BIO151 Final Exam ( - Exam 5 terms)

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You have isolated a previously unstudied protein, identified its complete structure in detail, and determined that it catalyzes the breakdown of a large substrate. You notice it has two binding sites. One of these is large, apparently the bonding site for the large substrate; the other is small, possibly a binding site for a regulatory molecule. What do these findings tell you about the mechanism of this protein?

It is probably an enzyme that works through allosteric regulation.

Gramicidin is an antibiotic that increases the permeability of bacterial cell walls to inorganic ions. What is the most likely mode of action of gramicidin?

It forms a channel in the membrane

When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?

It is lost to the environment.

Which of the following statements about the DNA in one of your brain cells is TRUE?

It is the same as the DNA in one of your heart cells

When ATP releases some energy, it also releases inorganic phosphate. What happens to the inorganic phosphate in the cell?

It may be used to form a phosphorylated intermediate.

What is the function of the group of amino acids on the RNA polymerase, called the rudder?

It moves template and non-template strands of DNA through channels inside the enzyme.

What is the function of the nuclear pore complex found in eukaryotes?

It regulates the movement of proteins and RNAs into and out of the nucleus.

If you were reading off the sequence of amino acids in the figure to a biologist friend, what should the first three letters be? A) M-N-G B) A-P-A C) It does not matter, since the protein has no polarity or directionality.

M-N-G

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?

a substrate

If a cell were unable to produce histone proteins, which of the following would be a likely effect?

The cell's DNA couldn't be packed into its nucleus.

How does a scientific theory differ from a scientific hypothesis?

Theories are usually an explanation for a more general phenomenon; hypotheses typically address more specific issues

_____ in natural science are based on a LOT of evidence

Theory

Why are lipids and proteins free to move laterally in membranes?

There are only weak hydrophobic interactions in the interior of the membrane.

What is the difference (if any) between the structure of ATP and the structure of the precursor of the A nucleotide in RNA?

There is no difference.

The primary difference between enhancers and promoter-proximal elements is that enhancers ________.

are at considerable distances from the promoter; promoter-proximal elements are close to the promoter

In comparison to eukaryotes, prokaryotes ________.

are smaller

A hydrocarbon skeleton is covalently bonded to an amino group at one end and a carboxyl group at the other end. When placed in water this molecule would function ________. A) only as an acid because of the carboxyl group B) only as a base because of the amino group C) as an acid and a base D) as neither an acid nor a base E) It is impossible to determine how it would function, based on the information provided.

as an acid and a base

A noncompetitive inhibitor decreases the rate of an enzyme reaction by _____.

changing the shape of the enzyme's active site

Cells are ______.

characteristics of prokaryotic and eukaryotic organisms

The difference in lipid and protein composition between the membranes of the endomembrane system is largely determined by

function of the golgi apparatus in sorting and directing membrane components

Beadle and Tatum discovered that metabolic pathways are studied most effectively using which of the following techniques?

Using single gene mutations resulting in nonfunctional enzymes specific to a metabolic pathway

Which one of the following is NOT a component of each monomer used to make proteins? A) a phosphorus atom, P B) an amino functional group, NH2 C) a side chain, R D) a carboxyl group, COOH

a phosphorus atom, P

What is responsible for termination of transcription in eukaryotic protein-coding genes?

a polyadenylation, or poly(A), signal

In negative control, a gene is switched off when ________.

a regulatory protein binds to DNA and shuts down transcription

If a molecular biologist deleted a sequence of DNA outside the protein-coding region of a gene and found that this increased the rate of transcription, the deleted sequence likely functions as ________.

a silencer

Which of the following mutations is most likely to cause a phenotypic change?

a single nucleotide deletion in an exon coding for an active site

During elongation, RNA polymerase has three prominent channels, or grooves. These channels provide sites for all of the following EXCEPT ________.

a site for the exit of the diphosphates removed from the nucleotide triphosphates

Some of the proteins that are to be released or will eventually find their way to the cell membrane need to be modified with addition of polysaccharides (sugars). This type of protein maturation is likely to occur in ______.

the Golgi apparatus

An example of a basal transcription factor is ________.

the TATA-binding protein

Death cap mushrooms produce a substance called alpha-amanitin. Alpha-amanitin efficiently blocks synthesis of mRNA, but not of tRNA or rRNA, in eukaryotic organisms. This is possible because alpha-amanitin efficiently interferes with

the action of RNA polymerase II, but not RNA polymerase I or III

A solution of starch at room temperature does NOT readily decompose to form a solution of simple sugars because ________.

the activation energy barrier for this reaction cannot easily be surmounted at room temperature

What ensures that the correct amino acid is added during translation?

the anticodon of a properly formed aminoacyl tRNA

According to the induced fit hypothesis of enzyme catalysis, ________.

the binding of the substrate changes the shape of the enzyme's active site

Eukaryotic telomeres replicate differently than the rest of the chromosome. This is a consequence of which of the following?

gaps left at the 5' end of the lagging strand

Phospholipids and triglycerides both ________. A) contain serine or some other organic compound B) have three fatty acids C) have a glycerol backbone D) have a phosphate

have a glycerol backbone

Recall Pasteur's experiment on spontaneous generation. If he had just warmed the nutrient-rich brother, rather than boiled it, what would have been the likely outcome of his experiment? Cells would ______.

have appeared in both flasks

If you were to observe the activity of methylated DNA (gene promoter or protein coding sequence), you would expect it to ________.

have turned off or slowed down the process of transcription

The greatest expression of the lac operon occurs when lactose levels are ________

high and glucose levels are low

In a nucleosome, the DNA is wrapped around ________.

histones

DNA double helices are soluble in water because of all the following except ________ (This has an important practical application for DNA isolation (extraction): when DNA is in alcohol, it is insoluble white-powder-like material that biologists and chemists call "precipitate")

hydrogen at 2' C

Water has a high specific heat because of the _______.

hydrogen bond formed between the hydrogen of one water molecule and the oxygen of another water molecule

What type of bonding is responsible for maintaining the shape of the tRNA molecule?

hydrogen bonding between bases

The amino acids of the protein keratin are arranged predominantly in an α-helix. This secondary structure is stabilized by ________. A) covalent bonds B) peptide bonds C) ionic bonds D) polar bonds E) hydrogen bonds

hydrogen bonds

Why type of bond must be broken for water to vaporize?

hydrogen bonds

which type of interaction stabilizes the α-helix and the β-pleated sheet structures of proteins? A) hydrophobic interactions B) disulfide bonds C) ionic bonds D) hydrogen bonds E) peptide bonds

hydrogen bonds

Which of the following is true of osmosis?

in osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration

Which structure - function pair is mismatched?

microtubule - muscle contraction

which structure-function is wrong?

microtubule-muscle contraction

Movement of vesicles within the cell depends on what cellular structures?

microtubules and motor proteins

Refer to the figure associated with this question. The mRNA is smaller than the length of the DNA that codes for it because ________.

post-transcriptional modification removes the introns

Which of the following levels of gene expression allows the most rapid response to environmental change?

post-translational control

If cells are grown in a medium containing radioactive 35S, which of these molecules will be labeled? A) phospholipids B) nucleic acids C) proteins D) amylose E) proteins and nucleic acids

proteins

Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules?

proteins

Which of the following did Watson and Crick already know when they were trying to determine the structure of DNA? The number of ________.

purines is always the same as pyrimidines

Proteins coded for by nuclear DNA but found within mitochondria move from the cytoplasm into mitochondria using ________.

signal sequences (peptides)

An atom has four electrons in its valence shell. What types of covalent bonds is it capable of forming?

single, double, or triple

Which of the following help(s) to hold the DNA strands apart while they are being replicated?

single-strand DNA binding proteins

Which of the following is the most spontaneous reaction? A reaction that is ______.

slightly exothermic and leads to a huge increase in entropy

The liver is involved in detoxification of many poisons and drugs. Thus, liver cells are likely to have abundant ______.

smooth ER

You need to represent a molecule to best illustrate the relative sizes of the atoms involved and their interrelationships. Which representation would work best?

space-filing model

To act as an effective coolant in a car's radiator, a substance has to have the capacity to absorb a great deal of heat. You have a reference book with tables listing the physical properties of many liquids. In choosing a coolant for your car, which table would you check first?

specific heat

A friend of yours calls to say that his car would not start this morning. He asks for your help. You say that you think the battery must be dead. If so, then jump-starting the car from a good battery will solve the problem. In doing so, you are _____.

stating a hypothesis and using that hypothesis to make a testable prediction.

