1.3 Proteins

Question 1

give five functions of proteins

Answer 1

immunity
growth + repair
hormones
structure
enzymes

Question 2

what three groups are an amino acid made of

Answer 2

amino group
carboxyl group
R-group

Question 3

what bond formed between a dipeptide

Answer 3

peptide bond

Question 4

describe the different structures of a protein

Answer 4

primary - long chain of amino acids(polypeptide)
secondary- repeating polypeptide ( alpha helix or beta pleat)
tertiary- 3D folding of secondary structure (globular)
quaternary- 3D arrangement of more than one tertiary polypeptide

Question 5

describe the three types of bonds in proteins

Answer 5

hydrogen bonds- involved in all levels of structure
disulfide bonds- the strongest bonds that only occur when sulfur is present
ionic bond- can form between positive and negative side chains

Question 6

what happens if there is a change to the amino acids

Answer 6

if there is a change to the order of amino acids, it causes a different R group to form and different bonding to occur so the protein is a different shape.

Question 7

properties of fibrous proteins

Answer 7

insoluble
long rope-like
parallel chains
chains held by cross links
high tensile strength
eg collagen or keratin

Question 8

properties of globular proteins

Answer 8

soluble
spherical
specific shape for transport and communication
eg haemoglobin

Question 9

describe the test for proteins

Answer 9

add biuret A solution
if protein is present it will turn lilac
if no protein is present, it will remain blue