Biochemistry (Proteins)

Question 1

protein structure

Answer 1

primary structure: primary structure is the sequence of amino acids. At this stage the molecule is called a polypeptide because it has no definite 3D shape

secondary structure: the polypeptide chain folds into regions of alpha helix and regions of beta pleated sheets. these are local sub-structures. alpha helice and beta pleated sheets are held together by hydrogen bonds.

tertiary structure: the polypeptide is folded into a specific 3D shape. The tertiary structure is held together by a number of different types of bond

quarternary structure: a quarternary structure occurs when 2 or more protein subunits are bonded together to make 1 molecule

Question 2

fibrous protein

Answer 2

tread-like, insoluble ie. keratin

Question 3

globular protein

Answer 3

round, soluble ie. pepsin

Question 4

how many different amino acids are there

Answer 4

20. the R/variable group is different.

Question 5

hydrophilic r group

Answer 5

polar amino acid

Question 6

hydrophobic r group

Answer 6

non-polar

Question 7

how cells use polar and non-polar amino acids

Answer 7

enzyme solubility: outer layer of an enzyme will contain many polar amino acids. helps make enzyme soluble.

membrane protein: inner pore of membrane channel will contain polar amino acids, while the amino acids in contact with the lipid bilayer will be non-polar.

protein stability: inner layer of amino acids will contan many non-polar amino acids. helps stabilize the shape of soluble protein.

Question 8

dipeptide

Answer 8

2 amino acids joined together by condensation reaction

Question 9

peptide bond

Answer 9

the bond in the centre of a dipeptide joining 2 amino acids

Question 10

where are amino acids joined together?

Answer 10

in cells, by fee ribosomes or ribosomes attached to the RER

Question 11

Functions of Proteins

Answer 11

insulin: a hormone involved in the regulation of blood glucose concentration
rhodopsin: necessary for normal vision. particular in low light conditions. found in specialized light receptor called rods
immuglobulins: Y shaped protines produced by B cells that are used by the immune system to identigy and neutralize foreign objects such as bacteria and viruses.
collagen: most abundant protein in mammals. it is composed of 3 interwoven polypeptide chains, found in fibrous tissues like tendons, ligaments, skin, cartilage, bones, blood vessels.
rubisco: enzyme that catalyzes carbon function in green plants

spider silk: spiders use it to make webs