Pedigrees And Human Traits

Question 1

Men have an increased chance of expressing what type of trait?

Answer 1

Men have an increased likelihood of expressing an x-linked recessive trait because they would only need a single recessive allele while women would need two since the presence of a dominant allele would cancel the effects of the recessive gene.

Question 2

In a pedigree, a circle represents a _____.

Answer 2

In a pedigree, a circle represents a female.

Question 3

In a pedigree, a square represents a _____.

Answer 3

In a pedigree, a square represents a male.

Question 4

What does a colored in circle/square indicate?

Answer 4

A colored in circle/square means that that individual is expressing the trait in question (the trait that is being tracked by the pedigree).

Question 5

What does a blank circle/square indicate?

Answer 5

A blank shape means that that individual is not expressing the trait in question (the trait that is being tracked by the pedigree).

Question 6

What are the four possible patterns of inheritance?

Answer 6

Autosomal recessive, autosomal dominant, x-linked recessive and x-linked dominant.

Question 7

What are autosomal recessive traits?

Answer 7

Autosomal recessive traits are traits controlled by gene loci on autosomal chromosomes. They are inherited in a recessive manner (must have 2 recessive alleles to have to the trait).

Question 8

Describe the behaviour of autosomal recessive traits.

Answer 8

The offspring of 2 affected parents will always be affected. Affected offspring can skip generations. Males and females are equally affected.

Question 9

What are autosomal dominant traits?

Answer 9

Autosomal dominant traits are controlled by gene loci on autosomal chromosomes. They are inherited in a dominant manner (only one allele is needed to express the trait).

Question 10

Describe the behaviour of autosomal dominant traits.

Answer 10

Affected parents do not always produce affected offspring. Affected offspring have at least one affected parent. Traits do not skip generation. Males and females are equally affected.

Question 11

Describe the behaviour of x-linked recessive traits.

Answer 11

More males are affected than females. Male offspring from an affected mother will always be affected, regardless of the father’s genotype. The trait is not passed from male to male.

Question 12

Describe the behaviour of x-linked dominant traits (rare).

Answer 12

More females are affected than males. All female offspring of an affected male will be affected (when the trait is passed from father to daughter).

Question 13

If the trait skips generations, than it is certainly _____.

Answer 13

If the trait skips generations, than it is certainly recessive.

Question 14

If the trait does not skip generations, then it is likely _____.

Answer 14

If the trait does not skip generations, than it is likely dominant.

Question 15

If the trait skips generations but mostly males are affected, than it is an _____ _____ trait.

Answer 15

If the trait skips generations but mostly males are affected, than it is a x-linked recessive trait.

Question 16

If the trait skips generations but males and females are affected equally, than it is an _____ _____ trait.

Answer 16

If the trait skips generations but males and females are affected equally, than it is an autosomal recessive trait.

Question 17

If the trait does not skip generations but mostly females are affected, than it is an _____ _____ trait.

Answer 17

If the trait does not skip generations but mostly females are affected, than it is an x-linked dominant trait.

Question 18

If the trait does not skip generations and males and females are affected equally, then it is an _____ _____ trait.

Answer 18

If the trait does not skip generations and males and females are affected equally, then it is an autosomal dominant trait.