B1.2 - Proteins

Role of proteins

• provide structure

• transportation and communication

• Protection

• Enzyme activity

What elements are in proteins?

C,H,O,N, (S)

Describe the structure of AAs

• amine group

• carboxyl group

• free hydrogen

• variable r group which determines the identity of the AA

What type of rxn bonds AAs together

condensation rxns

What is an essential AA and how many are there?

Essential AAs are not produced by the body and therefore must be in the diet

There are 9 essential AAs

Define denaturation

When a protein is subjected to stress, the weak hydrogen bonds that connect the overall shape of the protein change and that affect the function

If the AAs stay in tact the protein will reshape

What are the net charges on the generic amino acid? (aq)

the amine group has a positive charge bc it acts as a base and accepts a proton while the carboxyl group has a net negative charge bc it acts as an acid and donates a proton.

What dictates if an AA is polar or non polar?

The r group

Describe the primary structure

The peptide bonds between the individual AAs

Describe secondary structure

based on the charge of the AA which is determined by the amine and carboxyl groups

What is/are the shapes(s) created by a polypeptide made of AAs with r groups that are non-polar?

alpha helices and beta pleated sheets

They are bonded via H bonds

what is needed to determine the secondary structure?

the residues

(r groups are non involved)

The protein’s shape will be created such that what is maximized?

the number of h bonds

What is the name from proteins that are only in alpha helices or beta pleated sheets and what are their characteristics?

• They are fibrous proteins

• They are insoluble

• typically used for structure or motility

  • ex) actin and myosin

Ionized r groups

AAs with oppositely charged r groups will create an ionic bond