Catabolic pathways _____.

supply energy, primarily in the form of ATP, for the cell's work

Catabolic pathways ________.

supply energy, primarily in the form of ATP, for the cell's work

A cell with an extensive area of smooth endoplasmic reticulum is specialized to _____.

synthesize large quantities of lipids

At which level of protein structure are interactions between the side chains (R-groups) most important? A) primary B) secondary C) tertiary D) quaternary E) primary, secondary, tertiary, and quaternary

tertiary

Refer to the figure. Which level of structure is maintained by the disulfide bond? A) primary B) secondary C) tertiary D) quaternary

tertiary

A controlled experiment is one that ______.

tests experimental and control groups in parallel

Some bacteria are metabolically active in hot springs because ________.

their enzymes have high optimal temperatures

What feature of single nucleotides provides the energy needed for polymerization when nucleic acids are formed?

their phosphate groups

In all living species, DNA is the genetic material that codes for proteins (robots). In order for this, the DNA has to be ______ into messenger RNA (mRNA).

transcribed

The functioning of enhancers is an example of ________.

transcriptional control of gene expression

The first law of thermodynamics states that energy cannot be created or destroyed, but only ______ or transformed

transferred

Once a peptide bond has been formed between the amino acid attached to the tRNA in the P site and the amino acid associated with the tRNA in the A site, what occurs next?

translocation

Cells require which of the following to form cilia or flagella?

tubulin

What component of amino acid structure varies among different amino acids? A) the long carbon-hydrogen tails of the molecule B) the presence of a central C atom C) the components of the R-group D) the glycerol molecule that forms the backbone of the amino acid

the components of the R-group

What is a telomere?

the ends of linear chromosomes

When biological membranes are frozen and then fractured, they tend to break along the middle of the bilayer. The best explanation for this is that ________. a.the hydrophobic interactions that hold the membrane together are weakest at this point b. hydrophilic interactions between the opposite membrane surfaces are destroyed on freezing c. water that is present in the middle of the bilayer freezes and is easily fractured d. the carbon—carbon bonds of the phospholipid tails are easily broken the integral membrane proteins are not strong enough to hold the bilayer together

the hydrophobic interactions that hold the membrane together are weakest at this point.

The leading and the lagging strands differ in that ________.

the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction

The mathematical expression for the change in free energy of a system is ΔG=ΔH − TΔS. Which of the following is (are) correct?

ΔG is the change in free energy.

Which of the following is an example of post-transcriptional control of gene expression?

the removal of introns and alternative splicing of exons

The product of the lacI gene is ________.

the repressor

There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that ________.

the rules for base pairing between the third base of a codon and tRNA are flexible

Which of the following is the first event to take place in translation in eukaryotes?

the small subunit of the ribosome recognizing and attaching to the 5' cap of mRNA

What does it mean to say a system's energy is equal to zero?

the system is at equilibrium

Cilia and flagella bend because of ________.

a motor protein called dynein

Codons are three-base sequences that specify the addition of a single amino acid. How do eukaryotic codons and prokaryotic codons compare?

Codons are a nearly universal language among all organisms.

In E. coli, if RNA polymerase apoenzyme is missing ________, then transcription initiation would not occur

sigma

Transport vesicles with newly synthesized proteins bind to one side of the ______ and leave from the opposite side with mature proteins.

Golgi apparatus

When the atoms involved in a covalent bond have the same electronegativity, what type of bond results?

a nonpolar covalent bond

Which of the following crosses lipid bilayers the fastest?

A small, nonpolar molecule like oxygen (O2)

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?

-20 kcal/mol

An E. coli cell without a functional lacI gene is expected to ________.

always produce β-galactosidase

A solution with a pH of 10 has how many fewer protons in it than a solution with a pH of 7?

1000 times

A double-stranded DNA molecule contains a total of 120 purines and 120 pyrimidines. This DNA molecule could be composed of ________.

120 thymine and 120 adenine molecules

From its atomic number of 15, it is possible to predict that the phosphorus atom has ______.

15 protons and 15 electrons

A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is ________

3' UCA 5'

Put the following events of bacterial transcription in chronological order.1. Sigma binds to the promoter region.2. The double helix of DNA is unwound, breaking hydrogen bonds between complementary strands.3. Sigma binds to RNA polymerase.4. Sigma is released.5. Transcription begins.

3, 1, 2, 5, 4

Which of the following, if missing, would usually prevent translation from starting in eukaryotes?

5' cap or AUG codon

Which of the following pairs of base sequences could form a short stretch of a normal double helix of DNA?

5'-AGCT-3' with 5'-TCGA-3'

If the sequence in the coding strand of DNA for a particular amino acid is 5'AGT3', then the anticodon on the corresponding tRNA would be ________.

5'ACU3'

If one strand of a DNA molecule has the sequence of bases 5'ATTGCA3', the other complementary strand would have the sequence ________. Hint: you have to start in reverse because it is antiparallel.

5'TGCAAT3'

All of the following are polysaccharides EXCEPT _____. A) lactose B) glycogen C) chitin D) cellulose E) amylopectin

Upon chemical analysis, a particular polypeptide was found to contain 100 amino acids. How many peptide bonds are present in this protein? A) 101 B) 100 C) 99 D) 98 E) 97

Cell walls are used by many different organisms for protection from their environment and structural support. These cell walls must obviously be insoluble in water; otherwise, they would dissolve the first time an organism got wet. Which of the following carbohydrates would you expect to be most soluble in water? A) starch B) peptidoglycan C) cellulose D) chitin

Compare the molecular formula of a carbohydrate (CH2O)n with that of carbon dioxide (CO2). What does the presence of hydrogen atoms in carbohydrates indicate? A) Carbohydrates are more reduced than carbon dioxide. B) Carbohydrates are more oxidized than carbon dioxide. C) Every carbon atom in a carbohydrate is bonded to four different atoms. D) Carbohydrates contain a carbonyl functional group.

Enzymes that readily break starch apart cannot hydrolyze the glycosidic linkages found in cellulose. Why is this logical? A) The geometry of the bonds is different, and the shapes of enzyme active sites are highly specific. B) Starch is held together by hydrogen bonding, not covalent bonding. C) Cellulose molecules are highly branched, and enzymes are too bulky to fit. D) Starch is held together by peptide bonds, not glycosidic linkages.

How do the α and β forms of glucose differ? A) Their ring structures differ in the location of a hydroxyl group. B) Their linear structures differ in the location of a hydroxyl group. C) The α form can be involved in 1,4- and 1,6-glycosidic linkages; the β form can participate only in 1,4 linkages. D) The oxygen atom inside the ring is located in a different position.

Humans can digest starch but not cellulose because _____. A) humans have enzymes that can hydrolyze the α-glycosidic linkages of starch but not the β- glycosidic linkages of cellulose B) humans have enzymes that can hydrolyze the β-glycosidic linkages of starch but not the α- glycosidic linkages of cellulose C) starch monomers are joined by covalent bonds and cellulose monomers are joined by ionic bonds D) the monomer of starch is glucose, while the monomer of cellulose is galactose E) the monomer of starch is fructose, while the monomer of cellulose is glucose

If two molecules of the general type shown in the accompanying figure were linked together, carbon-1 of one molecule to carbon-4 of the other, the single molecule that would result would be _____. A) maltose B) fructose C) glucose D) galactose E) sucrose

Starch and cellulose _____. A) are polymers of glucose B) are cis-trans isomers of each other C) can be digested by humans D) are used for energy storage in plants E) are structural components of the plant cell wall

The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are in the α form. Which of the following could amylase break down? A) glycogen, starch, and amylopectin B) glycogen and cellulose C) cellulose and chitin D) starch and chitin E) starch, amylopectin, and cellulose

The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are the α form. Which of the following could amylase break down? A) starch B) cellulose C) chitin D) starch and chitin only E) starch, cellulose, and chitin

The following question is based on the reaction A + B ↔ C+ D shown in the accompanying figure. Which of the following represents the activation energy needed for the enzyme-catalyzed reverse reaction, C + D → A + B, in the figure?

The molecule shown in the accompanying figure is _____. A) a hexose B) a pentose C) a phosphate D) fructose E) maltose

What does the term insoluble fiber refer to on food packages? A) cellulose B) polypeptides C) starch D) amylopectin E) chitin

Which of the following can vary among monosaccharides? A) the number of carbon atoms B) the presence of a carbonyl group C) the presence of hydroxyl groups D) the presence of sulfur groups

Which of the following is NOT a polymer? A) glucose B) starch C) cellulose D) chitin E) DNA

Which of the following would you expect to have the most free energy per gram? The most free energy per gram would be found in a molecule with _____. A) carbon and hydrogen atoms only B) carbon, hydrogen, and oxygen atoms only C) a variety of atoms that are found in cells D) hydrogen and oxygen atoms only

Which of these best reflects the following relationship: monosaccharide versus polysaccharide? A) glucose versus glycogen B) glucose versus fructose C) 1,4-glycosidic linkage versus 1,6-glycosidic linkage D) α-linkage versus β-linkage

Which polysaccharide is an important component in the structure of many animals and fungi? A) chitin B) cellulose C) amylopectin D) amylose

Which of the following is a large organic molecule that is NOT assembled by polymerization of a few kinds of simple subunits?

A steroid

How does termination of translation take place?

A stop codon is reached

The solutions in the arms of a U-tube are separated at the bottom of the tube by a selectively permeable membrane. The membrane is permeable to sodium chloride but not to glucose. Side A is filled with a solution of 0.4 M glucose and 0.5 M sodium chloride (NaCl), and side B is filled with a solution containing 0.8 M glucose and 0.4 M sodium chloride. Initially, the volume in both arms is the same. If you examine side A after three days, you should find ________.

A decrease in the concentration of NaCl and a decrease in the water level

Which of the following observations may have resulted in the hypothesis that a codon is made up of three bases?

A codon of three bases in length, from four different bases, would code for a maximum of sixty-four different amino acids

The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following?

A gene from an organism can theoretically be expressed by any other organism

Which of the following factors would tend to increase membrane fluidity?

A greater proportion of saturated phospholipids

Which of the following effects can occur because of the high surface tension of water?

A raft spider can walk across the surface of a small pond

During elongation, which site in the ribosome represents the location where a codon is being read?

A site

Which of the following is most likely true of a protein that cotransports glucose and sodium ions into the intestinal cells of an animal?

