BSC2010 Exam III Homework
In DNA replication in bacteria, the enzyme DNA polymerase III (abbreviated DNA pol III) adds nucleotides to a template strand of DNA. But DNA pol III cannot start a new strand from scratch. Instead, a primer must pair with the template strand, and DNA pol III then adds nucleotides to the primer, complementary to the template strand. Each of the four images below shows a strand of template DNA (dark blue) with an RNA primer (red) to which DNA pol III will add nucleotides. In which image will adenine (A) be the next nucleotide to be added to the primer?
In the example above, DNA pol III would add an adenine nucleotide to the 3' end of the primer, where the template strand has thymine as the next available base. You can tell which end is the 3' end by the presence of a hydroxyl (-OH) group. The structure of DNA polymerase III is such that it can only add new nucleotides to the 3' end of a primer or growing DNA strand (as shown here). This is because the phosphate group at the 5' end of the new strand and the 3' -OH group on the nucleoside triphosphate will not both fit in the active site of the polymerase.
What kind of bond is formed when lithium and fluorine combine to form lithium fluoride?
Ionic The complete transfer of an electrons from lithium to fluorine results in a stable compound in which both atoms have full outermost shells.
What kind of bond is formed when lithium and fluoride combine to form lithium fluoride?
Ionic The complete transfer of an electron from lithium to fluorine results in a stable compound in which both atoms have full outermost shells
How does the enzyme telomerase meet the challenge of replicating the ends of linear chromosomes?
It catalyzes the lengthening of telomeres, compensating for the shortening that could occur during replication without telomerase activity.
Which of the following statements accurately describes the structure of a eukaryotic chromosome?
It is a single linear molecule of double-stranded DNA plus proteins.
What happens to the free energy released as electrons are passed from photosystem II to photosystem I through a series of electron carriers?
It is used to establish and maintain a proton gradient
Which of the following describes the process of glycolysis?
It represents the first stage in the chemical oxidation of glucose by a cell. Catabolism of glucose begins with glycolysis
Which of the following statements best describes the primary role played by oxygen in cellular respiration?
It serves as the final acceptor for electrons from the electron transport chain
Okazaki fragments are part of which of the following aspects of DNA replication?
Lagging strands
The overall function of the Calvin cycle is
making sugar Using the ATP and NADPH made during the light reactions, carbon is reduced in the Calvin cycle and sugar is made.
Where are the proteins of the electron transport chain located?
mitochondrial inner membrane
Energy released by the electron transport chain is used to pump H+ ions into which location in eukaryotic cells?
mitochondrial intermembrane space
This is an image of a(n) _____.
nucleotide Nucleotides are composed of a pentose sugar, a nitrogenous base, and a phosphate group
Semiconservative replication involves a template. What is the template?
one strand of the DNA molecule
Which of the following statements describes a primary function of both alcohol fermentation and lactic acid fermentation?
oxidation of NADH and NAD+
Carbon dioxide (CO2) is released during which of the following stages of cellular respiration?
oxidation of pyruvate to acetyl CoA and the citric acid cycle
When a compound donates (loses) electrons, that compound becomes _______. Such a compound is often referred to as an electron donor.
oxidized
Which of the following is a product of the light reactions of photosynthesis?
oxygen, ATP, and NADPH
This is an image of a _____.
phage This is a T2 phage, a type of phage that infects E. coli.
The letter A indicates _____.
phosphate group
What is the function of topoisomerase in DNA replication?
prevents supercoiling of DNA
Once the electron donor in glycolysis gives up its electrons, it is oxidized to a compound called ______.
pyruvate
Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions?
pyruvate, ATP, and NADH ATP is the main product of cellular respiration that contains energy that can be used by other cellular processes. Some ATP is made in glycolysis. In addition, the NADH and pyruvate produced in glycolysis are used in subsequent steps of cellular respiration to make even more ATP
Which of the following processes is directly associated with photosystem I?
receiving electrons from the thylakoid membrane electron transport chain
When a compound accepts (gains) electrons, that compound becomes ______. Such a compound is often referred to as an electron acceptor.
reduced
Which of the following processes is most directly drive by light energy?
removal of electrons from chlorophyll molecules
During DNA replication, an open section of DNA, in which a DNA polymerase can replicate DNA, is called a _____.
replication fork
The action of helicase creates _____.
replication forks and replication bubbles A replication fork is the transition region between paired and unpaired DNA strands.
