Question 1

DNA double helices are soluble in water but insoluble in alcohol.How do these physical properties reflect the chemical structure of the molecule?

Accepted Answer

A) The charged phosphate groups and sugars of DNA "like" to interact with polar water molecules. 
B) The purine and pyrimidine bases "like" to interact with polar water molecules. 
C) The 5 prime to 3 prime polarity of DNA make it soluble in water but not in alcohol. 
D) The charged R-groups of DNA "like" to interact with polar water molecules. 
A) The charged phosphate groups and sugars of DNA "like" to interact with polar water molecules. 
B) The purine and pyrimidine bases "like" to interact with polar water molecules. 
C) The 5 prime to 3 prime polarity of DNA make it soluble in water but not in alcohol. 
D) The charged R-groups of DNA "like" to interact with polar water molecules. A

Question 2

Bartel's research group showed that an RNA replicase ribozyme could be created by _____.

Accepted Answer

A) carefully synthesizing a novel ribozyme monomer by monomer based on the sequence of known ribozymes 
B) creating large numbers of random RNA segments and testing each one to see if any replicase activity was present 
C) starting with random components and allowing selection to result in molecules that were better and better at replicating 
D) examining protein replicases and reverse-engineering an RNA molecule capable of doing the same job 
A) carefully synthesizing a novel ribozyme monomer by monomer based on the sequence of known ribozymes 
B) creating large numbers of random RNA segments and testing each one to see if any replicase activity was present 
C) starting with random components and allowing selection to result in molecules that were better and better at replicating 
D) examining protein replicases and reverse-engineering an RNA molecule capable of doing the same job C

Question 3

Recall the Bartel lab group experiment to create a ribozyme from scratch.If they had created exact copies of each ribozyme (rather than creating copies with a few differences),what would have been the most likely result?

Accepted Answer

A) The ribozymes would have become more efficient with each round of selection. 
B) The ribozymes would have stayed the same with each round of selection. 
C) The ribozymes would have become less efficient with each round of selection. 
D) The ribozymes would have stopped catalyzing reactions after just a few rounds of selection. 
A) The ribozymes would have become more efficient with each round of selection. 
B) The ribozymes would have stayed the same with each round of selection. 
C) The ribozymes would have become less efficient with each round of selection. 
D) The ribozymes would have stopped catalyzing reactions after just a few rounds of selection. B

Question 4

What is gel electrophoresis used for?

Accepted Answer

A) to denature proteins for further analysis 
B) to separate macromolecules by size or charge 
C) to separate the two helices that make up the DNA double helix 
D) to identify the first self-replicating molecule that formed during chemical evolution 
A) to denature proteins for further analysis 
B) to separate macromolecules by size or charge 
C) to separate the two helices that make up the DNA double helix 
D) to identify the first self-replicating molecule that formed during chemical evolution

Question 5

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

Accepted Answer

A) nucleotides 
B) sugars 
C) amino acids 
D) nitrogenous bases 
A) nucleotides 
B) sugars 
C) amino acids 
D) nitrogenous bases

Question 6

Which one of the following is not a way that RNA is seen as intermediate between DNA and proteins?

Accepted Answer

A) RNA contains genetic information like DNA,but is not as stable. 
B) RNA can catalyze reactions,but not as well as can proteins. 
C) RNA is composed of nucleotides,but forms tertiary and quaternary structures like a protein. 
D) RNA has 5 and 3 termini like DNA,but it also has amino and carboxy termini like protein. 
A) RNA contains genetic information like DNA,but is not as stable. 
B) RNA can catalyze reactions,but not as well as can proteins. 
C) RNA is composed of nucleotides,but forms tertiary and quaternary structures like a protein. 
D) RNA has 5 and 3 termini like DNA,but it also has amino and carboxy termini like protein.

