Lecture 5 Unit 1 Flashcards
what are the basic units of proteins
amino acids
what are the parts to an amino acid
- alpha carbon
- carboxyl group
- amino group
- R group
what are the 3 groups of amino acids
- hydrophilic
- hydrophobic
- special amino acids
what are the three special amino acids
glycine, proline, cysteine
what’s special about glycine
its small, it is symmetric, allows for freer oration around C-N bond, increasing flexibility of the polypeptide backbone
what’s special about proline
R group linking back to amino group creates a kink in polypeptide chain, restricts rotation of C-N bond, increases rigidity of polypeptide bond
what special about cysteine
R group contains S-H bond. when two cysteine are close a disulfide bond can form
What happens mechanistically when a peptide bond forms
through condensation reactions a water molecule in liberated, carboxyl group of one amino acid attaches to the amino group of the next AA
what are the 4 levels of protein structure
primary, secondary, tertiary, quaternary
what is the primary structure
the sequence of amino acids
what is the secondary structure
results from interactions of nearby amino acids
what are the two types of secondary structures
beta sheets and alpha helices
how do strands run in beta sheets
they can either be parallel or antiparallel
where do hydrogen bonds form in beta sheets
between carbonyl groups in one polypeptide and an amide group in the other polypeptide
what is the tertiary structure
the 3D shape of a protein
