2.7.2 Genetic variation Flashcards
Why does sexual reproduction give variation?
Sexual reproduction gives rise to variation
because, when gametes fuse, one of each
pair of alleles comes from each parent.
How many pairs of chromosomes are there?
In human body cells, one of the 23 pairs of
chromosomes.
What are the male chromosomes and female chromosomes?
In females the sex chromosomes are the
same (XX); in males the sex chromosomes are
different (XY).
What are alleles?
Some characteristics are 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 is a dominant allele
What is DNA?
Chromosomes are made up of large molecules of DNA (deoxyribo nucleic acid) which has a double helix structure.
What is a gene?
A gene is a small section of DNA.
What does each gene do?
Each gene codes for a particular combination
of amino acids which make a specific protein.
What is the process to indentify individuals?
Each person (apart from identical twins) has
unique DNA. This can be used to identify
individuals in a process known as DNA
fingerprinting.