From 19 pre class to 11 post class (most but some)

Consider the consequences of a mutation in the DNA template sequence 5'ATG3' to 5'TTG3': What is (a) the resulting change in the mRNA codon and (b) the effect on the corresponding amino acid? View Available Hint(s) (a) CAU to CAA; (b) No change (a) AUG to UUG; (b) Met to Leu (a) UAC to AAC; (b) Tyr to Asn (a) CAU to CAA; (b) His to Gin

(a) CAU to CAA; (b) His to Gin

The central paradigm of biochemistry holds that information flows from DNA to RNA to protein. The process of making protein from the mRNA is called translation. Translation is carried out by the ribosome, which binds to the mRNA and binds tRNA, which recognizes the codons on the mRNA and brings the appropriate amino acid with it. The ribosome forms the peptide bond between the new amino acid and the growing peptide chain. Complete the following vocabulary exercise related to the process of translation of mRNA to protein by the ribosome. Match the words in the left-hand column with the appropriate blank in the sentences in the right-hand column. 1. The process, performed by the ribosome, of reading mRNA and synthesizing a protein is called _________ 2. The RNA that has an amino acid attached to it, and that binds to the codon on the mRNA, is called a __________ 3. ________ of translation always happens at the start codon of the mRNA. 4. Amino acids are attached to tRNA by enzymes called ___________ 5. __________ of translation happens when the ribosome hits a stop A. aminoacyl-tRNA synthetase B. Initiation C. tRNA D. termination E. translation

1. translation 2. tRNA 3. Initiation 4. aminoacyl-tRNA synthetase 5. Termination The process of translation, or protein synthesis, is a crucial part of the maintenance of living organisms. Proteins are constantly in use and will break down eventually, so new ones must always be available. If protein synthesis breaks down or stops, then the organism dies.

Organism X has a DNA composition that is 29% Adenine. What percentage of organism X's DNA composition is Guanine? 32% 21% 25% 58% 29% 18% 42%

21%

If a DNA double helix contains 28% T nucleotides, then what is the percentage of A nucleotides? View Available Hint(s) 56% 28% 22% 44%

28% A and T are complementary base pairs, so the amounts of A and T should be equal.

After publication by Watson and Crick of the double helical structure of DNA, researchers proposed three possible models to describe how the two strands of the helix could serve as templates for synthesis of a new double helix in DNA replication. Matthew Meselson and Franklin Stahl used a technique called density-gradient centrifugation to identify the correct model. When a solution of cesium chloride (CsCl) is subjected to high-speed centrifugation, a stable density gradient is formed. Meselson and Stahl found that when cell contents were subjected to centrifugation with a CsCl solution, a band of DNA formed at the CsCl density that matched the density of the DNA. This technique is called density-gradient centrifugation. The test tubes below show the results of density-gradient centrifugation of five different DNA samples. Drag the description of each DNA sample to the appropriate location to identify the expected appearance of the DNA band(s) after density-gradient centrifugation.

?? lecture 14 post q

Where would RNA polymerase attach? Question #26 A B C A and B B and C

A RNA polymerase attaches to DNA.

Put the following events of 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. A. 3, 1, 2, 5, 4 B. 2, 3, 1, 4, 5 C. 3, 2, 1, 4, 5 D. 2, 3, 4, 5, 1

A. 3, 1, 2, 5, 4

The following question refer to this table of codons. A peptide has the sequence NH2-phe-pro-lys-gly-phe-pro-COOH. Which of the following sequences in the coding strand of the DNA could code for this peptide? A. 5' TTT-CCC-AAA-GGG-TTT-CCC B. 3' AUG-AAA-GGG-TTT-CCC-AAA-GGG C. 5' GGG-AAA-TTT-AAA-CCC-ACT-GGG D. 5' ACT-TAC-CAT-AAA-CAT-TAC-UGA E. 3' UUU-CCC-AAA-GGG-UUU-CCC

