Protein Synthesis

Question 1

whats protein synthesis

Answer 1

process where protein is made

Question 2

what are the two stages of protein synthesis

Answer 2

transcription
translation

Question 3

whats transcription

Answer 3

where one gene of the DNA is copied into mRNA

Question 4

whats translation

Answer 4

where the mRNA joins with a ribosome and corresponding tRNA molecules bring the specific amino acids the codon codes for

Question 5

explain transcription

Answer 5

1. DNA helix unwinds and exposes its strands so ONE of them can act as a template
2. DNA helicase unwinds the helix by breaking the hydrogen bonds between bases
3. Free mRNA nucleotides align opposite their complementary bases on the template strand
4. RNA polymerase enzyme bonds together the RNA nucleotides to form a new RNA chain > entire gene copied
5. mRNA is modified and leaves nucleus through nuclear envelope pores

Question 6

how is the pre mRNA strand modified before leaving the nucleus

Answer 6

the pre mRNA has the introns spliced out of the base sequence with the enzyme splicesome, leaving behind the exons

Question 7

explain translation

Answer 7

polypeptide chain is created using mRNA and tRNA strand

1. modified mRNA leaves nucleus and attaches to a ribosome in cytoplasm
2. ribosome attaches at start codon
3. tRNA molecule with complementary anticodon to the start code aligns opposite the mRNA - ribosome holds in place
4. ribosome moves along mRNA molecule > allowing another complementary tRNA to attach to the next codon on the mRNA
5. two Aa that have been delivered by the tRNA molecule joined by a peptide bond which is catalysed by an enzyme and requires ATP
6. continues until the ribosome reaches the stop codon at end of mRNA > stop codon doesnt code for Aa so the ribosome detaches