Chem1113 exam4
How many subunits are involved in the quaternary structure of hemoglobin?
4
The CORN rule is used to classify __________ with the D− or L− configurations.
Amino acid molecules
What is the function of enzymes within living systems?
Catalysts
A complete protein supplies:
Essential and nonessential amino acids
A molecule that rotates the plane of polarized light to the left is described as __________ and is given the symbol __________. (Fill in the blanks)
Levorotatory; (−)
Which of the following does not contribute to the primary structure of a protein?
More than one response is correct
Myosin and actin are:
Movement proteins
Which of the following is a transport protein?
Myoglobin
A molecule that is optically active __________. (Fill in the blank)
Rotates the plane of polarized light
Denaturation of a protein involves a breakdown of the:
Secondary and tertiary structures of the protein
An enzyme that converts the amino acid serine to phosphoserine can be called a:
Serine phosphatase
Which statement is correct about molecules classifies as D−amino acids?
Some D−amino acid molecules rotate plane polarized light to the left and some D−amino acid molecules rotate plane polarized light to the right
Which term best describes the reactant in an enzyme-catalyzed reaction?
The substrate
Which of the following is not a protein denaturation agent.
water
An enzyme catalyzes the hydrolysis of triglyceride molecules. How would you classify this enzyme?
A hydrolase
A mixture containing equal amounts of two molecules that are optical isomers is called a __________. (Fill in the blank)
A racemic mixture
Keratin is an example of:
A structural protein
An enzyme catalyzes the transfer of a phosphate group from one molecule to another. How would you classify this enzyme?
A transferase
Hemoglobin is:
A transport protein
Which forces give rise to quaternary structure in protein molecules?
All of the above can give rise to quaternary structure in protein molecules
Many enzymes are regulated by having more than one binding site. What type of enzymes are these?
Allosteric enzymes
What type of bond is a peptide bond?
An amide bond
An amino acid contains:
An amino acid contains all of the items listed above.
Consider the reaction scheme below where "A" reacts in the presence of several enzymes to form "F". Molecule "F" acts as a reversible inhibitor on Enzyme 3. This is an example of:
An example of feedback control.
Which of the following statements concerning the effect of temperature change on an enzyme-catalyzed reaction is correct?
An increase in temperature can stop the reaction by denaturing the enzyme.
Proteins that function as enzymes are:
Catalytic proteins
A molecule that rotates the plane of polarized light to the right is described as __________ and is given the symbol __________. (Fill in the blanks)
Dextrorotatory; (+)
The concentration of ethanol in a mixture can be increased using a process called __________. (Fill in the blank)
Distillation
A beta-pleated sheet results from hydrogen bonds and covalent bonds that form between atoms in the backbone of a protein chain.
F
All enzymes can only act on a single substrate.
F
Alpha helix and beta-pleated sheets are both examples of quaternary structure.
F
An amino acid will be in its zwitterionic form regardless of the pH it is exposed to.
F
Catalytic proteins carry materials from one part of the body to another.
F
Chymotrypsin is an enzyme that catalyzes the denaturation of protein molecules.
F
Coenzymes can be organic molecules or metallic ions.
F
Ethanol fermentation is a purely chemical phenomena that has nothing to do with living cells.
F
Humans can sythesize all the amino acids they need inside their bodies.
F
Hydrophobic interactions are covalent bonds.
F
If you plot the reaction rate of an enzyme-catalyzed reaction on the vertical axis and the temperature of the reaction on the horizontal axis you will almost always get a straight line.
F
Once a noncompetitive inhibitor binds to an enzyme, the subtrate can bind to the active site.
F
One side chain in a protein contains only carbon and hydrogen atoms. Another side chain in the protein contains only carbon, hydrogen and oxygen atoms. These two side chains can form ionic bonds between each other.
F
One side chain in a protein contains only carbon, hydrogen and sulfur atoms. Another side chain in the protein contains only carbon and hydrogen atoms. These two side chains can form hydrogen bonds between each other.
F
Only organic molecules can be optically active. Inorganic molecules cannot be optically active.
F
Only quaternary structure of a protein affects the shape of the protein.
F
Protein molecules are small molecules. They generally contain less than 20 amino acid residues.
F
Some disulfide bonds are covalent and some are ionic.