The mechanism of DNA replication is described as ____.
semi-conservative
It became apparent to Watson and Crick after completion of their model that the DNA molecule could carry a vast amount of hereditary information. Which of the following characteristics of DNA is responsible for this?
sequence of bases
Which of the following types of molecules help to hold the DNA strands apart while they are being replicated?
single-strand DNA binding proteins
When light strike chlorophyll molecules, they lose electrons, which are ultimately replaced by _____.
splitting water The electrons removed from water are transferred to P680
The oxygen released by photosynthesis is produced by which of the following processes?
splitting water molecules
Where in a plant cell does the Calvin cycle take place?
storm of the chloroplast
In mitochondria, an electron transport chain pumps protons from the matrix into the inter membrane space, whereas in chloroplasts, an electron transport chain pumps protons from the _____.
stroma to the thylakoid space
In glycolysis, ATP molecules are produced by
substrate-level phosphorylation A phosphate group is transferred from glyceraldehyde phosphate to ADP
You can tell this is an image of a DNA nucleotide and not an RNA nucleotide because you can see a ____.
sugar with two, and not three, oxygen atoms DNA nucleotides are composed of deoxyribose sugars, whereas RNA nucleotides are composed of ribose sugars.
Which of the following processes would be most directly affected if a thylakoid membrane is punctured so that the interior of the thylakoid is no longer separated from the stroma?
synthesis of ATP
What are the repetitive DNA sequences present at the ends of eukaryotic chromosomes called?
telomeres Telomeres consists of many copies of a short DNA sequence that is bound by specific proteins
An old DNA strand is used as a _____ for the assembly of a new DNA strand.
template An old DNA strand is used as a template for the synthesis of a complementary new strand
After RNA primers are added, new DNA synthesis build on ____.
the 3' end of the primers
Which of the following events takes place in the electron transport chain?
the harnessing of energy from high-energy electrons derived from glycolysis and the citric acid cycle
Where are ATP synthesis complexes located in plant cells?
thylakoid membrane and inner mitochondrial membrane
Which of these nitrogenous bases is found in DNA but not in RNA?
thymine
In a DNA double helix an adenine of one strand always pairs with a(n) _____ of the complementary strand, and a guanine of one strand always pairs with a(n) _____ of the complementary strand.
thymine ... cytosine This is referred to as specific base pairing.
In mitochondrial electron transport, what is the direct role of O2?
to function as the final electron acceptor in the electron transport chain The only place that O2 participates in cellular respiration is at the end of the electrons transport chain, as the final electron acceptor. Oxygen's high affinity for electrons ensures its success in this role. Its contributions driving electron transport, forming a proton gradient, and synthesizing ATP are all indirect effects of its role as the terminal electron acceptor.
In the absence of oxygen, what is the net gain of ATP for each glucose molecule that enter glycolysis?
two ATP Four ATP are made, but two ATP are consumed to start the process of glycolysis
In glycolysis, for each molecule of glucose oxidized to pyruvate, ______.
two molecules of ATP are used and four molecules of ATP are produced
The light reactions of photosynthesis use _____ and produce _____.
water ... NADPH NADPH is the reactant in the Calvin cycle
The radioactive isotope 32P labels the T2 phage's _____.
DNA The T2 phage consists of a protein coat and DNA. It is the DNA that contains P.
Which of these is a difference between a DNA and an RNA molecule?
DNA is usually double-stranded, whereas RNA is usually single-stranded With some exceptions, DNA is a double-stranded molecule and RNA is a single-stranded molecule.
The enzyme that can replicate DNA is called _____.
DNA polymerase
What catalyzes DNA synthesis?
DNA polymerase
Which of these is NOT a product of glycolysis?
FADH2 FADH2 is a product of the citric acid cycle.
The oxidation of pyruvate to an acetyl group directly produces ATP
False
Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other?
Anion and cation Each atom will carry a charge from the transfer of electrons
Net redox reaction in acetyl CoA formation and the citric acid cycle
As in glycolysis, the electrons removed from carbon-containing intermediates during acetyl CoA formation and the citric acid cycle are passed to the electron carrier NAD+, reducing it to NADH. The citric acid cycle also uses a second electron carrier, FAD, the oxidized form, and FADH2, the reduced form
In the accompanying image, a nucleotide is indicated by the letter ____.
B B is indicating a single nucleotide
_____ releases energy that is used to pump hydrogen ions from the stroma into the thylakoid compartment.
B The energy released as electrons are passed along the electron transport chain is used to pump protons into the thylakoid compartment
Which of the summary statements below describes the results of the following reaction? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy
C6H12O6 is oxidized and O2 is reduced
The overall chemical reaction of photosynthesis is the reverse of cellular respiration. That means that which molecule is going to receive electrons and be reduced in photosynthesis?
