Chapter 14 - Mendelian Genetics

Question 1

True breeding

Answer 1

organisms that produce offspring of the same variety as the parent over generations
-parents are homozygous

Question 2

Achondroplasia

Answer 2

dwarfism

Autosomal dominant disease

Question 3

Examples of dominantly inherited diseases

Answer 3

Hunchback
Achondroplasia
Polydactyly
Huntington’s disease

Question 4

Examples of recessively inherited diseases

Answer 4

Cystic fibrosis
Phenylketonuria
Sickle cell anemia
Albinism

Question 5

Test cross

Answer 5

crossing dominant (genotype unknown) x homozygous recessive

Question 6

Laws of Mendelian Genetics

Answer 6

1) Law of Segregation
- 2 alleles of one gene are segregated into different gametes during Meiosis I (shown in anaphase I)
- explains the phenotype ratio of 3:1 in F2 generation of monohydbrid cross
2) Law of Independent Assortment
- each pair of alleles is positioned and segregated into different chromosomes during Meiosis I and this occurs independently of other allele pairs (shown in metaphase I)
- explains 9:3:3:1 ratio of F2 generation of dihybrid cross

Question 7

Multiplication rule of Mendelian Inheritance

Answer 7

determines probability of events that occur together

Question 8

Additional rule of Mendelian Inheritance

Answer 8

determines probability of events that occur independently (mutually exclusive)

Question 9

Exceptions to Mendelian Genetics

Answer 9

1) Incomplete dominance
e. g. snapdragron
2) Co-dominance
e. g. blood type
3) Multiple alleles
e. g. blood type
4) Pleiotropy - one gene influences multiple traits
e. g. CTFR gene defect
5) Polygenic inheritance
e. g. skin, height - continuous traits
6) Epistasis
e. g. labrador fur color
7) Multifactorial characters
e. g. polygenes like height, color or heart disease

Question 10

Exceptions to complete dominance of Mendelian Genetics

Answer 10

1) Incomplete dominance
e. g. snapdragron
2) Co-dominance
e. g. blood type

Question 11

Exceptions to having 2 alleles in Mendelian Genetics

Answer 11

3) Multiple alleles

e. g. blood type

Question 12

Exceptions to monogenic inheritance of Mendelian Genetics

Answer 12

4) Pleiotropy
e. g. CTFR gene defect
5) Polygenic inheritance
e. g. skin, height
6) Epistasis
e. g. labrador fur color

Question 13

Exceptions to environment having no effect on Mendelian Genetics

Answer 13

7) Multifactorial character

e. g. polygenes like height, color or heart disease

Question 14

Difference between incomplete and co-dominance

Answer 14

incomplete - snapdragon

co-dominance - blood type

Question 15

CFTR

Answer 15

Cystic fibrosis transmembrane regulator

Question 16

Sickle-cell anemia

Answer 16

• caused by mutation in 6th amino acid of hemoglobin beta-subunit
• change in 6th amino acid : glutamate -> valine
• nucleotide (substitution) mutation.
• resistant to malaria.