Cell Bio HW for Midterm 1

Which model of DNA replication is represented in this image? A. dispersive model B. semiconservative model C. conservative model

B. semiconservative model

What does depurination refer to? A. the loss of G or C bases from DNA B. the loss of A or G bases from DNA C. the loss of thymine due to damage from UV radiation D. the accumulation of mutations and subsequent loss of purity of a nucleotide sequence E. the breaking of the DNA backbone

B. the loss of A or G bases from DNA

Choose all of the following that correctly describe a characteristic of mismatch repair. A.DNA polymerase and ligase fill in the gap. B.Helicase unwinds the DNA in the mismatched area. C.Exonuclease removes the newly synthesized DNA in the mismatched area. D.Regions of improper base-pairing between parent and daughter strand are detected and repaired.

A.DNA polymerase and ligase fill in the gap. B.Helicase unwinds the DNA in the mismatched area. C.Exonuclease removes the newly synthesized DNA in the mismatched area. D.Regions of improper base-pairing between parent and daughter strand are detected and repaired.

The nucleotide sequence of one DNA strand in a DNA double helix is 5'-CATTGCCAGAAAAAT-3'. What is the sequence of the complementary strand produced during replication? 5'-CATTGCCAGAAAAAT-3' 5'-ATTTTTCTGGCAATG-3' 5'-TAAAAAGACCGTTAC-3' 5'-GTAACGGTCTTTTTA-3' 5'-GATTCGGAGTTTTTA-3'

5'-ATTTTTCTGGCAATG-3'

The nucleotide sequence of one DNA strand in a DNA double helix is 5'-CATTGCCAGAAAAAT-3'. What is the sequence of the complementary strand produced during replication? 5'-CATTGCCAGAAAAAT-3' 5'-TAAAAAGACCGTTAC-3' 5'-GTAACGGTCTTTTTA-3' 5'-ATTTTTCTGGCAATG-3' 5'-GATTCGGAGTTTTTA-3'

5'-ATTTTTCTGGCAATG-3'

Which base pairs are found in DNA? A-C and T-G A-G and C-T A-T and G-C T-T and C-C A-U and C-G

A-T and G-C

Which of the following statements about nucleosomes is false? A. Nucleosomes are found only in mitotic chromosomes. B. Nucleosomes represent the first and most fundamental level of chromatin packing. C. Nucleosomes can be seen in the electron microscope. D. Nucleosomes convert a DNA molecule into a chromatin thread about one-third the length of the initial DNA. E. A nucleosome consists of DNA wrapped around eight histone proteins, plus a short segment of linker DNA.

A. Nucleosomes are found only in mitotic chromosomes

Consider the process that a cell uses to replicate its double-stranded DNA before undergoing cell division. Which statement describes the DNA in the resulting daughter cells? A. The double helix in each daughter cell consists of one parental strand and one newly synthesized strand. B. Each daughter cell receives a random mix of parental chromosomes and new chromosomes. C. The daughter cells receive only newly synthesized DNA; the parent cell keeps the original DNA. D. Each strand of DNA in the daughter cells contains a mix of both newly replicated and parental DNA. E. The double helix in one daughter cell consists of two strands that were originally in the parent cell, while the double helix in the other daughter cell consists of two newly made strands.

A. The double helix in each daughter cell consists of one parental strand and one newly synthesized strand.

Why do phospholipids aggregate to form cell membranes? A. They are amphipathic. B. They are attached to sugars. C. They are water-fearing. D. They are water-loving. E. They are acids.