CO2
CO2 is converted to sugar during which stage of Photosynthesis?
Calvin cycle
Photosynthesis takes place in which organelle?
Chloroplast
Identify a thylakoid.
D
In nucleotide structure, the phosphate group is always attached to which carbon of the sugar?
5'
DNA replication is said to be semiconservative. What does this mean?
Each new double helix consists of one old and one new strand.
In glycolysis, as in all the stages of cellular respiration, the transfer of electrons from electron donors to electron acceptors plays a critical role in the overall conversion of the energy in foods to energy in ATP. These reactions involving electron transfers are known as oxidation-reduction, or redox reactions.
- When a compound donates (loses) elections, that compound becomes oxidized. Such a compound is referred to as an electron donor. - When a compound accepts (gains) elections, that compound becomes reduced. Such a compound is referred to as an electron acceptor. - In glycolysis, the carbon-containing compound that functions as the electron donor is glucose. - Once the electron donor in glycolysis gives up its electrons, it is oxidized to a compound called pyruvate. - NAD+ is the compound that functions as the electron acceptor in glycolysis. - The reduced form of the electron acceptor in glycolysis in NADH. In the net reaction for glycolysis, glucose (the electron donor) is oxidized to pyruvate. The electrons removed from glucose are transferred to the electron acceptor, NAD+, creating NADH
In a nucleotide structure, the nitrogenous base is always attached to which carbon of the sugar?
1'
In a nucleotide, the nitrogenous base is attached to the sugar's _____ carbon and the phosphate group is attached to the sugar's _____ carbon.
1' ... 5' The nitrogenous base is attached to the sugar's 1' carbon and the phosphate group is attached to the sugar's 5' carbon.
If glucose is the sole energy source, what fraction of the carbon dioxide exhale by animals is generated only by the reactions involved in the oxidation of pyruvate to acetyl CoA?
1/3
How many NADH are produced by glycolysis?
2 Two NADH molecules are produced by glycolysis.
In glycolysis, there is a net gain of ... ATP.
2 It takes 2 ATP to produce 4 ATP
In the Calvin cycle, how many ATP molecules are required to regenerate RuBP from five G3P molecules?
3
Hershey and Chase used _____ to radioactively label the T2 phage's proteins.
35S Hershey and Chase used radioactive sulfur to label the phage's proteins.
Use the following figure to answer the question What wavelength of light in the figure is most effective in drive photosynthesis?
420 nm
At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork:3' C C T A G G C T G C A A T C C 5'An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence?
5' A C G U U A G G 3'
New nucleic acid polymers are always assembled in which direction?
5' to 3'
Nucleic acids are assembled in the _____ direction.
5' to 3' New nucleotides are added to the 3' end of a growing polynucleotide.
How many carbon dioxide molecules must be added to RuBP to make a single molecule of glucose?
6 Six carbon dioxide molecules are required to produce two G3P molecules, which can be combined to make one glucose molecule
Which of these equations best summarize photosynthesis?
6 CO2 + 6 H2O → C6H12O6 + 6 O2 This is the equation that summarizes the reactions of photosynthesis
Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine?
8%
Identify the chloroplast
A
_____ splits water into 1/2 O2, H+, and e- .
A Photosystem II
Chlorophyll can be found in _____.
A and C Photosystem I and II
Which of the following statements is not true of most cellular redox reactions?
A hydrogen atom is transferred to the atom that loses an electron A hydrogen atom (proton, or H+) is often transferred to the atom that gains an electron
Which of the following statement is not true of most cellular redox reactions? - Changes in potential energy can be released as heat. - A hydrogen atom is transferred to the atom that loses an electron. - The electron acceptor is reduced. - The reactant that is oxidized loses electrons.
A hydrogen atom is transferred to the atom that loses an electron. A hydrogen atom (proton, or H+) is often transferred to the atom that gains an electron
Use the following figure to answer the question. If photosynthesizing green algae are provided with CO2 contained heavy oxygen (18O), which of the following molecules produced by the algae (refer to the accompanying figure) will fail to contain 18O in later biochemical analyses?
ADP
In glycolysis, what starts the process of glucose oxidation?
ATP Some ATP energy is used to start the process of glucose oxidation
Which of the following molecules are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?
ATP and NADPH
The Calvin cycle is an anabolic pathway. The energy required for this metabolic pathways comes, most directly, from ____.
