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BS 161: EXAM 2
ATP and NADPH |
The light reactions of photosynthesis supply the Calvin cycle with
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H2O --> NADPH --> Calvin Cycle |
Which sequence correctly represents the flow of electrons during photosynthesis?
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In both cases, rubisco is not used to fix carbon initially. |
How is photosynthesis similar in C4 plants and CAM plants?
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Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and other nutrients that are inorganic. |
What is the distinction between autotrophs and heterotrophs?
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the release of oxygen |
What does not occur in the Calvin cycle
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oxidative phosphorylation in cellular respiration. |
In mechanism, photophosphorylation is most similar to
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removal of electrons from chlorophyll molecules |
Which process is most directly driven by light energy?
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carbon dioxide |
In photosynthesis, plants use carbon from _____ to make sugar and other organic molecules.
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Fungi |
Which of the following groups of organisms contains only heterotrophs?
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through the stomata |
how does carbon dioxide enter the lead
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thylakoids, which are in chloroplasts in the mesophyll cells of a leaf |
in a rosebush chlorophyll is located in
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thylakoid membranes |
Chlorophyll molecules are in which part of the chloroplast?
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water |
The source of the oxygen produced by photosynthesis has been identified through experiments using radioactive tracers. The oxygen comes from _____.
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in sugar molecules and in water |
In photosynthesis, what is the fate of the oxygen atoms present in CO2? They end up _____.
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noncyclic electron flow during the light reactions |
Molecular oxygen is produced during _____.
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The Calvin cycle requires products only produced when the photosystems are illuminated. |
The reactions of the Calvin cycle are not directly dependent on light, but they usually do not occur at night. Why?
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stroma |
The Calvin cycle occurs in the _____.
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blue |
A photon of which of these colors would carry the most energy?
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capture light energy |
The most important role of pigments in photosynthesis is to _____.
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blue-violet and red-orange |
What is the range of wavelengths of light that are absorbed by the pigments in the thylakoid membranes?
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an action spectrum |
Based on the work of Engelmann, the wavelengths of light most effective in driving photosynthesis are referred to as _____.
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electrons become excited |
When chloroplast pigments absorb light, _____.
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the photosystem |
What structure is formed by the reaction center, light-harvesting complexes, and primary electron acceptors that cluster, and is located in the thylakoid membrane?
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water |
Where do the electrons entering photosystem II come from?
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H2O ... photosystem II |
During photosynthesis in chloroplasts, O2 is produced from _____ via a series of reactions associated with _____.
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transport electrons from photosystem II to photosystem I |
During photosynthesis, an electron transport chain is used to _____.
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electrons |
Which of the following is cycled in the cyclic variation of the light reactions?
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use chemiosmosis to produce ATP |
Both mitochondria and chloroplasts _____.
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have photosynthetic pigments |
You could distinguish a granum from a crista because the granum, but not the crista, would _____.
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thylakoid membrane |
During photosynthesis in a eukaryotic cell, an electrochemical gradient is formed across the ______.
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NAPDH....oxygen and ATP |
The light reactions of photosynthesis generate high-energy electrons, which end up in _____. The light reactions also produce _____ and _____.
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movement of H+ through a membrane |
The energy used to produce ATP in the light reactions of photosynthesis comes from _____.
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It is reduced and then carries electrons to the Calvin cycle. |
What is the role of NADP+ in photosynthesis?
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CO2 is reduced. |
Of the following, which occurs during the Calvin cycle?
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ATP is hydrolyzed and NADPH is oxidized. |
Of the following, which occurs during the Calvin cycle?
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the enzyme in plants that first captures CO2 to begin the Calvin cycle |
Rubisco is _____.
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a 5-carbon compound to form an unstable 6-carbon compound, which decomposes into two 3-carbon compounds |
In the Calvin cycle, CO2 is combined with _____.
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-It is produced from glucose during glycolysis.
-It is a 3-carbon sugar.
-For every three molecules of CO2, six molecules of G3P are formed but only one molecule exits the cycle to be used by the plant cell.
-For every three molecules of CO2, six molecules of G3P are formed but five molecules must be recycled to regenerate three molecules of RuBP |
Glyceraldehyde-3-phosphate (G3P) is produced in the stroma of chloroplasts. Which of the following statements is most true about this compound?
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The light reactions produce ATP and NADPH, both of which are used in the Calvin cycle. |
Which of the following statements correctly describes the relationship between the light reactions and the Calvin cycle?
