Lecture 3 Amino Acid Structures Flashcards
What are the 20 standard amino acids represented by?
One-letter and three-letter codes.
What functional groups are found on an amino acid?
An amino group (-NH₂), a carboxyl group (-COOH), and a side chain (R group).
What is a disulfide bond and what is its purpose?
A covalent bond formed between two cysteine residues, stabilizing protein structures.
How are amino acids classified?
Based on their side chains: non-polar, polar, acidic, or basic.
where are hydrophobic amino acids found in proteins and why? what role do they play in proteins?
They are usually found on the interior of proteins to avoid water, contributing to protein stability.
What are the key types of post-translational modifications (PTMs)? PUGAM
Phosphorylation, ubiquitination, glycosylation, acetylation, and methylation.
Why are only L-amino acids found in proteins?
L-amino acids are the physiologically relevant enantiomers in proteins.
What is the effect of adding a phosphate group to an amino acid called? what is its purpose?
It is known as phosphorylation and can alter protein function.
How do disulfide bonds contribute to protein structure?
They stabilize protein structures by forming covalent links between cysteine residues.
What is a hydrophilic amino acid’s role in proteins? where are they found?
It helps proteins interact with water and can be found on the protein’s surface.
How can salt bridges form in proteins? what is their purpose?
They form between positively and negatively charged amino acids, aiding in protein stability.
What is the alpha carbon like in a chiral amino acid in terms of symmetry? What does it lead to?
An amino acid with an asymmetric alpha carbon center leads to non-superimposable mirror images.
Which amino acid side chain contains an aromatic ring and is hydrophobic?
Tyrosine
