DNA and protein synthesis

Question 1

Genome

Answer 1

The complete set of genes in a cell and of the proteome as the full range of proteins that a cell is able to produce

Question 2

Structure of mRNA

Answer 2

It is a long polymeric molecule made up of nucleotides. mRNA is a long, single-stranded molecule consisting of nucleotides attached by phosphodiester bonds. It contains four nitrogenous bases, adenine, guanine, cytosine and uracil

Question 3

Structure of tRNA

Answer 3

tRNA has an L shaped 3D structure. It is specific to each amino acid and carries an amino acid to the growing chain of a polypeptide during the translation process

Question 4

Transcription

Answer 4

RNA polymerase controls transcription / is the enzyme used in transcription;
DNA is unwound by RNA polymerase;
DNA is split into two strands;
mRNA is made by transcription;
Promoter region (by start of gene) causes RNA polymerase to bind;
Anti-sense / template strand of DNA is transcribed;
Direction of transcription is 5’ to 3’;
Free nucleotide triphosphates used;
Complementary base pairing between template strand and RNA nucleotides / bases;
RNA contains uracil instead of thymine;
Terminator (sequence) stops RNA polymerase / transcription;
mRNA is released / RNA polymerase released

Question 5

Translation

Answer 5

A. consists of initiation, elongation and termination;
B. mRNA is used as a template / guide;
C. mRNA translated in a 5’ to 3’ direction;
D. binding of ribosome to mRNA;
E. small sub-unit then large;
F. first / initiator tRNA binds to start codon / to small subunit of ribosome;
G. AUG is the start codon;
H. second tRNA binds to ribosome;
I. large subunit moves down mRNA after a second tRNA binds;
J. mRNA “read” in base triplets / codon;
K. each codon specifying addition of a particular amino acid to the growing polypeptide;
L. tRNA bring amino acids (to mRNA-ribosome complex);
M. amino acid / polypeptide on first tRNA is transferred / bonded to amino acid on second tRNA;
N. peptide bonds between amino acids / peptidyl transferase;
O. requires GTP;
P. movement of ribosome / small subunit of ribosome down the mRNA;
Q. loss of tRNA and new tRNA binds;
R. reach a stop codon / termination;
S. stop codon has no corresponding tRNA / amino acid / causes release of polypeptide;
T. polypeptide released;
U. tRNA activating enzymes link correct amino acid to each tRNA;
V. (activated) tRNA has an anticodon and the corresponding amino acid attached;
W. many ribosome / polyribosomes bind to same mRNA