Question

THIS IS BIOCHEMISTRY

1. A peptide has a low pI value. Which of the following amino acids are likely to be present?
   1. Glycine
   2. Serine
   3. Valine
   4. Aspartic aci
   5. Arginine   
2. The R-groups of which of the following pairs of amino acids could participate in the formation of salt bridge electrostatic interaction?
3. Alanine and valine
4. Valine and lysine
5. Lysine and glutamate
6. Serine and isoleucine
7. Asparagine and glutamine

Which of the following interactions does NOT contribute to stabilizing tertiary structure?

Hydrophobic interactions

Electrostatic interations

Hydrogen bonds

Covalent bonds

All of the above DO stabilize tertiary structure

In the genetic expression flow of information the process ‘transcription’ refers to?

Information from DNA being used to make RNA

Info from RNA being used to make proteins

Info from proteins being used to make DNA

Info from RNA being used to make DNA

Info from proteins being used to make DNA

If an enzyme has Km for a substrate of 10 mM, what is the enzyme velocity if the substrate is present at 30mM and the Vmax is 40 mM/s?

1. 20 s^-1
2. 30 s^-1
3. 40 s^-1
4. 50 s^-1
5. 60 s^-1

7. The addition of a phosphate group to produce the active form of an enzyme is one example of what form of enzyme regulation?

1. Genetic control
2. Covalent modification
3. Allosteric regulation
4. Compartmentation
5. Enzyme induction

7. Invariant amino acids in a protein are presumed

1. To be unimportant in the structure and function of the protein
2. To be essential to the structure and function of the protein
3. Always to occur at the beginning of the amino acid sequence of an enzyme
4. Always to occur at the end of the amino acid sequence of an enzyme
5. To be part of the prosthetic group

7. The term hydrophobic collapse in describing protein folding refers to

1. Attraction of alpha helices to be packed together in bundles
2. The formation of disulfide bonds drives the sequestering of non-polar amino acids into the protein interior
3. The interactions involved in formation of quarternary structure
4. The hydrophobic interactions of non-polar amino acid side chain sequestering themselves into the water-excluded interior of the protein
5. The inability of the amino acid chain to find its mature conformation and remains a molten globule

7. which of the following amino acids lacks a center of asymmetry?

1. Alanine
2. Glycine
3. Valine
4. Isoleucine
5. Aspartic acid

Answer 1

Answer:

1) A peptide has a low pI value. Which of the following amino acids are likely to be present?

1. Glycine
2. Serine
3. Valine
4. Aspartic acid - Correct Option (Explanation: Aspartic acid amino acid has a low pI of 2.98 at 25°C, so a peptide containing Aspartic acid will have a low overall pI value)
5. Arginine   

2) The R-groups of which of the following pairs of amino acids could participate in the formation of salt bridge electrostatic interaction?

1. Alanine and valine
2. Valine and lysine
3. Lysine and glutamate - Correct Option (Explanation: Salt bridges are formed between oppositely charged residues. Anionic carboxylate (RCOO⁻) of glutamate and cationic ammonium (RNH₃⁺) from lysine amino acid in this case since Glutamate is negatively charged, and lysine is positively charged)
4. Serine and isoleucine
5. Asparagine and glutamine

3) Which of the following interactions does NOT contribute to stabilizing tertiary structure?

1. Hydrophobic interactions
2. Electrostatic interactions
3. Hydrogen bonds
4. Covalent bonds
5. All of the above DO stabilize tertiary structure - Correct Option (Explanation: Electrostatic forces, hydrogen bonding, hydrophobic interactions, and disulfide bonds all these interactions contribute to stabilizing the tertiary structure of a protein)

4) In the genetic expression flow of information the process ‘transcription’ refers to?

1. Information from DNA being used to make RNA - Correct Option (Explanation: Transcription refers to the process of copying DNA sequence into an RNA sequence)
2. Info from RNA being used to make proteins
3. Info from proteins being used to make DNA
4. Info from RNA being used to make DNA
5. Info from proteins being used to make DNA

5) If an enzyme has Km for a substrate of 10 mM, what is the enzyme velocity if the substrate is present at 30mM and the Vmax is 40 mM/s?

1. 20 s^-1
2. 30 s^-1 - Correct Option (Explanation below)
3. 40 s^-1
4. 50 s^-1
5. 60 s^-1

(Explanation:

6) The addition of a phosphate group to produce the active form of an enzyme is one example of what form of enzyme regulation?

1. Genetic control
2. Covalent modification - Correct Option (Explanation: Addition of phosphate functional group by covalent bond formation can affect the enzyme activity)
3. Allosteric regulation
4. Compartmentation
5. Enzyme induction

7) Invariant amino acids in a protein are presumed

1. To be unimportant in the structure and function of the protein
2. To be essential to the structure and function of the protein - Correct Option (Explanation: Invariant and highly conserved amino acids are often essential to the structure and function of the protein)
3. Always to occur at the beginning of the amino acid sequence of an enzyme
4. Always to occur at the end of the amino acid sequence of an enzyme
5. To be part of the prosthetic group

8) The term hydrophobic collapse in describing protein folding refers to

1. Attraction of alpha helices to be packed together in bundles
2. The formation of disulfide bonds drives the sequestering of non-polar amino acids into the protein interior
3. The interactions involved in formation of quaternary structure
4. The hydrophobic interactions of non-polar amino acid side chain sequestering themselves into the water-excluded interior of the protein - Correct Option
5. The inability of the amino acid chain to find its mature conformation and remains a molten globule

9) Which of the following amino acids lacks a center of asymmetry?

1. Alanine
2. Glycine - Correct Option
3. Valine
4. Isoleucine
5. Aspartic acid