8.1: Genes and the triplet code Flashcards
What is a gene
A section of DNA that codes for a polypeptide
What is a locus
The specific position of a gene on a DNA molecule
What does a gene code for
- The amino acid sequence of a polypeptide
2. Functional RNA, rRNA + tRNA
How many bases code for 1 amino acid
A minimum of 3 bases
How many amino acids occur regularly in proteins
20
What are 3 bases called
A triplet
How many amino acids are coded for by 1 triplet
Only a few
How many triplets code for the majority of amino acids
2-6
What does ‘Degenerate’ code mean
Most amino acids are coded for by more than 1 triplet
What does ‘Non-Overlapping’ code mean
Each base is read ONCE
What does ‘Universal’ code mean
Each triplet codes for the same amino acid in all organism. This is indirect evidence for evolution
Which direction is a triplet read
In 1 direction only along a DNA strand
What do just 3 triplets code for
No amino acid
These code for a ‘Stop-Codon’ which mark the end of polypeptide formation
What does most DNA not do
Code for any polypeptide/RNA, known as ‘INTRONS’
What is a codon
A set of 3 bases in MRNA NOT DNA (U, A, C, G)
