Variation And Inheritance Flashcards
What is an allele?
A different version of the same gene
What are the two type of alleles?
Dominant and recessive
What factors affect intelligence, sporting ability and health?
Genetic or environmental
When are recessive alleles expressed?
In the absence of dominant alleles
How many pairs of chromosomes are in a human cell?
23
How is gender determined?
Sex chromosomes:
- Females XX
- Males XY
What chromosomes to egg and sperm cells carry?
- Egg: X
- Sperm: X or Y
What are the chances of offspring being male or female?
50/50
What is genetic variation caused by?
- mutations (random changes in genes and chromosomes)
- rearrangement of genes during the formation of gametes
- fertilisation (results in a zygote with alleles from mother and father)
What is a monohybrid cross?
Involves a characteristic being controlled by a single gene with one allele being dominant and recessive
What is the difference between a homozygous and a heterozygous?
Homozygous - the same alleles
Heterozygous - different alleles
What is the difference between a genotype and a phenotype?
Genotype - a person’s genetic makeup
Phenotype - which alleles are expressed
What are inherited disorders caused by?
Faulty alleles, most of which are recessive
How can we predict the probability of inheriting a disorder?
Interpreting data and alleles grids.
