B1h - Variation Flashcards
How many chromosomes do sex cells have?
23.
How many pairs of chromosomes do normal body cells have?
23.
Is a female XX or XY?
XX.
What does homozygous mean?
When the alleles are identical in the chromosome - e.g TT or tt
What does heterozygous mean?
The alleles are different in a chromosome - e.g Tt
What are dominant and recessive alleles?
Dominant alleles will be the characteristic that is shown on the person - e.g if the person is Tt they will be the dominant allele (T). Recessive is the smaller case allele which will only be expressed in the person if they are homozygous with identical recessive alleles.
How can you find out how likely a person is to be born with a certain pair of alleles?
A genetic diagram.
What is a genotype?
The combination of alleles found in an organism. It is represent by letters, e.g. Tt
What is a phenotype?
The characteristics caused by the genes, e.g brown or blue eyes
What are carriers?
People who carry a disease in their chromosomes without showing it, as it would be a recessive allele ruled out by the dominant one.
