8.1 - Genes + the Genetic Code Flashcards
1
Q
What is a gene?
A
- a section of DNA containing the coded info for making polypeptides + functional RNA
2
Q
What do genes determine?
A
The nature + development of all organisms
3
Q
Where is a gene located?
A
- at a locus on a DNA molecule
4
Q
What do genes code for?
A
- the amino acid sequence of a polypeptide
- or a functional RNA, (rRNA + tRNA)
5
Q
How many different triplets are there?
A
64
6
Q
What is a triplet?
A
A sequence of 3 bases
7
Q
How many triplets are most amino acids coded for by?
A
- 2 - 6
- only a few are coded by only 1 triplet
8
Q
What is the genetic code known as?
A
- a ‘degenerate code’
9
Q
How is a triplet read?
A
- in 1 particular direction along the DNA strand
10
Q
What amino acid does the triplet at the start of a DNA sequence code for for a polypeptide?
A
- Methionine
11
Q
How many triplets don’t code for any animo acid?
A
3
12
Q
What are the triplets that don’t code for any amino acid called?
A
- stop codes
13
Q
What do ‘stop codes’ do?
A
- mark the end of a polypeptide chain
14
Q
What does the genetic code being non-overlapping mean?
A
- each base in the sequence is read only once
15
Q
What does the genetic code being universal mean?
A
- each triplet codes for the same amino acid in all organisms (w a few exceptions)