A. 5' TTT-CCC-AAA-GGG-TTT-CCC

Select the best model to complete this student's overview of how DNA forms a template for its own synthesis. On the left is a model consisting of outer left and right vertical lines, the left with an arrowhead at the bottom, the right with an arrowhead at the top. The inner portion contains letters on the left and right connected by horizontal dashes. From top to bottom the sequence runs: C dash G, C dash G, T dash A, G dash C, and A dash T. A horizontal arrow points to the next model consisting of the same outer left and right vertical lines with the same letter sequences, but there is a wide gap between the right and left groups. A horizontal arrow points to the next model consisting of outer left and right vertical lines, the left is black with an arrowhead at the bottom, and the right is red with an arrowhead at the top. The inner portion contains black letters on the left and red on the right, connected by black horizontal dashes. From top to bottom the sequence runs: C dash G, C dash G, T dash A, G dash C, and A dash T. A pale plus sign is drawn to the right of the model followed by a large question mark. Pair the pale plus sign with A. A model consisting of outer left and right vertical lines, the left is red with an arrowhead at the bottom, and the right is black with an arrowhead at the top. The inner portion contains red letters on the left and black on the right, connected by black horizontal dashes. From top to bottom the sequence runs: C dash G, C dash G, T dash A, G dash C, and A dash T. B. A model consisting of outer left and right vertical lines, the left is black with an arrowhead at the top, and the right is red with an arrowhead at the bottom. The inner portion contains black letters on the left and red on the right, connected by black horizontal dashes. From top to bottom the sequence runs: C dash G, C dash G, T dash A, G dash C, and A dash T. C. A model consisting of outer left and right vertical lines, the left is black with an arrowhead at the bottom, and the right is red with an arrowhead at the top. The inner portion contains black letters on the left and red on the right, connected by black horizontal dashes. From top to bottom the sequence runs: C dash G, C dash G, T dash A, G dash C, and A dash T. D. A model consisting of red outer left and right vertical lines, the left with an arrowhead at the bottom, the right with an arrowhead at the top. The inner portion contains red letters on the left and right, connected by red horizontal dashes. From top to bottom the sequence runs: C dash G, C dash G, T dash A, G dash C, and A dash T.

A. A model consisting of outer left and right vertical lines, the left is red with an arrowhead at the bottom, and the right is black with an arrowhead at the top. The inner portion contains red letters on the left and black on the right, connected by black horizontal dashes. From top to bottom the sequence runs: C dash G, C dash G, T dash A, G dash C, and A dash T.

Each codon shown below specifies an amino acid. For which one is it possible that a change in a single base could create a stop codon? View Available Hint(s) A. AAA B. ACC C. CAC D. ACA

A. AAA Changing the first base from A—>U creates the stop codon UAA.

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.) View Available Hint(s) A. Both electron transport and ATP synthesis would stop. B. Electron transport would stop but ATP synthesis would be unaffected. C. Electron transport would be unaffected but ATP synthesis would stop. D. Neither electron transport nor ATP synthesis would be affected.

A. 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.

Which of the following statements regarding the discovery of the function or structure of DNA is/are correct? Choose all that apply. A. Chromosomes are composed of chromatin. B. The ratio of adenine to guanine in double-stranded DNA is the same among all species. C. The ratio of adenine to cytosine in double-stranded DNA is the same among all species. D. Hereditary material resides on proteins. E. Chargaff created the AT/GC rule by using x-ray diffraction. F. The ratio of adenine to thymine in double-stranded DNA is the same among all species. G. DNA is made up of 20 nucleotides.

A. Chromosomes are composed of chromatin. F. The ratio of adenine to thymine in double-stranded DNA is the same among all species.

Refer to the figure above. What is the function of the ACC sequence at the 3' end? A. It attaches to an amino acid. B. It base pairs with the codon of mRNA. C. It is the active site of this ribozyme. D. It stabilizes the tRNA-amino acid complex.

A. It attaches to an amino acid.

Refer to the figure above. What is the function of the AGU on the loop of the tRNA? A. It base pairs with a codon of mRNA. B. It is the active site of this ribozyme. C. It attaches to the amino acid. D. It stabilizes the tRNA-amino acid complex.

A. It base pairs with a codon of mRNA.

How does the enzyme telomerase meet the challenge of replicating the ends of linear chromosomes? A. It catalyzes the lengthening of telomeres, compensating for the shortening that could occur during replication without telomerase activity. B. It adds numerous GC pairs, which resist hydrolysis and maintain chromosome integrity. C. It causes specific double-strand DNA breaks that result in blunt ends on both strands. D. It adds a single 5' cap structure that resists degradation by nucleases. E. It causes linear ends of the newly replicated DNA to circularize.

A. It catalyzes the lengthening of telomeres, compensating for the shortening that could occur during replication without telomerase activity.

Which sections in mature RNA do not code for amino acids? See Section 17.2 (Page 353) . View Available Hint(s) A. The 5'cap and the poly(A) tail at the 3' end are part of mature RNA and do not code for amino acids. B. The poly(A) tail is part of mature RNA and does not code for amino acids. C. The 5'cap does not code for amino acids. The poly(A) tail codes for the amino acid lysine. D. The 3'cap and the poly(A) tail at the 5' end are part of mature RNA and do not code for amino acids.

A. The 5'cap and the poly(A) tail at the 3' end are part of mature RNA and do not code for amino acids. Experiments have shown that mRNAs with a 5' cap and a poly(A) tail last longer and produce more proteins when introduced into cells. Neither one is transcribed.

