Exam 2
A cloned mammal is made by removing the DNA from the unfertilized egg of an egg donor, replacing it with DNA from a cell of a mature animal, and then implanting that cell into the uterus of a surrogate mother. The cell then divides and behaves as if it were a regular embryo. Answer the following question(s) regarding a clone. Will the clone typically be sterile or fertile? Sterile Fertile It depends on whether it is male or female.
Fertile
Choline group
Phospholipids vary in the small molecules attached to the phosphate group. The phospholipid shown in the figure has a _______ attached to phosphate.
What are carcinogens? All mutagens Errors during DNA replication Physical or chemical factors that can lead to mutations causing cancer Chemical factors that can treat cancer
Physical or chemical factors that can lead to mutations
have difficulty crossing the hydrophobic part
Polar molecules (water, sugars): able to cross lipid bilayer?
hydrophilic
Polar molecules (water, sugars): hydrophobic or hydrophilic
transport protein required to cross efficently
Polar molecules (water, sugars): transport protein required? transport protein required?
How does a cell typically know when to divide? Oncogenes code for growth factor proteins that initiate cell division. They have an internal clock and only divide when they reach a certain age. Tumor suppressor genes code for growth factor proteins that initiate cell division. Proto-oncogenes code for growth factor proteins that initiate cell division.
Proto-oncogenes code for growth factor proteins that initiate cell division.
If DNA directs the production of RNA, what does RNA make? RNA makes proteins. RNA makes membranes. RNA makes hereditary molecules. RNA makes more DNA
RNA makes proteins.
When 10,000 molecules of ATP are hydrolyzed to ADP and i in a test tube, about half as much heat is liberated as when a cell hydrolyzes the same amount of ATP. Which of the following is the best explanation for this observation? -The reaction in cells must be catalyzed by enzymes, but the reaction in a test tube does not need enzymes. - Cells are open systems, but a test tube is an isolated system. -Cells are less efficient at heat production than nonliving systems. -Reactant and product concentrations in the test tube are different from those in the cell. -The hydrolysis of ATP in a cell produces different chemical products than does the reaction in a test tube.
Reactant and product concentrations in the test tube are different from those in the cell.
What is the name of the enzyme that builds cDNA out of mRNA? RNA polymerase DNA polymerase DNA helicase Reverse transcriptase
Reverse transcriptase
increasing the proportion of unsaturated phospholipids in the membrane
The membranes of winter wheat are able to remain fluid when it is extremely cold by ________. -increasing the proportion of unsaturated phospholipids in the membrane -decreasing the percentage of cholesterol molecules in the membrane -decreasing the number of hydrophobic proteins in the membrane -increasing the proportion of glycolipids in the membrane
cotransport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis
The movement of glucose into a cell against a concentration gradient is most likely to be accomplished by which of the following? a. cotransport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis b. passive diffusion of the glucose through the lipid bilayer c. facilitated diffusion of the glucose using a carrier protein d. movement of glucose into the cell through a glucose channel e. receptor-mediated endocytosis
The competitive inhibitor competes with the substrate for the__________________ on the enzyme.
active site
highest energy form of Adenosine?
adenosine triphosphate=ATP
Usually, a(n)_____________________ inhibitor forms a covalent bond with an amino acid side group within the active site, which prevents the substrate from entering the active site or prevents catalytic activity.
irreversible
During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a G of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the G for the new reaction? +40 kcal/mol 0 kcal/mol +20 kcal/mol -20 kcal/mol -40 kcal/mol
-20 kcal/mol
Which temperature and pH profile curves on the graphs were most likely generated from analysis of an enzyme from a human stomach where conditions are strongly acid?
1 and 4 because 4 is acidic and the middle of 1 is at 98.6 degrees F and 36.6 C
The PCR technique doubles the amount of DNA in a sample in each cycle. If you started the PCR technique with two fragments of double-stranded DNA, calculate how many double-stranded DNA fragments you would you have after four cycles. 32 64 8 16
32
What is a "benign" tumor? A mass of cells that grows out of control but remains at the site of origin A mass of cells that grows out of control and spreads to other tissues A mass of cancerous cells A single mutated cell that could potentially develop into cancer
A mass of cells that grows out of control but remains at the site of origin
Permeability to glucose will increase
A phospholipid bilayer with equal amounts of saturated and unsaturated fatty acids displays a specific permeability to glucose. What effect will increasing the proportion of unsaturated fatty acids in the bilayer have on the membrane's permeability to glucose? - Permeability to glucose will decrease. -Permeability will decrease initially then increase as the bilayer fills with glucose. -Permeability to glucose will increase -Permeability to glucose will stay the same.
Fatty Acid
A phospholipid has 2 "tails" made up of 2 _______molecules, which consists of a carboxly group with a long hydrocarbon chain attached.
Phosphate Group
A phospholipid has a "head" made up of a glycerol molecule attached to a single _________, which is attached to another small molecule.
Which of the following statements about equilibrium of chemical reactions is correct? - A reaction that is at equilibrium is not capable of doing any work. - The equilibrium point is where the system has the highest free energy - Reactions can only go in the direction toward equilibrium. - The equilibrium point of a reaction represents the least stable configuration for that reaction. - Most reactions in a living cell are close to equilibrium.
