Dihybrid & Sex-linked inheritance Flashcards
1
Q
Define dihybrid inheritance
A
- inheritance of 2 pairs of traits
2
Q
Principle of independent assortment
A
- each pair of alleles segregate independently during gamete formation
- each pair of contrasted characters may be combined with another pair
3
Q
Reason for independent assortment
A
- behaviour of chromosomes at metaphase 1
- homologous chromosomes line up is random
- orientation of 1 pair does not influence others
- when separate during anaphase 1, assorted independently
- 4 diff types of gametes formed from heterozygous for 2 traits
4
Q
Define sex-linked inheritance
A
- involves traits found on either 1 of sex chromosomes
5
Q
Why males have higher chance of having a sex-linked condition
A
- XY chromosome, only have 1 X chromosome
- males always inherit X-linked trait from mother, Y from father
- females have 2 X chromosomes, potential of having at least 1 normal allele that will express phenotype over recessive allele
6
Q
Trends of X-linked recessive conditions
A
- only females can be carriers (heterozygous)
- females cannot inherit X-linked recessive condition frm normal father
- X-linked condition common in males, conditions cannot be masked by second allele
7
Q
X-linked dominant traits
A
- common in females