Protein Structure And Function

Question 1

Protein def and uses

Answer 1

Proteins are complex molecules and do most of the work in cells. They are important to the structure, function, and regulation of the body. Proteins are made up of amino acids.

Question 2

Amino acids, what they are

Answer 2

Twenty amino acids are found in proteins. They are joined together by peptide bonds to form polypeptide chains . A protein is one or more polypeptide chains.

Question 3

2 examples of amino acids

Answer 3

Glycine- H as side group
Alanine- CH3 as side group
Both non polar, aliphatic R groups

Question 4

Levels of protein structure

Answer 4

1. Primary- order of the amino acids in the peptide chain.
2. Secondary- regular, local structure of the protein backbone. Stabilized by hydrogen bonding of amide groups within the molecule and sometimes within two molecules. Alpha helix and beta pleated sheet.
3. Tertiary- three dimensional arrangement of polypeptide chain . Disufide bonds stabilize tertiary structure.
4. Quaternary- several protein chains in a closely packed arrangement held together by hydrogen bonds and van def walls forces between non polar side chains.

Question 5

Who discovered the genetic code is a triplet code?

Answer 5

Francis Crick in 1961

Question 6

Overlapping code def

Answer 6

When a single nucleotide may be included in more than one codon
AUA CGA
UAC.

Question 7

Stages of protein synthesis

Answer 7

1. tRNA charging- where tRNA bonds to amino acid
2. Initiation- the components necessary for translation are assembled at the ribosome. mRNA, small and large subunits of ribosome, initiation factors, initiator tRNA, GTP.
3. Elongation- amino acids are joined, one at a time, to the growing polypeptide chain. Requires 70S complex, tRNAs charged with their amino acids, several elongation factors, GTP
4. Termination- protein synthesis halts at the termination codon and the translation components are released from then ribosome.