Inheritance And Variation Flashcards
What does heterozygous mean?
Different alleles
What does homozygous mean?
Same alleles
What are alleles?
Different forms of the same gene
What are genes?
DNA which codes for polypeptides, characteristics
What is the genotype?
Combination of alleles
What allele is expressed?
Dominant
What is discontinuous variation?
Controlled by a few genes eg. Blood group
What is continuous variation?
Controlled by a group of genes eg. Height
What type of allele is cystic fibrosis?
Recessive
What type of allele is polydactyly?
Dominant
What is the position of genes called?
Loci which are in the same place on both maternal and paternal chromosomes
What does autosomal mean?
Recessive gene not found on a sex chromosome and so is found on 1 to 22 chromosome
What are sex linkage genes?
Genes carried on sex chromosomes
What is the ratio when 2 heterozygous parents breed?
9:3:3:1
What is the ratio when a heterozygous a recessive parents breed?
1:1:1:1
Define epistasis
Interacting of genes on different loci which prevents one gene being expressed
What does hypostatic mean?
The gene wich is effected by epistasis
When does repressive epistasis occur?
When 2 recessive alleles are inherited
When happens when dominant epistasis occur?
Dominant allele prevents other genes being expressed
Define allele frequency
Frequency of alleles of a single gene
Define gene pool
Total of all genes in a population
What is the equation for allele frequency?
P squared + 2×p×q + Q squared
Name a density dependant factor
Competition
Name some density independent factors
Climate change
