5.3 Environmental Effects On Phenotypes

Question 1

Environmental factors can influence ____ ____ and lead to ____ ____.

Answer 1

• gene expression

- phenotypic plasticity

Question 2

What do individuals with the same genotype exhibit?

Answer 2

-

Different phenotypes in different environments

Question 3

What are examples of environmental effects in phenotypes? (3)

Answer 3

• temp can change coat colour in rabbits and siamese cats
• soil pH can affect flower colour
• UV exposure can increase melanin production in the skin

Question 4

What causes some genetic disorders?

Answer 4

• linked to affected or mutated alleles of chromosomal changes

Question 5

Mutated Alleles: what kind of disease is Tay-Sachs disease, and what gene is mutated?

Answer 5

• autosomal recessive disease

- mutated HEXA gene

Question 6

Mutated Alleles: what does the mutation cause in Tay-Sachs disease, and what does it affect? (4)

Answer 6

• body fails to produce an enzyme that breaks down a particular lipid
• This enzyme is located in lysosomes in the brain
• affects CNS and results in blindness
  - do not live past 1 year of age

Question 7

Mutated alleles: what kind of diseases is sickle cell anemia, and what are the effects? (5)

Answer 7

• autosomal recessive
• mutated HBB gene
• sickle cells contain abnormal hemoglobin molecules
• “missense” gene mutation
• RBC take on a sickle shape

Question 8

Chromosomal Changes: what is nondisjunction?

Answer 8

• chromosomes fail to separate properly in meiosis I or meiosis II

Question 9

What can detect nondisjunction?

Answer 9

Karyotyping

Question 10

An example of nondisjuction is Down syndrome. What occurs here in terms of xmes?

Answer 10

• three copies of chromosome 21

- excess GART gene product causes cognitive disfunction