UNIT 1.3

Question 1

2 stages of protein synthesis

Answer 1

transcription and translation

Question 2

difference between RNA and DNA

Answer 2

DNA is double stranded, A-T, and is a deoxyribose sugar
RNA is single stranded, A-U, and is a ribose sugar

Question 3

mRNA

Answer 3

carries a copy of the genetic code from the nucleus to the cytoplasm

Question 4

tRNA

Answer 4

each carries a specific amino acid to the ribosome

Question 5

rRNA

Answer 5

forms the ribosome with proteins

Question 6

transcription

Answer 6

• enzyme RNA P moves along unwinding the double stranded helix and breaking bonds
• RNA P synthesises a primary transcript of mRNA from free RNA nucleotides by comp base pairing
• RNA P keeps adding nucleotides from the 5’ and to 3’ end of growing mRNA molecule, till stop codon is reached
• the resulting mRNA strand separates and is now called a Primary Transcript to mRNA

Question 7

translation

Answer 7

• mature mRNA transcript attaches to a ribosome in the cytoplasm
• the start codon begins PS
• comp tRNA anticodons attach to mRNA strand, bringing a specific amino acid to form the protein molecule
• peptide bonds join the amino acid molecule each tRNA molecule leaves the ribosome once the amino acids are attached
• a stop codon ends PS
• amino acids are linked by peptide bonds to from polypeptide (proteins)

Question 8

alt rna splicing

Answer 8

the mature transcript is formed by RNA splicing
1. removal of non coding introns and
2. joining together of the coding exons to form the mature mRNA transcript