Features of GENETIC CODE Flashcards
what are the 3 features of the genetic code
degenerate
universal
non overlapping
what is a “start codon”
the first 3 DNA bases - first triplet - that initiates translation
extra
DNA = TAC
mRNA = AUG
codes for amino acid methionine which is later removed from the structure if not needed
what is a “stop codon’ and what does it do
the 3 DNA bases at the end of the gene which mark the end of the polypeptide chain and allow ribosomes to detach and stop translation
extra
DNA = ATT, ATC and ACT
what does degenerate mean
there are more possible combinations of triplets than amino acids
- 20 amino acids but 64 triplets
- this means that some amino acids are coded for by more than one triplet
why can the degenerate feature be an advantage
if point mutation occurs, even if the bases have changed , they could still potentially code for the same amino acid meaning no overall change / effect
what does the universal feature mean
the same triplet bases code for the same amino acid in all organisms
why is the universal feature an advantage
allows genetic engineering between different species
explain the non overlapping feature
each base in the gene are only part of one triplet / codon
why is non overlapping an advantage
if point mutation occurs, it only affects one codon and therefore one amino acid rather than changing the whole translation
what are introns
sections of DNA that dont code for amino acids / polypeptide chains
- only found in eukaryotic DNA not prokaryotic
- they are spliced (removed) out of mRNA molecules
what are exons
the sections of DNA that do code for amino acids
whats the genome
an organisms complete set of DNA in one cell
whats the proteome
the full range of proteins in one cell
whats the differences between genomes and proteomes
- genome shouldn’t ever change whereas proteome constantly changes
- the genome between different organisms varies