A reaction that is at equilibrium is not capable of doing any work. *at equilibrium, delta G is zero
What is recombinant DNA? DNA that can no longer replicate DNA that is circular DNA that comes from plasmids A segment of DNA containing sequences from two different sources
A segment of DNA containing sequences from two different sources
moves three sodium ions out of a cell and two potassium ions into a cell using energy from ATP hydrolysis
A sodium-potassium pump ________. -move three sodium ions out of a cell and two potassium ions into a cell and generates an ATP in each cycle -moves three sodium ions out of a cell and two potassium ions into a cell using energy from ATP hydrolysis -moves three potassium ions out of a cell and two sodium ions into a cell using energy from ATP hydrolysis -moves three potassium ions out of a cell and two sodium ions into a cell while producing ATP for each cycle
How many nucleotides are required to code for 10 amino acids? A) 30 B) 10 C) 20 D) 3
A) 30
Within an operon, repressors _____. A) block gene transcription to RNA by attaching to the operator B) block gene transcription to RNA by attaching to the promoter C) block mRNA translation by attaching to the mRNA for a specific gene D) block gene transcription to RNA by attaching directly to the gene itself
A) block gene transcription to RNA by attaching to the operator
Which of these is exhibiting kinetic energy?
a space station orbiting Earth
What is the monomer of the DNA molecule? A-Nucleotide B-Polynucleotide C-Monosaccharide D-Peptide
A-Nucleotide
b. embedded in a lipid bilayer.
According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly a. spread in a continuous layer over the inner and outer surfaces of the membrane. b. embedded in a lipid bilayer. c. confined to the hydrophobic interior of the membrane. d.free to depart from the fluid membrane and dissolve in the surrounding solution. e. randomly oriented in the membrane, with no fixed inside-outside polarity.
You have an enzymatic reaction proceeding at the optimum pH and optimum temperature. You add a competitive inhibitor to the reaction and notice that the reaction slows down. What can you do to speed the reaction up again? Add more inhibitor to speed up the reaction. Add more substrate; it will outcompete the inhibitor and increase the reaction rate. Increase the temperature. Increase the pH.
Add more substrate; it will outcompete the inhibitor and increase the reaction rate.
How does an enzyme increase the rate of the chemical reaction it catalyzes? An enzyme's active site binds only the reactants, and not the products of a reaction, pushing the equilibrium for the reaction far to the right. An enzyme reduces the free energy of activation (EA) of the reaction it catalyzes. An enzyme reduces the free-energy change (ΔG) of the reaction it catalyzes.
An enzyme reduces the free energy of activation (EA) of the reaction it catalyzes.
Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics? As a consequence of growing, organisms cause a greater increase in entropy in their environment than the decrease in entropy associated with their growth. Life obeys the second law of thermodynamics because the decrease in entropy as the organism grows is exactly balanced by an increase in the entropy of the universe. Living organisms are able to transform energy into entropy. Living organisms do not follow the laws of thermodynamics. Living organisms do not obey the second law of thermodynamics, which states that entropy must increase with time.
As a consequence of growing, organisms cause a greater increase in entropy in their environment than the decrease in entropy associated with their growth.
Why does transcription occur in the nucleus and not in the cytoplasm in eukaryotes? A Ribosomes cannot leave the nucleus. B DNA cannot leave the nucleus. C RNA cannot exist in the cytoplasm. D Codons are only found in the nucleus.
B DNA cannot leave the nucleus.
Which process results in the creation of mRNA? A Translation B Transcription C Replication D All of the above
B Transcription
Your body is composed of a dazzling array of different cell types. Each cell type develops its own unique properties. How does this happen? A) Each cell type is provided with its own specialized set of genes during cell division. B) All cells (with very few exceptions) contain the same set of genes, but the process of gene expression determines which genes are active in each cell. C) The zygote contains one of each of the different cell types. These ancestor cells then divide to produce the diversity of cell types in the adult. D) none of the above
B) All cells (with very few exceptions) contain the same set of genes, but the process of gene expression determines which genes are active in each cell.
Alternative splicing allows the production of several different proteins from the same gene in both prokaryotes and eukaryotes. A) TRUE B) FALSE
B) FALSE
What does it mean when we say a gene is "turned off"? A) The gene is now activated. B) The gene cannot be transcribed and translated into a protein. C) The gene is no longer working properly. D) The gene has a mutation.
B) The gene cannot be transcribed and translated into a protein.
Which nucleic acid acts like an enzyme, stabilizing and orienting different molecules to facilitate the formation of bonds between them? A) DNA B) rRNA C) tRNA D) mRNA
B) rRNA
To begin the process of gene transcription, RNA polymerase attaches to _____. A) the gene that will be transcribed B) the promoter associated with the target gene C) the operator associated with the target gene D) none of the above
B) the promoter associated with the target gene
Hydrophobic
Because the C-H bonds in the fatty acid tails are relatively non polar, the phospholipid tails are ______, which means they are excluded from water.
When is cell-to-cell communication particularly important in regulating gene expression? During mitosis During meiosis During embryonic development During replication
C) During embryonic development
Where does translation occur in eukaryotes? A) In the nucleus only B) Both in the nucleus and in the cytoplasm C) In the cytoplasm only D) In neither the nucleus nor the cytoplasm
C) In the cytoplasm only
The lac operon controls expression of three genes that produce lactose-digesting enzymes. What role does lactose play in regulating the lac operon? A) It is not directly involved in gene regulation in this system. B) It turns off the gene that produces the repressor protein, thereby allowing production of the three enzymes. C) It binds to and disables the repressor protein, thereby allowing production of the three enzymes. D) It binds to the promoter region of the operon, thereby allowing RNA polymerase to attach and begin transcription of the three genes.