A. They are amphipathic.

Actin filaments, microtubules, and the spherical shells of certain virus particles are all structures built from which of the following? A. assemblages of identical proteins B. more than one type of protein C. only one type of polysaccharide D. more than one type of lipid E. a combination of proteins and polysaccharides

A. assemblages of identical proteins

What is the general name given to the most highly condensed form of chromatin? A. heterochromatin B. euchromatin C. 30-nm chromatin fiber D. X chromatin E. nucleosome

A. heterochromatin

In eukaryotes, which parts of a gene are transcribed into RNA? A. introns and exons B. introns only C. exons only D. the protein-coding region only

A. introns and exons

The majority of proteins belong to "protein families" that share which attribute? A. sequence patterns and therefore structural domains B. similar hydrogen bonds C. similar functions in the cell D. similar covalent modificationsE. an organism/cell type of origin

A. sequence patterns and therefore structural domains

The mismatch repair system recognizes mismatched base pairs, removes a portion of the DNA strand containing the error, and then resynthesizes the missing DNA using the correct sequence as a template. But what if the mismatch repair system instead removed a piece of the DNA strand that contained the correct sequence? What would replication of this improperly repaired sequence produce? A. two DNA molecules bearing the same mutation B. two DNA molecules that are missing one nucleotide pair C. two DNA molecules with a gap where the correct sequence was excised D. two DNA molecules with different mutations E. one DNA molecule with a mutation and one DNA molecule with a mismatch

A. two DNA molecules bearing the same mutation

Your company has developed an organic molecule with commercial potential and you know how to produce it in the lab. You want to increase production and make as much of the molecule as possible, but the reaction has a positive ΔG°. What can you do to try to drive the reaction toward your desired product? A.increase the concentration of reactants B.continually remove products C.add an enzyme that does not couple to another reaction D.add some products initially to get the reaction primed

A.increase the concentration of reactants B.continually remove products

Which statement is true about the removal of a terminal phosphate from ATP? A. The reaction is associated with a positive change in ΔG°. B. The reaction is energetically favorable. C. The reaction is a condensation reaction.

B. The reaction is energetically favorable.

How many different polypeptide chains are possible from a sequence that is 10 amino acids long? A. unlimited B. 20^10 C. 200 D. 2000 E. 10^20

B. 20^10

The ΔG° of the hydrolysis reaction of ATP is -7.3 kcal/mole, but in a cell the actual ΔG is much more negative. What is the reason for the ΔG° and ΔG difference? A. The concentration of ATP is much lower than the concentrations of its hydrolysis products, ADP and Pi. B. ATP is much higher in concentration than the products ADP and Pi. C. Cells use enzymes to perform these reactions, resulting in a difference between ΔG° and ΔG. D. None of the above address the ΔG° and the cellular ΔG difference.

B. ATP is much higher in concentration than the products ADP and Pi.

Indicate whether the following statement is true or false, and why. Chaperone proteins provide the energy needed for a protein to fold into the correct conformation. A. True, because protein folding is an energetically favorable process. B. False, because protein folding is an energetically favorable process. C. True, because protein folding is an energetically unfavorable process. D. False, because protein folding is an energetically unfavorable process.

B. False, because protein folding is an energetically favorable process.

Which statement is true? A. A cell takes in heat from the environment to power its biosynthetic reactions, thereby obeying the second law of thermodynamics. B. The heat released by an animal cell comes from the chemical bond energy present in the food molecules it metabolizes. C. Cells obey the first law of thermodynamics but are exempt from the second law. D. The breakdown of food molecules generates heat, which cells then use to drive the synthesis of large molecules. E. A cell generates order by decreasing the entropy of its surroundings.

B. The heat released by an animal cell comes from the chemical bond energy present in the food molecules it metabolizes.

In an α helix, hydrogen bonds form between which of the following? A. acidic and basic amino acid side chains B. every fourth amino acid C. the peptide bonds and DNA D. every other amino acidE. nonpolar amino acid side chains

B. every fourth amino acid

Is the following statement true, false, or impossible to determine?Phosphorylation is the only form of covalent modification that can affect a protein's activity or location. A. true B. false C. impossible to determine

B. false

Photosynthetic bacteria contain chloroplasts. A. true B. false C. impossible to determine

