3.10 Protein synthesis

Question 1

what is transcription

Answer 1

process of copying sections of DNA base sequence to produce smaller molecules of mRNA

Question 2

process of transcription

Answer 2

1. DNA helicase unzips and unwinds DNA (breaks hydrogen bonds)
2. free RNA nucleotides pair with exposed bases on antisense strand
3. DNA polymerase causes phosphodiester bonds to form between RNA nucleotides
4. mRNA is formed and detaches from DNA template and leaves through nuclear pore
5. DNA double helix reforms and mRNA moves to ribosome

Question 3

what are the 2 DNA strands

Answer 3

sense strand (5’ to 3’) = code for protein to be synthesised

antisense strand (3’ to 5’) = acts as template strand so RNA has same bases as sense strand

Question 4

what is translation

Answer 4

process by which the complementary code carried by mRNA is decoded by tRNA into sequence of amino acids

Question 5

rRNA

Answer 5

• makes up ribosome
• maintains structural stability of protein synthesis sequence
• biochemical role in catalysing the reaction

Question 6

tRNA

Answer 6

-carries amino acid specific to its anti-codon to correct position along mRNA in translation

Question 7

process of translation

Answer 7

1. mRNA binds to small subunit of ribosome at it start codon
2. tRNA with complementary anticodon binds with it
3. another tRNA binds go next codon on mRNA (max 2 tRNAs can be bound at one time)
4. first amino acid is transferred to amino acid on second tRNA by formation of peptide bond by peptidyl transferase
5. ribosome moves along tRNA releasing first tRNA
6. steps 3-5 repeated until reaching stop codon