Chapter 3- Genetics & Heredity

Question 1

What is a genotype?

Answer 1

genetic endowment inherited from ancestors

Question 2

What is a phenotype?

Answer 2

observable, measurable characteristics

Question 3

What was one early notions of heredity?

Answer 3

-Traits inherited from fathers

• 17th century – Anton van Leeuwenhoek

Question 4

What does preformationism mean?

Answer 4

Sperm contains a tiny, preformed homunculus (little human/miniature version of themselves), in which creates a baby

Question 5

What did Caspar Wolff (1759) believe?

Answer 5

Sperm and ovum unite to create a single cell

Question 6

What did the ‘father of modern genetics’ Gregor Mendel believe about inherited characteristics and gametes?

• Inherited characteristics produced by BLANK
  
  • transmitted BLANK from generation to generation
• Each characteristic determined by pair of BLANK
  
  • one BLANK from each parent
• Members of gene pair may BLANK in their effects
  
  • one may BLANK the other
• When gametes produced:
  
  • gene pair for each attribute BLANK
  • each gamete contains only one member of each BLANK of BLANK

Answer 6

• Inherited characteristics produced by genes
  
  • transmitted unchanged from generation to generation
• Each characteristic determined by pair of genes
  
  • one inherited from each parent
• Members of gene pair may differ in their effects
  
  • one may dominate the other
• When gametes produced:
  
  • gene pair for each attribute divides
  • each gamete contains only one member of each pair of genes

Question 7

What are the current notions about chromosomes?

2pts

Answer 7

• normal human cells contain 2 sets of 23 chromosomes (23-pair)
• 1 member of each pair from mother, 1 from father

Question 8

What are the current notions about gametes?

2pts

Answer 8

• cells that are involved in reproduction
• contain only 23 individual chromosomes (1/2 of each of the 23 pairs)

Question 9

What is meiosis in regards to gametes and the 23 chromosomes?

3pts

Answer 9

• gamete formation
• each of the 23 pairs split
• result is two “child” cells containing 23 individual chromosomes

Question 10

Exchange of equivalent genetic material between homologous chromosomes at points where they cross-over during lining up.

What process am i?

Answer 10

crossing over in meiosis

Question 11

What is meiosis in simple terms?

Answer 11

A process where a single cell divides twice to produce four cells containing half the original amount of genetic information. These cells are our sex cells – sperm in males, eggs in females

Question 12

How are sex chromosomes determined, what are autosomes?

6pts

Answer 12

• Autosomes: 22 of the 23 pairs are found in both males and females
• the 23rd pair determines sex
  
  • X- longer of the two
• y - shorter
• Females- 23rd pair- both X’s (XX)
• Males- 23rd pair one X and one Y (XY)

Question 13

What is the androsperm vs Gynosperm ?

4 pts each.

Answer 13

Androsperm:
- Y- carrying sperm
- Lighter, swim faster, short lived

Gynosperm:
- X-carrying sperm
- heavier, swim more slowly, longer-lived

Question 14

Alternative forms of a gene coded for a particular trait.

What am I?

Answer 14

Alleles

Question 15

If both alleles are the same, child is BLANK with respect to that trait.

What am I?

Answer 15

Homozygous

Question 16

If alleles are different, then BLANK for the that trait.

What am I?

Answer 16

Heterozygous

Question 17

Genotype lead to the phenotype/ the phenotype is determined by its genotype.

True or false

Answer 17

True

Question 18

Autosomal Genetic Abnormalities

Tay Sachs disease is an example of what type of abnormality?

Answer 18

Recessive abnormality

Question 19

Autosomal Genetic Abnormalities

Cystic fibrosis is an example of what type of abnormality?

Answer 19

Recessive abnormality

Question 20

Autosomal Genetic Abnormalities

Phenylketonuria (PKU) is an example of what type of abnormality?

What is PKU in simple terms

Answer 20

Recessive abnormality

-cannot metabolize phenylalanine, build up of pyruvic acid

Question 21

Autosomal Genetic Abnormalities

What is one dominant abnormality?

Answer 21

Huntington’s disease

Question 22

What are two sex-linked characteristics ?

Answer 22

• recessive genes
• located on X chromosome

Question 23

What are 4 sex-linked disorders?

Answer 23

• Red-Green colour blindness
• Hemophilia
• Duchenne’s muscular dystrophy
• Fragile- X syndrome

Question 24

What is an example of a chromosomal abnormality (1pt), its characteristics (5pts) and a possible reason why it can occur (1pt)?

Answer 24

Down syndrome
- Trisomy 21: an extra copy of a chromosome

Characteristics:
- intellectual impairment, eye, ear, heart, and tongue defects

-incidence related to mother’s age

Question 25

What are 3 disorders of the sex chromosomes?

3pts

Answer 25

• Turner’s syndrome: X0- girls who have when one of the X chromosomes missing or partially missing
• Klinefelter’s syndrome: XXY- boys born with extra female chromosome (X)
• Poly-Y syndrome: XYY- extra copy of y chromosome

Question 26

Heritability of psychological characteristics

What are the two methods of assessing heritability?

2pts for each.

Answer 26

Selective Breeding:
- Robert Tryon
- Cross-fostering

Family studies:
- Pedigree studies
- Kinship (consanguinity studies)