B. false

The DNA in eukaryotic chromosomes is folded into a compact form by interactions with which of the following? A. microtubules B. histones C. RNA D. centrioles

B. histones

When compared to each other, the two replication forks that form at an origin of replication move in which direction? A. toward the origin B. in opposite directions C. toward the template strand D. in the 5'-to-3' direction E. in the 3'-to-5' direction

B. in opposite directions

The DNA helicase animation shows the bacteriophage T7 helicase unwinding DNA. Which of the following are critical components of the helicase mechanism of action necessary to unwind DNA? A.dissociation of the helicase subunits B.oscillating loops pulling the single-stranded DNA through a central hole C.ATP binding and hydrolysis D.conformational changes of subunits E.binding of four helicase subunits to the double-stranded DNA

B.oscillating loops pulling the single-stranded DNA through a central hole C.ATP binding and hydrolysis D.conformational changes of subunits

Which of the following statements is false? A. The lifetime of a eukaryotic mRNA is controlled in part by nucleotide sequences in the mRNA itself. B. The longer the lifetime of an mRNA, the more protein it can produce. C. In a eukaryotic mRNA, the poly-A tail promotes degradation of the molecule. D. Many eukaryotic mRNAs have a longer lifetime than bacterial mRNAs.

C. In a eukaryotic mRNA, the poly-A tail promotes degradation of the molecule.

Phosphorylation can only take place in the cell nucleus. A. impossible to determine B. true C. false

C. false

In the absence of repair, what would the replication of a double helix containing a mismatch yield? A. two DNA molecules containing the mismatch B. two DNA molecules with a mutated sequence C. one DNA molecule with the normal sequence and one DNA molecule with a mutated sequence D. two DNA molecules containing different mismatches at the site of the original error E. one DNA molecule with the normal sequence and one DNA molecule with a mismatch

C. one DNA molecule with the normal sequence and one DNA molecule with a mutated sequence

Everyone is exposed regularly to ionizing radiation found in the soil, water, and air and from cosmic rays. In fact, 80% of the ionizing radiation people are exposed to comes from naturally occurring sources. Ionizing radiation can cause double-strand breaks in the DNA. Often, the DNA breaks have missing nucleotides at the broken ends. What type of repair would likely be used, and what would be the result of repairing this type of damage? A. Direct repair would be used to join the DNA, but errors would still remain B. Direct repair would be used and would lead to properly repaired DNA. C. Nonhomologous end joining would be used to join the DNA, but errors would still remain. D. Nonhomologous end joining would be used and would lead to properly repaired DNA.

C. Nonhomologous end joining would be used to join the DNA, but errors would still remain.

Generally speaking, what determines the biological activity of a protein? A. ability to form hydrogen bonds B. peptide bonds C. amino acid sequence D. ability to form β sheets E. ability to form α helices

C. amino acid sequence

What is the definition of a protein-binding site? A. a pocket on a protein where a small molecule can be covalently attached and thus modify the protein B. the region of the cell where proteins are assembled based on information from the genetic code C. any region on a protein's surface that interacts with another molecule through noncovalent bonding D. the portion of a protein that attaches to the cell membrane and tethers the protein as a peripheral membrane protein

C. any region on a protein's surface that interacts with another molecule through noncovalent bonding

Which of these three classifications is included under one of the others: prokaryotes, eukaryotes, archaea? A. prokaryotes B. eukaryotes C. archaea D. None of these, as these are all distinct cell types from one another.

