Question 1

Proteins in biological systems _____.

Accepted Answer

A) store genetic information 
B) link together to form the plasma membrane 
C) may be high-energy intermediates (for example,ATP) 
D) may be enzymes that catalyze reactions 
A) store genetic information 
B) link together to form the plasma membrane 
C) may be high-energy intermediates (for example,ATP) 
D) may be enzymes that catalyze reactions

Question 2

You've discovered an enzyme that can catalyze two different chemical reactions.Which of the following is most likely to be correct?

Accepted Answer

A) The enzyme contains both α-helices and β-pleated sheets. 
B) The enzyme is subject to both competitive inhibition and allosteric regulation. 
C) Two types of allosteric regulation occur: The binding of one molecule activates the enzyme,while the binding of a different molecule inhibits it. 
D) Either the enzyme has two distinct active sites,or the reactants involved in the two reactions are very similar in size and shape. 
A) The enzyme contains both α-helices and β-pleated sheets. 
B) The enzyme is subject to both competitive inhibition and allosteric regulation. 
C) Two types of allosteric regulation occur: The binding of one molecule activates the enzyme,while the binding of a different molecule inhibits it. 
D) Either the enzyme has two distinct active sites,or the reactants involved in the two reactions are very similar in size and shape.

Question 3

In solution,why do hydrolysis reactions occur more readily than condensation reactions?

Accepted Answer

A) Hydrolysis increases entropy and is exergonic. 
B) Hydrolysis raises G,or Gibbs free energy. 
C) Hydrolysis decreases entropy and is exergonic. 
D) Hydrolysis increases entropy and is endergonic. 
A) Hydrolysis increases entropy and is exergonic. 
B) Hydrolysis raises G,or Gibbs free energy. 
C) Hydrolysis decreases entropy and is exergonic. 
D) Hydrolysis increases entropy and is endergonic.

Question 4

What is the process component of the theory of chemical evolution?

Accepted Answer

A) Acid-base reactions resulted in the formation of large,complex organic molecules. 
B) Kinetic energy was transformed into chemical energy. 
C) During polymerization reactions,hydrolysis was completed with condensation. 
D) The process occurred at black smokers,in the atmosphere and oceans,and in outer space. 
A) Acid-base reactions resulted in the formation of large,complex organic molecules. 
B) Kinetic energy was transformed into chemical energy. 
C) During polymerization reactions,hydrolysis was completed with condensation. 
D) The process occurred at black smokers,in the atmosphere and oceans,and in outer space.

Question 5

You determine the amino acid sequence of a protein and find it contains a long sequence of methionine,followed by a long sequence of proline,followed by a long sequence of valine.Using these data you predict the sequence of this protein's secondary structure will be _____.

Accepted Answer

A) beta sheets,then a region of no secondary structure,then beta sheets 
B) alpha helices,then a region of no secondary structure,then alpha helices 
C) beta sheets,then a region of no secondary structure,then alpha helices 
D) alpha helices,then a region of no secondary structure,then beta sheets 
A) beta sheets,then a region of no secondary structure,then beta sheets 
B) alpha helices,then a region of no secondary structure,then alpha helices 
C) beta sheets,then a region of no secondary structure,then alpha helices 
D) alpha helices,then a region of no secondary structure,then beta sheets

Question 6

You have isolated a previously unstudied protein,identified its complete structure in detail,and determined that it catalyzes the breakdown of a large substrate.You notice it has two binding sites.One of these is large,apparently the bonding site for the large substrate;the other is small,possibly a binding site for a regulatory molecule.What do these findings tell you about the mechanism of this protein?

Accepted Answer

A) It is probably a structural protein that is involved in cell-to-cell adhesion. 
B) It is probably an enzyme that works through allosteric regulation. 
C) It is probably an enzyme that works through competitive inhibition. 
D) It is probably a cell membrane transport protein-like an ion channel. 
E) It is probably a structural protein found in cartilage or skeletal tissue. 
A) It is probably a structural protein that is involved in cell-to-cell adhesion. 
B) It is probably an enzyme that works through allosteric regulation. 
C) It is probably an enzyme that works through competitive inhibition. 
D) It is probably a cell membrane transport protein-like an ion channel. 
E) It is probably a structural protein found in cartilage or skeletal tissue.