ATP made in the light reactions
The oxygen consumed during cellular respiration is involved directly in which process or event?
Accepting electrons at the end of the electron transport chain
For a science fair project, two students decided to repeat the Hershey and Chase experiment, with modifications. They decided to radioactively label the nitrogen of the DNA, rather than the phosphate. They reasoned that each nucleotide has only one phosphate and two to five nitrogen atoms. Thus, labeling the nitrogen atoms would provide a stronger signal than labeling the phosphates. Why won't this experiment work?
Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.
Which of the following events accompanies of energy by chlorophyll molecules of the reaction-center complex?
An electron is excited
Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other?
Anion and cation Each atom will carry a change from the transfer of electrons
How would anaerobic conditions (when no O2 is present) affect the rate of electron transport and ATP production during oxidative phosphorylation? (Note that you should not consider the effect on ATP synthesis in glycolysis or the citric acid cycle.)
Both electron transport and ATP synthesis would stop Oxygen plays an essential role in cellular respiration because it is the final electron acceptor for the entire process. Without O2, mitochondria are unable to oxidize the NADH and FADH2 produced in the first three steps of cellular respiration, and thus cannot make any ATP via oxidative phosphorylation. In addition, without O2 the mitochondria cannot oxidize the NADH and FADH2 back to NAD+ and FAD, which are needed as inputs to the first three stages of cellular respiration.
A nitrogenous base is indicated by the letter _____.
C
Energized electrons from ____ are used to reduce NADP+.
C Photosystem I
Which of these is (are) pyrimidines?
C, D, and E Pyrimidines are single-ring structures
In this activity, you will demonstrate your understanding of antiparallel elongation at the replication forks. Keep in mind that the two strands in a double helix are oriented in opposite directions, that is, they are antiparallel. Drag the arrows onto the diagram below to indicate the direction that DNA polymerase III moves along the parental (template) DNA strands at each of the two replication forks. Arrows can be used once, more than once, or not at all.
DNA polymerase III can only add nucleotides to the 3' end of a new DNA strand. Because the two parental DNA strands of a double helix are antiparallel (go from 3' to 5' in opposite directions), the direction that DNA pol III moves on each strand emerging from a single replication fork must also be opposite. For example, in the replication fork on the left, the new strand on top is being synthesized from 5' to 3', and therefore DNA pol III moves away from the replication fork. Similarly, the new strand on the bottom of that same replication fork is being synthesized from 5' to 3'. But because the bottom parental strand is running in the opposite direction of the top parental strand, DNA pol III moves toward the replication fork. In summary, at a single replication fork, one strand is synthesized away from the replication fork, and one strand is synthesized toward the replication fork. When you look at both replication forks, note that a single new strand is built in the same direction on both sides of the replication bubble.
Why does a new DNA strand elongate only in the 5' to 3' direction during DNA replication?
DNA polymerase can add nucleotides only to the free 3' end.
Why is the new DNA strand complementary to the 3' to 5' strands assembled in short segments?
DNA polymerase can assemble DNA only in the 5' to 3' direction Since DNA polymerase can assemble DNA only in the 5' to 3' direction, the new strand complementary to the 3' to 5' strand must be assembled either in short 5' to 3' segments, which are later joined together by ligase, or be assembled continuously.
Enzymes responsible for assembling new DNA strands are called ____.
DNA polymerases
During DNA replication, the leading strand is synthesized continuously, whereas the lagging strand is synthesized as Okazaki fragments. Why is this so?
DNA synthesis can take place only in the 5' to 3' direction.
Some photosynthetic organisms contain chloroplasts that lack photosystem II, yet are able to survive. Which of the following approaches would be the best way to detect the lack of photosystem II in these organisms?
Determine whether they produce O2 in the light
Drag the correct labels to the appropriate locations in the diagram to show the composition of the daughter DNA molecules after one and two cycles of DNA replication. In the labels, the original parental DNA is blue and the DNA synthesized during replication is red.
During DNA replication, each strand in the parental DNA serves as the template for the production of a daughter strand by complementary base pairing. Therefore, one cycle of replication will produce two daughter DNA molecules, each with one parental strand and one newly synthesized strand. During a second cycle of replication, all four strands in the two DNA molecules will serve as templates, resulting in four molecules (eight strands of DNA).
Drag the labels to their appropriate locations in the diagram to describe the name or function of each structure. Use pink labels for the pink targets and blue labels for the blue targets.