C. archaea

How do protein, nucleic acid, and polysaccharide molecules polymerize (grow in length)? A. by hydrolysis reactions B. by oxidation reactions C. by condensation reactions D. none of these

C. by condensation reactions

What is the covalent linkage between two adjacent amino acids in a protein called? A. glycosidic bond B. phosphodiester bond C. peptide bond D. hydrogen bond E. phosphoanhydride bond

C. peptide bond

What does the primary structure of a protein refer to?: A. the locations of the protein's α helices and β sheets B. the overall three-dimensional shape of the protein C. the linear amino acid sequence of the protein D. the locations of the peptide bonds that form the protein's backbone E. the structure that forms first as the protein folds into its most stable form

C. the linear amino acid sequence of the protein

Which statement represents the cell theory? A. All cells can be seen using a microscope. B. All cells contain DNA. C. All cells resemble square or rectangular chambers. D. All cells are formed by the growth and division of existing cells. E. All cells require a continual input of energy to sustain life.

D. All cells are formed by the growth and division of existing cells.

What is a drawback to using light microscopy? A. It requires the use of fluorescent probes. B. It can be used only to view samples that are sliced very thinly. C. It cannot be used to view living cells. D. It cannot be used to view structures smaller than a bacterium. E. It cannot be used to view a whole cell or organism.

D. It cannot be used to view structures smaller than a bacterium.

Which of the following statements regarding NADPH and NADH is true? A. NADPH and NADH deliver electrons to the same set of enzymes. B. NADPH loses a phosphate group to form NADH during biosynthetic reactions. C. NADH carries electrons in animal cells and NADPH does the same in plants. D. NADPH and NADH are used in separate biochemical pathways in cells.

D. NADPH and NADH are used in separate biochemical pathways in cells.

In the 1920s, bacteriologist Fred Griffith demonstrated that a heat-killed, infectious pneumococcus produced a substance that could convert a harmless form of the bacterium into a lethal one. Fifteen years later, researchers prepared an extract from the disease-causing S strain of pneumococci and showed that this material could transform the harmless R-strain pneumococci cells into the infectious S-strain form. This change to the bacteria was both permanent and heritable, suggesting that this "transforming principle" represents the elusive genetic material of the cells. The researchers subjected their extract to a variety of tests to determine the chemical identity of the "transforming principle." In one experiment, they treated the material with enzymes that destroy all proteins. This treatment did not affect the ability of the extract to transform harmless bacteria into an infectious form.From this result, what could the researchers conclude? A. The transforming principle is not genetic material. B. DNA acts as the genetic material. C. The transforming principle is not DNA. D. The genetic material is not protein. E. Proteins act as the genetic material.

D. The genetic material is not protein.

What type of enzyme seals the newly added (repaired) DNA to the rest of the DNA molecule? A. helicase B. DNase C. polymerase D. ligase E. primase

D. ligase

A coiled-coil can be formed from α helices that have which of the following attributes? A. the same twist, either right-handed or left-handed B. alternating polar and nonpolar side chains C. many polar, hydrophilic side chains along one side of the helix D. many nonpolar, hydrophobic side chains along one side of the helix

D. many nonpolar, hydrophobic side chains along one side of the helix

Prokaryotes have chromosomes that are circular in structure. Which of the following would such chromosomes lack? A. complementary base pairs B. DNA double helix C. replication origin D. telomeres E. sugar-phosphate backbone

D. telomeres

Which of the following does not occur in cells? A. the conversion of sunlight into energy stored in chemical bonds during photosynthesis B. the metabolism of nutrients to produce useful energy stores C. the use of chemical energy to transport organelles through the cytosol D. the use of heat to burn foodstuffs and transport glucose

D. the use of heat to burn foodstuffs and transport glucose

How does ultraviolet radiation in sunlight typically damage DNA? A. It removes bases from nucleotides in DNA. B. It breaks the sugar-phosphate backbone of DNA. C. It converts cytosine into uracil. D. It breaks hydrogen bonds between the two strands of DNA. E. It causes two adjacent pyrimidine bases to become covalently linked.