C) It binds to and disables the repressor protein, thereby allowing production of the three enzymes.
Operons are a standard method for gene regulation in _____. A) all organisms B) eukaryotes but not prokaryotes C) prokaryotes but not eukaryotes D) E. coli, but they are rare in other organisms
C) prokaryotes but not eukaryotes
What do the letters D-N-A stand for? A) Dioxyribonuclear acid B)Deoxyrobonuclear acid C)Deoxyribonucleic acid D)Dioxyribonucleic acid
C)Deoxyribonucleic acid
What is a gene? A) A section of DNA that codes for a portion of a protein B) A discrete sequence of DNA nucleotides C) A section of DNA that codes for one or more proteins D) All of these and more are part of the expanding definition of a gene.
D) All of these and more are part of the expanding definition of a gene.
What does "transfer RNA" actually transfer? A) Transcripts B) Codons C) Ribosome D) Amino acids
D) Amino acids
If the base sequence of template strand reads GCCATTAC, what is the base sequence of the mRNA? A) CGGTAATG B) GCCAUUAC C) CGGTUUTG D) CGGUAAUG
D) CGGUAAUG
Do all cells of the body express the same genes? A) No, since they don't contain the same DNA B) Yes, since they all make the same proteins C) Yes, since they all contain the same DNA D) No, since they don't all need to make the same proteins
D) No, since they don't all need to make the same proteins
Barr bodies are associated with ________. A) proto-oncogenes B)frameshift mutations C)signal transduction D) X chromosome inactivation
D) X chromosome inactivation
The signal transduction pathway allows ________. A) a cell to repair damage to its DNA B) genes from one organism to be inserted into the nucleus of another organism's cells C) whole genomes to be sequenced D) one cell to regulate the gene expression of another cell
D) one cell to regulate the gene expression of another cell
Which enzyme is responsible for adding complementary DNA bases to an exposed DNA strand? DNA helicase DNA polymerase DNA ligase DNA peptidase
DNA polymerase
Passive Transport
Diffusion across a biological membrane is called
Which of the following statements is incorrect regarding DNA and RNA? A They are found in different locations in the cell. B DNA is double stranded, and RNA is a single strand. C One of the bases is different. D They each contain a slightly different sugar molecule. E All of the above are correct.
E All of the above are correct.
Which of the following statements is a logical consequence of the second law of thermodynamics? Every chemical reaction must increase the total entropy of the universe. Every energy transfer requires activation energy from the environment. If there is an increase in the energy of a system, there must be a corresponding decrease in the energy of the rest of the universe. Energy can be transferred or transformed, but it cannot be created or destroyed. If the entropy of a system increases, there must be a corresponding decrease in the entropy of the universe.
Every chemical reaction must increase the total entropy of the universe.
What is the main cause of cancer? Exposure to carcinogens in the environment Old age, during which the cells of the body no longer work properly DNA replication no longer working properly We do not currently know the main cause of cancer.
Exposure to carcinogens in the environment
a. passive transport
Facilitated diffusion is a type of _______. a. passive transport b. phagocytosis c. pinocytosis d. active transport
What separates the strands of DNA in the polymerase chain reaction (PCR) technique? Restriction enzymes Helicase Heat Centrifuge
Heat
Which genes are responsible for your overall structure, such as how many legs you have and where they develop? Proto-oncogenes Homeotic genes Oncogenes Growth factor genes
Homeotic genes
Lipids are mostly nonpolar.
How can a lipid be distinguished from a sugar? a. A lipid dissolves in water b. A lipid is made up of only hydrocarbons. c. Lipids are mostly nonpolar d. Lipids are mostly unsaturated
The polar heads interact with water; the nonpolar tails do not.
How do membrane phospholipids interact with water? -The polar heads interact with water; the nonpolar tails do not. -They have hydrophilic tails that face outward and are exposed to water and hydrophobic heads that face the center of the membrane and are shielded from water. -The polar heads repel water and the nonpolar tails attract water. -Phospholipids do not interact with water because they are lipids, and thus are hydrophobic
DNA helicase breaks which type of bond in the DNA molecule? Covalent bonds Ionic bonds Peptide bonds Hydrogen bonds
Hydrogen bonds
nonpolar molecules that repel water molecules.
Hydrophobic substances like salad oil are -nonpolar molecules that repel water molecules. -nonpolar molecules that have an affinity for water because they contain many hydrogens that can form hydrogen bonds with water. -polar molecules that repel water molecules. -polar molecules that have an affinity for water because they contain many hydrogens that can form hydrogen bonds with water.
glycoprotein
Identify Structure A a. Cholesterol b. extracellular matrix c. glycoprotein d. phospholipid e. protein
phospholipid bilayer of membrane
Identify Structure D a. extracellular matrix b. glycoprotein c. cholesterol d. protein e. phospholipid bilayer of membrane
Hypotonic
If a red blood cell is placed in a salt solution and bursts, what is the tonicity of the solution relative to the interior of the cell? a.Hypotonic b. Hypertonic c. Osmotic d. Isotonic
The water level would go down.
If more sugar were added to the solution on the left side of the tube, what would happen to the water level on the right side of the tube? -The water level would go down. -The water level would rise. -The water level would stay the same.
active transport
If the concentration of phosphate in the cytosol is 2.0 mM and the concentration of phosphate in the surrounding fluid is 0.1 mM, how could the cell increase the concentration of phosphate in the cytosol? a. passive transport b. diffusion c. active transport d. osmosis e. facilitated diffusion
The final water levels would be the same as shown in the figure, but the solutions would reach near equal concentrations faster.