A substance that blocks sodium ions from binding to the cotransport protein will also block the transport of glucose

A membrane protein that spans the phospholipid bilayer one or more times is ________.

A transmembrane protein

Which of the following nucleotide triplets best represents a codon?

A triplet in the same reading frame as an upstream AUG

A particular triplet of bases in the template sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is ________.

AAA

Misfolding of polypeptides is a serious problem in cells. Which of the following diseases are associated with an accumulation of misfolded polypeptides? A) Alzheimer's only B) Parkinson's only C) diabetes mellitus only D) Alzheimer's and Parkinson's only E) Alzheimer's, Parkinson's, and diabetes mellitus

Alzheimer's and Parkinson's only

Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when lactose enters the cell?

Allolactose binds to the repressor protein.

Which of the following is NOT synthesized from a DNA template?

Amino acids

Which of the following is TRUE for this reaction? 3H2 + N2 <----> 2NH3

Ammonia is being formed and decomposed simultaneously

Suppose several genes are grouped together in a bacterial genome and the group results in an assembly line of enzymes. If one of these genes is mutated and that enzyme is no longer active, this gene must be part of __________________

An Operon

Which of the following allows water to move much faster across cell membranes?

Aquaporins

One interesting and surprising finding regarding the regulation of the ara operon is that it is under both positive and negative control. What protein is responsible for the dual action of this operon?

AraC is responsible for both the positive and negative control of the ara operon.

Lipids ________.

Are insoluble in water

Steroids are considered to be lipids because they ________.

Are not soluble in water

A glycosidic linkage is analogous to which of the following in proteins? A) an amino group B) a peptide bond C) a disulfide bond D) a β-pleated sheet

Dairy cattle were unknown in Thai culture until recently, and 97 percent of Thai people are lactose intolerant as adults. Which explanation for such widespread lactose intolerance is most likely correct? A) Allergies are becoming more common in humans as more chemicals are being encountered during longer lifetimes. B) Evolutionarily, producing an enzyme to break down a sugar that will never be encountered is wasteful. C) The ability to digest sugar in milk is determined by environment, and most humans are not exposed to milk as a food source beyond childhood years. D) There is no good explanation for this situation in humans.

Glucose (C6H12O6) has a single carbonyl group (-C=O) in its linear form. Based on the number of oxygen atoms in glucose, how many hydroxyl groups (-OH) would you expect glucose to have? A) 6 B) 5 C) 3 D) 1

How do carbohydrates contain and/or display information for cells? A) Carbohydrates store information in the nucleus. B) Carbohydrates contain and display information at the cell surface. C) Carbohydrates display information used by mitochondria to bond to substrates and catalyze reactions. D) Carbohydrates have no role in containing or displaying information for cells.

The molecular formula for glucose is C6H12O6. What would be the molecular formula for a molecule made by linking three glucose molecules together by dehydration reactions? A) C18H36O18 B) C18H32O16 C) C6H10O5 D) C18H30O15 E) C3H6O3

Which of the following do starch and cellulose have in common? A) the type of glycosidic linkage used B) the size of their monosaccharide subunits C) the amount of hydrogen bonding that occurs between parallel strands D) their main function in plants

Which of the following represents the activation energy required for the enzyme-catalyzed reaction in the figure?

Why do plants require sunlight? A) Sunlight helps plants break down their food products so they can extract the energy stored in them. B) Sunlight energy can be used by plants to reduce the carbon atoms in carbon dioxide. C) Sunlight oxidizes carbon dioxide and water to form glucose. D) Sunlight can be used directly by plants to perform a number of physiological processes.

You isolate an organic molecule that contains C, H, O, N, and S. This molecule _____. A) is a disaccharide B) could be a glycoprotein C) is a nucleic acid D) could be cellulose or glycogen

Which of the following is the best explanation for why cholesterol decreases the permeability of biological membranes?

Because cholesterol is amphipathic, it fits in between the phospholipids and blocks diffusion through the membrane.

Which of the following linkages would you expect to find at a branch point in glycogen or amylopectin? A) α-1,4-glycosidic linkage B) β-1,4-glycosidic linkage C) α-1,6-glycosidic linkage D) β-1,6-glycosidic linkage

Chitin is a major component of the _____. A) skeleton of mammals B) hydrostatic skeletons of earthworms C) exoskeleton of insects D) body hairs of mammals E) skeleton in birds

Diffusion _____. A) is very rapid over long distances B) requires an expenditure of energy by the cell C) is a passive process in which molecules move from a region of higher concentration to a region of lower concentration D) is an active process in which molecules move from a region of lower concentration to one of higher concentration E) requires integral proteins in the cell membrane

If you were going to develop a new antibiotic against bacteria, you would probably need to become an expert on which of these carbohydrates? A) glycogen B) chitin C) peptidoglycan D) cellulose E) starch

In the metabolic pathway illustrated below, If all products (A-F) are essential for survival, then a strain mutant for the gene encoding enzyme 2 would be able to grow only if the medium was supplemented with ________

Peptidoglycan forms sheets that stiffen the cell walls of bacteria. How is the formation of sheets possible? A) The polysaccharides in peptidoglycan are highly branched and form a network. B) The glycosidic linkages between monosaccharides in peptidoglycan are extraordinarily strong. C) Individual strands are joined by peptide bonds, a type of covalent bond. D) The polysaccharides in peptidoglycan form helical structures, as in cellulose.

Refer to the associated figure. In the branched metabolic pathway indicated in the figure, if enzyme 4 is defective and the amount of each enzyme is constant, you might expect to see an increase in the amount of which intermediate or product?

The molecular formula for glucose is C6H12O6. What would be the molecular formula for a polymer made by linking ten glucose molecules together by dehydration reactions? A) C60H120O60 B) C6H12O6 C) C60H102O51 D) C60H100O50 E) C60H111O51

What is the difference between an aldose sugar and a ketose sugar? A) the number of carbons B) the position of the hydroxyl groups C) the position of the carbonyl group D) One is a ring form, the other is a linear chain

Which of the following best explains why "carbs" (carbohydrates) are advertised by manufacturers of candy bars and sports drinks as a "quick energy boost"? A) The energy in them can be stored as fat, which has high energy per unit weight. B) The carbons in carbohydrates are rich in energy because they are highly oxidized. C) Carbohydrates are reduced molecules that have high-energy electrons. D) This is an advertising gimmick that has no scientific evidence to support it.

Which of the following structural features is common to cellulose, chitin, and peptidoglycan? A) They are all composed of glucose in either the α or β form. B) They all contain peptide bonds. C) They can all form bonds between polymer chains that create parallel strands. D) They are all composed of highly branched fibers.

Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly?

CO2

Alternative RNA splicing ________.

Can allow the production of proteins of different sizes and functions from a single mRNA

Bacterial and eukaryotic cells primarily control gene expression at the level of transcription. If instead cells exerted control of gene expression primarily at the post-translational level, what would be different?

Cells would expend significantly more energy.

Which of the following statements is representative of the second law of thermodynamics?

Cells require a constant input of energy to maintain their high level of organization.

How do cells use the ATP cycle shown in the figure?

Cells use the cycle to recycle ADP and phosphate.

Under what condition is the AraC protein an activator? The AraC protein is an activator when it is bound to _______.

arabinose

The statement "DNA → RNA → Proteins" ________

Central Dogma

_______ us the process by which DNA is read to make proteins in ALL cells on Earth.

Central dogma

In what way do the membranes of a eukaryotic cell vary?

Certain proteins are unique to each membrane.

Thylakoids, DNA, and ribosomes are all components found in ______.

Chloroplast

Which of the following involves a decrease in entropy?

condensation reactions

You have just sequenced a new protein found in mice and observe that sulfur-containing cysteine residues occur at regular intervals. What is the significance of this finding? A) Cysteine residues are required for the formation of α-helices and β-pleated sheets. B) It will be important to include cysteine in the diet of the mice. C) Cysteine residues are involved in disulfide bridges that help form tertiary structure. D) Cysteine causes bends, or angles, to occur in the tertiary structure of proteins.

Cysteine residues are involved in disulfide bridges that help form tertiary structure.

Bacteria, insects, and plants use carbohydrates to build structures. Which of the following is true of structural carbohydrates? A) Different types of pentose monomers form the basis of all carbohydrate-based structures. B) Structural carbohydrates show a high degree of branching. C) All structural carbohydrates are made from the same monomer, α-glucose. D) Structural carbohydrates are long strands, which are chemically linked into a network.

Cellulose is _____. A) a polymer composed of fructose monomers B) a storage polysaccharide for energy in plant cells C) used by plants to make glycogen D) a major structural component of plant cell walls E) a monomer of starch.

Lactose, a sugar in milk, is composed of one glucose molecule joined by a glycosidic linkage to one galactose molecule. How is lactose classified? A) as a pentose B) as a hexose C) as a monosaccharide D) as a disaccharide E) as a polysaccharide

Refer to the paragraph about Kawakubo's group. Kawakubo's group created a glycoprotein with a terminal NAG (i.e., a protein with NAG attached to its end). Their hypothesis is that the terminal NAG, and not the protein component, is responsible for the damage to the cell wall in H. pylori. What would be the most appropriate control for testing this hypothesis? A) Grow H. pylori in a test tube (in vitro) with no glycoprotein. B) Destroy the H. pylori by exposing them to a hypotonic solution. Then add the glycoprotein and observe. C) Expose other species of bacteria to the glycoprotein. D) Grow H. pylori in a test tube with a glycoprotein that has its terminal NAG removed.

