Protein Synthesis Flashcards
What are the 3 types of RNA?
o rRNA (ribosomal) o mRNA (messenger) o tRNA (transfer)
What is the role of rRNA?
Forms ribosomes with protein in the nucleolus
What is the role mRNA?
o Complementary to the DNA strand (anti-codon)
o Carries information out of the nucleus
What molecule is transcription from/to and where does it occur?
DNA —-> mRNA, Nucleus
What molecule is translation from/to and where does it occur?
mRNA —-> proteins, Ribosomes
What is the process of transcription?
o RNA polymerase separates strands
o Synthesises mRNA copy from a DNA strand
o RNA nucleotides align their opposite bases
o RNA polymerase joins the nucleotides (phosphodiester bonds)
o RNA polymerise detaches and the helix reforms.
Which DNA strand is identical to the RNA strand?
Coding strand
Which DNA strand is complimentary to the RNA strand?
Template strand
What are the 3 stages of transcription?
Initiation, Elongation and Termination
What happens in the Elongation stage?
The RNA nucleotides align with their complimentary base pairs on the template strand and the RNA polymerase catalyses the formation of phosphodiester bonds to form a strand of mRNA.
What happens in the Termination stage?
The process stops when the end codon is reached and DNA polymerase detaches, double helix reforms.
What happens in the Initiation stage?
RNA polymerase unwinds the DNA and exposes the bases.
What is the function of ribosome?
Protein synthesis (making proteins)
What is a codon?
a triplet of bases of mRNA
What happens in translation?
o The ribosome binds to the mRNA and moves along the molecule in a 5-3 direction until it reaches the start codon (AUG)
o The first tRNA carrying the amino acid, methionine marching AUG
o mRNA is read one codon at a time and anticodons on tRNA molecules align to their codons
o Peptidyl transferase catalyses the formation of peptide bonds between amino acids
o The ribosome reaches a stop codon and the polypeptide chain Ian released.