E. It causes two adjacent pyrimidine bases to become covalently linked.

In the late 1920s, bacteriologist Fred Griffith was studying Streptococcus pneumoniae. This bacterium comes in two forms: one that is highly infectious (called the "S strain" because it forms colonies that appear smooth when grown on a nutrient plate in the lab) and one that is relatively harmless (called the "R strain" because its colonies appear rough). When injected into mice, the S strain is lethal, whereas the R strain causes no ill effect. Griffith confirmed that when the S strain is killed by heating, it is no longer infectious. But he then discovered that if he injected mice with both the heat-killed S strain pneumococci and the live, harmless R strain bacteria, the animals died of pneumonia. Furthermore, their blood was swarming with live, S strain bacteria that, when grown in culture, remained infectious and lethal.Based on these results, what could Griffith conclude? A. The infectious S strain of bacteria cannot be killed by heating. B. The R strain of bacteria is more deadly than previously thought. C. DNA is conclusively confirmed as the genetic material of cells. D. S. pneumoniae is a poor choice for investigating the molecular basis of heredity, as most bacteria behave unpredictably in the laboratory. E. Some substance in the infectious S strain can change the harmless R strain into the more lethal form.

E. Some substance in the infectious S strain can change the harmless R strain into the more lethal form

For a given protein, hydrogen bonds can form between which of the following? A. atoms in the polypeptide backbone B. atoms of two peptide bonds C. atoms in two side chains D. a side chain and water E. all of the above F. none of the above

E. all of the above

What is the measure of disorder in a system called? A. enthalpy B. free energy C. catabolism D. second law of thermodynamics E. entropy

E. entropy

Determine whether the following statement is true or false: Because introns are largely genetic junk, they do not need to be removed with any degree of precision during RNA splicing.

False

Determine whether the following statement is true or false: If an origin of replication is removed from a eukaryotic chromosome, the DNA on either side will also be lost, as it cannot be replicated.

False

In both plants and animals, the process of "controlled burning" extracts energy from food molecules. This is a gradual of what? photosynthesis oxidation biosynthesis reduction hydrolysis

oxidation

How do enzymes maximize the energy harvested from the oxidation of food molecules? They allow oxidation reactions to take place without an input of activation energy. They allow the stepwise oxidation of food molecules, which releases energy in small amounts. They allow what would otherwise be an energetically unfavorable oxidation reaction to occur. They guarantee that each reaction involved in the oxidation of food molecules proceeds in just one direction. They allow a larger amount of energy to be released from food molecules such as glucose.

They allow the stepwise oxidation of food molecules, which releases energy in small amounts.

Determine whether the following statement is true or false: At a replication fork, both strands of DNA are replicated in the 5'-to-3' direction.

True

Determine whether the following statement is true or false: Energetically unfavorable reactions can occur if they are coupled to a second reaction with a negative ΔG so large that the net ΔG of the entire process is negative.

True

Determine whether the following statement is true or false: In isolation, the formation of an activated carrier, such as ATP, NADH, or NADPH, is an energetically unfavorable reaction.

True

Determine whether the following statement is true or false: The majority of human DNA does not code for genes.

True

Double-strand breaks can be repaired flawlessly by which of the following? DNA maintenance methyl transferaseDNA ligase homologous recombination DNA mismatch repair system nonhomologous end joining

homologous recombination

What do the segments of a transmembrane protein that cross the lipid bilayer usually consist of? an α helix with mostly nonpolar side chains an α helix with mostly polar side chains a β sheet with alternating polar and nonpolar side chains a β sheet with mostly polar side chains

an α helix with mostly nonpolar side chains

Which option correctly describes the two strands of DNA in a double helix? held together by covalent bonds between bases antiparallel in orientation identical parallel in orientation

antiparallel in orientation

Which of the following best defines a mutation? mistake created by faulty mismatch repair by-product of natural selection permanent change in a DNA sequence harmful change in a DNA sequence change in DNA sequence that causes a change in an amino acid in a protein

permanent change in a DNA sequence

Where does DNA synthesis always begin? the telomeres CpG islands ATG the centromere replication origins

replication origins