State four functions of proteins, giving a named example of each.

Outline the structure of ribosomes.

Explain the process of transcription leading to the formation of mRNA.

a. structure – collagen;

b. transport – transthyretin / hemoglobin;

c. enzyme/catalyst – lysozyme;

d. movement – actin / tubulin;

e. hormones – insulin;

f. antibodies – immunoglobulin;

g. storage – albumin;

Accept any other valid function of proteins with a named example.

For example sodium potassium pump, but do not accept simply “in membranes” without a clear function.

To award [4 max], responses need a function of protein and a named example.

Only accept the first four answers.

a. made of protein;

b. made of rRNA;

c. large subunit and small subunit;

d. three tRNA binding sites;

e. Aminacyl/A, Peptidyl/P and Exit/E;

f. mRNA binding site (on small subunit);

g. 70S in prokaryotes / 80S in eukaryotes;

h. can be free / bound to RER (in eukaryotes);

a. RNA polymerase; (polymerase number is not required)

b. binds to a promoter on the DNA;

c. unwinding the DNA strands;

d. binding nucleoside triphosphates;

e. to the antisense strand of DNA;

f. as it moves along in a 5'→3' direction;

g. using complementary pairing/A-U and C-G;

h. losing two phosphates to gain the required energy;

i. until a terminator signal is reached (in prokaryotes);

j. RNA detaches from the template and DNA rewinds;

k. RNA polymerase detaches from the DNA;

l. many RNA polymerases can follow each other;

m. introns have to be removed in eukaryotes to form mature mRNA;

Most candidates gained some marks here with knowledge of functions of proteins with examples. However many answers were very descriptive rather than “stating with an example” as asked.

Most knew about the two ribosome subunits and the mRNA binding site. Very few knew that they were made from protein and rRNA. Several answered that there were 3 binding sites, but not what was bound there (tRNA) or what they were called.

The process of transcription was well known by most candidates who attempted this question.