During elongation, RNA polymerase has three prominent channels, or grooves. These channels provide sites for all of the following EXCEPT _____. A. a site for the exit of the diphosphates removed from the nucleotide triphosphates B. a site for the entry of ribonucleoside triphosphates C. a site for the double-stranded DNA molecule D. a site for the growing RNA strand

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

5' caps and 3' poly(A) tails of eukaryotic mRNAs ______. View Available Hint(s) A. protect mRNA from degradation and enhance translation B. mark the beginning and end of introns, respectively C. protect mRNA from degradation and enhance transcription D. act as sites for the start and stop of translation, respectively

A. protect mRNA from degradation and enhance translation Research has shown that mRNAs that have a cap and tail last longer in cells than mRNAs that don't.

What is this an image of? Question #28 A. supercoils B. a nucleosome C. a DNA double helix D. histones E. loops

A. supercoils This is an image of supercoils.

Which molecule or reaction supplies the energy for polymerization of nucleotides in the process of transcription? A. the phosphate bonds in the nucleotide triphosphates that serve as substrates B. ATP only C. the energy released when hydrogen bonds are broken as the DNA molecule is unwound D. the interaction between RNA polymerase and the promoter

A. the phosphate bonds in the nucleotide triphosphates that serve as substrates

DNA melting temperature (Tm) is: Choose all that apply. A. the temperature at which 50% of a population of identical DNA molecules is completely denatured, while the other half is still completely annealed. B. higher if the DNA strand is stabilized by salts in the buffer. C. the temperature at which all identical DNA molecules in a population are halfway unwound. D. higher if the DNA helix has more GC base pairs compared to AT base pairs.

B, C, D

Which of the following statements about nucleases is/are correct? Choose all that apply. A. Nucleases nick, wind or unwind, and religate DNA. B. Kornberg's treatment of eukaryotic DNA with nuclease resulted in free 8-polypeptide complexes wrapped in DNA. C. Treatment of eukaryotic DNA with nuclease causes the 8 core histone proteins to dissociate from each other. D. When Kornberg treated eukaryotic DNA with nuclease followed by salt treatment, 146 bp oligonucleotides were present. E. Nucleases can only digest eukaryotic DNA.

B, D

A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is _____. A. 5' TCA 3' B. 3' UCA 5' C. 3' UGA 5' D. 3' ACU 5' E. either UCA or TCA, depending on wobble in the first base

B. 3' UCA 5'

The direction of synthesis of an RNA transcript is _____. A. 1' —> 5' B. 5' —> 3' C. 1' —> 3' D. 3' —> 5' E. 2' —> 4'

B. 5' —> 3' Nucleotides are added to the 3' end of RNA.

Which of the following observations may have resulted in the hypothesis that a codon is made up of three bases? A. A codon of two bases in length, from four different bases, would code for a maximum of thirty-two different amino acids. B. A codon of three bases in length, from four different bases, would code for a maximum of sixty-four different amino acids. C. A codon of three bases in length, from four different bases, would code for a maximum of twelve different amino acids. D. A codon of four bases in length, from four different bases, would code for a maximum of twenty-four different amino acids.

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

The micrograph in Figure 17.5a shows a DNA-mRNA hybrid. If the noncoding regions of the gene did not exist, what would the micrograph look like? A. There would be the same number of loops, but they would be smaller. B. All of the loops would be missing. C. There would be additional loops. D. Some, but not all, of the loops would be missing.

B. All of the loops would be missing. If there were no introns (noncoding regions of DNA not present in mRNA), then the DNA and mRNA would match up exactly when they base-pair with each other. There would be no loops, which correspond to the noncoding DNA.

Codons are three-base sequences that specify the addition of a single amino acid. How do eukaryotic codons and prokaryotic codons compare? A. Prokaryotic codons usually specify different amino acids than those of eukaryotes. B. Codons are a nearly universal language among all organisms. C. Prokaryotic codons usually contain different bases than those of eukaryotes. D. The translation of codons is mediated by tRNAs in eukaryotes, but translation requires no intermediate molecules such as tRNAs in prokaryotes.

B. Codons are a nearly universal language among all organisms.

Which one of the following statements about RNA processing is true? A. A primary transcript is often much shorter than the final RNA molecule that leaves the nucleus. B. Ribozymes may function in RNA splicing. C. Exons are cut out before mRNA leaves the nucleus. D. RNA splicing can be catalyzed by tRNA.

B. Ribozymes may function in RNA splicing.

What is the difference (if any) between the structure of ATP and the structure of the precursor of the A nucleotide in RNA? A. The number of phosphates is three instead of two. B. There is no difference. C. The number of phosphates is three instead of one. D. The nitrogen-containing base is different. E. The sugar molecule is different.