The following question is based on the reaction A + B ↔ C + D shown in the accompanying figure. Which of the following in the figure would be the same in either an enzyme-catalyzed or a noncatalyzed reaction?

What is the major structural difference between starch and glycogen? A) the types of monosaccharide subunits in the molecules B) the type of glycosidic linkages in the molecule C) whether glucose is in the α or β form D) the amount of branching that occurs in the molecule

What role, if any, did polysaccharides play in chemical evolution? A) Polysaccharides catalyzed chemical reactions. B) Polysaccharides used complementary pairing between monosaccharides to copy themselves. C) Glycosidic linkages formed spontaneously between monosaccharides. D) Polysaccharides played little, if any, role in chemical evolution.

Which component is a peripheral protein?

Which of the following categories includes all others in the list? A) monosaccharide B) disaccharide C) starch D) carbohydrate E) polysaccharide

Which of the following molecules contains at least one peptide bond? A) glycogen B) cellulose C) chitin D) peptidoglycan

Which of the following polymers contain nitrogen? A) starch B) glycogen C) cellulose D) chitin E) glucose

What is the most likely pathway taken by a newly synthesized protein that will be secreted by a cell?

ER → Golgi → vesicles that fuse with plasma membrane

If you wanted to prevent a regulatory protein from directly changing gene expression, you would have to prevent physical contact between the protein and ________.

DNA

Two potential devices that eukaryotic cells use to regulate transcription are ________.

DNA methylation and histone modification

Which of the following is the strongest evidence that protein structure and function are correlated? A) Proteins function best at certain temperatures. B) Proteins have four distinct levels of structure and many functions. C) Enzymes tend to be globular in shape. D) Denatured (unfolded) proteins do not function normally.

Denatured (unfolded) proteins do not function normally.

If cells of an individual contain the same set of genes, how do these cells become different from each other during development?

Differences in extracellular signals received by each cell lead to differences in the types of regulatory proteins present in each cell.

A molecule with the chemical formula C6H12O6 is probably a _____. A) fatty acid B) polysaccharide C) phospholipid D) nucleic acid E) monosaccharide

A primary function of carbohydrates attached to the glycoproteins and glycolipids of animal cell membranes is to _____. A) facilitate diffusion of molecules down their concentration gradients B) actively transport molecules against their concentration gradients C) maintain the integrity of a fluid mosaic membrane D) maintain membrane fluidity at low temperatures E) mediate cell-cell recognition

The following question is based on the reaction A + B ↔ C+ D shown in the accompanying figure. Which of the following represents the activation energy needed for the noncatalyzed reverse reaction, C + D → A + B, in the figure?

You have discovered an enzyme that can catalyze two different chemical reactions. Which of the following is most likely to be correct?

Either the enzyme has two distinct active sites or the reactants involved in the two reactions are very similar in size and shape.

Ions diffuse across membranes through specific ion channels down ________.

Electrochemical gradient

______ theory explains how eukaryotes have evolved.

Endosymbiosis

During chemical evolution, which of the following occurred in the molecules involved?

Entropy decreased while potential energy increased

Which of the following is TRUE of enzymes?

Enzymes increase the rate of chemical reaction by lowering activation energy to the substrate.

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.

Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small intestine, however, rapidly move large quantities of glucose from the glucose-rich food into their glucose-poor cytoplasm. Using this information, which transport mechanism is most probably functioning in the intestinal cells?

Facilitated diffusion

When many genes of an organism are globally regulated, those genes are considered as regulon genes. What is the common theme of such genetic regulation?

Genes of regulons are silenced by a common repressor.

More than 99.99% of our cells have the same ______, yet each cell is a little different from the rest.

Genome

______ atoms determine the overall chemical behavior of organic molecules (containing carbon).

H, N, and O

Which of the following statements is TRUE of histones?

Histone H1 is not present in the nucleosome bead; instead, it draws the nucleosomes together.

Which of the following is most critical for the association between histones and DNA?

Histones are positively charged

Why do histones bind tightly to DNA?

Histones are positively charged, and DNA is negatively charged.

In solution, why do hydrolysis reactions occur more readily than condensation reactions? A) Hydrolysis increases entropy and is exergonic. B) Hydrolysis decreases entropy and is endergonic. C) Hydrolysis decreases entropy and is exergonic. D) Hydrolysis increases entropy and is endergonic.

Hydrolysis increases entropy and is exergonic.

Which of the following statements best distinguishes scientific hypotheses from scientific theories?

Hypotheses are usually narrower in scope; theories have broader explanatory power

Which of the following is TRUE when comparing an uncatalyzed reaction to the same reaction with a catalyst?

The catalyzed reaction will have the same ∆G.

How many electrons are involved in a double covalent bond?

four

You have a planar bilayer with equal amounts of saturated and unsaturated phospholipids. After testing the permeability of this membrane to glucose, you increase the proportion of unsaturated phospholipids in the bilayer. What will happen to the membrane's permeability to glucose?

Increase

In the first step of their experiments, Jacob and Monod treated E. colicells with ultraviolet light or X-rays to ________

Increase the frequency of mutations in all genes

When a membrane is freeze-fractured, the bilayer splits down the middle between the two layers of phospholipids. In an electron micrograph of a freeze-fractured membrane, the bumps seen on the fractured surface of the membrane are ________.

Integral Protein

As scientists were unraveling the mysteries associated with transcription and translation in eukaryotes, they discovered there was not a one-to-one correspondence between the nucleotide sequence of a gene and the base sequence of the mRNA it codes for. They proposed the genes-in-pieces hypothesis. How can the genes-in-pieces hypothesis be explained?

Introns are noncoding segments of DNA that are present in the initial transcript, but are removed by splicing.

Which of the following statement about ionic bonds is correct?

Ionic bonds involve the electrical attraction between charged atoms

Which of the following is a characteristic feature of a carrier protein (facilitated diffusion) in a plasma membrane? a. It is a peripheral membrane protein. b. It has no hydrophobic regions. c. It works against diffusion. d. It exhibits a specificity for a particular type of molecule. e. It requires the expenditure of cellular energy to function.

It exhibits specificity for a particular type of molecule.

Which one of the following is TRUE? A codon ________

Is the basic unit of the genetic code

At about pH 7 in most cells, what happens to the amino R-group on an amino acid? A) It acts as a base and gains a proton, giving it a positive charge. B) It acts as an acid and loses a proton, giving it a negative charge. C) It is reduced and tends to act as an electron donor in redox reactions. D) It remains neutral, like water, and does not have a charge.

It acts as a base and gains a proton, giving it a positive charge

At about pH 7 in most cells, what happens to the carboxyl R-group on an amino acid? A) It acts as a base and gains a proton, giving it a positive charge. B) It acts as an acid and loses a proton, giving it a negative charge. C) It is oxidized and tends to act as an electron acceptor in redox reactions. D) It remains neutral, like water, and does not have a charge.

It acts as an acid and loses a proton, giving it a negative charge.

Why is carbon so important in biology?

It can form a variety of carbon skeletons and host functional groups.

Which of the following is TRUE of carbon?

It can form both polar and nonpolar bonds.

There is a mutation in the repressor that results in a molecule known as a super-repressor because it represses the lac operon permanently. Which of these would characterize such a mutant?

It cannot bind to the inducer.

How do enzymes telomerase meet the challenge of repeating the ends of linear chromosomes?

It catalyzes the lengthening of telomerase.

How is the structure of kinesin related to its function?

Kinesin has a tail region that binds to vesicles and two heads that can attach to microtubules.

The R-group, or side chain, of the amino acid serine is -CH2-OH. The R-group, or side chain, of the amino acid leucine is -CH2-CH-(CH3)2. Where would you expect to find these amino acids in a globular protein in aqueous solution? A) Serine would be in the interior, and leucine would be on the exterior of the globular protein. B) Leucine would be in the interior, and serine would be on the exterior of the globular protein. C) Serine and leucine would both be in the interior of the globular protein. D) Serine and leucine would both be on the exterior of the globular protein.

Leucine would be in the interior, and serine would be on the exterior of the globular protein.

Who performed classic experiments that supported the semiconservative model of DNA replication?

Meselson and Stahl

Which of the following correctly matches a component of the cytoskeleton to one of its functions?

Microtubules move chromosomes.

What does it mean when we say the genetic code is redundant?

More than one codon can specify the addition of the same amino acid

Rate of an enzyme-catalyzed reaction as a function of varying reactant concentration, with the concentration of enzyme constant. In the accompanying figure, why does the reaction rate plateau at higher reactant concentrations?

Most enzyme molecules are occupied by substrate at high reactant concentrations.

You have two beakers. One contains pure water, the other contains pure methanol (wood alcohol). The covalent bonds of methanol molecules are nonpolar, so there are no hydrogen bonds among methanol molecules. You pour crystals of table salt (NaCl) into each beaker. Predict what will happen.

NaCl crystals will dissolve readily in water but will not dissolve in methanol

On a NOIR scale, your course section number is on _______ scale.

Nominal Categorical

A phospholipid is a ________.

Nonpolar lipid molecule that is made amphipathic by the addition of a phosphate

Which of the following affects the osmolarity of a solution?

Only I and II

In what general way are regulons regulated?

Regulons can be under either positive or negative control.

Some fatty acids and lipids are broken down using oxidation. Such processes are likely to occur in ______.

Peroxisomes

Suppose that an induced mutation removes most of the 5' end of the 5' UTR of an mRNA. What is most likely to happen?