Question 7

Use the following information when answering the corresponding question(s).
Shu-ichi Nakano reported in Science in February 2000 that "The RNA enzyme (ribozyme)from hepatitis delta virus catalyzes self-cleavage of a ...[chemical] ...bond." This reaction is inherently slow due to the formation of an unfavorable negative charge on the ribozyme.The author goes on to show that this self-cleavage is made faster by joining it with an acid-base reaction that neutralizes the negative charge.Nakano's model describes a positively charged cytosine base on the ribozyme acting as the acid,and magnesium hydroxide acting as the base.Specifically,the cytosine donates its proton (H⁺)to neutralize the unstable negative charge that would have formed on the ribozyme.
-Refer to Nakano's quote.What can be inferred about the free-energy profile for the self-cleavage reaction from the information provided in the paragraph?

Accepted Answer

A) It must be endergonic. 
B) It must be exergonic. 
C) It must be endothermic. 
D) It must be exothermic. 
A) It must be endergonic. 
B) It must be exergonic. 
C) It must be endothermic. 
D) It must be exothermic.

Question 8

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?

Accepted Answer

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

Question 9

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

Accepted Answer

A) the phosphate group 
B) the sugar 
C) the base 
D) the sugar and the base 
A) the phosphate group 
B) the sugar 
C) the base 
D) the sugar and the base

Question 10

You isolate what you think is DNA from a tissue sample.Which of the following will verify that you do,indeed,have DNA (rather than some other type of molecule)?

Accepted Answer

A) You determine the molecule has carbon-carbon bonds. 
B) You determine the molecule has primary and secondary structure. 
C) You determine the molecule contains nitrogen and phosphorus. 
D) None of answers A-C will verify that the isolated molecule is DNA. 
A) You determine the molecule has carbon-carbon bonds. 
B) You determine the molecule has primary and secondary structure. 
C) You determine the molecule contains nitrogen and phosphorus. 
D) None of answers A-C will verify that the isolated molecule is DNA.

Question 11

RNA and proteins combine in cells to form structures called ribosomes.Ribosomes contain the active site for peptide bond formation.Based on their chemical structures,do you think protein or RNA molecules actually form the active site within the ribosome?

Accepted Answer

A) protein,because RNA cannot catalyze reactions 
B) RNA,because proteins cannot catalyze a reaction that involves another protein 
C) proteins,because only proteins can catalyze a reaction that involves another protein 
D) It could be either,because both molecules have catalytic properties. 
A) protein,because RNA cannot catalyze reactions 
B) RNA,because proteins cannot catalyze a reaction that involves another protein 
C) proteins,because only proteins can catalyze a reaction that involves another protein 
D) It could be either,because both molecules have catalytic properties.

Question 12

Use the following information when answering the corresponding question(s).
Shu-ichi Nakano reported in Science in February 2000 that "The RNA enzyme (ribozyme)from hepatitis delta virus catalyzes self-cleavage of a ...[chemical] ...bond." This reaction is inherently slow due to the formation of an unfavorable negative charge on the ribozyme.The author goes on to show that this self-cleavage is made faster by joining it with an acid-base reaction that neutralizes the negative charge.Nakano's model describes a positively charged cytosine base on the ribozyme acting as the acid,and magnesium hydroxide acting as the base.Specifically,the cytosine donates its proton (H⁺)to neutralize the unstable negative charge that would have formed on the ribozyme.
-Is Nakano's quote from Science consistent with the textbook's claim that RNA is a good candidate for the first life-form?

Accepted Answer

A) yes 
B) no 
A) yes 
B) no

Question 13

Why is it that RNA can catalyze reactions but DNA cannot?

Accepted Answer

A) The sugar of RNA is much more reactive than the sugar of DNA. 
B) The bases of RNA are much more reactive than the bases of DNA. 
C) The phosphate groups of RNA are much more reactive than the phosphate groups of DNA. 
D) The primary structure of RNA is fundamentally different than the primary structure of DNA. 
A) The sugar of RNA is much more reactive than the sugar of DNA. 
B) The bases of RNA are much more reactive than the bases of DNA. 
C) The phosphate groups of RNA are much more reactive than the phosphate groups of DNA. 
D) The primary structure of RNA is fundamentally different than the primary structure of DNA.