B. There is no difference.

The "universal" genetic code is now known to have exceptions. Evidence for this can be found if which of the following is true? A. if a single mRNA molecule is found to translate to more than one polypeptide when there are two or more AUG sites B. if UGA, usually a stop codon, is found to code for an amino acid such as tryptophan (usually coded for by UGG only) in a different organism C. if prokaryotic organisms are able to translate a eukaryotic mRNA and produce the same polypeptide D. if several codons are found to translate to the same amino acid, such as serine E. if one stop codon, such as UGA, is found to have a different effect on translation than another stop codon, such as UAA

B. if UGA, usually a stop codon, is found to code for an amino acid such as tryptophan (usually coded for by UGG only) in a different organism

An organism is discovered that thrives in both the presence and absence of oxygen in the air. Curiously, the consumption of sugar increases as oxygen is removed from the organism's environment, even though the organism does not gain much weight. This organism _____. A.is an anaerobic organism B. is a facultative anaerobe C. is photosynthetic D. is a normal eukaryotic organism E. must use a molecule other than oxygen to accept electrons from the electron transport chain

B. is a facultative anaerobe

The following question refer to this table of codons. What amino acid sequence will be generated, based on the following mRNA codon sequence? 5' AUG-UCU-UCG-UUA-UCC-UUG 3' A. met-arg-glu-arg-glu-arg B. met-ser-ser-leu-ser-leu C. met-glu-arg-arg-glu-leu D. met-leu-phe-arg-glu-glu E. met-ser-leu-ser-leu-ser

B. met-ser-ser-leu-ser-leu

What is recognized by an aminoacyl tRNA synthetase? View Available Hint(s) A. the nucleotides needed to synthesize a tRNA B. one amino acid and the set of tRNAs that are coupled to that amino acid C. one specific codon D. the set of redundant codons that specify one amino acid

B. one amino acid and the set of tRNAs that are coupled to that amino acid Aminoacyl tRNA synthetases "charge" tRNAs by catalyzing the addition of amino acids to them.

What do the red arrows in this student-drawn model represent? A student-drawn model consisting of outer left and right red vertical lines, the left with an arrowhead at the bottom, the right with an arrowhead at the top. The inner portion contains black letters on the left and right, connected by black horizontal dashes. From top to bottom the sequence runs: T dash A, C dash G, T dash A, G dash C, and A dash T. A.phosphate strands B. sugar-phosphate strands C. the movement of information D. nitrogenous bases

B. sugar-phosphate strands

A researcher heats a solution of DNA and notices that as the temperature increases, the absorbance of ultraviolet light at 260 nm increases dramatically. This is because __________. A.the DNA becomes supercoiled B. the double strands of DNA are separating C. there are more base pairs synthesized D. DNA gyrase relaxes supercoiling of the DNA

B. the double strands of DNA are separating

The polarity of a DNA strand refers to the fact that ______. View Available Hint(s) A. the two ends of the strand have the same chemical groups B. the two ends of the strand have different chemical groups C. DNA lacks a hydroxyl group (OH) at one position of the ribose sugar D. only A and T and G and C base pairs form E. when two DNA strands pair they run in the same direction

B. the two ends of the strand have different chemical groups

You can tell this diagram is showing transcription rather than replication because ... (a) an enzyme is doing it. Replication doesn't need an enzyme. (b) only one strand is being used as template. (c) the product contains U. Both (b) and (c). (a), (b), and (c).

Both (b) and (c) Yes! You picked out two important differences between transcription and replication, and you gave due credit to enzymes for both processes.

Which of the following statements about the organization of DNA is/are correct? Choose all that apply. A. Bacterial chromosomes are small enough that they do not need to be coiled. B. Topoisomerases remove bases from DNA in order to coil the DNA. C. There is a very high degree of similarity between histones of a given type among species that possess them. D. In bacteria, chromosomes are supercoiled. E. In eukaryotes, DNA is coupled with proteins called histones and other proteins to make up chromatin.

C, D, E

How many copies of DNA polymerase III are in the replisome? View Available Hint(s) A. 0 B. 1 C. 2 D. 3 E. 4

C. 2 Each DNA polymerase III molecule adds DNA nucleotides to the end of a single DNA chain.

Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base? A. One of the daughter cells, but not the other, would have radioactive DNA. B. Radioactive thymine would pair with nonradioactive guanine. C. DNA in both daughter cells would be radioactive. D. Neither of the two daughter cells would be radioactive. E. All four bases of the DNA would be radioactive.

C. DNA in both daughter cells would be radioactive.

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? A. There is more NADH than FADH2 made for every glucose that enters cellular respiration. B. It takes more energy to make ATP from ADP and Pi using FADH2 than using NADH. C. Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor. D. FADH2 is made only in the citric acid cycle while NADH is made in glycolysis, acetyl CoA formation, and the citric acid cycle. E. The H+ gradient made from electron transport using NADH is located in a different part of the mitochondrion than the H+ gradient made using FADH2.

C. 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 results 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.

Which one of the following statements about euchromatin is incorrect? A. It is most frequently found in the form of 30nm fibers. B. It is more difficult to see under the electron microscope than heterochromatin. C. It is typically found at the periphery of the nucleus. D. It is less densely packed than heterochromatin. It gets condensed during M-phase.

