4. Genetic Information - DNA, Genes And Chromosomes

Question 1

What is a gene?

Answer 1

A gene is a section of DNA that contains the coded information for making polypeptides and functional RNA.

Question 2

What is a locus?

Answer 2

Where on a chromosome a specific gene is.

Question 3

How many bases code for each amino acid? What is this called?

Answer 3

3 - hence called a triplet

Question 4

What are the 3 types of genetic code?

Answer 4

1. Degenerate code
2. Non-overlapping
3. Universal

Question 5

What is ’degenerate code’?

Answer 5

• It refers to the fact that multiple codons can code for the same amino acid, and most amino acids are coded for by more than one triplet

Question 6

What is ’non-overlapping’ code?

Answer 6

Each base in the sequence is only read once.

For example, the code 123456 is read as triplets 123 and 456, rather than as 123, 234, 345, 456,

Question 7

What is ’universal’ code?

Answer 7

With a few minor exceptions, each triplet codes for the same amino acid in all organisms.

Question 8

How many triplets are ’stop codes’?

Answer 8

Three triplets that do not code for any amino acid are ’stop codes’.

Question 9

What do ’stop codes’ do?

Answer 9

They mark the end of a polypeptide chain.