Chapter 4: Epigenetics and Development

Question 1

How does performance change through development?

Answer 1

Like the sea lion, capacity to store O2 undergoes a major developmental change as they mature into adulthood b/c concentration of hemoglobin in blood increases and enables each volume of blood to combine with more O2

Question 2

Phenotypic plasticity due to genetically programmed responses

Answer 2

• programmed by a genetically coded physiological control system that determines which phenotypes are expressed under which environmental conditions.
• consequence of earlier menarche in European girls due to improved nutirion and health

Question 3

Plasticity due to environmental forcing

Answer 3

working class kids in 1800’s were shorter than aristocratic kids because of harsh conditions they lived in

Question 4

Describe polyphonic development

Answer 4

• phenomenon in which genetically identical individuals can assume two or more distinct body forms, induced by the environment
• butterflies in spring v. summer have different coloring to camouflage
• migratory locusts exhibit gregarious and solitary behavioral phenotypes.

Question 5

Why do we say phenotypic plasticity is adaptive?

Answer 5

The control systems that determine the phenotypes are subject to natural selection over evolutionary time and represent adaptations

Question 6

Identify mechanisms of epigenetic marking

Answer 6

• DNA methylation - attachment of methyl groups by covalent bonds to cytosine residues in structure of DNA
• covalent modification of histones - around which DNA is wrapped in the nucleosomes of the chromatin of a cell.

Question 7

How are epigenetic marks transmitted to daughter cells?

Answer 7

When marks are replicated from cell to cell as cells divide, the marks induced by the environment are perpetuated throughout life and potentially into the offspring.

Question 8

Describe the mechanism of genomic imprinting

Answer 8

-one allele form one of the parents is predominantly expressed over the other allele from the other parent

Question 9

Define epigenetics

Answer 9

refers to modification of gene expression - with no change in DNA sequence - that are transmitted when genes replicate.

Question 10

define gene expression

Answer 10

the appearance in a phenotype of a characteristic or effect attributed to a particular gene

Question 11

When do mammals and birds achieve their full capacity of homeothermy?

Answer 11

At birth.