C. It is typically found at the periphery of the nucleus.

What would the consequence of deleting telomerase from a human cell line? A. The ends of each chromosome would grow after each cell division. B. Deleting telomerase would have no effect on the human cell line. C. The ends of each chromosome would shrink after each cell division. D. The cell would be unable to undergo cell division.

C. The ends of each chromosome would shrink after each cell division.

The letter A indicates _____. Question #25 A. supercoils B. a nucleosome C. a DNA double helix D. histones E. loops

C. a DNA double helix This is a decondensed DNA double helix.

The redundancy of the genetic code is a consequence of ______. View Available Hint(s) A. having four different letters (As, Cs, Gs, and Us) in the genetic alphabet B. having an equal number of codons and amino acids C. having more codons than amino acids D. having three-letter-long genetic words (codons) E. having fewer codons than there are amino acids

C. having more codons than amino acids

The primers used for DNA synthesis are ______. View Available Hint(s) A. proteins that bind to single-stranded DNA B. short amino acid sequences (peptides C. short RNA sequences D. RNA polymerases E. short DNA sequences

C. short RNA sequences

In mitochondrial electron transport, what is the direct role of O2? A. to provide the driving force for the synthesis of ATP from ADP and Pi B. to provide the driving force for the production of a proton gradient C. to function as the final electron acceptor in the electron transport chain D. to oxidize NADH and FADH2 from glycolysis, acetyl CoA formation, and the citric acid cycle

C. 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 electron transport chain, as the final electron acceptor. Oxygen's high affinity for electrons ensures its success in this role. Its contributions to driving electron transport, forming a proton gradient, and synthesizing ATP are all indirect effects of its role as the terminal electron acceptor.

During transcription, in which direction is (1) RNA synthesized and in which direction is (2) the DNA template "read"? View Available Hint(s) A. (1) 3'—>5' (2) 3'—>5' B. (1) 5'—>3' (2) 5'—>3' C. (1) 3'—>5' (2) 5'—>3' D. (1) 5'—>3' (2) 3'—>5'

D. (1) 5'—>3' (2) 3'—>5'

The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following? A. DNA was the first genetic material. B. Different organisms have different types of amino acids. C. The same codons in different organisms translate into different amino acids. D. A gene from an organism can theoretically be expressed by any other organism. E. All organisms have experienced convergent evolution.

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

Refer to the figure associated with this question. What bases will be added to the primer as DNA replication proceeds? The bases should appear in the new strand in the order that they will be added starting at the 3' end of the primer. A. T, C, T, G, C, T, G B. G, T, C, G, T, C, T C. C, A, G, C, A, G, A D. A, G, A, C, G, A, C

D. A, G, A, C, G, A, C

For the experiment shown in Figure 15.2, which additional piece of evidence would prove that the viral capsids were shaken off the bacterial cells by the agitation step? View Available Hint(s) A. Testing of the solution for 32P radioactivity to show that none is present B. Examination of the pellet by electron microscopy to show that capsids are present C. Examination of the solution by electron microscopy to show that no capsids are present D. Examination of the pellet by electron microscopy to show that no capsids are present

D. Examination of the pellet by electron microscopy to show that no capsids are present If the agitation step was successful, all viral capsids would be found in the solution after the centrifugation step.

Complementary base pairing is possible only if two DNA strands align in antiparallel—instead of parallel—fashion. Which statement best explains why? A. Only antiparallel strands contain the nitrogenous bases necessary to form complementary base pairs. B. Only antiparallel strands create the geometry that allows complementary base pairs to form via van der Waals interactions. C. Only antiparallel strands contain unusual backbone atoms which allow complementary base pairing D. Only antiparallel strands create the geometry that allows complementary base pairs to form via hydrogen bonding.

D. Only antiparallel strands create the geometry that allows complementary base pairs to form via hydrogen bonding.

With respect to RNA processing, which of the following is false? A. It leads to the production of alternative gene products. B. Some introns are removed by spliceosomes. C. Some introns are self-splicing. D. Prokaryotic mRNAs are polyadenylated at the 3' end. E. Chemical modification occurs with tRNA transcripts.

D. Prokaryotic mRNAs are polyadenylated at the 3' end.

In the diagram below, the gray unit represents _____. A. RNA B. DNA C. transcription factors D. RNA polymerase E. the promoter

D. RNA polymerase RNA polymerase untwists a portion of the DNA double helix.

Why are ribonucleoside triphosphates the monomers required for RNA synthesis rather than ribonucleoside monophosphates? View Available Hint(s) A. Only ribonucleoside triphosphates contain the sugar ribose. B. Ribonucleoside monophosphates cannot form complementary base pairs with the DNA template. C. Ribonucleoside triphosphates have low potential energy, making the polymerization reaction endergonic. D. Ribonucleoside triphosphates have high potential energy, making the polymerization reaction exergonic.