If the pores in the selectively permeable membrane became larger, but still not large enough to let the sugar pass through, what would happen during osmosis in the U-shaped tube compared to what is shown in the figure? -More water could pass to the right side of the tube so the water level would rise even higher. -There would be less free water on the left side of the tube, so the water level on the right would not get as high. -The final water levels would be the same as shown in the figure, but the solutions would reach near equal concentrations faster. -Some water would be pushed back to the left side through the larger pores, so the water level on the right would not get as high.
Transport proteins provide a hydrophilic route for the solute to cross the membrane.
In facilitated diffusion, what is the role of the transport protein? -Transport proteins provide a hydrophilic route for the solute to cross the membrane. -Transport proteins organize the phospholipids to allow the solute to cross the membrane. -Transport proteins provide a protein site for ATP hydrolysis, which facilitates the movement of a solute across a membrane. -Transport proteins provide the energy for diffusion of the solute. -Transport proteins provide a low-resistance channel for water molecules to cross the membrane.
Transport proteins provide a hydrophilic route for the solute to cross the membrane.
In facilitated diffusion, what is the role of the transport protein? See Concept 7.3 (Page 135) -Transport proteins organize the phospholipids to allow the solute to cross the membrane. -Transport proteins provide a hydrophilic route for the solute to cross the membrane. -Transport proteins provide a protein site for ATP hydrolysis, which facilitates the movement of a solute across a membrane. -Transport proteins provide a low-resistance channel for water molecules to cross the membrane. -Transport proteins provide the energy for diffusion of the solute.
-Certain proteins are unique to each membrane.
In what way do the membranes of a eukaryotic cell vary? -Certain proteins are unique to each membrane. -Only certain membranes of the cell are selectively permeable. -Phospholipids are found only in certain membranes. -Some membranes have hydrophobic surfaces exposed to the cytoplasm, while others have hydrophilic surfaces facing the cytoplasm.
have difficulty crossing the hydrophobic part
Ions ( Na+, K+, Ca2+, Cl-): able to cross lipid bilayer
hydrophilic
Ions ( Na+, K+, Ca2+, Cl-): hydrophobic or hydrophilic
transport protein required to cross efficiently
Ions ( Na+, K+, Ca2+, Cl-): transport protein required
How does a scientist get the corrected version of a gene into the cells of a gene therapy patient? By attaching it to the surface of microscopic beads, it is then shot into the individual (i.e., shotgun method). It is directly injected with a microscopic hypodermic needle. It is delivered with a modified virus. By attaching it to a food molecule, like glucose, it is then ingested by the individual.
It is delivered with a modified virus.
For the hydrolysis of ATP to ADP + i, the free energy change is -7.3 kcal/mol under standard conditions (1 M concentration of both reactants and products). In the cellular environment, however, the free energy change is about -13 kcal/mol. What can we conclude about the free energy change for the formation of ATP from ADP and i under cellular conditions? It is less than +7.3 kcal/mol. It is greater than +13 kcal/mol. It is about +13 kcal/mol. It is +7.3 kcal/mol. The information given is insufficient to deduce the free energy change.
It is greater than +13 kcal/mol.
When ATP releases some energy, it also releases inorganic phosphate. What happens to the inorganic phosphate in the cell? -It is secreted as waste. -It may be used to form a phosphorylated intermediate. -It enters the nucleus and affects gene expression. -It is used only to regenerate more ATP. -It is added to water and excreted as a liquid.
It may be used to form a phosphorylated intermediate.
Select the correct statement about chemical energy, a term used by biologists to refer to potential energy available for release in a chemical reaction. -A photosynthetic cell within a plant leaf produces chemical energy, stored within glucose molecules. -Light energy is converted to chemical energy during photosynthesis. -When a glucose molecule is catabolized to CO2 and H2O, chemical energy is lost.
Light energy is converted to chemical energy during photosynthesis.
Which of the following is true of metabolism in its entirety in all organisms? Metabolism depends on a constant supply of energy from food. Metabolism manages the increase of entropy in an organism. Metabolism uses all of an organism's resources. Metabolism consists of all the energy transformation reactions in an organism. Metabolism depends on an organism's adequate hydration.
Metabolism consists of all the energy transformation reactions in an organism.
Is most of our DNA made up of genes? Yes, the vast majority of human DNA consists of genes. No, genes make up only 1.5% of our DNA.
No, genes make up only 1.5% of our DNA.
hydrophobic
Nonpolar molecules (hydrocarbons, O2, CO2) Hydrophobic or Hydrophilic?
can cross easily
Nonpolar molecules (hydrocarbons, O2, CO2) able to cross lipid bilayer
no transport protein required
Nonpolar molecules (hydrocarbons, O2, CO2) transport protein required?
transport protein
Structure A in the figure is a(n) _____. a. receptor molecule b. structural protein c. transport protein d. antibody e. enzyme
In a biological reaction, succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, a substance that resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the amount of succinate molecules to those of malonic acid reduces the inhibitory effect if malonic acid. Select the correct identification of the molecules described in the reaction. -Succinate dehydrogenase is the enzyme, and fumarate is the substrate in the reaction. -Fumarate is the product, and malonic acid is a noncompetitive inhibitor in the reaction. -Succinate is the substrate, and fumarate is the product in the reaction. -Succinate dehydrogenase is the enzyme, and malonic acid is the substrate in the reaction.