Removal of the 5' UTR also removes the 5' cap and the mRNA will quickly degrade.

Major difference between Eukaryotic DNA replication and Prokaryotic DNA Replication

Prokaryotic chromosomes have a single origin of replication

_____ is thought to have given rise to LUCA because it has been shown in the lab that random assembly of its building blocks can lead to a self-replication molecule.

RNA

The phenomenon in which RNA molecules in a cell are destroyed if they have a sequence complementary to an introduced double-stranded RNA is called ________.

RNA interference

In the process of transcription, ________

RNA is synthesized

In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a globin protein (one of the protein components of hemoglobin)?

RNA polymerase II

When 10,000 molecules of ATP are hydrolyzed to ADP and i in a test tube, about half asmuch heat is liberated as when a cell hydrolyzes the same amount of ATP. Which of the

Reactant and product concentrations in the test tube are different from those in the cell.

Since Watson and Crick described DNA in 1953, which of the following might best explain why the function of small RNAs (miRNAs) is still not well understood?

Recent advances in technology and our understanding of how DNA is expressed have made this possible.

What is the difference between a ribonucleotide and a deoxyribonucleotide?

Ribonucleotides have a hydroxyl group on the 2 carbon of their sugar subunit.

Which one of the following statements about RNA processing is TRUE?

Ribozymes may function in RNA splicing

If you mechanically shook a mixture of phospholipids and water, what would you expect to see when you observe the solution using an electron microscope?

Some lipids will have formed tiny vesicles filled with water.

which component is a peripheral protein D which component is cholesterol E which component is a protein fiber of the extracellular matrix A which component is a microfilament (actin filament) of the cytoskeleton C which component is a glycolipid B

SCIENCE

The ribosome-binding sequence on mRNA in prokaryotes is also known as the

Shine—Dalgarno sequence

Mammals have a family between 500 and 1000 genes that encode receptor proteins on the surface of odor-receptor neurons. If all mammals have these genes, why do some mammals have a better sense of smell than others do?

Some of the genes may have been mutated and rendered inactive in some species but not in others.

Side A is hypotonic to side B

______ is primarily involved in the synthesis of lipids, phospholipids, and steriods?

Smooth ER

Where would you most likely find an integral membrane protein?

Spanning the cell membrane, with parts of the protein visible from both the inside and the outside of the cell

Why does ice float in liquid water?

Stable hydrogen bonds keep water molecules of ice farther apart than water molecules of liquid water.

How does primary protein structure affect the function of protein enzymes? A) Substrates interact with R-groups at the enzyme's active site. B) Substrates interact with R-groups at the enzyme's external surface. C) Substrates interact with hydrophobic R-groups at any region of the enzyme. D) Substrates permanently bind to R-groups at the enzyme's active site.

Substrates interact with R-groups at the enzyme's active site.

The figure below shows a branched metabolic pathway that synthesizes two related amino acids (D and F). If there is a genetic defect, resulting in a nonfunctional enzyme (3), how could you ensure that adequate amounts of the amino acid F are synthesized?

Supplement with intermediate E

Telomere shortening puts a limit on the number of times a cell can divide. Research has shown that telomerase can extend the lifespan of cultured human cells. How might adding telomerase affect cellular aging?

Telomerase eliminates telomere shortening and retards aging.

Scientists have found that polypeptides which are normally synthesized in the endoplasmic reticulum are about 20 amino acids longer when they are synthesized by ribosomes not attached to the endoplasmic reticulum. What is a possible explanation for the greater length of these polypeptides?

The 20 amino acids serve as a signal (peptide) sequence that directs the forming polypeptides to the endoplasmic reticulum, where they are cleaved off during processing.

How does the simple primary and secondary structure of DNA hold the information needed to code for the many features of multicellular organisms?

The base sequence of DNA carries the information needed to code for proteins

In the Morse code, a series of dots and dashes code for letters of the alphabet. (If you do not know Morse code, it is OK - just imagine a language with the above rules.) How is this analogous to the genetic code?

The bases of DNA code for the more complex amino acid sequence of the proteins in cells

To attach a particular amino acid to the tRNA molecule that will transport it, an enzyme, an aminoacyl-tRNA synthetase, is required, along with ATP. Initially, the enzyme has an active site for ATP and another for the amino acid, but it is not able to attach the tRNA. What must occur in order for the final attachment to occur?

The binding of the first two molecules must cause a 3-D change that opens another active site on the enzyme.

The binding of the two molecules must cause a 3-D change in the enzyme.

Which of the following is an exception to the central dogma?

The discovery of RNA viruses that synthesize DNA using reverse transcriptase

According to the table, which enzyme is defective in the strain with the arg2 mutation?

The enzyme that converts ornithine to citrulline

Which of the following mechanism is (are) used to coordinate the expression of multiple, related genes in eukaryotic cells?

The genes share a single common enhancer, which allows appropriate activators to turn on their transcription at the same time

All three domains (Bacteria, Archaea, and Eukarya) follow the same genetic code. Therefore, which of the following statements would most likely be correct?

The genetic code evolved before the different domains diverged

Imagine that you have isolated a yeast mutant that contains a constitutively (constantly) active histone deacetylase. What phenotype do you predict for this mutant?

The mutant will show low levels of gene expression.

Why are hydrocarbons insoluble in water?

The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages.

You have just discovered an organism that lives in extremely cold environments. Which of the following would you predict to be TRUE about the phospholipids in its membranes, compared to phospholipids in the membranes of organisms that live in warmer environments?

The membrane phospholipids of cold-adapted organisms will have more unsaturated hydrocarbon tails

In an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell after she has removed its 5' cap and poly-A tail. Which of the following would you expect her to find?

The molecule is digested by enzymes because it is not protected at the 5' end.

There should be a strong positive correlation between the rate of protein synthesis and ________.

The number of ribosomes

For living organisms, which of the following is an important consequence of the first law of thermodynamics?

The organism ultimately must obtain all of the necessary energy for life from its environment.

Steroid hormones are large communication molecules that are modified cholesterol molecules. How do you think they enter a cell? (remember this for Ch8)

Their lipid nature probably allows them to diffuse through the plasma membrane.

A patient was involved in a serious accident and lost a large quantity of blood. In an attempt to replenish body fluids, distilled water—equal to the volume of blood lost—is added to the blood directly via one of his veins. What will be the most probable result of this transfusion?

The patient's red blood cells will swell and possibly burst because the blood has become hypotonic compared to the cells

Enzymes that break down DNA catalyze the hydrolysis of the covalent bonds that join nucleotides together (reverse of polymerization). What would happen to DNA molecules treated with these enzymes?

The phosphodiester linkages of the polynucleotide backbone would be broken.

A solution contains 0.0000001 (10^-7) moles of hydroxyl ions [OH-] per liter. Which of the following best describes this solution?

neutral

Which of the following correctly describes a reaction that has reached chemical equilibrium?

The rate of the forward reaction is equal to the rate of the reverse reaction

Which of the following is TRUE for all exergonic reactions?

The reaction proceeds with a net release of free energy.

Which of the following is directly related to a single amino acid?

The three-base sequence of mRNA

How are RNA hairpin turns related to transcriptional termination in E. coli?

The turns are formed from complementary base pairing and cause separation of the RNA transcript and RNA polymerase.

Ions diffuse across membranes through specific ion channels down _________.

Their electrochemical gradient

Franklin and Wilkins analyzed DNA by bombarding DNA crystals with X-rays. Their analysis yielded two numbers that sparked interest, 3.4 nm and 0.34 nm. What is the significance of these numbers?

These numbers demonstrate there are 10 rungs, or steps, on the DNA "ladder" for every turn of the helix.

Aquaporins are proteins that control the passage of water molecules across a cell membrane. The protein forms a pore, or opening, in the membrane. You isolate what you think are two different molecules of aquaporin and determine that one of the proteins has a larger pore diameter than the second. Which of the following do you conclude? A) These two forms of aquaporin will have identical sequences of amino acids. B) These two forms of aquaporin will have different sequences of amino acids. C) You will have to sequence the proteins to compare their primary structure, because it should have no effect on pore diameter. D) These two forms of aquaporin have identical primary structure but differ in their tertiary structure.

These two forms of aquaporin will have different sequences of amino acids.

Which aspect of phospholipids is most important to the formation of bilayers?

They are amphipathic

Eukaryotic cells manufacture cytoskeletal proteins, which help to maintain cell shapes and functions. What would you predict about these proteins?

They are manufactured on free ribosomes in the cytoplasm.

Which of the following statements is TRUE about protein synthesis in prokaryotes?