Question 14

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

Accepted Answer

A) beta-pleated sheet 
B) double parallel helical strands 
C) turn-loop-turn 
D) double antiparallel helical strands 
A) beta-pleated sheet 
B) double parallel helical strands 
C) turn-loop-turn 
D) double antiparallel helical strands

Question 15

Nucleic acids have a definite polarity,or directionality.Stated another way,one end of the molecule is different from the other end.How are these ends described?

Accepted Answer

A) One end has a hydroxyl group on the 2 carbon;the other end has a hydrogen atom on the 2 carbon. 
B) One end contains a nitrogenous base;the other end lacks it. 
C) One end has an unlinked 3 carbon;the other end has an unlinked 5 carbon. 
D) One end has one phosphate group;the other end has two phosphate groups. 
A) One end has a hydroxyl group on the 2 carbon;the other end has a hydrogen atom on the 2 carbon. 
B) One end contains a nitrogenous base;the other end lacks it. 
C) One end has an unlinked 3 carbon;the other end has an unlinked 5 carbon. 
D) One end has one phosphate group;the other end has two phosphate groups.

Question 16

Why do researchers think the first self-replicating molecule was RNA?

Accepted Answer

A) RNA is the only type of molecule that can catalyze a chemical reaction. 
B) RNA has the capacity to provide a template and is known to catalyze reactions (although no existing self-replicating molecules of RNA have been discovered). 
C) Self-replicating molecules of RNA exist today,in human cells. 
D) Fossil evidence of such a molecule was recently discovered. 
A) RNA is the only type of molecule that can catalyze a chemical reaction. 
B) RNA has the capacity to provide a template and is known to catalyze reactions (although no existing self-replicating molecules of RNA have been discovered). 
C) Self-replicating molecules of RNA exist today,in human cells. 
D) Fossil evidence of such a molecule was recently discovered.

Question 17

Use the following information when answering the corresponding question(s).
Shu-ichi Nakano reported in Science in February 2000 that "The RNA enzyme (ribozyme)from hepatitis delta virus catalyzes self-cleavage of a ...[chemical] ...bond." This reaction is inherently slow due to the formation of an unfavorable negative charge on the ribozyme.The author goes on to show that this self-cleavage is made faster by joining it with an acid-base reaction that neutralizes the negative charge.Nakano's model describes a positively charged cytosine base on the ribozyme acting as the acid,and magnesium hydroxide acting as the base.Specifically,the cytosine donates its proton (H⁺)to neutralize the unstable negative charge that would have formed on the ribozyme.
-In the acid-base reaction described in the preceding paragraph about Nakano's research on RNAs,a proton (H⁺)is being transferred.What is acting as the proton acceptor?

Accepted Answer

A) cytosine 
B) magnesium hydroxide 
C) the virus 
D) cytosine,magnesium hydroxide,or the virus 
A) cytosine 
B) magnesium hydroxide 
C) the virus 
D) cytosine,magnesium hydroxide,or the virus

Question 18

When nucleotides polymerize to form a nucleic acid _____.

Accepted Answer

A) a covalent bond forms between the sugar of one nucleotide and the phosphate of a second 
B) a hydrogen bond forms between the sugar of one nucleotide and the phosphate of a second 
C) covalent bonds form between the bases of two nucleotides 
D) hydrogen bonds form between the bases of two nucleotides 
A) a covalent bond forms between the sugar of one nucleotide and the phosphate of a second 
B) a hydrogen bond forms between the sugar of one nucleotide and the phosphate of a second 
C) covalent bonds form between the bases of two nucleotides 
D) hydrogen bonds form between the bases of two nucleotides

Question 19

Which of the following is a difference between RNA and DNA?