During replication, DNA synthesis occurs in the 5′ to 3′ direction along both template strands. On one template strand, synthesis proceeds continuously toward the replication fork, generating the leading strand. On the other template strand, DNA is synthesized away from the replication fork in segments called Okazaki fragments, generating the lagging strand. Several proteins are involved in DNA replication, including the following: Topoisomerase cuts, swivels, and rejoins DNA strands ahead of the replication fork. Helicase breaks the hydrogen bonds between the parental DNA strands and unwinds the double helix. Single-strand binding proteins bind to the single strands of DNA, preventing them from re-forming hydrogen bonds with each other and allowing synthesis to occur on both strands. DNA polymerase III synthesizes the new strands, but it requires an existing 3′ hydroxyl (—OH) group to add nucleotides. Primase creates short RNA primers, initiating DNA synthesis on both template strands. DNA polymerase I removes the RNA primers and replaces them with DNA nucleotides. On the lagging strand, DNA ligase joins Okazaki fragments by forming phosphodiester bonds between them, thus completing DNA replication.
Identify the stroma
E
Which of these phosphorylates ADP to make ATP?
E ATP synthase phosphorylates ADP
Where does the Calvin cycle occur?
E The Calvin cycle occurs in the stroma
NADH and FADH2 are both electron carriers that donate their electrons to the electron transport chain. The electrons ultimately reduce O2 to water in the final step of electron transport. However, the amount of ATP made by electrons from an NADH molecule is greater than the amount made by electrons from an FADH2 molecule. Which statement best explains why more ATP is made per molecule of NADH than per molecule of FADH2?
Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor. Electrons derived from the oxidation of FADH2 enter the electron transport chain at Complex II, farther down the chain than electrons from NADH (which enter at Complex I). This result in fewer H+ ions being pumped across the membrane for FADH2 compared to NADH, as this diagram shows, Thus, more ATP can be produced per NADH than FADH2.
Each of the four stages of cellular respiration occurs in a specific location inside or outside the mitochondria. These locations permit precise regulation and partitioning of cellular resources to optimize the utilization of cellular energy glycolysis, acetyl CoA formation, citric acid cycle, oxidative phosphorylation
Glycolysis: cytosol Acetyl CoA formation: mitochondrial matrix Citric acid cycle: mitochondrial matrix Oxidative phosphorylation: inner mitochondrial membrane Cellular respiration begins with glycolysis in the cytosol. Pyruvate, the product of glycolysis, then enters the mitochondrial matrix, crossing both the outer and inner membranes. Both acetyl CoA formation and the citric acid cycle take place in the matrix. The NADH and FADH2 produced during the first three stages release their electrons to the electron transport chain of oxidative phosphorylation at the inner mitochondrial membrane. The inner membrane provides the barrier that creates an H+ gradient during electron transport, which is used for ATP synthesis.
ATP synthase has which of the following functions?
H+ channel
The overall chemical reaction of photosynthesis is the reverse of cellular respiration. That means that which molecule is going to lose electrons and be oxidized in photosynthesis?
H2O
Which of the following sequences correctly represents the flow of electrons during photosynthesis?
H2O → NADPH → Calvin cycle
As DNA replication continues and the replication bubble expands, the parental double helix is unwound and separated into its two component strands. This unwinding and separating of the DNA requires three different types of proteins: helicase, topoisomerase, and single-strand binding proteins. Sort the phrases into the appropriate bins depending on which protein they describe. Proteins: helicase, topoisomerase, single-stranding binding proteins Phrases: breaks H-bonds between bases, binds at the replication fork, binds ahead of the replication fork, breaks covalent bonds in DNA backbone, binds after the replication fork, prevent H-bonds between bases
Helicase: breaks H-bonds between bases and binds at the replication fork Topoisomerase: binds ahead of the replication fork and breaks covalent bonds in DNA backbone Single-strand binding protein: binds after the replication fork, prevents H-bonds between bases
Who demonstrated that DNA is the genetic material of the T2 phage?
Hershey and Chase Hershey and Chase did a series of classic experiments demonstrating that DNA is the genetic material of the T2 phage.
Gaseous hydrogen burns in the presence of oxygen to form water: 2H2 + O2 → 2H2 O + energy Which molecule is oxidized and what kind of bond is formed?
Hydrogen, polar Hydrogen loses electrons to oxygen, which is more electronegative and thus pulls the electrons closer to itself in the water molecule
Gaseous hydrogen burns in the presence of oxygen to form water: 2 H2 + O2 -> 2H20 + energy Which molecule is oxidized and what kind of bond is formed?