F
Some disulfide bonds are hydrogen bonds.
F
Structural proteins are generally soluble in water.
F
The net charge on the zwitterionic form of an amino acid is +2.
F
The side chain in an amino acid contains only carbon and hydrogen atoms. This amino acid is likely to be a polar, neutral amino acid.
F
The side chain of an amino acid contains an amino group. This amino acid is probably an acidic amino acid.
F
There are only about 100 different protein molecules that exist in nature.
F
Two cysteine amino acids cannot form a peptide bond between them. They can only form a disulfide bond.
F
What type of enzyme regulation occurs when the final product of a pathway shuts off the entire pathway?
Feedback control
Molecules that __________ have optical activity. (Fill in the blank)
Have no plane of symmetry
Which ion is particulary effective in causing protein denaturation?
Hg2+
Which of the following does not contribute to tertiary structure in a protein?
Hydrogen bonds between atoms on the backbone of a protein chain
Which of the following side-chain interactions would involve non-polar side chains?
Hydrophobic interactions
Which of the following is a hormone?
Insulin
The pH at which the positive and negative charges of an amino acid balance each other is called the:
Isoelectric point
Which of the following elements are found in the side chains of amino acids?
Only carbon, hydrogen, nitrogen, sulfur and oxygen
Two molecules that are mirror images and not superimposable are called __________. (Fill in the blank)
Optical isomers
Which molecule is sometimes used to induce labor in pregnant women?
Oxytocin
Which of the following is a proteolytic enzyme?
Pepsin
Which of the following does not contribute to the tertiary structure of a protein?
Peptide bonds
Which of the following enzyme properties is explained by the lock-and-key model of enzyme action?
Specificity
A mixture containing equal amounts of two molecules that are optical isomers does not show optical activity.
T
A noncompetitive inhibitor changes the shape of the active site in an enzyme.
T
Amino acids can act as acids and as bases.
T
Amino acids can react with acids and with bases.
T
An organic, but nonprotein, portion of an enzyme is called a coenzyme.
T
Catalysis is an important function of proteins.
T
Glucose and fructose have the same molecular formula. An enzyme that catalyzes the conversion of glucose to fructose could be classified as an isomerase.
T
Ionic bonding can occur between charged side chains in a protein.
T
Many coenzymes in the body are formed from vitamins.
T
Many naturally occurring substances are optically active.
T
Proteins that come from plant sources are generally incomplete proteins.
T
Proteins, fats and carbohydrates are used as energy sources in humans.
T
The alpha-helix and beta-pleated sheets are both examples of secondary structure.
T
The amino acid cysteine contains a sulfur atom.
T
The digestion of proteins requires the presence of proteolytic enzymes.
T
The enzyme trypsin is a digestive enzyme.
T
The induced-fit model for enzyme action allows for changes in the shape of the active site of an enzyme.
T
The ion Pb2+ can denature a protein.
T
The protein portion of an enzyme is called an apoenzyme.
T
Interactions between the side chains of a protein are responsible for which of the following levels of protein structure?
Tertiary structure and quaternary structure
The most common reason for optical activity in organic molecules is __________. (Fill in the blank)
That the molecule contains a carbon atom attached to four different groups
The secondary structure of proteins are held together by bonding between:
The carbonyl and amide groups on the backbone
The main distinguishing feature between the different amino acids is:
The composition of the side chain (R-group)
The R/S system is a system used to indicate __________. (Fill in the blank).
The configurations of optical isomers
Which of the following levels of protein structure is not disrupted when a protein is hydrolyzed?
The correct answer is not given. All the levels of protein structure are disrupted during hydrolysis.
What can be deduced about the reaction catalyzed by the enzyme lysine decarboxylase?
The enzyme removes a CO2 group from lysine
Consider the molecule shown below. Which statement is correct about this molecule?
The molecule has a N-terminal end and a C-terminal end
During the digestive process, which of the following happens to protein molecules?
They are hydrolyzed
The hydrolysis of a dipeptide would result in the formation of:
Two amino acid molecules
The active site of an enzyme is the location in an enzyme where the substrate molecules:
Undergo change
The amino acid cysteine is special because it:
can form disulfide bonds with other cysteine amino acids
Which of the following serves as an antibody?
immunoglobulin
Which term best describes a protein molecule?
polymer
