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Questions and Answers
Which amino acid is most likely to be found on the surface of a protein in a hydrophilic environment?
Which amino acid is most likely to be found on the surface of a protein in a hydrophilic environment?
- Isoleucine
- Glutamate (correct)
- Valine
- Phenylalanine
A mutation in a gene results in the replacement of a glycine residue with a tryptophan residue in the active site of an enzyme. How might this affect the enzyme's function?
A mutation in a gene results in the replacement of a glycine residue with a tryptophan residue in the active site of an enzyme. How might this affect the enzyme's function?
- The enzyme will only be affected at high temperatures as tryptophan will denature at lower temperatures than glycine.
- The mutation could disrupt the enzyme's active site due to the significant difference in size and chemical properties between glycine and tryptophan. (correct)
- The enzyme will exhibit increased activity due to tryptophan's aromatic properties enhancing substrate binding.
- The enzyme's activity will remain unchanged, as both glycine and tryptophan are small amino acids.
If a protein's isoelectric point (pI) is 6.0, at what pH would the protein have a net negative charge?
If a protein's isoelectric point (pI) is 6.0, at what pH would the protein have a net negative charge?
- pH 5.0
- pH 6.0
- pH 4.0
- pH 7.0 (correct)
Which amino acid is capable of forming disulfide bonds and how does this contribute to protein structure?
Which amino acid is capable of forming disulfide bonds and how does this contribute to protein structure?
How would the substitution of valine by glutamate at a specific position in a protein affect protein folding and stability?
How would the substitution of valine by glutamate at a specific position in a protein affect protein folding and stability?
In what scenario would proline most likely disrupt the secondary structure of a protein?
In what scenario would proline most likely disrupt the secondary structure of a protein?
Which of the following amino acids is most likely to participate in acid-base catalysis?
Which of the following amino acids is most likely to participate in acid-base catalysis?
How would a deficiency in the enzyme phenylalanine hydroxylase, which converts phenylalanine to tyrosine, impact the levels of other aromatic amino acids, and what broader metabolic consequences might arise?
How would a deficiency in the enzyme phenylalanine hydroxylase, which converts phenylalanine to tyrosine, impact the levels of other aromatic amino acids, and what broader metabolic consequences might arise?
How does the unique structure of glycine contribute to the flexibility of polypeptide chains, and in what specific structural contexts is this flexibility most critical?
How does the unique structure of glycine contribute to the flexibility of polypeptide chains, and in what specific structural contexts is this flexibility most critical?
Which strategy would be most effective to stabilize a protein structure consisting of multiple subunits that are held together by hydrophobic interactions?
Which strategy would be most effective to stabilize a protein structure consisting of multiple subunits that are held together by hydrophobic interactions?
Flashcards
Nonpolar, aliphatic R groups
Nonpolar, aliphatic R groups
Amino acids with nonpolar, aliphatic R groups. Includes Glycine, Alanine, Proline, Valine, Leucine, Isoleucine, and Methionine.
Polar, uncharged R groups
Polar, uncharged R groups
Amino acids with polar, uncharged R groups. Includes Serine, Threonine, Cysteine, Asparagine, and Glutamine.
Aromatic R groups
Aromatic R groups
Amino acids with aromatic R groups. Includes Phenylalanine, Tyrosine, and Tryptophan.
Positively charged R groups
Positively charged R groups
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Negatively charged R groups
Negatively charged R groups
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Study Notes
Nonpolar, Aliphatic R Groups
- This group includes Glycine, Alanine, Proline, Valine, Leucine, Isoleucine, and Methionine.
- Glycine's R group is simply a hydrogen atom.
- Alanine's R group is a methyl group (CH3).
- Proline's R group is a cyclic structure, connecting to the amino group, forming a five-membered ring.
- Valine, Leucine, and Isoleucine have branched hydrocarbon R groups.
- Methionine contains a sulfur atom in its R group.
Polar, Uncharged R Groups
- This group includes Serine, Threonine, Cysteine, Asparagine, and Glutamine.
- Serine and Threonine have hydroxyl groups (-OH) in their R groups.
- Cysteine contains a sulfhydryl group (-SH) in its R group.
- Asparagine and Glutamine have amide groups (C=O with an -NH2 group attached) in their R groups.
Aromatic R Groups
- This group includes Phenylalanine, Tyrosine, and Tryptophan.
- Phenylalanine has a phenyl group (benzene ring) as its R group.
- Tyrosine has a phenol group (benzene ring with a hydroxyl group) as its R group.
- Tryptophan has an indole group (a fused benzene and pyrrole ring system) as its R group.
Positively Charged R Groups
- This group includes Lysine, Arginine, and Histidine.
- Lysine has an amino group (-NH3+) at the end of its hydrocarbon R group.
- Arginine has a guanidinium group (a positively charged group with the structure (NH2)2C=NH2+) in its R group.
- Histidine has an imidazole ring (a five-membered ring with two nitrogen atoms) in its R group.
Negatively Charged R Groups
- This group includes Aspartate and Glutamate.
- Aspartate has a carboxylate group (-COO-) in its R group, one carbon away from the main chain.
- Glutamate has a carboxylate group (-COO-) in its R group, two carbons away from the main chain.
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