Biochem c785 Module 2Biochem c785 Module 2
Primary structure consists of the order of ______ in a protein. These are held together with ______ bonds that are formed by a ______ reaction.
Select one:
a. Amino acids, pe
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Biochem c785 Module 2Biochem c785 Module 2
Primary structure consists of the order of ______ in a protein. These are held together with ______ bonds that are formed by a ______ reaction.
Select one:
a. Amino acids, peptide, dehydration
b. Nucleotides, peptide, dehydration
c. Amino acids, peptide, hydrolysis Incorrect. A part of the response is correct. Amino acids are bonded together to make proteins. The bonds holding these amino acids are referred to as peptide bonds. However, the combination of the two amino acids results in loss of a water molecule referred to as dehydration reaction. Hydrolysis of a peptide bond would result in breaking of the bond rather than building the peptide bond.
d. Nucleotides, phosphodiester, dehydration
Several types of side chain interactions stabilize the tertiary structure of proteins, including which of the following?
Select one:
a. Hydrogen bonds, phosphodiester bonds, peptide bonds, covalent bonds
b. Ion pairs, peptide bonds, protein bonds, hydrogen bonds.
c. Ion pairs, hydrophobic interactions, hydrogen bonds, disulfide bonds Correct! The stability of a tertiary structure of a protein depends on the various interactions and bonds that occur between the side chains of different amino acids.
d. Peptide bonds, hydrogen bonds, ester bonds, covalent bonds
Which of the following statements is true about the secondary structure of proteins?
Select one:
a. It includes alpha helices as a common form.
b. It includes beta pleated sheets as a common form.
c. All of these.
d. It involves hydrogen bonding between the backbone atoms. This is partially correct.
In order to fulfill their function, proteins must fold in proper, three-dimensional conformations. Which one of the following molecules, available in a cell, is likely to help a protein fold properly?
Select one:
a. Glycine
b. Cysteine
c. Chaperone Correct!
d. Polymerase
Which of the following is true about a misfolded protein?
Select one:
a. It can be degraded by the cell.
b. It will lose its normal function.
c. It can be the result of denaturation.
d. All of these. Correct! All of these are true.
e. It can cause protein aggregation.
** Peptide bonds are formed between amino group and carboxylic acid group of amino acids**
A substrate binds to an enzyme at a specific site, referred to as a(n)_________________.
Select one:
a. Enzymatic site
b. Allosteric site
c. Active site Correct!
d. Substrate site
You are in charge of designing a drug that inhibits the activity of a specific enzyme. An important criteria for the drug selection is to ensure that the drug is directly in competition with the original substrate when binding to the active site of the enzyme. Which of the following kind of inhibitor would be an ideal choice?
Select one:
a. Non-specific inhibitor
b. Non-competitive inhibitor
c. Uncompetitive inhibitor
d. Competitive inhibitor Correct!
Which of the following factors can affect the protein folding and activity of an enzyme?
Select one:
a. pH
b. Reducing agents
c. Heat
d. All of these Correct
One way a cell can avoid overproduction of a molecule is by using a particular type of inhibition in which the molecule itself acts as an inhibitor for an enzyme in its production pathway. This type regulation is known as ___________ inhibition.
Select one:
a. regulatory
b. feedback Correct!
c. allosteric
d. specific
What type of enzyme adds a phosphate to another molecule?
Select one:
a. Phosphatase Incorrect. Kinases add phosphates to molecules while phosphatases remove them.
b. Protease
c. Kinase
d. Dehydrogenase
Which of the following are possible effect(s) that phosphorylation/dephosphorylation can have on the activity of an enzyme?
Select one or more:
a. Alter the amino acid sequence of the enzyme Incorrect. Phosphorylation is a post-translational modification, meaning that it occurs after the protein is made and the amino acid sequence has been completed. Phosphorylation can alter the conformation of an enzyme, but not the amino acid sequence.
b. Turn the enzyme "off". Correct! Some enzymes are activated by phosphorylation while others are deactivated by the addition of a phosphate.
c. Turn the enzyme "on". Correct! Some enzymes are activated by phosphorylation while others are deactivated by the addition of a phosphate.
d. Increase the amount of substrate for the enzyme.
**In the enzymatic cycle, the enzyme shape is changed when the substrate binds and resumes its original shape when the product is released after substrate is converted to product. **
The rate of an enzyme reaction can be increased by which of the following:
Select one:
a. Increasing activation energy of the reaction.
b. Decreasing the temperature inside a cell.
c. Increasing the temperature inside a cell. Incorrect. Enzymes do not directly affect the temperature of a cell.
d. Decreasing the activation energy of the reaction. The rate (or speed) of a chemical reaction depends on the size of the activation energy barrier. Increasing temperature can provide the energy needed to get over the activation barrier, while lowering the temperature will reduce the available energy to overcome the barrier. However, enzymes cannot affect the temperature around them. Instead, enzymes decrease the activation energy of a reaction, thus allowing more reactions to take place at any given temperature.
Compared to a patient that is not on a statin medication, In a patient taking a statin medication the concentration of cholesterol would [decrease], the concentration of HMG-CoA would [increase], and the concentration of Acetoacetyl CoA would [stay the same].
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