D. Ribonucleoside triphosphates have high potential energy, making the polymerization reaction exergonic. Because ribonucleoside triphosphates have three negatively charged phosphates close together, they have high potential energy, which is released during polymerization, making RNA synthesis spontaneous (ΔG<0) in cells.

Which statement is correct concerning DNA synthesis catalyzed by DNA polymerases? View Available Hint(s) A. The new DNA strand is synthesized in the 3—>5' direction; the template strand is read in the 3'—>5' direction. B. The new DNA strand is synthesized in the 5'—>3' direction; the template strand is read in the 5'—>3' direction. C. The new DNA strand is synthesized in the 3'—>5' direction; the template strand is read in the 5'—>3' direction. D. The new DNA strand is synthesized in the 5'—>3' direction; the template strand is read in the 3'—>5' direction.

D. The new DNA strand is synthesized in the 5'—>3' direction; the template strand is read in the 3'—>5' direction. DNA synthesis by DNA polymerases always proceeds in the 5'—>3' direction, using a complementary, antiparallel strand as template (Figure 15.6).

How does the bacterial ribosome recognize where to start translation? View Available Hint(s) A. The small ribosomal subunit binds to the 3' poly(A) tail of the mRNA. B. The small ribosomal subunit binds to the 5' cap of the mRNA. C. The small ribosomal subunit binds to the start codon. D. The small ribosomal subunit binds to a sequence in the mRNA just upstream of the start codon.

D. The small ribosomal subunit binds to a sequence in the mRNA just upstream of the start codon.

A promoter is ______. View Available Hint(s) A. a sequence in RNA that promotes the release of RNA polymerase from DNA B. one or more eukaryotic proteins that bind to DNA near the start of a gene C. a protein that associates with bacterial RNA polymerase to help it bind to DNA D. a sequence in DNA that brings RNA polymerase near the site for transcription

D. a sequence in DNA that brings RNA polymerase near the site for transcription The promoter is upstream of the DNA to be transcribed.

David Pribnow studied the base sequences of promoters in bacteria and bacterial viruses. He found two conserved regions in these promoters (the -10 box and the -35 box). These two regions of the promoter _____. A. attach the correct nucleotide triphosphate to the template DNA strand B. signal the initiation site C. separate the two DNA strands D. bind the sigma subunit that is associated with RNA polymerase

D. bind the sigma subunit that is associated with RNA polymerase

The letter C indicates _____. Question #27 A. supercoils B. a nucleosome C. a DNA double helix D. histones E. loops

D. histones These are histone proteins.

In a nucleic acid polymer, the bonds that help to hold regions of double-strandedness together occur between what parts of the nucleotide monomers? View Available Hint(s) A. sugars B. sugars and phosphates C. nitrogenous bases and phosphates D. nitrogenous bases

D. nitrogenous bases Three hydrogen bonds form between GC base pairs and two hydrogen bonds form between AT base pairs.

Which of the following is not associated with mRNA processing in eukaryotes? A. addition of a 5' methyl guanosine cap B. 3' polyadenylation C. removal of introns D. removal of exons

D. removal of exons

What do the arrowheads in this student-drawn model represent? A student-drawn model consisting of outer left and right vertical lines, the left with an arrowhead at the bottom, the right with an arrowhead at the top. The inner portion contains letters on the left and right connected by horizontal dashes. From top to bottom the sequence runs: T dash A, C dash G, T dash A, G dash C, and A dash T. A. the nitrogenous base end of the strand B. the phosphate group end of the strand C. the 5' end of the DNA strand D. the 3' end of the DNA strand

D. the 3' end of the DNA strand

When an amino acid is specified by more than one codon, what is usually shared by the set of codons that specify this amino acid? View Available Hint(s) A. their entire base sequence B. the second base C. the first base D. the first and second bases E. the third base

D. the first and second bases This minimizes errors in translation.

The Hershey-Chase experiment answered the question of whether protein or DNA was the genetic material by learning whether ______. View Available Hint(s) A. enzymes that destroyed DNA or destroyed protein prevented transformation of bacteria B. DNA or protein migrated at the same or different rates when centrifuged C. DNA could be radioactively labeled using 32P D. protein could be radioactively labeled using 35S E. DNA or protein from a virus entered bacterial cells during infection

E. DNA or protein from a virus entered bacterial cells during infection

Which of the following statements about histones is incorrect? A. Histone H1 is not part of a core nucleosome particle. B. Histones serve an important function of compacting DNA in eukaryotic cells. C. Histones have tails that can be acetylated, methylated or phosphorylated. D. Histones are rich in basic amino acids in order to bind the negatively charged DNA. E. Histones are found in bacteria, where they assist with the supercoiling of circular chromosomes.

