Chapter 6

Question 1

Pedigree

Answer 1

A pictorial representation of a family history; A family tree that outlines the inheritance of one or more characteristics.

Question 2

Proband

Answer 2

The person from whom the pedigree is initiated and is usually designated by an arrow

Question 3

Mode of inheritance

Answer 3

The way in which a trait is inherited. Either mitochondrial, autosomal recessive, autosomal dominant, x-linked recessive, x-linked dominant, or y-linked

Question 4

Mitochondrial mode of inheritance

Answer 4

All offspring inherit their mitochondria from their mother. If a trait is inherited through the mitochondria, the mother and all of her offspring will have it.

Question 5

Autosomal recessive mode of inheritance

Answer 5

Appear with equal frequency in both sexes. Appear only when inherited alleles are homozygous recessive. If parents are heterozygous, 1/4 of the offspring are expected to have the trait.

Question 6

Autosomal dominant mode of inheritance

Answer 6

Appear in both sexes with equal frequency. Both sexes can pass it to their offspring. These traits do not skip generations.

Question 7

X-linked recessive traits

Answer 7

Appear mo frequently in males because males only need to inherit a single copy of the allele from, their mother, whereas females have to inherit 2 copies of the sole from both parents. Affected males are usually born to unaffected mothers who are carriers of the trait. Not passes from father to son. Affected fathers will most likely have unaffected daughters who are carriers. Affected women are homozygous for the trait.

Question 8

X-linked dominant traits

Answer 8

Appear in both sexes, although affect females more than they affect males. Each affected person must have an affected parent. Does not skip generations. Not passed on from father to son. Females can inherit trait from, mother or father.

Question 9

Y-linked traits

Answer 9

Only males are affected. Passed on from father to all sons. Do not skip generations.

Question 10

Consanguinity

Answer 10

Mating between closely related people.

Question 11

Dizygotic twins

Answer 11

Non identical twins. Arise when two separate eggs are fertilized by two separate sperm, producing genetically distinct zygotes. 50% of their genes are in common (same as any pair of siblings)

Question 12

Monozygotic twins

Answer 12

Identical twins. Result when a single egg is fertilized by a single sperm. It splits early in development into two separate embryos. 100% of their genes are in common.

Question 13

Concordance

Answer 13

If both members of a twin pair have a trait, they are concordant. Concordance is the percentage of twins that are concordant for a trait.

Question 14

Karyotype

Answer 14

A picture of a complete set of metaphase chromosomes. Used to analyze chromosomal abnormalities.