✅8 - DNA, Genes and Protein Synthesis Flashcards
What is a gene?
A section of DNA that contains the coded information for making polypeptides and functional RNA
What is a locus?
The particular positions of a gene in a section of DNA
Why was it suggested that there were a minimum of three bases coding for each amino acid?
Only 20 amino acids occur in proteins
Each amino acid must have its own code
There are only four bases
4^2 is 16, while 4^3 is 64 amino acids
Why is the code degenerate?
Because most amino acids are coded for by more than one triplet
How is the triplet always read?
In one direction
What is always the first triplet in an amino acid sequence?
That coding for the amino acid methionine
Why is the code non-overlapping?
Because each base sequence is only read once, as triplets rather than individually
Why is the code universal?
Because with a few minor exceptions each triplet codes for the same amino acid in all organisms - indirect evidence for evolution
What are introns?
Triplets which do not code for any amino acids
What are exons?
Triplets that are expressed
What are histones?
Proteins associated with DNA
What is a chromatid?
A thread of DNA which makes up a chromosome
What are homologus pairs?
One chromosome from each parent in a pair, with the same genes but not necessarily the same alleles
What is the human chromosome number?
46
What is an allele?
One of a number of alternative forms of a gene