E. Histones are found in bacteria, where they assist with the supercoiling of circular chromosomes

Which of the following statements regarding the central dogma is correct? A. Information carried in our genes passes directly from DNA to proteins. B. RNA is transcribed into proteins. C. Transcription converts RNA into DNA. D. Translation copies DNA into proteins. E. The nucleotide sequence of our genes is transcribed into RNA.

E. The nucleotide sequence of our genes is transcribed into RNA.

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? A. The width of a DNA molecule is 3.4 nm, whereas the width of a nucleotide monomer is 0.34 m. B. DNA molecules are 3.4 nm long and 0.34 nm wide. C. The 10 to 1 ratio signifies that DNA molecules are ten times longer than they are wide. D. It turned out to be just a coincidence. E. These numbers tell us there are ten rungs, or steps, on the DNA "ladder" for every turn of the helix.

E. These numbers tell us there are ten rungs, or steps, on the DNA "ladder" for every turn of the helix.

What is this an image of? Question #29 A. supercoils B. a nucleosome C. a DNA double helix D. histones E. loops

E. loops This is an image of loops.

A new antibiotic is able to bind the rho (ρ) factor associated with some transcription processes; as a result this antibiotic would affect A. initiation of transcription. B. elongation of transcription. C. binding of the RNA polymerase. D. termination of all transcription. E. termination of some transcription.

E. termination of some transcription.

In the diagram below, the green unit represents _____. A. RNA B. DNA C. transcription factors D. RNA polymerase E. the promoter

E. the promoter The promoter is the region of DNA at which the process of transcription begins.

Interpret the student-drawn model. A student-drawn model consisting of outer left and right vertical lines, the left with an arrowhead at the bottom, the right with an arrowhead at the top. The inner portion contains letters on the left and right. From left to right and top to bottom, the sequence runs: G C, C G, G C, T A, A T, C G, C G, and G C. Drag "True" or "False" to the end of each statement. True False Hydrogen bonds are not shown but are suggested by the base pairing in the model. _____ The vertical lines represent sugar-phosphate backbones. ______ The nitrogenous bases are paired correctly. _____ The arrowheads represent the phosphate group at the end of the strand. _____ This is double-stranded DNA. ______ The arrowheads represent the 3' ends of the strands. ______

Hydrogen bonds are not shown but are suggested by the base pairing in the model. True The vertical lines represent sugar-phosphate backbones. True The nitrogenous bases are paired correctly. True The arrowheads represent the phosphate group at the end of the strand. False This is double-stranded DNA. True The arrowheads represent the 3' ends of the strands. True

Refer to the treatments listed below to answer the following question. You isolate an infectious substance capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. You have four methods at your disposal to analyze the substance and determine the nature of the infectious agent. I. Treat the substance with enzymes that destroy all nucleic acids and then determine whether the substance is still infectious. II. Filter the substance to remove all elements smaller than what can be easily seen under a light microscope. III. Culture the substance on nutritive medium, away from any plant cells. IV. Treat the sample with proteases that digest all proteins and then determining whether the substance is still infectious. If you already know that the infectious agent was either bacterial or viral, which method(s) listed above would allow you to distinguish between these two possibilities? I II II or III IV either II or IV

II or III

DNA is transcribed to messenger RNA (mRNA), and the mRNA is translated to proteins on the ribosomes. A sequence of three nucleotides on an mRNA molecule is called a codon. As you can see in the table, most codons specify a particular amino acid to be added to the growing protein chain. In addition, one codon (shown in blue) codes for the amino acid methionine and functions as a "start" signal. Three codons (shown in red) do not code for amino acids, but instead function as "stop" signals. During translation, nucleotide base triplets (codons) in mRNA are read in sequence in the 5' → 3' direction along the mRNA. Amino acids are specified by the string of codons. What amino acid sequence does the following mRNA nucleotide sequence specify? 5′−AUGGCAAGAAAA−3′ Express the sequence of amino acids using the three-letter abbreviations, separated by hyphens (e.g., Met-Ser-Thr-Lys-Gly).

Met-Ala-Arg-Lys An amino acid sequence is determined by strings of three-letter codons on the mRNA, each of which codes for a specific amino acid or a stop signal. The mRNA is translated in a 5' → 3' direction.