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It forms NADPH to be used in the Calvin cycle. |
What is the role of NADP+ in photosynthesis?
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-It reduces water loss.
-It prevents carbon dioxide from entering the leaf.
-In a process called photorespiration, rubisco binds oxygen instead of carbon dioxide.
-It builds up oxygen from the light reactions in the leaf. |
The use of non-C3 and non-CAM plants as crops may be limited in some regions because on hot, dry days, they close their stomata. What happens as a result of closing their stomata?
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Unlike C3 plants, they keep fixing carbon dioxide even when the concentration of carbon dioxide in the leaf is low. |
Why are C4 plants more suited to hot climates than C3 plants?
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While it did have access to light, the plant stored energy in the form of sugars or starch, and it was able to derive energy from the stored molecules during your vacation. |
You have a large, healthy philodendron that you carelessly leave in total darkness while you are away on vacation. You are surprised to find that it is still alive when you return. What has the plant been using for an energy source while in the dark?
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a plant cell in the process of cytokinesis |
Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely
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disruption of mitotic spindle formation |
Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of micro-tubules, its effectiveness must be related to
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continue to divide even when they are tightly packed together |
One difference between cancer cells and normal cells is that cancer cells
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the degradation of cyclin |
The decline of MPF activity at the end of mitosis is due to
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cells with more than one nucleus. |
In the cells of some organisms, mitosis occurs without cytoki-nesis. This will result in
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replication of the DNA |
which of the following does not occur during mitosis
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G1 |
A particular cell has half as much DNA as some other cells in a mitotically active tissue. The cell in question is most likely in
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cleavage furrow formation and cytokinesis |
The drug cytochalasin B blocks the function of actin. Which of the following aspects of the animal cell cycle would be most disrupted by cytochalasin B?
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rudolf virchow |
The person credited with first recognizing (in the 1860s) that living cells cannot arise spontaneously, but arise only from previously existing cells, is _____.
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are genetically identical to the parent cell (assuming no mutation has occurred) |
The function of the mitotic cell cycle is to produce daughter cells that _____.
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false |
Both of the sister chromatids end up in the same daughter cell after cytokinesis has occurred. true or false
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true |
Sister chromatids are separated during mitosis. true or false
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a chromatin |
The complex of DNA and protein that makes up a eukaryotic chromosome is properly called
|
centromere |
region of a chromosome holding the two double strands of replicated DNA together is called
|
centromere |
the region where sister chromatids are attached to one another in prophase
|
23 |
how many maternal chromosomes are present in a somatic human cell not engaged in cell division
|
cytokinesis |
division of the cytoplasm
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chromatids |
identical copies of each other if they are part of the same chromosome
|
30 |
if a cell contains 60 chromatids at the start of mitosis how many chromosomes will be found in each daughter cell at the completion of the cell cycle
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between G1 and G2 phases |
a biochemist measured the amount of DNA in cells growing in the lab and found that the quantity of DNA in the cells doubled
|
100 units |
a cell biologist carefully measured the quantity of DNA in grasshopper cells growing in cell culture. Cells examined during G2 phase of the cell cycle contained 200 units of DNA. what would be the amount of DNA at G1 of the the cell cycle in one of the grasshopper daughter cells
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dispersed in the nucleus as long strands of chromatin |
during interphase, the genetic material of a typical eukaryotic cell is
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the s phase of interphase in both somatic and reproductive cells |
DNA replication occurs in
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92 |
if a somatic human cell is just about to divide it has ____ chromatids
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94 |
Down syndrome is characterized by cells having three copies of chromosome 21. As a cell in an individual with Down syndrome prepares to enter mitosis, how many chromatids would be present?
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replication of chromosomes |
Which of the following does NOT occur during mitosis?
|
G2 |
During what phase in the cell cycle would you find the most DNA per cell?
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prophase |
In telophase of mitosis, the mitotic spindle breaks down and the chromatin uncoils. This is essentially the opposite of what happens in _____.
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telophase |
Which of the following phases of mitosis is essentially the opposite of prometaphase in terms of the nuclear envelope?
|
0 |
Assume that you are dealing with a species in which the number of chromosomes in each somatic cell is 14. How many sister chromatids are present in the early telophase of mitosis?
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prophase |
In a human skin cell that is going through the cell cycle, when do the centrosomes separate?
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two |
Following cytokinesis in an animal cell, how many centrioles does each new daughter cell possess?
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anaphase |
The phase of mitosis during which the chromosomes move toward separate poles of the cell is _____.