Question 7

How does primary protein structure affect the function of protein enzymes?

Accepted Answer

A) Substrates interact with R-groups at the enzyme's active site. 
B) Substrates interact with R-groups at the enzyme's external surface. 
C) Substrates interact with hydrophobic R-groups at any region of the enzyme. 
D) Substrates permanently bind to R-groups at the enzyme's active site. 
A) Substrates interact with R-groups at the enzyme's active site. 
B) Substrates interact with R-groups at the enzyme's external surface. 
C) Substrates interact with hydrophobic R-groups at any region of the enzyme. 
D) Substrates permanently bind to R-groups at the enzyme's active site.

Question 8

In interstellar space,millions of ice-encrusted dust particles contain simple carbon-containing compounds.When particles like these are exposed to solar radiation,more complex organic molecules form on the surfaces of the dust.What is the significance of these findings?

Accepted Answer

A) Chemical evolution occurs only in outer space and was not possible on Earth. 
B) Life began in outer space. 
C) Life exists in outer space. 
D) Chemical evolution can occur in outer space. 
A) Chemical evolution occurs only in outer space and was not possible on Earth. 
B) Life began in outer space. 
C) Life exists in outer space. 
D) Chemical evolution can occur in outer space.

Question 9

Why are polymerization reactions endergonic?

Accepted Answer

A) They reduce entropy. 
B) They release heat,making the reactant monomers move faster. 
C) The condensation and hydrolysis reactions are equally spontaneous. 
D) Polymers are energetically more stable and have lower potential energy than monomers do. 
A) They reduce entropy. 
B) They release heat,making the reactant monomers move faster. 
C) The condensation and hydrolysis reactions are equally spontaneous. 
D) Polymers are energetically more stable and have lower potential energy than monomers do.

Question 10

A peptide bond _____.

Accepted Answer

A) forms between the functional groups of different amino acids 
B) forms between the central carbon and the amino group of a single amino acid 
C) forms the primary structure of proteins 
D) does not play a role in maintaining the tertiary structure of proteins 
A) forms between the functional groups of different amino acids 
B) forms between the central carbon and the amino group of a single amino acid 
C) forms the primary structure of proteins 
D) does not play a role in maintaining the tertiary structure of proteins

Question 11

Suppose that Miller repeated his chemical evolution experiment but without a source of electrical sparks.What would be the purpose?

Accepted Answer

A) to test if electrical energy is required for chemical evolution 
B) to test the hypothesis that reduced molecules are required for chemical evolution 
C) to test the hypothesis that both reduced molecules and electrical energy are required for chemical evolution 
D) to make sure that the glassware had not been contaminated,and that any new molecules found were actually produced by chemical evolution 
A) to test if electrical energy is required for chemical evolution 
B) to test the hypothesis that reduced molecules are required for chemical evolution 
C) to test the hypothesis that both reduced molecules and electrical energy are required for chemical evolution 
D) to make sure that the glassware had not been contaminated,and that any new molecules found were actually produced by chemical evolution

Question 12

You are studying a protein that is shaped like a doughnut.The shape is a function of which level(s)of protein structure?

Accepted Answer

A) primary only 
B) secondary only 
C) tertiary only 
D) secondary and tertiary only 
E) primary,secondary,and tertiary 
A) primary only 
B) secondary only 
C) tertiary only 
D) secondary and tertiary only 
E) primary,secondary,and tertiary

Question 13

Refer to the following paragraph and Figure 3.1 to answer the following questions.
   
