Chapter 7 - The Inheritance of Single-Gene Differences

Question 1

Reasons why man is an unsuitable research subject

Answer 1

1. has long life cycle
2. can’t be made to interbreed randomly. Can only bear a comparatively small no. of progeny
3. can’t be subjected to rigorous experimental conditions

Question 2

methods used to study human genetics

Answer 2

1. Pedigree analysis
2. Karyotyping

Question 3

• mode of transmission can be revealed
• also known as family histories

Answer 3

pedigree analysis

Question 4

• stained preparations of mitotic metaphase chromosomes are potographed, individual chromosomes are cut apart and arranged in pairs
• one can detect numerical and structural abnormalities

Answer 4

karyotyping

Question 5

chief method used in human genetics

Answer 5

pedigree analysis

Question 6

what can be observed in families

Answer 6

inheritance of traits

Question 7

a pedigree indicates the structure of a family __

Answer 7

schematically

Question 8

pedigree give information on:

Answer 8

• dominance or recessiveness of alleles
• risks (probabilities) of having affected offspring

Question 9

Modes of Transmission of Hereditary Traits

Answer 9

1. autosomal dominance
2. autosomal recessive
3. sex-linked dominance
4. sex-linked recessive

Question 10

trait that is due to an __ __ gene never skips a generation

Answer 10

autosomal dominant

Question 11

• marriage between affected individuals produces offsprings who are also affected by the trait
• affected progenies may also result from mating between unaffected parents if they are heterozygous for the gene pair

Answer 11

autosomal recessive

Question 12

pedigrees show affected males with unaffected wives transmit the trait to daughters only

Answer 12

sex-linked dominance

Question 13

pedigrees show affected families with unaffected husbands transmit the traits to sons only, although the daughters are carriers of the gene

Answer 13

sex-linked recessive

Question 14

Example of autosomal dominant disorder

Answer 14

achondroplasia

Question 15

Examples of autosomal recessive disorders

Answer 15

1. phenylketonuria
2. cystic fibrosis
3. sickle cell

Question 16

• hereditary disorder characterized by lung congestion and infection and malabsorption of nutrients by the pancreas
• most common disease in the US
• affected individuals die before reproductive age

Answer 16

cystic fibrosis

Question 17

why is there a high frequency of cystic fibrosis carriers

Answer 17

due to overcompensation
- average no. of children in families with CF child is 25% higher than normal families

Question 18

encodes a large protein that functions in cell membrane to regulate water balance inside cells

Answer 18

CF gene

Question 19

what does defective CF protein prevent

Answer 19

chlorides ions from exiting cells, resulting in excess water inside the cell

Question 20

act as recessive traits in females, but dominant traits in males

Answer 20

x-linked recessive disorders

Question 21

Examples of x-linked recessive disorders

Answer 21

1. hemophilia A
2. fragile X syndrome
3. Duchenne muscular dystrophy
4. colorblindess

Question 22

hereditary hemorrhagic disorder resulting from a congenital deficit of factor VIII that manifests as protracted and excessive bleeding either spontaneously or secondary to trauma

Answer 22

hemophilia A

Question 23

inherited genetic disorder that causes physical abnormalities, behavioral issues and a wide range of other health problems, including: Developmental delays. Intellectual disabilities. Learning disabilities. Anxiety.

Answer 23

Fragile X syndrome (FXS)

Question 24

• most common hereditary neuromuscular disease and does not exhibit a predilection for any race or ethnic group
• Mutations in the dystrophin gene lead to progressive muscle fiber degeneration and weakness.

Answer 24

Duchenne muscular dystrophy

Question 25

classification of chromosomes according to centromeric position

Answer 25

1. metacentric
2. submetacentric
3. acrocentric
4. telocentric

Question 26

centromeres in the middle of the chromosome

Answer 26

metacentric

Question 27

centromeres slightly off center

Answer 27

submetacentric

Question 28

centromeres almost at the ends

Answer 28

acrocentric

Question 29

terminal centromeres

Answer 29

telocentric

Question 30

Examples of Inherited Human Traits

Answer 30

1. widow’s peak
2. straight hairline
3. hitchhiker’s thumb
4. tongue rolling
5. bent little finger
6. cleft chin
7. hand clasping
8. unattached/attached ear lobes