Accepted Answer

A) One is typically single stranded and the other is typically triple stranded. 
B) One contains uracil and the other does not. 
C) One contains ribose sugar and the other contains a deoxyribose sugar. 
D) One is made from nucleotide monomers and the other one is not. 
A) One is typically single stranded and the other is typically triple stranded. 
B) One contains uracil and the other does not. 
C) One contains ribose sugar and the other contains a deoxyribose sugar. 
D) One is made from nucleotide monomers and the other one is not.

Question 20

In the context of chemical evolution,DNA's structure is interesting because it suggests a possible copying mechanism.What about DNA's structure facilitates copying?

Accepted Answer

A) It has the same number of purines and pyrimidines. 
B) The nitrogenous bases are located on the inside of the double helix. 
C) The strands of the double helix are complementary. 
D) DNA always goes from 5 to 3. 
A) It has the same number of purines and pyrimidines. 
B) The nitrogenous bases are located on the inside of the double helix. 
C) The strands of the double helix are complementary. 
D) DNA always goes from 5 to 3.

Exam 4: Nucleic Acids and the Rna World

DNA double helices are soluble in water but insoluble in alcohol.How do these physical properties reflect the chemical structure of the molecule?

Bartel's research group showed that an RNA replicase ribozyme could be created by _____.

Recall the Bartel lab group experiment to create a ribozyme from scratch.If they had created exact copies of each ribozyme (rather than creating copies with a few differences),what would have been the most likely result?

What is gel electrophoresis used for?

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

Which one of the following is not a way that RNA is seen as intermediate between DNA and proteins?

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?

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

You isolate what you think is DNA from a tissue sample.Which of the following will verify that you do,indeed,have DNA (rather than some other type of molecule)?

RNA and proteins combine in cells to form structures called ribosomes.Ribosomes contain the active site for peptide bond formation.Based on their chemical structures,do you think protein or RNA molecules actually form the active site within the ribosome?

Why is it that RNA can catalyze reactions but DNA cannot?

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

Nucleic acids have a definite polarity,or directionality.Stated another way,one end of the molecule is different from the other end.How are these ends described?

Why do researchers think the first self-replicating molecule was RNA?

When nucleotides polymerize to form a nucleic acid _____.

Which of the following is a difference between RNA and DNA?

In the context of chemical evolution,DNA's structure is interesting because it suggests a possible copying mechanism.What about DNA's structure facilitates copying?

Biology and the Tree of Life

Water and Carbon: the Chemical Basis of Life

Protein Structure and Function

An Introduction to Carbohydrates

Lipids, membranes, and the First Cells

Inside the Cell

Cell-Cell Interactions

Cellular Respiration and Fermentation

Photosynthesis

The Cell Cycle

Meiosis

Mendel and the Gene

Dna and the Gene: Synthesis and Repair

How Genes Work

Transcription and Translation

Control of Gene Expression in Bacteria

Control of Gene Expression in Eukaryotes

Analyzing and Engineering Genes

Genomics

Principles of Development

An Introduction to Animal Development

An Introduction to Plant Development

Evolution by Natural Selection

Evolutionary Processes

Speciation

Phylogenies and the History of Life

Bacteria and Archaea

Protists

Green Plants

Fungi

An Introduction to Animals

Protostome Animals

Deuterostome Animals

Viruses

Plant Form and Function

Water and Sugar Transport in Plants

Plant Nutrition

Plant Sensory Systems, signals, and Responses

Plant Reproduction

Animal Form and Function

Water and Electrolyte Balance in Animals

Animal Nutrition

Gas Exchange and Circulation

Electrical Signals in Animals

Animal Sensory Systems and Movement

Chemical Signals in Animals

Animal Reproduction

The Immune System in Animals

An Introduction to Ecology

Behavioral Ecology

Population Ecology

Community Ecology

Ecosystems

Biodiversity and Conservation Biology

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