Translation can begin while transcription is still in progress

HIV, the causative agent of AIDS, is a retrovirus. A retrovirus ________

Uses reverse transcriptase to make DNA from RNA

Which of the following descriptions best fits the class of molecules known as nucleotides?

a nitrogenous base, a phosphate group, and a sugar

Of the following, which is the most current description of a gene?

a DNA sequence that is expressed to form a functional product: either RNA or polypeptide

You want to engineer a eukaryotic gene into a bacterial colony and have it expressed. What must be included in addition to the coding exons of the gene?

a bacterial promoter sequence

zinc, and essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. the zinc most likely functions as

a cofactor necessary for enzyme activity

When nucleotides polymerize to form a nucleic acid ________.

a covalent bond forms between the sugar of one nucleotide and the phosphate of a second

The DNA of telomeres has been highly conserved throughout the evolution of eukaryotes. This most likely reflects ________.

a critical function of telomeres

Which of the following is most likely to have a small protein called ubiquitin attached to it?

a cyclin protein, which usually acts in G1, in a cell that is in G2

The partial negative charge at one end of a water molecule is attracted to the partial positive charge of another water molecule. What is this attraction called?

a hydrogen bond

Which of the following is NOT found in a prokaryote?

a mitochondrion

Which of the following is an example of potential rather than kinetic energy?

a molecule of glucose

Which of the following crosses lipid bilayers the slowest? a. a sodium ion b. a small, polar molecule like water c. a large, polar molecule like glucose d. a small, nonpolar molecule like oxygen (O2)

a. a sodium ion

Based on the accompanying figure (inside is to the left), which of these experimental treatments would increase the rate of sucrose transport into the cell? a. decreasing extracellular pH b. decreasing cytoplasmic pH c. adding a substance that makes the membrane more permeable to hydrogen ions d. decreasing extracellular sucrose concentration e. adding an inhibitor that blocks the regeneration of ATP

a. decreasing extracellular pH

Under what circumstances does membrane transport require energy? a. whenever a solute is moved against its electrochemical gradient b. whenever an ion moves through a phospholipid bilayer membrane c. wherever large molecules are moved within a cell d. whenever oxygen moves through a phospholipid bilayer membrane

a. whenever a solute is moved against its electrochemical gradient

Spherocytosis is a human blood disorder associated with a defective cytoskeletal protein in the red blood cells (RBCs). What do you suspect is the consequence of such a defect?

abnormally shaped RBCs

Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's ________.

activation energy

Mutations in the DNA may lead to _______ that increases fitness and lays the foundation for natural selection to 'select' a particular trait that is inheritable.

adaptation

Actin filaments have polarity. This means that the two ends can be identified due to structural differences. The plus end is the end to which subunits are added more rapidly, or the end of polymerization. Which of the following would enable you to identify the plus end of actin filaments?

adding radiolabeled actin subunits to a mixture of actin filaments in which conditions are favorable for polymerization

Recall the experiment on ant navigation. To run a controlled experiment, what parameters were held constant for the test group of 75 ants?

all variables except leg length

Altering patterns of gene expression in prokaryotes would most likely serve an organism's survival by ________.

allowing an organism to adjust to changes in environmental conditions

You determine the amino acid sequence of a protein and find it contains a long sequence of methionine, followed by a long sequence of proline, followed by a long sequence of valine. Using these data you predict the sequence of this protein's secondary structure will be ________. A) beta sheets, then a region of no secondary structure, then beta sheets B) alpha-helices, then a region of no secondary structure, then alpha helices C) beta sheets, then a region of no secondary structure, then alpha-helices D) alpha-helices, then a region of no secondary structure, then beta sheets

alpha-helices, then a region of no secondary structure, then beta sheets

Normal hemoglobin is a tetramer, consisting of two molecules of β hemoglobin and two molecules of α hemoglobin. In sickle-cell disease, as a result of a single amino acid change, the mutant hemoglobin tetramers associate with each other and assemble into large fibers. Based on this information alone, we can conclude that sickle-cell hemoglobin exhibits ________. A) only altered primary structure B) only altered secondary structure C) only altered tertiary structure D) only altered quaternary structure E) altered primary structure and altered quaternary structure; the secondary and tertiary structures may or may not be altered

altered primary structure and altered quaternary structure; the secondary and tertiary structures may or may not be altered

Which of the following allows more than one type of protein to be produced from one gene?

alternative forms of RNA splicing

Changing a single amino acid in a protein consisting of 325 amino acids would ________. A) alter the primary structure of the protein but not its tertiary structure or function B) cause the tertiary structure of the protein to unfold C) always alter the biological activity or function of the protein D) always alter the secondary structure of the protein and disrupt its biological activity E) always alter the primary structure of the protein, sometimes alter the tertiary structure of the protein, and sometimes affect its biological activity

always alter the primary structure of the protein, sometimes alter the tertiary structure of the protein, and sometimes affect its biological activity

A ribozyme is ________.

an RNA with catalytic activity

an allosteric inhibitor.

All of the following are part of a prokaryotic cell EXCEPT _____.

an endoplasmic reticulum

Spontaneous generation ______.

apparently occurred at least once- when life on Earth began

Which of the following is TRUE of osmosis? a. Osmosis only takes place in red blood cells. b. In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration. c. Osmosis is an energy-demanding or "active" process. d. In osmosis, solutes move across a membrane from areas of lower water concentration to areas of higher water concentration.

b. In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration.

What is the most important factor in explaining why osmosis occurs spontaneously? a. It leads to an increase in entropy. b. It leads to a decrease in entropy. c. The process is endothermic. d. The process is exothermic.

b. It leads to a increase in entropy.

What is/are the variable structure(s) of a nucleotide?

base and sugar

Ribosomes can attach to prokaryotic messenger RNA ________.

before transcription is complete

There are two conserved regions in the promoter sequences of bacterial genes. These two regions (−10 box and the −35 box) of the promoter ________.

bind the sigma subunit that is associated with RNA polymerase

In eukaryotes, general transcription factors ________ .

bind to other proteins or to the TATA box

Which of the following processes is central to the initiation of transcription in bacteria?

binding of sigma to the promoter region

Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the ________.

binding of the tRNA anticodon to the mRNA codon

The lock-and-key analogy for enzymes applies to the specificity of enzymes ________.

binding to their substrate

If you guys had any other questions i missed the password to edit is :

bio151

How might a change of one amino acid at a site, distant from the active site of an enzyme, alter an enzyme's substrate specificity?

by changing the shape of an enzyme

Which aspect of phospholipids is most important to the formation of bilayers? a. Their polar heads can interact with water. b. The length of their hydrocarbon tails can be altered to modulate membrane fluidity. c. They are amphipathic. d. Their hydrocarbon tails can consist of fatty acids or isoprene subunits.

c. They are amphipathic.

c. facilitated diffusion

What region of a steroid is hydrophilic? a. the methyl (—CH3) groups b. the ring structures c. the terminal hydroxyl group d. the long hydrocarbon chain

c. the terminal hydroxyl group

A system at chemical equilibrium ________.

can do no work

Imagine that you have set up a genetic screen to identify E. colimutants that cannot metabolize the amino acid tryptophan for energy. Beginning with a master plate containing many colonies, you prepare replica plates on medium with glucose or tryptophan as the only energy source. You would look for colonies that ________.

can grow only on the plates with glucose

______ atoms give organic molecules their overall shape.

carbon

Amino acids are acids because they always possess which functional group? A) amino B) carbonyl C) carboxyl D) phosphate E) hydroxyl

carboxyl

Which of the functional groups below acts most like an acid in water?

carboxyl

which two functional groups are always found in amino acids? A) ketone and methyl groups B) carbonyl and amino groups C) carboxyl and amino groups D) amino and sulfhydryl groups E) hydroxyl and carboxyl groups

carboxyl and amino groups

Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?

catabolism (catabolic pathways)

Proteins in biological systems ________. A) store genetic information B) link with other proteins to form bilayers in cell membranes C) form high-energy intermediates such as ATP D) catalyze reactions

catalyze reactions

The first chemicals that provided potential energy on Earth may have been formaldehyde and hydrogen cyanide. While these were produced by sunlight-driven reactions, they also occurred around deep-sea vents. If the first organisms on Earth evolved around these vents, the first life on Earth was _____.

chemosynthetic, obtaining energy from chemicals

HIV is the virus that causes AIDS. In the mid-1990s, researchers discovered an enzyme in HIV called protease. Once the enzyme's structure was known, researchers began looking for drugs that would fit into the active site and block it. If this strategy for stopping HIV infections were successful, it would be an example of what phenomenon?

competitive inhibition

What is the structural feature that allows DNA to replicate in anti-parallel manner?

complementary pairing of the nitrogenous bases

The anticodon of a particular tRNA molecule is ________.

complementary to the corresponding mRNA codon

Motor proteins provide for molecular motion in cells by interacting with what types of cellular structures?

components of cytoskeleton

Which of the following occurs in prokaryotes but not in eukaryotes?

concurrent transcription and translation

Anabolic pathways ________.

consume energy to build up polymers from monomers

Which method is utilized by eukaryotes to control their gene expression that is NOT used in bacteria?

control of both RNA splicing and chromatin remodeling

A carbon atom is most likely to form what kind of bond(s) with other atoms?

covalent

Identify the location of the disulfide bond in the figure, located at the bottom of the third transmembrane segment. What is the name of the amino acids that are forming this bond? A) cytosine B) aspartic acid C) cysteine D) glycine

cysteine

What is the location of the C-terminus of the protein in the figure? A) extracellular B) cytoplasm C) embedded within the membrane D) nucleus

cytoplasm

Which of the following are pyrimidine nitrogenous bases?

cytosine and uracil

Which of the following includes all of the pyrimidines found in RNA and DNA?

cytosine, uracil, and thymine

Which of the following in the figure would be the same in either an enzyme-catalyzed or a noncatalyzed reaction?