Hydrogen, polar Hydrogen loses electrons to oxygen, which is more electronegative and thus pulls the electrons closer to itself inn the water molecule.
As the two parental (template) DNA strands separate at a replication fork, each of the strands is separately copied by a DNA polymerase III (orange), producing two new daughter strands (light blue), each complementary to its respective parental strand. Because the two parental strands are antiparallel, the two new strands (the leading and lagging strands) cannot be synthesized in the same way. Drag each phrase to the appropriate bin depending on whether it describes the synthesis of the leading strand, the synthesis of the lagging strand, or the synthesis of both strands. Phrase: made continuously, only one primer needed, daughter strand elongates toward replication fork, daughter strand elongates away from replication fork, multiple primers needed, made in segments, synthesis 5' to 3'
Leading Strand: made continuously, only one primer needed, daughter strand elongates toward replication fork Lagging strand: daughter strand elongates away from replication fork, multiple primers needed, made in segments Both strands: synthesized 5' to 3'
Where does the citric acid cycle take place in a eukaryotic cell?
Mitochondrial matrix
______ is the compound that functions as the electron acceptor in glycolysis.
NAD+
Which of the following statement about NAD+ is true?
NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle.
Following glycolysis and the citric acid cycle, but before the electron transport chain and oxidative phosphorylation, the carbon skeleton of glucose has been broken down to CO2 with some net gain of ATP. Most of the energy from the original glucose molecule at that point in the process, however, is in the form of _____.
NADH
The reduced form of the electron acceptor in glycolysis is ______.
NADH
When electrons are removed from glucose (as it is oxidized), which molecules holds most of these electrons and therefore contains that energy?
NADH
Which molecule is the final electron acceptor for electrons from photosystem I?
NADP+
The reducing power for Calvin cycle reactions is provided by which of the following molecules?
NADPH
After 3-PGA is phosphorylated, it is reduced by _____.
NADPH NADPH supplies the electrons that reduce the phosphorylated 3-PGA
Which of the following products of the light reactions of photosynthesis is consumed during the Calvin cycle?
NADPH During the Clavin cycle electrons stored in NADPH are used to reduce carbon
In acetyl CoA formation, the carbon-containing compound from glycolysis is oxidized to produce acetyl CoA. From the following compounds involved in cellular respiration, choose those that are the net input and net outputs of acetyl CoA formation. glucose, NAD+, ADP, ATP, NADH, pyruvate, CO2, acetyl COA, coenzyme A, O2
NET INPUTS: NAD+, coenzyme A, pyruvate NET OUTPUTS: NADH, acetyl CoA, CO2 NOT INPUT OR OUTPUT: glucose, ADP, O2, ATP In acetyl CoA formation, pyruvate (a product of glycolysis) is oxidized to acetyl CoA, with the reduction of NAD+ to NADH and the release of one molecule of CO2
In the last stage of cellular respiration, oxidative phosphorylation, all of the reduced electron carriers produced in the previous stages are oxidized by oxygen via the electron transport chain. The energy from this oxidation is stored in a form that is used by most other energy-requiring reaction in cells. From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of oxidative phosphorylation. glucose, NAD+, ADP, ATP, NADH, pyruvate, CO2, acetyl COA, coenzyme A, O2
NET INPUTS: NADH, ADP, O2 NET OUTPUTS: NAD+, ATP, water NOT INPUT OR OUTPUT: glucose, pyruvate, acetyl CoA, coenzyme A, CO2 In oxidative phosphorylation, the NADH and FADH2 produced by the first three stages of cellular respiration are oxidized in the electron transport chain, reducing O2 to water and recycling NAD+ and FAD back to the first three stages of cellular respiration. The electron transport reactions supply the energy to drive most of a cell's ATP production.
In the citric acid cycle (also known as the Krebs cycle), acetyl CoA is completely oxidized. From the following compounds involved in cellular respiration, choose those that are net inputs and net outputs of the citric acid cycle glucose, NAD+, ADP, ATP, NADH, pyruvate, CO2, acetyl COA, coenzyme A, O2
NET INPUTS: acetyl CoA, NAD+, ADP NET OUTPUTS: ATP, CO2, NADH, coenzyme A NOT INPUT OR OUTPUT: glucose, O2, pyruvate In the citric acid cycle, the two carbons from the acetyl group of acetyl CoA are oxidized to two molecules of CO2, while several molecules of NAD+ are reduced to NADH and one molecule of FAD is reduced to FADH2. In addition, one molecule of ATP is produced
From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of glycolysis: glucose, NAD+, ADP, ATP, NADH, pyruvate, CO2, acetyl COA, coenzyme A, O2
NET INPUTS: glucose, NAD+, ADP NET OUTPUTS: ATP, NADH, pyruvate NOT INPUT OR OUTPUT: CO2, acetyl CoA, coenzyme A, O2 In glycolysis, the six-carbon sugar glucose is converted to two molecules of pyruvate (three carbons each), with the next production of 2 ATP and 2 NADH per glucose molecule. There is no O2 uptake or CO2 release in glycolysis.
