2.3 The Genetic Code Flashcards
What is a gene?
A section of DNA
What does each gene code for?
A specific polypeptide
What do bases code for?
Amino acids
What does the order of bases in a gene determine?
The order of amino acids and as a result, the type of polypeptide made
What is a codon?
A sequence of 3 bases
What else is a codon called?
A triplet or base triplet
Why is it important that different proteins have a different number and order of amino acids?
It gives them a different shape and thus allows them to carry out their function
What is each amino acid coded for by?
One codon
How many amino acids have a single codon?
Very few
Give an example of an amino acid coded for by single codon?
Methionine which is only coded for by ATG
This is the start codon
The genetic code is…
- degenerate
- universal
- non overlapping
What does it mean that the genetic code is degenerate? Why?
- Most amino acids have more than 1 codon
- as there are more possible combinations (64) than there are amino acids (20)
What does it mean that the genetic code is universal?
The same codons are used for the same amino acids in all living organisms
What does it mean that the genetic code is non overlapping?
Each base is only read once, no base is shared between triplets
Where are start and stop codons found?
At the beginning and end of each gene