Succinate is the substrate, and fumarate is the product in the reaction.
According to the base pairing rules of DNA, if the sequence of bases on one strand was AGGCTTA, what would be the sequence of bases on the complementary strand? AGGCTTA ATTCGGA TCCGAAT CGGATTC
TCCGAAT
Which of the following is NOT a way in which an enzyme can speed up the reaction that it catalyzes? -The binding of two substrates in the active site provides the correct orientation for them to react to form a product. -Binding of the substrate to the active site can stretch bonds in the substrate that need to be broken. -The active site can provide heat from the environment that raises the energy content of the substrate. -The enzyme binds a cofactor that interacts with the substrate to facilitate the reaction. - The active site of the enzyme can provide a microenvironment with a different pH that facilitates the reaction.
The active site can provide heat from the environment that raises the energy content of the substrate.
What is different from one DNA nucleotide to the next? The base The phosphate group The sugar molecule The protein
The base
Which of the following statements about ATP (adenosine triphosphate) is correct? The hydrolysis of ATP is an endergonic process. Almost all of the free energy released on the hydrolysis of ATP is released as heat. The cycling between ATP and ADP + Pi provides an energy coupling between catabolic and anabolic pathways. The hydrolysis of ATP can supply energy needed for catabolic pathways. The energy release on hydrolysis of ATP is the result of breaking a high-energy bond.
The cycling between ATP and ADP + Pi provides an energy coupling between catabolic and anabolic pathways.
Which of the following statements about the combustion of glucose with oxygen to form water and carbon dioxide (C6H12O6 + 6 O2 → 6 CO2 + 6 H2O) is correct? -The free energy lost in this combustion is less than the energy that appears as heat. - The reverse reaction, making glucose from water and carbon dioxide, must be an exergonic reaction. - The entropy of the universe decreases as the result of this reaction. -The entropy of the products is greater than the entropy of the reactants. - This is the process of cellular respiration, an anabolic pathway that releases free energy.
The entropy of the products is greater than the entropy of the reactants.
You have added an irreversible inhibitor to a sample of enzyme and substrate. At this point, the reaction has stopped completely. What can you do to regain the activity of the enzyme? -Removing the irreversible inhibitor should get the reaction working again. - The enzyme is inactive at this point. New enzyme must be added to regain enzyme activity. -Adding more substrate will increase the rate of reaction. -Adding more inhibitor should get the reaction up to speed again.
The enzyme is inactive at this point. New enzyme must be added to regain enzyme activity.
Which of the following statements about feedback regulation of a metabolic pathway is correct? -Accumulation of the product of the pathway increases further formation of that product. -The compound that regulates the pathway acts as a competitive inhibitor or a positive allosteric regulator. -The enzyme that is regulated by feedback inhibition is usually the last enzyme in the metabolic pathway. -The final product of a metabolic pathway is usually the compound that regulates the pathway. -The products of the pathway become the reactants for a different reaction, and thus products are unable to accumulate.
The final product of a metabolic pathway is usually the compound that regulates the pathway.
What is the free energy change (ΔG) of the hydrolysis of ATP to ADP?
The free-energy change (ΔG) of the hydrolysis of ATP to ADP and Pi may vary considerably with variations in pH, temperature, atmospheric pressure, and concentrations of reactants and products.
Why can a person who is unable to produce insulin be successfully treated with insulin derived from genetically modified bacteria? The insulin-producing gene of bacteria was altered to have the same base sequence as the human counterpart and now produces the human version of insulin. The gene that produces insulin in humans was inserted into the bacteria where it continues to produce human insulin. Typical bacterial insulin is exactly the same as human insulin. Bacterial insulin is similar enough to human insulin to serve the same purpose.
The gene that produces insulin in humans was inserted into the bacteria where it continues to produce human insulin.
For living organisms, which of the following is an important consequence of the first law of thermodynamics? The energy content of an organism is constant. The entropy of an organism decreases with time as the organism grows in complexity. Organisms grow by converting energy into organic matter. The organism ultimately must obtain all of the necessary energy for life from its environment. Life does not obey the first law of thermodynamics.
The organism ultimately must obtain all of the necessary energy for life from its environment.
the types of transport proteins in the membrane
The permeability of a biological membrane to a specific polar solute depends primarily on which of the following? -The amount of cholesterol in the membrane -the types of transport proteins in the membrane -the phospholipid composition of the membrane -the presence of unsaturated fatty acids in the membrane -the types of polysaccharides present in the membrane
the types of transport proteins in the membrane
The permeability of a biological membrane to a specific polar solute may depend on which of the following? a. the amount of cholesterol in the membrane b. the types of transport proteins in the membrane c.the phospholipid composition of the membrane d. the presence of unsaturated fatty acids in the membrane e. the types of polysaccharides present in the membrane
Which of the following is true for all exergonic reactions? -The reaction proceeds with a net release of free energy. - A net input of energy from the surroundings is required for the reactions to proceed. -The reactions are rapid. - The products have more total energy than the reactants. - The reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants.
The reaction proceeds with a net release of free energy.
Three of the following statements are correct. Identify the statement that is not correct regarding genetically modified organisms. There are no risks associated with GM crops. GM crops have been produced with increased nutrition. GM crops have been produced that are disease resistant. GM animals are not in our food supply.
There are no risks associated with GM crops.
