Inheritence Flashcards
Def of autosomal allele
All chromosomes except the X & Y
Dihybrid cross
Inheritance of two genes at the same time
Height and petal colour are controlled by separate genes on different chromosomes
Height gene: tall (T) and short (t)
Petal Colour: red (R) and white (r)
1) draw the possible gamete’s produced by heterozygous plant
2) show the results of crossing over 2 heterozygous plants
3) list the 4 possible phenotypes and the ratio they are found in of the offspring
1) possible gametes
TR Tr tR tr
2) draw a dihybrid cross with the 4 gamates on the top and the bottom.
(See notes for more info)
3) possible phenotypes
Tall & Red - TTRR , TTRr, TtRR, TtRr
Small & White - ttRr, ttRR
Tall & White - TTrr, Ttrr
Small & Red - ttrr
Ratio of phenotypes is 9:3:3:1
Coat texture and colour are controlled by separate genes on different chromosomes
Texture : rough (R) and smooth (r)
Colour: black (B) and white (b)
1) show the results of crossing over a rough, black male (RrBb) and smooth,black female (rrBb)
2) list the 4 possible phenotypes and the ratio they are found in of the offspring
Males gamates= RB, Rb, rB, rb
Female gametes = rB, rb
1) Use dihybrid cross (see notes for more info)
2) rough, black - RrBB, RrBb
Rough, white - Rrbb
Smooth, black - rrBB, rrBb
Smooth white - rrbb
Ratio = 3:1:3:1
Def of epistasis
Alleles of one gene are needed for expression of a second gene
(The relationship between genes where the allele of one gene affects the expression of different gene)
Def of genotype
All the alleles that an organism carries on its chromosome
Def of Phenotypes
Observable characteristics of an organism which result of the genotype as well as environmental factors
Def of dominant allele
Only 1 allele is required for the characteristic to be expressed in the phenotype.
Def of recessive
The characteristic is only expressed if there is no dominant allele present in order for the phenotype to be expressed
Def of Codominant
Both alleles are expressed equally and contribute to the phenotype, with there being a blend of the 2 characteristics or both seen together
Def of allele
An alternative form of a gene
Def of locus
The specific position of the gene on the chromosome
Def of monohybrid inheritance
When a phenotype or trait is controlled y a single gene
Draw a monohybrid cross
E.g if the colour of peas
Is green (G) and yellow (g)
And parents are green homozygous
And yellow homozygous
See notes for cross
A ratio of 3:1 green: yellow
Def of sex linkage alleles
The expression of an allele depends on the gender of the individual as the gene is located on a sex chromosome