The Genetic Code Flashcards
How many different bases are there in DNA?
4
How many common amino acids are there?
20
How many possible codons are there?
64
What is a codon?
A sequence of 3 bases
Why are there 64 possible codons?
4 possible bases in 3 possible positions, 4 x 4 x 4
What is a gene?
A sequence of bases which code for a protein
What does degenerate mean when applied to the genetic code?
Some amino acids are coded for by more than one codon
What is the start code sequence?
AUG
How many start codons are there?
1
How many stop codons are there?
3
What is the function of a stop codon?
They indicate when translation is complete and the protein has been sythesised
What does non-overlapping mean?
There is no sharing of bases between codons
Why is the genetic code described as universal?
all livi g organisms use the sam genetic code
Why is the genetic code described as universal?
all living organisms use the same genetic code
What is the advantage of a non-overlapping code?
It means there is no restriction on the amino acids you have in a protein
What does the universal nature of DNA suggest?
That all organisms originate from a common ancestor
What are advantages of the genetic code being degenerate?
-means if a mutation were to occur a protein could still be reduces and it minimises the deletious effects pf mutations
How do mutations to a gene affect the structure of a protein?
- change in base could lead to change in amino acid produced
- this amino acid would have a different R-group to the original amino acid
- the R-group might interact differently with other R-groups
- the folding of the tertiary structure is affected
How many proteins does 1 gene code for?
1
What does a gene being switched on mean?
The gene is actively being used to produce proteins
If all cells contain the same DNA, how can cells specialise?
-different genes are switched on and off in different cells
