Genetic Variation Flashcards
How many pairs of chromosomes are there in human body cells?
23
What happens when gametes fuse?
One of each pair of alleles comes from each parent
What does one of the 23 pairs of chromosomes in human body cells comtain?
Carries the genes that determine sex
What are the sex chromosomes in females?
The same (XX)
What are the sex chromosomes in males?
They are different (XY)
What are some characteristics controlled by?
A single gene
Each gene may have different forms called alleles
What is a dominant allele?
An allele that controls the development of a characteristic when it is present on only one of the chromosomes
What is a recessive allele?
An allele that controls the development of characteristics only if the dominant allele is not present
What is a gene?
A small section of DNA
What are chromosomes made up of?
Large molecules of DNA which have a double helix structure
What does each gene code for?
A particular combination of amino acids which make a specific protein
What does each person have apart from identical twins?
Unique DNA
