic reaction is used to drive an endergonic reaction usually ATP
First Law of Thermodynamics ( law of conservation of energy)
whenever energy is converted from one form to another in a physical or chemical change, no energy is created or destroyed. When applied to the universe the amount of energy present in all forms must be the same before and after any process or reaction occurs. In an open system such as a cell, during the course of any retain or process, the total amount of energy that leaves the system must be equal to the energy that enters minus any energy that remains behind and is therefore stored with the system
Physical and chemical process under any conditions for a chemical reaction
ΔE= E products- E reactants
Exothermic
ΔH will be negative if heat content of products is less than that of reactants heat is released.
Endothermic
ΔH will be positive if heat content of products is greater than that of reactants. Heat is absorbed in the system. Example- melting of ice cube
