Revision Resource on Variation
A gene is a section of DNA that is responsible for a characteristic like eye colour or blood group. Humans have around 20,000 genes. DNA makes up genes, which makes up chromosomes. One copy of all your chromosomes is called your genome.
DNA
How many chromosomes does it contain?
A chromosome contains hundreds to thousands of genes. Every normal human cell contains 23 pairs of chromosomes, for a total of 46 chromosomes.
What is consists of
2 strands that wind around each other like a twisted ladder.
Chromosomes
how many genes are in on chromosomes?
hundreds and thousands
What is the DNA shape called?
The double helix
Who invented the double helix?
James D. Watson
What it is
A piece of DNA that contains genes.
How many chromosomes are in an egg cell?
46 Chromosomes
How many chromosomes are in a sperm?
23
Genes
What it is made up of
A different pattern of the four bases of DNA
What they are
A section of DNA that controls an inherited feature
what is it made up of?
Where they are located
Chromosomes
A chromosome is made up of proteins and DNA organized into genes
What it is
deoxyribonucleic acid
What causes animals become extinct?
Climate Change
Hunting
Deforestation
Poaching