2.3 The Genetic Code Flashcards Preview

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Flashcards in 2.3 The Genetic Code Deck (20):
1

What is a gene?

A section of DNA

2

What does each gene code for?

A specific polypeptide

3

What do bases code for?

Amino acids

4

What does the order of bases in a gene determine?

The order of amino acids and as a result, the type of polypeptide made

5

What is a codon?

A sequence of 3 bases

6

What else is a codon called?

A triplet or base triplet

7

Why is it important that different proteins have a different number and order of amino acids?

It gives them a different shape and thus allows them to carry out their function

8

What is each amino acid coded for by?

One codon

9

How many amino acids have a single codon?

Very few

10

Give an example of an amino acid coded for by single codon?

Methionine which is only coded for by ATG
This is the start codon

11

The genetic code is...

- degenerate
- universal
- non overlapping

12

What does it mean that the genetic code is degenerate? Why?

-Most amino acids have more than 1 codon
-as there are more possible combinations (64) than there are amino acids (20)

13

What does it mean that the genetic code is universal?

The same codons are used for the same amino acids in all living organisms

14

What does it mean that the genetic code is non overlapping?

Each base is only read once, no base is shared between triplets

15

Where are start and stop codons found?

At the beginning and end of each gene

16

What are the three stop codons?

UAG
UAA
UGA

17

What is the start codon?

ATG (methionine)

18

What happens to the start codon later in the process of forming a polypeptide?

It is removed as it doesn't form part of the polypeptide

19

In what direction is he triplet code always read?

Three prime to five prime

20

What is the genetic code of an organism?

The sequence of bases along its DNA

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