Figure 3.1
Since structure correlates so well with function,biochemists are constantly looking for new ways to probe the complex structure of proteins in order to understand what they do and how they do it.One of the most powerful techniques in existence today is X-ray crystallography.The main difficulty with this technique is getting the protein to crystallize.Once crystallized,the protein is bombarded with X-rays to create a pattern that can be analyzed mathematically to determine the three-dimensional structure of the protein.This analysis has been performed by Krzysztof Palczewski on the protein rhodopsin,which is a light-sensitive protein found in species ranging from ancient bacteria (archaea)to humans.The structure (schematically shown above,where each letter represents an amino acid)is characterized by a single polypeptide chain with several α-helical segments that loop back and forth across the cell membrane.Another notable feature is the disulfide bond (-S-S-)that can be seen at the bottom of the third transmembrane segment.[Figure adapted from K.Palczewski et al. ,Science 289 (2000): 739.]
-Which term best describes the type of membrane protein in Figure 3.1?

Accepted Answer

A) peripheral 
B) external 
C) internal 
D) integral 
A) peripheral 
B) external 
C) internal 
D) integral

Question 14

Consider the HIV enzyme called protease.The amino acid residues at the active site are highly hydrophobic.In designing a drug that would bind to the active site and jam it,researchers should use which type of molecule?

Accepted Answer

A) hydrophobic 
B) polar 
C) charged 
D) acidic 
A) hydrophobic 
B) polar 
C) charged 
D) acidic

Question 15

Refer to the following paragraph and Figure 3.1 to answer the following questions.
   
Figure 3.1
Since structure correlates so well with function,biochemists are constantly looking for new ways to probe the complex structure of proteins in order to understand what they do and how they do it.One of the most powerful techniques in existence today is X-ray crystallography.The main difficulty with this technique is getting the protein to crystallize.Once crystallized,the protein is bombarded with X-rays to create a pattern that can be analyzed mathematically to determine the three-dimensional structure of the protein.This analysis has been performed by Krzysztof Palczewski on the protein rhodopsin,which is a light-sensitive protein found in species ranging from ancient bacteria (archaea)to humans.The structure (schematically shown above,where each letter represents an amino acid)is characterized by a single polypeptide chain with several α-helical segments that loop back and forth across the cell membrane.Another notable feature is the disulfide bond (-S-S-)that can be seen at the bottom of the third transmembrane segment.[Figure adapted from K.Palczewski et al. ,Science 289 (2000): 739.]
-If you were reading off the sequence of amino acids in Figure 3.1 to a biologist friend,what should the first three letters be?

Accepted Answer

A) M-N-G 
B) A-P-A 
C) It doesn't matter,since the protein has no polarity or directionality. 
A) M-N-G 
B) A-P-A 
C) It doesn't matter,since the protein has no polarity or directionality.

Question 16

How does the structure of an amino acid enable it to play its most important roles in cells?

Accepted Answer

A) It can serve a wide variety of functions in a cell,because it contains the atoms most commonly found in organisms (C,H,N,and O). 
B) Because both carboxyl and amino groups are present,polymerization is exergonic.In addition,the presence of a side chain makes the molecule water soluble. 
C) The presence of carboxyl and amino groups gives it the ability to form peptide bonds,and its side chain gives it unique chemical properties. 
D) Because each amino acid contains a variety of functional groups,they can participate in a wide variety of chemical reactions. 
A) It can serve a wide variety of functions in a cell,because it contains the atoms most commonly found in organisms (C,H,N,and O). 
B) Because both carboxyl and amino groups are present,polymerization is exergonic.In addition,the presence of a side chain makes the molecule water soluble. 
C) The presence of carboxyl and amino groups gives it the ability to form peptide bonds,and its side chain gives it unique chemical properties. 
D) Because each amino acid contains a variety of functional groups,they can participate in a wide variety of chemical reactions.

Question 17

Consider the experiment that Stanley Miller did to simulate chemical evolution.Recall that a glass flask held the reduced gases NH₃,CH₄,and H₂ and that the gases were exposed to electrical sparks.What is the null hypothesis in the experiment?

Accepted Answer

A) Chemical evolution does not occur. 
B) Chemical evolution requires the presence of reduced molecules. 
C) Chemical evolution requires continuous heating. 
D) Chemical evolution requires a source of kinetic energy. 
E) Chemical evolution occurs only on Earth. 
A) Chemical evolution does not occur. 
B) Chemical evolution requires the presence of reduced molecules. 
C) Chemical evolution requires continuous heating. 
D) Chemical evolution requires a source of kinetic energy. 
E) Chemical evolution occurs only on Earth.