For a protein to be an integral membrane protein, it would have to be ________. a. hydrophilic b. hydrophobic c. exposed on only one surface of the membrane d. amphipathic, with at least one hydrophobic region e. completely covered with phospholipids

d. amphipathic, with at least one hydrophobic region

Celery stalks (and chopped lettuce for salad) that are immersed in freshwater for several hours become stiff. Similar stalks left in a 0.15 M salt solution become limp. From this we can deduce that the freshwater ________. a. is isotonic and the salt solution is hypertonic to the cells of the celery stalks b. is hypertonic and the salt solution is hypotonic to the cells of the celery stalks c. is hypotonic and the salt solution is hypertonic to the cells of the celery stalks d. and the salt solution are both hypotonic to the cells of the celery stalks e. and the salt solution are both hypertonic to the cells of the celery stalks

d. and the salt solution are both hypotonic to the cells of the celery stalks

Cooking oil and gasoline (a hydrocarbon) are NOT amphipathic molecules because they ________. a. do not have a nonpolar region b. have hydrophobic and hydrophilic regions c. are highly reduced molecules d. do not have a polar or charged region

d. do not have a polar or charged region

Which of the following increases the strength of the hydrophobic interactions in lipid bilayers and thus makes them less permeable to polar molecules? a. removing cholesterol b. the presence of double bonds c. increasing temperature d. increasing length of the hydrocarbon chains

d. increasing length of the hydrocarbon chains

The membranes of winter wheat are able to remain fluid when it is extremely cold by ________. a. using active transport b. decreasing the number of hydrophobic proteins in the membrane c. increasing the percentage of cholesterol molecules in the membrane d. increasing the percentage of unsaturated phospholipids in the membrane e. cotransport of glucose and hydrogen

d. increasing the percentage of unsaturated phospholipids in the membrane

Which of the following types of molecules are the major structural components of the cell membrane? a. phospholipids and cellulose b. proteins and cellulose c. glycoproteins and cholesterol d. phospholipids and proteins e. nucleic acids and proteins

d. phospholipids and proteins

DNA contains the template needed to copy itself, but it has no catalytic activity in cells. What catalyzes the formation of phosphodiester bonds between adjacent nucleotides in the DNA polymer being formed?

deoxyribonucleotide triphosphates

Histone acetyl transferases exert their effect on gene activity by ________.

neutralizing positive charges on the lysines of histones

here are 20 different amino acids. What makes one amino acid different from another? A) different side chains (R-groups) attached to a carboxyl carbon B) different side chains (R-groups) attached to the amino groups C) different side chains (R-groups) attached to an α carbon D) different structural and optical isomers E) different asymmetric carbons

different side chains (R-groups) attached to an α carbon

Several of the different globin genes are expressed in humans but at different times in development. What mechanism could allow for this?

differential gene regulation over time

What type of covalent bond between amino acid side chains (R-groups) functions in maintaining a polypeptide's specific three-dimensional shape? A) ionic bond B) hydrophobic interaction C) van der Waals interaction D) disulfide bond E) hydrogen bond

disulfide bond

Lysosomes that lack mannose-6-phosphate receptors _____.

don't receive enzyme shipments from the Golgi

Which of the following best describes DNA's secondary structure?

double antiparallel helical strands

Which of the following processes includes all others? a. transport of an ion down its electrochemical gradient b. osmosis c. diffusion of a solute across a membrane d. facilitated diffusion e. passive transport

e. passive transport

Which of the following is a correct statement about the atoms in ammonia (NH3)?

each hydrogen atom has a partial positive charge; the nitrogen atom has a partial negative charge

Van der Waals interactions may result when ________. A) hybrid orbitals overlap B) electrons are not symmetrically distributed in a molecule C) molecules held by ionic bonds react with water D) two polar covalent bonds react E) a hydrogen atom loses an electron

electrons are not symmetrically distributed in a molecule

An ionic bond is one in which ______.

electrons are removed from one atom and transferred to another atom so that the two atoms become oppositely charged

The presence of cholesterol in the plasma membranes of some animal cells ________.

enables the membranes to stay fluid when cell temperature drops

A chemical reaction that has a positive ΔG is best described as _____.

endergonic

A chemical reaction that has a positive ΔG is best described as ________.

endergonic

The evolution of eukaryotic cells most likely involved ______.

endosymbiosis of an aerobic bacterium in a larger, phagocytic host cell

Second law of Thermodynamics states that ______ always increases in an isolated system.

entropy chaos

Whenever energy is transformed, there is always an increase in the ________.

entropy of the universe

DNA methylation and histone acetylation are examples of ______

epigenetic phenomena

Which of the following is a major difference between prokaryotic cells an eukaryotic cells?

eukaryotic cells have more intracellular organelles than prokaryotes

Gene expression can be altered more easily at the level of post-transcriptional processing in eukaryotes than in prokaryotes because ________.

eukaryotic exons may be spliced in alternative patterns

Muscle cells differ from nerve cells mainly because they ________.

express different genes

The predominant mechanism driving cellular differentiation is the difference in gene ________.

expression

A peptide bond ________. A) forms between the functional R-groups of different amino acids B) forms between the central carbon and the amino R-group of a single amino acid C) forms the primary structure of proteins D) does not play a role in maintaining the tertiary structure of proteins

forms the primary structure of proteins

Although the expression of most genes is tightly regulated, some genes are expressed at roughly constant rates. Which of the following genes would you predict to be constitutively (constantly) expressed?

genes that code for cellular infrastructure

Amoebae move by crawling over a surface (cell crawling), which involves ________.

growth of actin filaments to form bulges in the plasma membrane

Which of the following are purine nitrogenous bases?

guanine and adenine

Which of the following is a property of liquid water? Liquid water ______.

has a heat of vaporization that is higher than that for most other substances

Biological evolution of life on Earth, from simple prokaryote-like cells to large, multicellular eukaryotic organisms, _____.

has occurred in accordance with the laws of thermodynamics

What type of interaction is directly responsible for the formation of secondary structure? A) peptide bonds between adjacent amino acids B) peptide bonds between nonadjacent amino acids C) hydrogen bonds between sections of the polypeptide backbone D) hydrogen bonds between side chains of amino acids

hydrogen bonds between sections of the polypeptide backbone

Which of the following involves an increase in entropy? A) hydrolysis B) reactions that join monomers C) polymerization D) chemical evolution

hydrolysis

Suppose you discovered a new amino acid. Its R-group contains only hydrogen and carbon atoms. Predict the behavior of this amino acid. A) It is hydrophobic. B) It is hydrophilic. C) Relative to the amino acids found in organisms, its interactions with water will be intermediate. D) Relative to the amino acids found in organisms, its interactions with water will be very high.

hydrophobic

celery stalks that are immersed in freshwater for several hours become stiff and hard. Similar stalks left in a salt solution become limp and soft. From this we can deduce that the cells of the celery stalk.

hypertonic to fresh water but hypotonic to the salt solution

A good experimental design has all of the following except _______.

implemented by an expert

Where are proteins produced other than on ribosomes free in the cytosol or ribosomes attached to the ER?

in mitochondria

Some of the drugs used to treat HIV patients are competitive inhibitors of the HIV reverse transcriptase enzyme. Unfortunately, the high mutation rate of HIV means that the virus rapidly acquires mutations with amino acid changes that make them resistant to these competitive inhibitors. Where in the reverse transcriptase enzyme would such amino acid changes most likely occur in drug-resistant viruses?

in or near the active site

In a normal cellular protein, where would you expect to find a hydrophobic amino acid like valine? A) in the interior of the folded protein, away from water B) on the exterior surface of the protein, interacting with water C) in the transmembrane portion interacting with lipid fatty-acid chains D) in the interior of the folded protein, away from water, or in a transmembrane portion interacting with lipid fatty-acid chains E) anywhere in the protein, with equal probability

in the interior of the folded protein, away from water, or in a transmembrane portion interacting with lipid fatty-acid chains

A controlled experiment ______.

includes at least two groups, one of which does not receive the experimental treatment.

In comparing DNA replication with RNA transcription in the same eukaryotic cell, only DNA replication ________.

incorporates the entire template molecule in the product

In the first step of their experiments, Jacob and Monod treated E. coli cells with ultraviolet light or X-rays to ________.

increase the frequency of mutations in all genes

Enzymes ________.

increase the rate of a reaction by lowering the activation energy barrier

Most repressor proteins are allosteric. Which of the following binds with the repressor to alter its conformation?

inducer

Which of the following, when taken up by a cell, binds to a repressor so that the repressor no longer binds to the operator?

inducer

Regulatory transcription factors ________.

influence the assembly of the basal transcription complex

Histogram graph is the best choice when you are reporting observational data that can be measured on a _______ scale.

interval

The active site of an enzyme is the region that ________.

is involved in the catalytic reaction of the enzyme

What can you infer about a high molecular weight protein that cannot be transported into the nucleus?

it lacks a nucleus localization signal (NLS)

why is ATP an important molecule in metabolism?

it provides energy coupling between exergonic and endergonic reactions

Consider the following reaction at equilibrium: CO2 + H2O <-> H2CO3. What would be the effect of adding additional H2CO3?

it would drive the equilibrium dynamics to the left

Eukaryotes have three nuclear RNA polymerases. The primary function of RNA polymerase II is transcription of ________.

protein-coding genes

Asbestos is a material that was once used extensively in construction. One risk from working in a building that contains asbestos is the development of asbestosis caused by the inhalation of asbestos fibers. Cells will phagocytize asbestos but are not able to degrade it. As a result, asbestos fibers accumulate in ________.

lysosomes

According to the central dogma, what molecule should go in the blank?DNA → ________ → Proteins

mRNA

Codons are part of the molecular structure of ________

mRNA

Which of the following macromolecules leaves the nucleus of a eukaryotic cell through pores in the nuclear membrane?

