Proteins + Nucleic Acids

polypeptides structure

unbranched polymers built from the same set of 20 amino acids

structure of amino acids

alpha carbon (central carbon), R group, carboxyl group, amino group

categories of amino acids

nonpolar or polar side chains

Nonpolar side chains

methyl, C, H, no oxygens or nitrogens

Polar side chains

hydroxyl, amino, suflhydryl could be at the end (hydrogen bonded to more electronegative things so it’s more attracted to water forming hydrogen bonds)

polypeptides bond during dehydration synthesis

peptide bonds

polypeptide’s size range

few to more than a 1000 monomers

structure of polypeptides

carboxyl end + unique linear sequence of amino acids + amino end

how do peptide bonds form in polypeptides

carboxyl end gives Oh and amino group gives H they join to make water and water is removed to join them together through dehydration synthesis

protein structure

1 or more polypeptides twisted, folded, and coiled

What determines how proteins fold?

Order of amino acids

What determines proteins function?

structure

Four levels of protein structure

primary, secondary, tertiary, quaternary

Primary function

sequence of amino acids (alpha felix)

Primary level function

different side chains join to make a long polypeptide chain + amino end + carboxyl end

Secondary level structure

coils and folds in polypetide chains because of backbone interactionsS

Secondary level function

hydrogen bonding between various parts of the backbone (carbon, carboxyl joined to hydroxyl, alpha carbs so they lead alpha helix shape and beta plated sheet,; hydrogen which used to be a part of amino bonded to oxygen double bonded to one carboxyl group)

Tertiary structure

interaction of R groups

Tertiary function

could have hydrogen bonds, hydrophobic interactions, covalent bonds, or ionic bonds

Quaternary structure

structure when protein consists of multiple polypeptide chains

4 identical polypeptides

Quaternary function

carboxyl end gives Oh amino group gives H joins to make water so peptide bonds are formed