Evolution - Lecture 6, Genomes Flashcards
How many base pairs do human DNA have?
3 billion
What is the C paradox?
Where some genomes are different sizes
EG an onion has 16 billion base pairs and humans have 3 billion
How much of human DNA codes for proteins?
3%
How many genes are in a human?
19,000
What proportion of our DNA is junk DNA?
85%
What are transposons?
Sequences of DNA that move around the genome
Retrotransposons produce RNA which is transcribed into DNA and inserts itself into the genome
What are the potential risks of transposons?
The movement can produce mutations and may be involved in cancer
Anything preventing transposition is favoured
How are new genes made?
Duplication in non-coding sequences causes a base change
These leads to a new gene beginning from a non-coding section
Natural selection occurs
How do new structures form?
EG the placenta
Requires synctins, genes that once encoded the envelope of a retrovirus
What is horizontal gene transfer?
Gene transfer that isn’t through offspring
EG ticks bite and take the blood of different species which is then passed along
What is environmental DNA? (eDNA)
The extraction of sequences without an organism
Mainly from soil and water
How much do humans differ from each other on average?
By 0.1%
