MCAT Biochemistry 🧬

What are the essential amino acids (obtained from the diet)?

Histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

What are the non-essential amino acids (synthesized by the body)?

Alanine, asparagine, aspartic acid, glutamic acid, serine, arginine, cysteine, glutamine, glycine, proline, and tyrosine.

What post-translational modifications can amino acids undergo to affect protein function, localization, and interactions?

Phosphorylation, glycosylation, acetylation, methylation, and ubiquitination.

In sickle cell anemia, what is the incorrect sequence change in the hemoglobin polypeptide chain?

The sixth amino acid of the beta chain, glutamic acid, is replaced by a hydrophobic valine.

💡This change occurs in both beta chains that make up hemoglobin, making sickle cell anemia an effect of just 2 incorrect amino acids in a sequence of 600.

What molecular interactions make up the secondary structures of proteins?

Hydrogen bonds formed between the carbonyl oxygen of one amino acid and the amine hydrogen of another.

In an alpha helix secondary structure, how many amino acids are contained in each turn of the helix?

3.6 amino acids per helical turn.

💡The carbonyl O bonds to the amine H of an amino acid that is four down the chain; ie. carbonyl of amino acid 1 would bond with the amine of amino acid 5.