Key Area 4- Variation and inheritance Flashcards
What is discrete variation?
A single gene inheritance. Can fall into distinct groups e.g eye colour
What is continuous variation?
A polygenic inheritance. Can have a range of volumes e.g height
What is a gene?
A stand of DNA that codes for protein
What is an allele?
Different versions of the same gene
What is a phenotype?
The physical description e.g blue eyes, brown hair
What is a genotype?
The allele description e.g BB, Bb
What does dominant mean?
An allele that will determine a phenotype. Shown with a capital letter e.g R
What does recessive mean?
An allele that can be dominated by another. Shown with a lowercase letter e.g r
What does homozygous mean?
Both alleles are the same e.g BB, rr
What does heterozygous mean?
Both alleles are different e.g Rr, Bb
What does P1, F1 and F2 mean?
P1=The parent generation (Your grandparents)
F1=The first generation of offspring (Your parents)
F2=The second generation of offspring (You and siblings)
What are two reasons why predicted phenotype ratios among offspring are not always achieved?
1) Fertilisation is random
2) The number of offspring can be small