In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin of replication. Which of the following events would you expect to occur as a result of this mutation?
No replication fork will be formed.
____________ are the short sections of DNA that are synthesized on the lagging strand of the replicating DNA.
Okazaki fragments
In autumn, chlorophyll is degraded in the leaves of deciduous trees. Why do the leaves change color to shades of yellow, orange, or red?
Other pigments such as carotenoids are still present in the leaves
What molecule is indicated by the letter D?
Oxygen Oxygen is the final electron acceptor of cellular respiration.
Which of the following statements is true of the bonds in a water molecule?
Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero The oxygen and hydrogen atoms in water have partial charges, but the molecule has a net charge of zero
which of the following statements is true of the bonds in a water molecule?
Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero The oxygen and hydrogen atoms in water have partial charges, but the molecules has a net charge of zero
Which part of a deoxynucleoside triphosphate (dNTP) molecule provides the energy for DNA synthesis?
Phosphate groups The potential energy stored in the bonds of the phosphates provides the energy for DNA synthesis.
Photosynthesis is responsible for the production of O2 gas which is released in the atmosphere. Which stage of photosynthesis is responsible for O2 production?
Photosystem II
The ATP produced in Photosynthesis is most closely associated with which set of reactions?
Photosystem II
The NADPH (an electron carrier) is produced during which set of reactions in Photosynthesis?
Photosytem I
Which of the following enzymes creates a primer for DNA polymerase?
Primase This RNA polymerase synthesizes an RNA primer antiparallel to the template DNA strand.
Which of the following statements about DNA synthesis is true?
Primers are short sequences that allow the initiation of DNA synthesis. When a primer is added to a single strand of DNA, DNA polymerase can start adding nucleotides to synthesize a complementary strand.
When the protein gramicidin is integrated into a membrane, an H+ channel forms and the membrane becomes very permeable to protons (H+ ions). If gramicidin is added to an actively respiring muscle cell, how would it affect the rates of electron transport, proton pumping, and ATP synthesis in oxidative phosphorylation? (Assume that gramicidin does not affect the production of NADH and FADH2 during the early stages of cellular respiration.) Sort the labels in the correct bin according to the effect that gramicidin would have on each process. Categories: remain the same, decrease (or goes to zero), and increases Labels: proton pumping rate, electron transport rate, rate of oxygen uptake, size of the proton gradient, and rate of ATP synthesis
Remains the same: proton pumping rate, electron transport rate, and rate of oxygen uptake Decreases (or goes to zero): size of the proton gradient and rate of ATP synthesis Increases: None Gramicidin causes membranes to become very leaky to protons, so that a proton gradient cannot be maintained and ATP synthesis stops. However, the flakiness of the membrane has no effect on the ability of electron transport to pump protons. Thus, the rates of proton pumping, electron transport, and oxygen uptake remain unchanged
Carbon fixation involves the addition of carbon dioxide to _____.
RuBP In the Calvin cycle, carbon dioxide is added to RuBP
Drag the labels to their appropriate locations in the flowchart below, indicating the sequence of events in the production of fragment B. (Note that pol I stands for DNA polymerase I, and pol III stands for DNA polymerase III.)
Step 1: A new fragment begins with DNA polymerase III binding to the 3' end of the most recently produced RNA primer, primer B in this case, which is closest to the replication fork. DNA pol III then adds DNA nucleotides in the 5' to 3' direction until it encounters the previous RNA primer, primer A. Step 2: DNA pol III falls off and is replaced by DNA pol I. Starting at the 5' end of primer A, DNA pol I removes each RNA nucleotide and replaces it with the corresponding DNA nucleotide. (DNA pol I adds the nucleotides to the 3' end of fragment B.) When it encounters the 5' end of fragment A, DNA pol I falls off, leaving a gap in the sugar-phosphate backbone between fragments A and B. Step 3: DNA ligase closes the gap between fragments A and B. These steps will be repeated as the replication fork opens up. Try to visualize primer C being produced to the right (closest to the replication fork). Fragment C would be synthesized and joined to fragment B following the steps described here.
