The Genetic Code

Question 1

How many different bases are there in DNA?

Answer 1

4

Question 2

How many common amino acids are there?

Answer 2

20

Question 3

How many possible codons are there?

Answer 3

64

Question 4

What is a codon?

Answer 4

A sequence of 3 bases

Question 5

Why are there 64 possible codons?

Answer 5

4 possible bases in 3 possible positions, 4 x 4 x 4

Question 6

What is a gene?

Answer 6

A sequence of bases which code for a protein

Question 7

What does degenerate mean when applied to the genetic code?

Answer 7

Some amino acids are coded for by more than one codon

Question 8

What is the start code sequence?

Answer 8

AUG

Question 9

How many start codons are there?

Answer 9

1

Question 10

How many stop codons are there?

Answer 10

3

Question 11

What is the function of a stop codon?

Answer 11

They indicate when translation is complete and the protein has been sythesised

Question 12

What does non-overlapping mean?

Answer 12

There is no sharing of bases between codons

Question 13

Why is the genetic code described as universal?

Answer 13

all livi g organisms use the sam genetic code

Question 14

Why is the genetic code described as universal?

Answer 14

all living organisms use the same genetic code

Question 15

What is the advantage of a non-overlapping code?

Answer 15

It means there is no restriction on the amino acids you have in a protein

Question 16

What does the universal nature of DNA suggest?

Answer 16

That all organisms originate from a common ancestor

Question 17

What are advantages of the genetic code being degenerate?

Answer 17

-means if a mutation were to occur a protein could still be reduces and it minimises the deletious effects pf mutations

Question 18

How do mutations to a gene affect the structure of a protein?

Answer 18

• 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

Question 19

How many proteins does 1 gene code for?

Answer 19

1

Question 20

What does a gene being switched on mean?

Answer 20

The gene is actively being used to produce proteins

Question 21

If all cells contain the same DNA, how can cells specialise?

Answer 21

-different genes are switched on and off in different cells