What is the role of primers in the PCR techniques? To target specific areas of DNA To add free nucleotides to the newly formed DNA molecule To allow single strands of DNA to bind together To separate strands of double-stranded DNA
To target specific areas of DNA
True
True or false? Osmosis is a type of diffusion.
True
True or false? The water-soluble portion of a phospholipid is the polar head, which generally consists of a glycerol molecule linked to a phosphate group.
solute
What are the triangles in the facilitated diffusion? a. solute b. water molecule c. phospholipid d. solvent e. transport protein
d. Oxygen (O2)
Which of the following particles could diffuse easily through a cell membrane? a. Hydrogen ion (H+) b. Sodium ion (Na+) c. Glucose d. Oxygen (O2)
a. Water molecules move between the two solutions, but there is no net movement of water across the membrane.
What happens when two solutions separated by a selectively permeable membrane reach osmotic equilibrium? a. Water molecules move between the two solutions, but there is no net movement of water across the membrane. b. Water molecules continue to move from the hypotonic solution to the hypertonic solution. c. Water molecules no longer move between the solutions.
stabilization of the phospholipids
What is the function of Structure E? a. stabilization of the phospholipids b. cell-cell communication c. structural support of the cell d. detection of environmental change e. transport across the plasma membrane
transport protein
What is the purple round thing? a. solute b. transport protein c. phospholipid d. solvent e. water molecules
small and hydrophobic
What kinds of molecules pass through a cell membrane most easily? large polar small and ionic small and hydrophobic large and hydrophobic
c. Amphipathic nature
What property of dishwashing liquid (detergent) makes it useful to wash grease from pans? a. Hydrophobic nature b. Solubility in water c. Amphipathic nature d. Permeability
more concentrated; less concentrated
When molecules move down their concentration gradient, they move from where they are ___________ to where they are_____________
Which statement about the binding of enzymes and substrates is correct? When substrate molecules bind to the active site of the enzyme, the enzyme undergoes a slight change in shape. Substrate molecules fit into the active site of an enzyme like a key fits into a lock. Substrate molecules bind to the active site of the enzyme only by weak bonds, such as hydrogen bonds or hydrophobic attraction.
When substrate molecules bind to the active site of the enzyme, the enzyme undergoes a slight change in shape.
small ions
Which of the following are least likely to diffuse through the phospholipid bilayer of a cell membrane? small ions carbon dioxide small hydrophobic molecules large hydrophobic molecules
two layers of phospholipids with proteins either crossing the layers or on the surface of the layers
Which of the following best describes the structure of a biological membrane? a. two layers of phospholipids with proteins either crossing the layers or on the surface of the layers b. two layers of phospholipids with proteins embedded between the two layers c. a mixture of covalently linked phospholipids and proteins that determines which solutes can cross the membrane and which cannot d. two layers of phospholipids (with opposite orientations of the phospholipids in each layer) with each layer covered on the outside with proteins e. a fluid structure in which phospholipids and proteins move freely between sides of the membrane
two layers of phospholipids with proteins either crossing the layers or on the surface of the layers
Which of the following best describes the structure of a biological membrane? -a mixture of covalently linked phospholipids and proteins that determines which solutes can cross the membrane and which cannot -two layers of phospholipids with proteins either crossing the layers or on the surface of the layers -two layers of phospholipids with proteins embedded between the two layers -two layers of phospholipids (with opposite orientations of the phospholipids in each layer) with each layer covered on the outside with proteins -a fluid structure in which phospholipids and proteins move freely between sides of the membrane
The polarity of membrane phospholipids
Which of the following factors does not affect membrane permeability? a. The saturation of hydrocarbon tails in membrane phospholipids b. The amount of cholesterol in the membrane c. The polarity of membrane phospholipids d. Temperature
a greater proportion of unsaturated phospholipids
Which of the following factors would tend to increase membrane fluidity? a. a relatively high protein content in the membrane b. a greater proportion of saturated phospholipids c. a greater proportion of relatively large glycolipids compared with lipids having smaller molecular masses d. a lower temperature e. a greater proportion of unsaturated phospholipids
Most prokaryotic cells have no internal membranes; eukaryotic cells do.
Which of the following is a major difference between prokaryotic and eukaryotic cells? -Prokaryotic cells have no phospholipids; eukaryotic cells do. -Prokaryotic cells have no DNA; eukaryotic cells have DNA. -Most prokaryotic cells have no internal membranes; eukaryotic cells do. -Eukaryotic cells have a plasma membrane, whereas prokaryotic cells do not.
covalent interactions between the phospholipid and protein components of the membrane
Which of the following is least likely to be important in holding the components of a biological membrane together? a. hydrophobic interactions between the phospholipid tails and the surface of integral membrane proteins buried in the membrane b. hydrophobic interactions among the fatty acid tails of phospholipids on opposite sides of the membrane c. polar interactions among the phospholipid head groups on the same surface of the membrane d. covalent interactions between the phospholipid and protein components of the membrane e. hydrophobic interactions among the fatty acid tails of phospholipids on the same side of the membrane
movement of Na+ ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid
Which of the following membrane activities requires energy from ATP hydrolysis? -movement of carbon dioxide out of a paramecium -movement of glucose molecules into a bacterial cell from a medium containing a higher concentration of glucose than inside the cell -facilitated diffusion of chloride ions across the membrane through a chloride channel -movement of Na+ ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid
aquaporins
Which of the following molecules dramatically increases the rate of diffusion of water across cell membranes? -ATP -gated ion channels -aquaporins -the sodium-potassium pump
passive transport
Which of the following processes includes all of the others? -transport of an ion down its electrochemical gradient -facilitated diffusion -passive transport -osmosis
It exhibits specificity for a particular type of molecule.
