4.2 DNA and protein synthesis

Question 1

Messenger RNA

Answer 1

Single polynucleotide strand made during transcription, carries the genetic code from the DNA to the ribosomes. Used to make a protein during translation

Question 2

Transfer RNA

Answer 2

Involved in translation, carries amino acid to ribosomes, folded into a clover shape held by hydrogen bonds, have an anticodon and an amino acid binding site

Question 3

Transcription

Answer 3

1. RNA polymerase attaches to the DNA double-helix at beginning of gene
2. Hydrogen bonds broken by DNA helicase attached to RNA polymerase, uncoils and exposes DNA bases
3. One strand used as a template
4. RNA assembles the mRNA strand made by complementary base pairing
5. Hydrogen bonds reform after RNA polymerase has passed by

Question 4

Eukaryotic transcription

Answer 4

Introns and exons both copied, forms pre-mRNA. Splicing occurs to remove introns and join exons together. Takes place in nucleus

Question 5

Prokaryotic transcription

Answer 5

mRNA produced directly from the DNA without splicing, no introns in prokaryotes

Question 6

Translation

Answer 6

1. mRNA attaches itself to a ribosome and tRNA molecules carry amino acids to it, ATP provides energy needed for the bond between amino acid and tRNA
2. tRNA anti-codon complementary to the first codon on mRNA attaches
3. Second tRNA attaches and amino acids are joined by peptide bond
4. Continues until there’s a stop signal on mRNA molecule