Question 18

Refer to the following paragraph and Figure 3.1 to answer the following questions.
   
Figure 3.1
Since structure correlates so well with function,biochemists are constantly looking for new ways to probe the complex structure of proteins in order to understand what they do and how they do it.One of the most powerful techniques in existence today is X-ray crystallography.The main difficulty with this technique is getting the protein to crystallize.Once crystallized,the protein is bombarded with X-rays to create a pattern that can be analyzed mathematically to determine the three-dimensional structure of the protein.This analysis has been performed by Krzysztof Palczewski on the protein rhodopsin,which is a light-sensitive protein found in species ranging from ancient bacteria (archaea)to humans.The structure (schematically shown above,where each letter represents an amino acid)is characterized by a single polypeptide chain with several α-helical segments that loop back and forth across the cell membrane.Another notable feature is the disulfide bond (-S-S-)that can be seen at the bottom of the third transmembrane segment.[Figure adapted from K.Palczewski et al. ,Science 289 (2000): 739.]
-Identify the location of the disulfide bond in Figure 3.1.What is the name of the amino acids that are forming this bond?

Accepted Answer

A) cytosine 
B) aspartic acid 
C) cysteine 
D) glycine 
A) cytosine 
B) aspartic acid 
C) cysteine 
D) glycine

Question 19

What aspects of amino acid structure vary among different amino acids?

Accepted Answer

A) the long carbon-hydrogen tails of the molecule 
B) the presence of a central C atom 
C) the components of the R-group 
D) the glycerol molecule that forms the backbone of the amino acid 
A) the long carbon-hydrogen tails of the molecule 
B) the presence of a central C atom 
C) the components of the R-group 
D) the glycerol molecule that forms the backbone of the amino acid

Question 20

What prediction does the chemical evolution hypothesis make?

Accepted Answer

A) Nothing will happen-meaning that no new types of molecules will appear. 
B) Molecules with carbon-carbon bonds will form. 
C) Proteins will be produced before any other macromolecule. 
D) A self-replicating macromolecule cannot exist all need interaction with another macromolecule. 
A) Nothing will happen-meaning that no new types of molecules will appear. 
B) Molecules with carbon-carbon bonds will form. 
C) Proteins will be produced before any other macromolecule. 
D) A self-replicating macromolecule cannot exist all need interaction with another macromolecule.

Exam 3: Protein Structure and Function

Proteins in biological systems _____.

You've discovered an enzyme that can catalyze two different chemical reactions.Which of the following is most likely to be correct?

In solution,why do hydrolysis reactions occur more readily than condensation reactions?

What is the process component of the theory of chemical evolution?

You determine the amino acid sequence of a protein and find it contains a long sequence of methionine,followed by a long sequence of proline,followed by a long sequence of valine.Using these data you predict the sequence of this protein's secondary structure will be _____.

How does primary protein structure affect the function of protein enzymes?

In interstellar space,millions of ice-encrusted dust particles contain simple carbon-containing compounds.When particles like these are exposed to solar radiation,more complex organic molecules form on the surfaces of the dust.What is the significance of these findings?

Why are polymerization reactions endergonic?

A peptide bond _____.

Suppose that Miller repeated his chemical evolution experiment but without a source of electrical sparks.What would be the purpose?

You are studying a protein that is shaped like a doughnut.The shape is a function of which level(s)of protein structure?

Consider the HIV enzyme called protease.The amino acid residues at the active site are highly hydrophobic.In designing a drug that would bind to the active site and jam it,researchers should use which type of molecule?

How does the structure of an amino acid enable it to play its most important roles in cells?

Consider the experiment that Stanley Miller did to simulate chemical evolution.Recall that a glass flask held the reduced gases NH₃,CH₄,and H₂ and that the gases were exposed to electrical sparks.What is the null hypothesis in the experiment?

What aspects of amino acid structure vary among different amino acids?

What prediction does the chemical evolution hypothesis make?

Biology and the Tree of Life

Water and Carbon: the Chemical Basis of Life

Nucleic Acids and the Rna World

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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