Which of the following statements describes a characteristic feature of a carrier protein in a plasma membrane? -It exhibits specificity for a particular type of molecule. -It has no hydrophobic regions. -It requires the expenditure of cellular energy to function. -It works against diffusion.
Both sodium and potassium ions are transported against their concentration gradients
Which of the following statements is TRUE with regard to this animation? -Both sodium and potassium ions are transported against their concentration gradients. -Sodium ions are transported down their concentration gradient. -Potassium ions are transported down their concentration gradient. -The cell does not expend ATP. -The cell is not expending energy.
The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.
Which of the following statements is a reasonable explanation for why unsaturated fatty acids help keep a membrane more fluid at lower temperatures? -The double bonds block interaction among the hydrophilic head groups of the lipids. -The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly. -Unsaturated fatty acids have a higher cholesterol content, which prevents adjacent lipids from packing tightly. -Unsaturated fatty acids are more nonpolar than saturated fatty acids.
B, C, and D
Which of these cannot rapidly pass directly through the phospholipids of the plasma membrane? C only B, C, and D A only B only D only
Are there ways to prevent cancer? No, cancer cannot be prevented or treated. Yes, there are many ways cancer can be prevented, including through a healthy diet and exercise. Yes, cancer can be prevented, but only with intense exercise. No, cancer cannot be prevented; it can only be treated.
Yes, there are many ways cancer can be prevented, including through a healthy diet and exercise.
A series of enzymes catalyze the reaction X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. What is substance X? an allosteric inhibitor a substrate the product a coenzyme an intermediate
a substrate
The process of cellular respiration, which converts simple sugars such as glucose into CO2 and water, is an example of _____. an endergonic pathway a pathway that converts organic matter into energy a pathway that occurs in animal cells but not plant cells a catabolic pathway a pathway in which the entropy of the system decreases
a catabolic pathway
Chemical equilibrium is relatively rare in living cells. Which of the following could be an example of a reaction at chemical equilibrium in a cell? -a chemical reaction in which both the reactants and products are not being produced or used in any active metabolic pathway at that time in the cell - an endergonic reaction in an active metabolic pathway where the energy for that reaction is supplied only by heat from the environment - no possibility of having chemical equilibrium in any living cell - a reaction in which the free energy at equilibrium is higher than the energy content at any point away from equilibrium -a chemical reaction in which the entropy change in the reaction is just balanced by an opposite entropy change in the cell's surroundings
a chemical reaction in which both the reactants and products are not being produced or used in any active metabolic pathway at that time in the cell
Which of the following is an example of cooperatively? -the binding of an end product of a metabolic pathway to the first enzyme that acts in the pathway -the effect of increasing temperature on the rate of an enzymatic reaction -one enzyme in a metabolic pathway passing its product to act as a substrate for the next enzyme in the pathway -binding of an ATP molecule along with one of the substrate molecules in an active site -a molecule binding at one unit of a tetramer, allowing faster binding at each of the other three
a molecule binding at one unit of a tetramer, allowing faster binding at each of the other three
Which of the following types of reactions would decrease the entropy within a cell? digestion catabolic reactions respiration anabolic reactions hydrolysis
anabolic reactions
Hydrophilic
because the phosphate group and its attachments are either charged or polar, the phospholipid head is ________which means it has an affinity for water.
In your body, what process converts the chemical energy found in glucose into the chemical energy found in ATP? - cellular respiration -redox - anabolism - digestion - potentiation
cellular respiration
When you have a severe fever, what grave consequence may occur if the fever is not controlled? - binding of your enzymes to inappropriate substrates - destruction of your enzymes' primary structure - change in the tertiary structure of your enzymes - removal of the amino acids in active sites of your enzymes - removal of amine groups from your proteins
change in the tertiary structure of your enzymes
Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as a(n) - coenzyme derived from a vitamin. -allosteric activator of the enzyme. -cofactor necessary for enzyme activity. -noncompetitive inhibitor of the enzyme. -competitive inhibitor of the enzyme.
cofactor necessary for enzyme activity.
A _______________ inhibitor has a structure that is so similar to the substrate that it can bond to the enzyme just like the substrate.
competitive
Increasing the substrate concentration in an enzymatic reaction could overcome which of the following? allosteric inhibition saturation of the enzyme activity competitive inhibition insufficient cofactors denaturation of the enzyme
competitive inhibition
A chemical reaction that has a positive ΔG is best described as exergonic. entropic spontaneous. endergonic. enthalpic.
endergonic
"Conservation of energy" refers to the fact that _____. -the net amount of disorder is always increasing - if you conserve energy you will not be as tired - no chemical reaction is 100 percent efficient - energy cannot be created or destroyed but can be converted from one form to another - the entropy of the universe is always increasing
energy cannot be created or destroyed but can be converted from one form to another
What is the correct label for "A"?
energy of activation
When the noncompetitive inhibitor is bonded to the enzyme , the shape of the ___________ is distorted.
enzyme
The following question is based on the reaction A + B ↔ C + D shown in the figure. Which of the following terms best describes the forward reaction in the figure?