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the beginning of the formation of a spindle apparatus |
One event occurring during prophase is _____.
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anaphase |
begins when the paired centromeres of each chromosome separate, liberating the sister chromatids, which begin moving toward opposite poles of the cell.
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anaphase |
stage of cell cycle where sister chromatids separate
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metaphase |
during this phase the chromosomes align along the metaphase plate
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cytokinesis |
In animal cell mitosis, the cleavage furrow forms during which stage of the cell cycle
|
metaphase |
At which stage of mitosis are chromosomes lined up in one plane in preparation for their separation to opposite poles of the cell?
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it formed a cell plate |
You would know a dividing cell was a plant cell rather than an animal cell if you saw that _____.
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mitosis |
hich of the following processes does NOT occur in dividing bacteria?
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the origins of replication move apart |
During binary fission in a bacterium _____.
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happens during binary fission of bacteria |
distribution of a copy of the single parental chromosome to each daughter cell happens during
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When a cell in S phase is fused with a cell in G1, _____. |
DNA synthesis begins immediately in the original G1 nucleus
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fibroblasts fail to divide |
Tissue culture experiments with PDGF demonstrate that without this substance _____.
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nerve cell |
You would be unlikely to see which of the following human cells dividing?
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do not exhibit density-dependent inhibition |
bservations of cancer cells in culture support the hypothesis that cancer cells _____.
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Cells of benign tumors do not metastasize; those of malignant tumors do. |
What is the difference between a benign tumor and a malignant tumor?
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some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic. |
In his work with pneumonia-causing bacteria and mice, Griffith found that
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DNA polymerase can join new nucleotides only to the 39 end of a growing strand. |
What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized?
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A + G = C + T |
In analyzing the number of different bases in a DNA sample, which result would be consistent with the base-pairing rules?
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depends on the action of DNA polymerase. |
The elongation of the leading strand during DNA synthesis
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histones |
In a nucleosome, the DNA is wrapped around
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one low-density and one intermediate-density band |
E. coli cells grown on 15N medium are transferred to 14N medium and allowed to grow for two more generations (two rounds of DNA replication). DNA extracted from these cells is centrifuged. What density distribution of DNA would you expect in this experiment?
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DNA ligase |
A biochemist isolates, purifies, and combines in a test tube a variety of molecules needed for DNA replication. When she adds some DNA to the mixture, replication occurs, but each DNA molecule consists of a normal strand paired with numerous segments of DNA a few hundred nucleotides long. What has she probably left out of the mixture?
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nuclease, DNA polymerase, DNA ligase |
The spontaneous loss of amino groups from adenine in DNA results in hypoxanthine, an uncommon base, opposite thymine. What combination of proteins could repair such damage?
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heat-killed virulent ... living nonvirulent |
During Griffith's experiments with Streptococcus pneumoniae in mice, material from _____ bacteria transformed _____ bacteria.
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was the substance that transformed the bacteria in Griffith's experiment |
Avery and his colleagues' 1944 experiment showed that DNA _____
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the protein and DNA of T4 |
A scientist assembles a bacteriophage with the protein coat of phage T2 and the DNA of phage T4. If this composite phage were allowed to infect a bacterium, the phages produced in the host cell would have _____.
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the genetic material of the phage is DNA |
In an important experiment, a radioactively labeled bacteriophage was allowed to infect bacteria. In a first trial, the phage contained radioactive DNA, and radioactivity was detected inside the bacteria. Next, phage containing radioactive protein was used, and the radioactivity was not detected inside the bacteria. These experiments led to the conclusion that _____.
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proteins because they were thought to be the only molecule with both the variety and specificity of function to account for the array of heritable traits observed |
Up until Hershey and Chase showed that DNA was the genetic molecule, what molecule was considered the best candidate for carrying genetic information and why?
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nucleotides |
Monomers for the synthesis of DNA are called _____.
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chargoffs finding in DNA |
the ratio of A to T is close to 1:1 and the ratio of G to C is close to 1:1
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X-ray crystallography |
What technique was most helpful to Watson and Crick in developing their model for the structure of DNA?
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adenine and guanine ... cytosine and thymine |
In DNA, the two purines are _____, and the two pyrimidines are _____.
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two...three |
Adenine forms ______ hydrogen bonds with thymine; guanine forms _____ hydrogen bonds with cytosine.