DNA is transcribed to messenger RNA (mRNA), and the mRNA is translated to proteins on the ribosomes. A sequence of three nucleotides on an mRNA molecule is called a codon. As you can see in the table, most codons specify a particular amino acid to be added to the growing protein chain. In addition, one codon (shown in blue) codes for the amino acid methionine and functions as a "start" signal. Three codons (shown in red) do not code for amino acids, but instead function as "stop" signals. Before a molecule of mRNA can be translated into a protein on the ribosome, the mRNA must first be transcribed from a sequence of DNA. The diagram shows a scheme of translation of DNA into a protein on the ribosome. There is a fragment of DNA with two strands (the strand from 3 prime to 5 prime is a template strand). The template strand is transcribed into mRNA (complementary nitrogenous bases are selected - U for A, A for T, C for G and G for C). Then the mRNA is translated into the protein of the ribosome, and each codon is translated into a certain amino acid (e. g., UGG is translated into Trp). The sequence of amino acids forms the protein. What amino acid sequence does the following DNA nucleotide sequence specify? 3′−TACAGAACGGTA−5′ Express the sequence of amino acids using the three-letter abbreviations, separated by hyphens (e.g., Met-Ser-His-Lys-Gly).

Met-Ser-Cys-His Before mRNA can be translated into an amino acid sequence, the mRNA must first be synthesized from DNA through transcription. Base pairing in mRNA synthesis follows slightly different rules than in DNA synthesis: uracil (U) replaces thymine (T) in pairing with adenine (A). The codons specified by the mRNA are then translated into a string of amino acids.

Carefully inspect the double-stranded DNA molecule shown here, and notice that it has twofold rotational symmetry: 3′ A−G−C−G−C−T−A−T−A−G−C−G−C−T 5′ 5′ T−C−G−C−G−A−T−A−T−C−G−C−G−A 3′ Label each of the following statements as true or false. Drag the appropriate items to their respective bins True False A. If a solution of these molecules were heated to denature them, every single-stranded molecule in the solution would be capable of hybridizing with every other molecule. B. If the molecule were cut at its midpoint into two halves, it would be possible to distinguish the left half from the right half. C. If the two single strands were separated from each other, it would not be possible to distinguish one strand from the other. D. In a single strand from this molecule, it would be impossible to determine which is the 3' end and which is the 5' end. E. There is no way to distinguish the right end of the double helix from the left end.

True E. There is no way to distinguish the right end of the double helix from the left end. A. If a solution of these molecules were heated to denature them, every single-stranded molecule in the solution would be capable of hybridizing with every other molecule. C. If the two single strands were separated from each other, it would not be possible to distinguish one strand from the other. False B. If the molecule were cut at its midpoint into two halves, it would be possible to distinguish the left half from the right half. D.In a single strand from this molecule, it would be impossible to determine which is the 3' end and which is the 5' end.

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 into the correct bin according to the effect that gramicidin would have on each process. remains the same decreases (or goes to zero) increases the proton gradient electron transport rate rate of oxygen uptake proton pumping rate rate of ATP synthesissize of

remains the same proton pumping rate electron transport raterate of oxygen uptake decreases (or goes to zero) rate of ATP synthesissize of the proton gradient increases

DNA is transcribed to messenger RNA (mRNA), and the mRNA is translated to proteins on the ribosomes. A sequence of three nucleotides on an mRNA molecule is called a codon. As you can see in the table, most codons specify a particular amino acid to be added to the growing protein chain. In addition, one codon (shown in blue) codes for the amino acid methionine and functions as a "start" signal. Three codons (shown in red) do not code for amino acids, but instead function as "stop" signals. Part A - Understanding the genetic codePart complete Use the table to sort the following ten codons into one of the three bins, according to whether they code for a start codon, an in-sequence amino acid, or a stop codon. Drag each item to the appropriate bin. View Available Hint(s) ResetHelp start/methionine amino acid stop codon UGA UAG AUG AAA GCA AUC CAC ACU UGC UAA

start/methionine AUG stop codon UGA UAA UAG amino acid AAA GCA ACU CAC AUC UGC Nearly every mRNA gene that codes for a protein begins with the start codon, AUG, and thus begins with a methionine. Nearly every protein-coding sequence ends with one of the three stop codons (UAA, UAG, and UGA), which do not code for amino acids but signal the end of translation.

DNA is transcribed to messenger RNA (mRNA), and the mRNA is translated to proteins on the ribosomes. Aterm-17 sequence of three nucleotides on an mRNA molecule is called a codon. As you can see in the table, most codons specify a particular amino acid to be added to the growing protein chain. In addition, one codon (shown in blue) codes for the amino acid methionine and functions as a "start" signal. Three codons (shown in red) do not code for amino acids, but instead function as "stop" signals. Part A - Understanding the genetic codePart complete Use the table to sort the following ten codons into one of the three bins, according to whether they code for a start codon, an in-sequence amino acid, or a stop codon. Drag each item to the appropriate bin. start/methionine stop codon amino acid UGA AUG UAA UAG AAA ACU CAC AUC GCA UGC

start/methionine AUG stop codon UGA UAA UAG amino acid AAA GCA ACU CAC AUC UGC Nearly every mRNA gene that codes for a protein begins with the start codon, AUG, and thus begins with a methionine. Nearly every protein-coding sequence ends with one of the three stop codons (UAA, UAG, and UGA), which do not code for amino acids but signal the end of translation.