Extensions and modifications of basic principles

Question 1

complete dominance

Answer 1

the dominant allele completely masks the recessive. F2 ratio 3:1

Question 2

incomplete dominance

Answer 2

dominant allele doesn’t fully mask recessive allele, offspring is somewhere between the two alleles. F2 ratio 1:2:1

Question 3

codominance

Answer 3

both alleles are simultaneously expressed. F2 ratio 1:2:1

Question 4

variable expressivity

Answer 4

occurs when individuals with the same genotype show the associated trait to different degrees

Question 5

incomplete penetrance

Answer 5

a trait associated with a particular genotype is expressed only some of the time.

Question 6

ABO blood type dominance

Answer 6

A and B express codominance while O is recessive and A and B are completely dominant to it

Question 7

what is epistasis

Answer 7

a special form of gene interaction in which the genotype at one locus masks (epistatic gene) the expression of the genotype at a second locus (hypostatic gene). forms a modified 9:3:3:1 ratio

Question 8

why do a complementation test?

Answer 8

test to know if mutations affecting a characteristic occur at the same locus or different loci.

Question 9

Sex influenced traits

Answer 9

determined by autosomal genes and are inherited according to Mendel’s principles, but they are expressed differently in males and females.

Question 10

sex-limited traits

Answer 10

encoded by autosomal genes that are expressed in only one sex. the trait has zero penetrance in the other sex