Genetic Code Flashcards
What are the 3 features of the genetic code?
Degenerate
Universal
Non-overlapping
What is a start codon?
The three bases at the start of a gene. They code for an amino acid.
What does the start codon initiate?
Translation
What is the stop codon?
The final three bases on the end of DNA. They don’t code for amino acids.
What do the stop codons mark the end of? What happens at the stop codon?
A polypeptide chain. This causes the ribosomes to detach and stop translation.
How many different amino acids are there?
20
What is the formula used for degenerate?
4^n
What is meant by degenerate?
Each amino acid is coded for by more than one triplet of bases.
Advantage of the genetic code being degenerate?
If a mutation occurs, even though the triplet of bases will be different it may code for the same amino acid and thus have no effect.
What is meant by universal?
The same triplet of bases code for the same amino acid in all organisms.
Advantage of the genetic code being universal?
Allows genetic engineering to be possible. For example, inserting the human gene for insulin into bacteria.
What is meant by non-overlapping?
Each triplet of bases is read as a discrete unit.
Advantage of the genetic code being non-overlapping?
If a mutation occurs it’ll only affect one codon and thus one amino acid. Not much of an impact on the polypeptide chain.
What are introns?
Sections of DNA that don’t code for an amino acid and thus polypeptide chains.
Where are introns found and not found?
Eukaryotic DNA not prokaryotic DNA.