The DNA double helix is composed of two strands of DNA; each strand is a polymer of DNA nucleotides. Each nucleotide consists of a sugar, a phosphate group, and one of four nitrogenous bases. The structure and orientation of the two strands are important to understanding DNA replication. Drag the labels to their appropriate locations on the diagram below. Pink labels can be used more than once.
The DNA double helix is constructed from two strands of DNA, each with a sugar-phosphate backbone and nitrogenous bases that form hydrogen bonds, holding the two strands together. Each DNA strand has two unique ends. The 3' end has a hydroxyl (-OH) group on the deoxyribose sugar, whereas the 5' end has a phosphate group. In the double helix, the two strands are antiparallel, that is, they run in opposite directions such that the 3' end of one strand is adjacent to the 5' end of the other strand.
If a cell were unable to produce histone proteins, which of the following results would be a likely effect on the cell?
The cell's DNA could not be packed into its nucleus.
What process occurs within Box B?
The citric acid cycle The citric acid cycle transfers electrons to NADH and FADH2
What happens when electrons are passed from one atom to a more electronegative atom?
The more electronegative atom is reduced, and energy is released. Gain an electron -> energy is released Lose an electron -> energy is gained
Which of the following statements about Okazaki fragments in E. coli is true?
They are formed on the lagging strand of DNA. While DNA is synthesized continuously on the leading strand, Okazaki fragments are formed on the lagging strand because DNA synthesis always proceeds in the 5' to 3' direction.
Which of the following enzymes is important for relieving the tension in a helix as it unwinds during DNA synthesis
Topoisomerase This enzyme untwists the coils that occur in the DNA as it is being unwound into a single-stranded template
Prokaryotic DNA replication is faster than eukaryotic DNA replication
True
True or false? Single-stranded DNA molecules are said to be antiparallel when they are lined up next to each other but oriented in opposite directions.
True When the 3' end of one DNA strand points in the same direction as the 5' end of the other DNA strand, the strands are said to be antiparallel.
Chlorophyll is a pigment which means that is _____.
absorbs light of certain wavelengths
Why do eukaryotic chromosomes require telomeres?
because they are linear
After replication is complete, the new DNAs, called _____, are identical to each other.
daughter DNA
After DNA replication is completed, _____.
each new DNA double helix consists of one old DNA strand and one new DNA strand
Which term describes the degree to which an element attracts electrons?
electronegativity Electronegativity is the tendency of an atom to attract electrons toward itself
What term describes the degree to which an element attracts electrons?
electronegativity Electronegativity is the tendency of an atom to attract electrons toward itself.
In chemiosmosis, what is the most direct source of energy that is used to convert ADP +Pi to ATP?
energy released from the movement of protons through ATP synthase, down their electrochemical gradient
In glycolysis, the carbon-containing compound that functions as the electron donor is ______.
glucose
Which of the following sequences describes the path by which electrons travel downhill energetically in aerobic respiration?
glucose → NADH → electron transport chain → oxygen
What process occurs in Box A?
glycolysis Glycolysis occurs in the cytosol
Which of the following metabolic processes take place in the cytosol of a eukaryotic cell?
glycolysis and fermentation
Rank the primers in the order they were produced. If two primers were produced at the same time, overlap them.
h and a, b and g, c and f As soon as the replication bubble opens and the replication machinery is assembled at the two replication forks, the two primers for the leading strands (primers a and h) are produced. The production of the first primers on the lagging strands (those closest to the origin of replication, b and g) is delayed slightly because the replication forks must open up further to expose the template DNA for the lagging strands. After completion of the first segments of the lagging strands, additional template DNA must be exposed before the second primers (c and f) can be produced. And after completion of the second segments, additional template DNA must be exposed before the third primers (d and e) can be produced. In summary, because of the way the replication bubble expands, the lagging strand primers near the origin of replication were produced before the primers near the replication forks.
Where is the electron transport chain located?
inner mitochondrial membrane
After allowing phages grown with bacteria in a medium that contained 32P and 35S, Hershey and Chase used a centrifuge to separate the phage ghosts from the infected cell. They then examined the infected cells and found that they contained _____, which demonstrated that _____ is the phage's genetic material.
labeled DNA ... DNA Since the phage DNA entered the infected cell, it makes sense that DNA is the genetic material.
The new DNA strand that grows continuously in the 5' to 3' direction is called the _____.
leading strand
Short segments of newly synthesized DNA are joined into a continuous strand by _____.
ligase Ligase joins DNA segments into a continuous strand.
