Biochemistry Help: Answers to Proteins, Helix & Hemoglobin/Myoglobin Questions

[littlelady]

Biochemistry Help :)

I need help ...can someone help me out please :)

1) Denatured proteins
(‘1’) have higher viscosities than their native conformation counterparts.
(‘2’) have higher water water-accessible surface area compared to their native
conformation counterparts.
(‘3’) have lost their biological activity.
(‘4’) may have more titrable residues per molecule than their native conformation
counterparts.

A) if 1, 2, 3 are correct
B) if 1 and 3 are correct
C) if 2 and 4 are correct
D) if 4 only is correct
E) if all are correct

I think the correct answer is A

3) The forces or bonds broken during the process of denaturation are
(‘1’) hydrogen bonds.
(‘2’) electrostatic interactions.
(‘3’) hydrophobic interactions.
(‘4’) peptide bonds.

A) if 1, 2, 3 are correct
B) if 1 and 3 are correct
C) if 2 and 4 are correct
D) if 4 only is correct
E) if all are correct

I think correct answer is A because peptide bonds are primary structure. Primary structure remain the same during protein denaturing. Because denaturing means protein unfold.

4) The a helix
(‘1’) can be disrupted by high concentrations of urea.
(‘2’) is left-handed in most naturally occurring proteins.
(‘3’) can be terminated by proline residues.
(‘4’) exists only in combination with pleated sheet structures.
A) if 1, 2, 3 are correct
B) if 1 and 3 are correct
C) if 2 and 4 are correct
D) if 4 only is correct
E) if all are correct

I think it's B because hight concentration or urea can disrupt protein ( denature protein). Also, proline has no H; therefore, it's going to discript the structure. Therefore..proline always at the end of the chain

5) Properties of disulfide bonds include
(‘1’) cleavage only through reduction by mercaptoethanol, for example.
(‘2’) stabilization of tertiary structures of proteins..
(‘3’) stabilization of secondary structures of proteins.
(‘4’) the joining of polypeptide chains into multisubunit proteins.
A) if 1, 2, 3 are correct
B) if 1 and 3 are correct
C) if 2 and 4 are correct
D) if 4 only is

I think it's E...because disulfide bonds can help to link everything together. is it right?


6) Factors that are of importance in the maintenance of an a helix are
(‘1’) constituent amino acids are of the “L” configuration.
(‘2’) peptide bonds have a partially planar character.
(‘3’) the =O and –H components present in each peptide bond are “trans” with
respect to each other.
(‘4’) in three dimensions, the =O of the first peptide bond is sufficiently close to the
–H of the fourth peptide bond in the carboxyl-terminal direction to form a
hydrogen bond.
A) if 1, 2, 3 are correct
B) if 1 and 3 are correct
C) if 2 and 4 are correct
D) if 4 only is correct

A is correct because protein always in L configuration, peptide bond have planar character. This is correct.. =O of first peptide hydrogen bond to amine not carboxyl termninal..so I elimate $4...i think 4 is correct.


18) Carbon dioxide generated in peripheral tissue is transported to the lungs via the blood stream
as
(‘1’) carbamino residues.
(‘2’) “dissolved” CO2.
(‘3’) bicarbonate ions.
(‘4’) carbonate ions.

A) if 1, 2, 3 are correct
B) if 1 and 3 are correct
C) if 2 and 4 are correct
D) if 4 only is correct


20) In sickle cell anemia,
(‘1’) glutamate in position 6 of the b-chain of HbA is substituted by valine.
(‘2’) HbS is present in red cells, which electrophoretically moves more slowly than
HbA.
(‘3’) red cell shapes are distorted and asymmetric.
(‘4’) HbS forms gel polymers in oxygenated form.
A) if 1, 2, 3 are correct
B) if 1 and 3 are correct
C) if 2 and 4 are correct
D) if 4 only is correct

21) Concerning hemoglobin and myoglobin, which binds oxygen and iron changes from Fe2Å to Fe3Å?

A) hemoglobin
B) myoglobin
C) both
D) neither

22) Concerning hemoglobin and myoglobin, which demonstrates oxygen bound by iron and a proximal histidyl residue?
A) hemoglobin
B) myoglobin
C) both
D) neither

23) Concerning hemoglobin and myoglobin, which ancestral gene evolved at least 475 million
years ago?
A) hemoglobin
B) myoglobin
C) both
D) neither

 

[Nino MMP]

The correct answer is B. Myoglobin evolved at least 475 million years ago, while hemoglobin only evolved about 200 million years ago.

 

[Blueshift5]

Hi there, I am happy to help with your biochemistry questions! Here are my responses:

1) Denatured proteins can have higher viscosities than their native conformation counterparts, as the unfolding and disruption of the protein structure can lead to a more tangled and less fluid molecule. They also have higher water-accessible surface area, as the hydrophobic regions of the protein become exposed. Denatured proteins also lose their biological activity, as the specific shape and structure of the protein is necessary for its function. They may also have more titrable residues per molecule, as the unfolding of the protein can expose more acidic or basic groups. Therefore, the correct answer is E.

2) The forces or bonds broken during the process of denaturation can include hydrogen bonds, electrostatic interactions, and hydrophobic interactions. However, peptide bonds are not typically broken during denaturation, as they make up the primary structure of the protein and remain intact. So, the correct answer is B.

3) The alpha helix can be disrupted by high concentrations of urea, as well as other denaturants. It is typically right-handed in naturally occurring proteins, not left-handed. Proline residues can disrupt the alpha helix, as they introduce a kink in the structure. The alpha helix can exist independently of the beta pleated sheet structure, so the correct answer is B.

4) Disulfide bonds can be cleaved through reduction by mercaptoethanol, and they do play a role in stabilizing tertiary structures of proteins. However, they do not stabilize secondary structures, as those are typically held together by hydrogen bonds. Disulfide bonds can also join polypeptide chains into multisubunit proteins. Therefore, the correct answer is C.

5) Factors that are important in maintaining the alpha helix include the presence of amino acids in the "L" configuration, the partially planar character of peptide bonds, and the trans configuration of the =O and -H components in each peptide bond. In addition, the distance between the =O of the first peptide bond and the -H of the fourth peptide bond in the carboxyl-terminal direction is important in forming hydrogen bonds and maintaining the structure. Therefore, the correct answer is A.

18) Carbon dioxide is transported to the lungs as bicarbonate ions, which are formed when CO2 combines with water in the blood. Therefore, the correct answer is C.

20) In sick