Genes and The Genetic Code

Question 1

What is a gene

Answer 1

A section of dna that contains the coded information for making polypeptides and functional rna.

Question 2

What is the coded information in the form of

Answer 2

A specific sequence of bases along the dna molecule

Question 3

What determines the nature and development of all organisms

Answer 3

Genes, along with environmental factors

Question 4

How are genes responsible for an organisms development and activities

Answer 4

Polypeptides make up proteins so genes determine the proteins of an organism. Enzymes are proteins. As enzymes control chemical reactions they are responsible for an organisms development and activities

Question 5

What’s the locus

Answer 5

The position of a gene on a chromosome / dna molecule

Question 6

The gene is a base sequence of DNA that codes for what?

Answer 6

The amino acid sequence of a polypeptide

Or a functional rna, including ribosomal rna and transfer rna’s

Question 7

How many bases code for an amino acid

Answer 7

3

Question 8

How many amino acids regularly occur in proteins

Answer 8

20

Question 9

Why are some amino acids coded for by more than one triplet

Answer 9

As there are 64 possible triplets and only 20 amino acids

Question 10

Why is the code known as degenerate code

Answer 10

Because most amino acids are coded for by more then one triplet

Question 11

What are stop codes

Answer 11

3 triplets don’t code for any amino acid. They mark the end of the polypeptide chain

Question 12

Which triplet is always at the start

Answer 12

That code for the amino acid methionine

Question 13

What does it mean by the code is non overlapping

Answer 13

Each base sequence is only read once

Question 14

What makes the code universal

Answer 14

Each triplet codes for the same amino acid in all organisms

Question 15

what are introns

Answer 15

sections of a gene that dont code for amino acids

Question 16

What’s an exon

Answer 16

All the bits of a gene that do code for amino acids

Question 17

Explain how a change in one base along a dna molecule may result in an enzyme becoming non functional

Answer 17

A different base might code for a different amino acid. The sequence of amino acids in the polypeptide produced will be different. This change to the primary structure of the protein might result in a different shaped tertiary structure. The enzyme shape will be different and may not fit the substrate. The enzyme substrate complex cannot be formed and so the enzyme is non functional