Chapter 6 Vocab

Question 1

What is a pedigree?

Answer 1

A pedigree is a pictorial representation of a family history, essentially a family tree that outlines the inheritance of one or more characteristics.

Question 2

List characteristics of an Autosomal Dominant Trait

Answer 2

• Appears in both sexes with equal frequency.
• Both sexes transmit the trait to their offspring.
• Does not skip generations.
• Affected offspring must have an affected parent, unless they possess a new mutation.
• When one parent is affected (heterozygous) and the other parent is unaffected, approximately 1⁄2 of the offspring will be affected.
• Unaffected parents do not transmit the trait.

Question 3

• Appears in both sexes with equal frequency.
• Both sexes transmit the trait to their offspring.
• Does not skip generations.
• Affected offspring must have an affected parent, unless they possess a new mutation.
• When one parent is affected (heterozygous) and the other parent is unaffected, approximately 1⁄2 of the offspring will be affected.
• Unaffected parents do not transmit the trait.

Answer 3

Autosomal Dominant Trait

Question 4

List characteristics of an Autosomal Recessive Trait

Answer 4

• Appears in both sexes with equal frequency.
• Trait tends to skip generations.
• Affected offspring are usually born to unaffected parents.
• When both parents are heterozygous, approximately 1⁄4 of the offspring will be affected.
• Appears more frequently among children of consanguine marriages.

Question 5

• Appears in both sexes with equal frequency.
• Trait tends to skip generations.
• Affected offspring are usually born to unaffected parents.
• When both parents are heterozygous, approximately 1⁄4 of the offspring will be affected.
• Appears more frequently among children of consanguine marriages.

Answer 5

Autosomal Recessive Trait

Question 6

List characteristics of an X-Linked Recessive Trait

Answer 6

• More males than females are affected.
• Affected sons are usually born to unaffected mothers;
thus, the trait skips generations.
• Approximately 1⁄2 of a carrier (heterozygous) mother s sons are affected.
• It is never passed from father to son.
• All daughters of affected fathers are carriers.

Question 7

• More males than females are affected.
• Affected sons are usually born to unaffected mothers;
thus, the trait skips generations.
• Approximately 1⁄2 of a carrier (heterozygous) mother s sons are affected.
• It is never passed from father to son.
• All daughters of affected fathers are carriers.

Answer 7

X-Linked Recessive Trait

Question 8

List characteristics of an X-Linked Dominant Trait

Answer 8

• Both males and females are affected; more often females than males affected.
• Does not skip generations.
– affected sons must have an affected mother
– affected daughters must have either an affected mother or an affected father.
• Affected fathers will pass the trait on to all their daughters.
• Affected mothers (if heterozygous) will pass the trait on to 1⁄2 of their sons and 1⁄2 of their daughters.

Question 9

• Both males and females are affected; more often females than males affected.
• Does not skip generations.
– affected sons must have an affected mother
– affected daughters must have either an affected mother or an affected father.
• Affected fathers will pass the trait on to all their daughters.
• Affected mothers (if heterozygous) will pass the trait on to 1⁄2 of their sons and 1⁄2 of their daughters.

Answer 9

List characteristics of an X-Linked Dominant Trait

Question 10

List characteristics of an Y-Linked Trait

Answer 10

• Only males are affected.

* It is passed from father to all sons. • It does not skip generations.

Question 11

• Only males are affected.

* It is passed from father to all sons. • It does not skip generations.

Answer 11

Y-Linked Trait

Question 12

Monozygotic twins

Answer 12

result when a single egg, fertilized by a single sperm, splits early in development into two separate embryos. (Identical twins, 100% genes shared)

Question 13

result when a single egg, fertilized by a single sperm, splits early in development into two separate embryos. (Identical twins, 100% genes shared)

Answer 13

Monozygotic twins

Question 14

Dizygotic twins

Answer 14

arise when two separate eggs are fertilized by two different sperm, producing genetically distinct zygotes. (Non-identical twins, 50% genes shared, same as any pair of siblings.

Question 15

arise when two separate eggs are fertilized by two different sperm, producing genetically distinct zygotes. (Non-identical twins, 50% genes shared, same as any pair of siblings.

Answer 15

dizygotic twins

Question 16

If both members of a twin pair have a trait, the twins are said to be ______________

Answer 16

concordant

Question 17

If only one member of a twin pair have a trait, the twins are said to be ______________.

Answer 17

discordant

Question 18

___________________ is the percentage of twin pairs that are concordant for a trait.

Answer 18

concordance

Question 19

Genetically influenced traits should exhibit higher concordance in monozygotic twins, because _______

Answer 19

identical twins (monozygotic) have 100% of their genes in common and dizygotic twins on average only 50% in common

Question 20

What is genetic testing used for?

Answer 20

– screen newborns for genetic diseases,
– detect persons who are heterozygous for recessive diseases
– detect disease-causing alleles in those who have not yet developed symptoms of the disease
– detect defective alleles in unborn babies.