mRNA

Translation requires ________.

mRNA, tRNA, and rRNA

Translation directly involves ________.

mRNA, tRNA, ribosomes, and GTP

Cloning of plants from cuttings demonstrates that ________.

mature plant cells retain the full genetic information needed to carry out the developmental processes to produce a new individual plant

Side chains of amino acids ________. A) are all nonpolar B) are nonpolar if they contain N or S C) are all polar D) may be polar or nonpolar

may be polar or nonpolar

What are prions? A) mobile segments of DNA B) tiny circular molecules of RNA that can infect plants C) viral DNA that attaches itself to the host genome and causes disease D) misfolded versions of normal protein that can cause disease E) viruses that invade bacteria

misfolded versions of normal protein that can cause disease

A biologist ground up some plant leaf cells and then separated organelles into different tubes (by centrifuging the mixture and fractionating [separating] the mixture). One tube could produce ATP in the dark, suggesting that it is likely to contain ______.

mitochondria

Cyanide binds with at least one molecule involved in producing ATP. If a cell is exposed to cyanide, most of the cyanide will be found within the _______.

mitochondria

When yeast cells are transferred from anaerobic to aerobic growth conditions, which of these organelles become much more numerous?

mitochondria

Which structure is common to plant and animal cells?

mitochondrion

Evolution is descent with ______.

modification change

Researchers tried to explain how vesicular transport occurs in cells by attempting to assemble the transport components. They set up microtubular tracks along which vesicles could be transported, and they added vesicles and ATP (because they knew the transport process requires energy). Yet, when they put everything together, there was no movement or transport of vesicles. What were they missing?

motor proteins

what is true of the cytoskeleton?

movement of cilia and flagella is the result of motor proteins causing microtubules to move relative to each other.

______meter is 10^-9 of a meter, and 10^-6 of a millimeter (the smallest hatch-mark or a regular ruler)/.

nano

Which component of the complex described enters the exit tunnel in the large subunit of the ribosome?

newly formed polypeptide

At the beginning of this century there was a general announcement regarding the sequencing of the human genome and the genomes of many other multicellular eukaryotes. Many people were surprised that the number of protein-coding sequences was much smaller than they had expected. Which of the following could account for much of the DNA that is NOT coding for proteins?

non-protein-coding DNA that is transcribed into several kinds of small RNAs with biological function

Bonds between two atoms that are equally electronegative are _____.

nonpolar covalent bonds

If cells are grown in a medium containing radioactive 32P-labeled phosphate, which of these molecules will be labeled?

nucleic acids

Nucleic acids are polymers made up of which of the following monomers?

nucleotides

Why is each element unique with respect to its chemical properties? Each element has a distinctive _____.

number of protons

In eukaryotes, the normal or default state is that genes are turned _______

off through their association in nucleosomes

In receptor-mediated endocytosis, receptor molecules initially project to the outside of the cell. Where do they end up after endocytosis?

on the inside surface of the vesicle

Semiconservative replication uses _____ as a template.

one strand of the DNA molecule

Eukaryotes have three nuclear RNA polymerases. The primary function of RNA polymerase I is transcription of ________.

only rRNA-coding genes

Eukaryotes have three nuclear RNA polymerases. The primary function of RNA polymerase III is transcription of ________.

only tRNA-coding genes

Stanley Miller's 1953 experiments with heating of simple molecules and applying electric current supported the hypothesis that ______.

organic molecules can be synthesized under conditions that may have existed on early Earth

Activator proteins in eukaryotes usually have a domain that binds to DNA and other activation domains that often bind to ________.

other regulatory proteins

What is the pH of a solution with a hydroxyl ion [OH-] concentration of 10^-12 M?

pH 2

The product of the lacI gene functions most like a car's ________.

parking brake

Within a double-stranded DNA molecule, adenine forms hydrogen bonds with thymine and cytosine forms hydrogen bonds with guanine. This arrangement ________.

permits complementary base pairing

Like many molecules, nucleotides have asymmetry. This gives nucleic acids a specific direction for polymerization. The 3' carbon of a nucleotide has a hydroxyl group, while the 5' carbon is covalently bonded to _____.

phosphate group

Some viruses consist only of a protein coat surrounding a nucleic acid core. If you wanted to radioactively label the nucleic acids separately from the protein, you would use radioactive ________. (Which atom is in nucleotides but not proteins?)

phosphorus

The arabinose operon (ara) provides a particularly interesting example of ________ in that when arabinose is present in the environment, the operon is transcribed.

positive control

Water is an excellent solvent for polar molecules and ions. What part of the solute will interact with oxygen atoms of water?

positively charged

Pasteur's experiment showed that all life comes from ______.

preexisting cells cells life

Pasteur's experiments proved that ______.

preexisting cells present in the air can grow in sterilized nutrient broth

A cell with a lot of free ribosomes and few attached to rough endoplasmic reticulum is most likely

primarily producing proteins in the cytosol

A cell with a predominance of free ribosomes is most likely ______.

primarily producing proteins in the cytosol

When polymerization of a protein is complete, but a protein is still completely linear, what is the highest level of structure in the protein? A) primary B) secondary C) tertiary D) quaternary

primary

You disrupt all hydrogen bonds in a protein. What level of structure will be preserved? A) primary structure B) secondary structure C) tertiary structure D) quaternary structure

primary

The structural level of a protein LEAST affected by a disruption in hydrogen bonding is the ________. A) primary level B) secondary level C) tertiary level D) quaternary level E) All structural levels are equally affected by a disruption in hydrogen bonding.

primary level

You are studying a protein that is shaped like a doughnut. The shape is a function of which level(s) of protein structure? A) primary only B) secondary only C) tertiary only D) secondary and tertiary only E) primary, secondary, and tertiary

primary, secondary, and tertiary

A scientific theory has two components: a pattern based on observations and a ______ to explain that pattern.

process

How do chromatin-remodeling complexes recognize the genes they should act on? Chromatin-remodeling complexes ________.

recognize specific transcription factors bound to regulatory sequences of DNA

Why are polymerization reactions endergonic? Polymerization reactions ________. A) reduce entropy B) release heat, making the reactant monomers move faster C) release energy D) are at equilibrium

reduce entropy

The bonding of two amino acid molecules to form a larger molecule requires the ________. A) release of a water molecule B) release of a carbon dioxide molecule C) addition of a carbon dioxide molecule D) addition of a water molecule E) addition of a water molecule and a carbon dioxide molecule

release of a water molecule

Which of the following is a protein produced by a regulatory gene?

repressor

Which of the following is present in all prokaryotic cells?

ribosome

What molecules in the spliceosome catalyze the intron removal reactions?

ribozymes

Which level of protein structure do the α-helix and the β-pleated sheet represent? A) primary B) secondary C) tertiary D) quaternary E) primary, secondary, tertiary, and quaternary

secondary

DNA is synthesized through a process known as ________.

semiconservative replication

a primary objective of cell fractionation (including differential centrifiguration) is to ___

separate the major organelles

The reason for differences in the sets of proteins expressed in a nerve and a pancreatic cell of the same individual is that nerve and pancreatic cells contain different ________.

sets of regulatory proteins

In eukaryotic cells, transcription cannot begin until ________.

several transcription factors have bound to the promoter

Which of these provide evidence of the common ancestry of all life?

shared genetic sequences

In a bacterium, we will find DNA in _____.

the nucleoid

Knowing the atomic mass of an element allows inferences about which of the following?

the number of protons plus neutrons in the element

Which molecule or reaction supplies the energy for polymerization of nucleotides in the process of transcription?

the phosphate bonds in the nucleotide triphosphates that serve as substrates

Motor proteins require energy in the form of ATP. ATP hydrolysis results in a conformational change that allows the protein to move along microtubular tracks (pathways). What structural component of the motor protein contains the ATP binding site and, therefore, changes shape to enable movement?

the portion of the molecule that binds to the microtubular track along which the vesicle is being transported

Cell differentiation always involves ________.

the production of tissue-specific proteins, such as muscle actin

If the DNA sequence was substantially altered from one of the following, which would prevent the binding of the TATA-binding protein (TBP)?

the promoter

An enzyme has a total of four active sites. When you denature the molecule and study its composition, you find that each active site occurs on a different polypeptide. Which of the following hypotheses does this observation support? A) The enzyme is subject to regulation. B) The enzyme requires a cofactor to function normally. C) The protein's structure is affected by temperature and pH. D) the protein has a quaternary structure

the protein has a quaternary structure

Which of the following always tend to make chemical reactions spontaneous?

the reactants are more ordered than the product

What is the function of DNA polymerase III?

to add nucleotides to the 3' end of a growing DNA strand

Enthalpy (H) is the ________.

total energy in biological systems

The tertiary structure of a protein is the ________. A) bonding together of several polypeptide chains by weak bonds B) order in which amino acids are joined in a polypeptide chain C) unique three-dimensional shape of the fully folded polypeptide D) organization of a polypeptide chain into an α-helix or β-pleated sheet E) overall protein structure resulting from the aggregation of two or more polypeptide subunits

unique three-dimensional shape of the fully folded polypeptide

A series of hydrophobic side chains will congregate together as a protein folds in an aqueous solution and be stabilized by ________. A) disulfide bonds B) van der Waals interactions C) hydrogen bonds D) quaternary structure bonds

van der Waals interactions

An important group of peripheral membrane proteins are enzymes such as the phospholipases that cleave the head groups of phospholipids. What properties must these enzymes exhibit?

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