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 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
