protein synthesis

Question 1

outline the process of transcription

hint: 5 points

Answer 1

1) DNA helicase breaks hydrogen bonds between complimentary base pairs
- bases are exposed
2) ONE strand acts as a template
3) free nucleotides align by complimentary base pairing
4) RNA polymerase joins adjacent nucleotides by phosphodiester bonds
5)pre- mRNA is spliced to remove introns, forming mRNA

Question 2

outline the process of translation

hint: 7 points

Answer 2

1) mRNA attatches at the ribosome
2) codon on mRNA
3) binds to anti codon on tRNA
4) each tRNA brings specific amino acid
5) sequence of codons determines order of amino acids
6) amino acids bond forming peptide bonds via condensation reaction
7)process is repeated until stop codon is reached

Question 3

define genome?

Answer 3

the complete set of genes in a cell

Question 4

define proteome

Answer 4

the full range of proteins a cell is able to produce

Question 5

compare and contrast DNA in eukaryotic cells with the DNA in prokayrotic cells (5 marks)

Answer 5

differences:
- eukaryotic DNA is longer than prokaryotic DNA
- eukaryotic DNA contains introns, prokaryotic doesnt
- eukaryotic DNA is liner, prokaryotic DNA is circular
- eukaryotic DNA is associated with histones, prokaryotic DNA is not

similarities:
- both contain nucleotides joined by phosphodiester bonds
- nucleotide structure is identical

Question 6

what is the difference between the production of eukaryotic mRNA and prokaryotic mRNA

Answer 6

eukaryotic mRNA:
- introns and exons are copied into mRNA during trancription to produce pre- mRNA
-** pre mRNA** is then spliced to remove introns

WHEREAS

prokaryotic mRNA:
- mRNA produced directly from DNA, splicing DOES NOT take place
- because there are no introns in prokaryotic DNA

Question 7

where does translation take place?

Answer 7

ribosomes in the cytoplasm

Question 8

where does transcription take place?

Answer 8

in eukaryotes:
- nucleus
in prokaryotes:
- cytoplasm

Question 9

what are non coding base sequences and where are they positioned in the genome?

Answer 9

• sections of DNA that does not code for sequence of amino acid
• positioned between genes

must say ‘sequence’ not just ‘an amino acid’!!!

Question 10

compare DNA found in nucleus vs DNA found in chloroplast

this question may also be asked about ‘mitchondria’ - the same answers would apply here !!!

Answer 10

DNA found in nucleus:
- longer
-linear
- associated with proteins/histones

DNA found in chloroplasts
- shorter
- circular
- not associated with proteins/histones