exergonic G<0
A collection of cloned DNA fragments representing the organism's entire genome is called a ________. genomic library complementary DNA collection clonal anthology transgenic assembly
genomic library
Which of these are by-products of cellular respiration? - heat, carbon dioxide, and water -carbon dioxide and water -glucose, carbon dioxide, and water - ATP and carbon dioxide - ATP, carbon dioxide, and water
heat, carbon dioxide and water
What type of reaction breaks the bonds that join the phosphate groups in an ATP molecule?
hydrolysis
An enzyme _____. can bind to nearly any molecule is a inorganic catalyst increases the EA of a reaction is an organic catalyst is a source of energy for endergonic reactions
is an organic catalyst
As a result of its involvement in a reaction, an enzyme _____. loses energy permanently alters its shape. is unchanged is used up loses a phosphate group
is unchanged
Gel electrophoresis separates DNA fragments according to their ________. polarity charge length base sequences
length
Besides turning enzymes on or off, what other means does a cell use to control enzymatic activity? -hydrophobic interactions -connecting enzymes into large aggregates -localization of enzymes into specific organelles or membranes -cessation of cellular protein synthesis - exporting enzymes out of the cell
localization of enzymes into specific organelles or membranes
The spread of cancer cells from their site of origin to sites distant in the body is called ________. transformation growth metastasis mitosis
metastasis
A _____________ inhibitor binds to a site on the enzyme that is not the active site.
noncompetitive
Which of the following statements is most likely to be true in the case of the feedback-regulated enzymatic pathway shown?
p4 binds E1 and deactivates it
The small circular molecules of DNA commonly found in bacteria are called ________. chromatids chromophores plasmids plastids
plasmids
chemical energy is a form of ________ energy
potential energy
Gene cloning is used to ________. produce large quantities of human proteins cure genetic disorders help cure cancer make other organisms, such as Dolly, the first cloned sheep
produce large quantities of human proteins
In general, enzymes are what kinds of molecules?
proteins
Enzymes work by _____. increasing the potential energy difference between reactant and product decreasing the potential energy difference between reactant and product adding energy to a reaction reducing EA adding a phosphate group to a reactant
reducing EA
The type of mutation that alters the nucleotide sequence of a gene but does not alter the amino acid sequence of the protein produced from that gene is called ________ mutation. frameshift silent missense nonsense
silent
Enzyme inhibitors disrupt normal interactions between an enzyme and its .________________
substrate
What name is given to the reactants in an enzymatically catalyzed reaction?
substrate
A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because - the starch solution has less free energy than the sugar solution. - starch hydrolysis is nonspontaneous. - starch cannot be hydrolyzed in the presence of so much water. - the hydrolysis of starch to sugar is endergonic. - the activation energy barrier for this reaction cannot easily be surmounted at room temperature.
the activation energy barrier for this reaction cannot easily be surmounted at room temperature.
Protein kinases are enzymes that catalyze phosphorylation of target proteins at specific sites, whereas protein phosphatases catalyze removal of phosphate(s) from phosphorylated proteins. Phosphorylation and dephosphorylation can function as an on-off switch for a protein's activity, most likely through -the excision of one or more peptides. - the change in a protein's charge leading to a conformational change. -a change in the optimal pH at which a reaction will occur. -the change in a protein's charge leading to cleavage. -a change in the optimal temperature at which a reaction will occur.
the change in a protein's charge leading to a conformational change.
Energy is observed in two basic forms: potential and kinetic. Which of the following correctly matches these forms with a source of energy? -the covalent bonds of a sugar molecule: potential energy - the motion of individual molecules: potential energy -the energy related to the height of a bird above the ground: kinetic energy - the energy associated with a gradient of ions across a membrane: kinetic energy - the heat released from a living organism: potential energy
the covalent bonds of a sugar molecule: potential energy the bonds in covalent bonds create energy from the relative positions that form the bonds
Which of the following statements about the role of ATP in cell metabolism is true? - The energy from the hydrolysis of ATP may be directly coupled to endergonic processes by the transfer of the phosphate group to another molecule. -The free energy released by ATP hydrolysis has a much more negative ΔG value than the hydrolysis of phosphate groups from other phosphorylated molecules. -The phosphate bonds of ATP are unusually strong bonds.
the energy from the hydrolysis of ATP may be directly coupled to endergonic processes by the transfer of the phosphate group to another molecule.
how do cells use the ATP cycle shown above?
to recycle ADP and Phosphate
Genetically modified organisms that acquire genes from a different species are called ________ organisms. synthetic cloned mutant transgenic
transgenic
Cancer is ________. cells with proto-oncogene activated any tumor in the body what happens when cells get old uncontrolled cell growth
uncontrolled cell growth
DNA profiling relies on an individual's ________, no two of which are the same between different people, except identical twins. unique fingerprints unique set of short tandem repeats within DNA unique set of genes unique mRNA sequences
unique set of short tandem
The mathematical expression for the change in free energy of a system is ΔG =ΔH - TΔS. Which of the following is (are) correct? T is the temperature in degrees Celsius. ΔH is the change in entropy, the energy available to do work. ΔG is the change in free energy. ΔS is the change in enthalpy, a measure of randomness.
ΔG is the change in free energy.
Which part of the adenosine triphosphate molecule is released when it is hydrolyzed to provide energy for biological reactions? α -phosphate (the phosphate closest to ribose) β-phosphate (the middle phosphate) γ-phosphate (the terminal phosphate) adenine group ribose sugar
γ-phosphate (the terminal phosphate)