1 The side chain of valine is not polar because it does not have two types of at
ID: 55339 • Letter: 1
Question
1 The side chain of valine is not polar because it does not have two types of atoms that have large differences in electronegativity
a.) True b.) False
2 Ethanol is a polar molecule because there are large differences in electronegativity of the atoms and the molecule is asymmetric in shape.
a.) True b.) False
3 Which best describes a protein that is found in the cytosol?
a.) Polar amino acids will be found on the surface b.) Acidic amino acids will be found on the surface
c.) Basic amino acids will be found on the surface d.) Non-polar amino acids will be found in the interior
e.) All of the above
4 What will likely happen if two glutamates at pH 5 are next to each other in a polypeptide chain?
a.) The side chains of these amino acids will be uncharged and there will be no effect.
b.) The side chains of these amino acids will be charged and they will attract each other.
c.) The side chains of these amino acids will be charged and they will repel each other.
d.) Not enough information is given to determine the effect.
5 The difference between fetal and adult hemoglobin with regard to oxygen binding occurs because fetal hemoglobin has an amino acid substitution in one of its chains that results in a serine being replaced by a histidine.
a.) True b.) False
Explanation / Answer
1. The side chain of valine is not polar because it does not have two types of atoms that have large differences in electronegativity - a) True.
The side chain of Valine is -CH(CH3)2 .The number of alkyl groups influences the polarity. The more alkyl groups present, the more non-polar the amino acid will be. The greater the electronegativity difference between atoms in a bond, the more polar the bond. As Valine has two alkyl groups in its side chain with no electronegativity difference it is non-polar.
2. Ethanol is a polar molecule because there are large differences in electronegativity of the atoms and the molecule is asymmetric in shape. - b) False
The molecule is polar because there are large differences in electronegativity of the atoms -this part of the statement is true because the difference in electronegativity of the carbon-oxygen bond is 0.89. In these bonds, the electrons are more attracted to the oxygen. As a result, this net polar force can lead to hydrogen bonds between two ethanol molecules or with a water molecule.But, the molecule is asymmetric in shape -this part of the statement is false because ethanol is not asymmetric in shape.
3. Which best describes a protein that is found in the cytosol?
e.) All of the above
4. What will likely happen if two glutamates at pH 5 are next to each other in a polypeptide chain?
c.) The side chains of these amino acids will be charged and they will repel each other.
Both glutamates at pH 5 will have net -1 charge over the glutamate residue and two -1 charges so close or next to each other will result in repulsion of like charges.
5 The difference between fetal and adult hemoglobin with regard to oxygen binding occurs because fetal hemoglobin has an amino acid substitution in one of its chains that results in a serine being replaced by a histidine.
a.) True
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