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hydrogen bonds between nucleotide bases |
The two sugar-phosphate strands that form the rungs of a DNA double helix are joined to each other through _____
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he sequence of nucleotides along the length of the two strands of the DNA molecule |
The information in DNA is contained in _____.
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watson and crick |
Who is credited with explaining the structure of the DNA double helix?
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its specific base pairing and hydrogen bonding |
Which of the following attributes of DNA is most crucial to its accurate duplication?
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replication of DNA |
both strands of a molecule act as templates during....
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both have a sugar-phosphate backbone |
The DNA structures of prokaryotes and eukaryotes are different in several ways, but one way in which they are the same is that _____.
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a replication fork |
At each end of a DNA replication bubble is _____.
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ttach free nucleotides to the new DNA strand |
The role of DNA polymerases in DNA replication is to _____.
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much faster then |
The rate of elongation in prokaryotes is _____ the rate in eukaryotes.
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one strand runs in the 5' to 3' direction, and the other runs in the 3' to 5' direction |
The two strands of a DNA double helix are antiparallel. This means that _____.
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TATCCA |
One strand of a DNA molecule has the base sequence 5′-ATAGGT-3′. The complementary base sequence on the other strand of DNA will be 3′-_____-5′.
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3'end....3'end |
DNA polymerase adds nucleotides to the _____ of the leading strands, and to the _____ of the lagging strands (Okazaki fragments).
|
DNA ligase |
What enzyme joins Okazaki fragments?
|
helicases, primase, DNA polymerases, ligase |
After the formation of a replication bubble, which of the following is the correct sequence of enzymes used for the synthesis of the lagging DNA strand?
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RNA primer |
Which of the following components is required for DNA replication?
|
DNA polymerase 1 |
The removal of the RNA primer and addition of DNA nucleotides to the 3' end of Okazaki fragments in its place is carried out by _____.
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topoisomerase |
The unwinding of DNA at the replication fork causes twisting and strain in the DNA ahead of the fork, which is relieved by an enzyme called _____.
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Single-strand binding proteins bind the unwound DNA and prevent the double helix from re-forming. |
Once the DNA at the replication fork is unwound by helicases, what prevents the two strands from coming back together to re-form a double helix?
|
DNA replication |
Helicases separate the two strands of the double helix, and DNA polymerases then construct two new strands using each of the original strands as templates.
|
1 error per 10,000,000,000 nucleotides |
The overall error rate in the completed DNA molecule is approximately _____.
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can be repaired by the mismatch repair system |
The incorporation of an incorrect base into the DNA during replication _____.
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nuclease, DNA polymerase, and ligase |
Which set of enzymes is involved in nucleotide excision repair?
|
cannot be completed by DNA polymerase |
Unlike prokaryotic DNA replication, replication of eukaryotic chromosomes _____.
|
telomeres |
get shorter with continued cell division
|
telomerase |
is an enzyme that lengthens telomeres
|
In a temporally variable environment, a population of bacteria with an elevated rate in replication error can have a selective advantage over other populations with lower rates in replication error. |
Which of the following best illustrates the importance of altered DNA nucleotides in evolutionary processes?
|
Being asexual and single-celled, all uncorrected errors of replication in bacteria are transmitted to subsequent generations. Multicellular eukaryotes typically reproduce sexually, so uncorrected errors are transmitted only if they occur in germ cells that meiotically divide to produce gametes. |
In a comparison between asexually reproducing bacteria and sexually reproducing multicellular eukaryotes, uncorrected errors in replication are more likely to be transmitted to subsequent generations in bacteria than in multicellular eukaryotes. Which of the following provides the best evidence-based explanation for this difference?
|
Bacteria have a single circular chromosome whereas eukaryotes have several linear chromosomes. |
What is the major difference between bacterial chromosomes and eukaryotic chromosomes?
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virus, bacteria, eukaryote |
Put the following DNA-containing entities in order according to the amount of DNA found in their genomes.
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nucleosomes |
The "beads on a string" seen in interphase chromatin are _____.
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several transcription factors have bound to the promoter |
In eukaryotic cells, transcription cannot begin until
|
It extends from one end of a tRNA molecule. |
Which of the following is not true of a codon?
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complementary to the corresponding mRNA codon. |
The anticodon of a particular tRNA molecule is
|
Exons are cut out before mRNA leaves the nucleus. |
Which of the following is not true of RNA processing?
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DNA |
Which component is not directly involved in translation?
|
a single nucleotide insertion downstream of, and close to, the start of the coding sequence |
Which of the following mutations would be most likely to have a harmful effect on an organism? |