Module 3

Question 1

Maternal effect

Answer 1

Inheritance pattern for nuclear genes in which the genotype of mother directly determines the phenotype of offspring (due to oogenesis)

(ex. water snail shell)

Question 2

Epigenetic inheritance

Answer 2

A modification occurs to a nuclear gene/chromosome, altering gene expression and passed from cell to cell

Not permanent, no change to DNA sequence (rather DNA modification via methylation or chromatin structure)

Can occur during gamete formation or embryonic development

Question 3

Dosage compensation

Answer 3

Meant to offset differences in number of active sex chromosomes, occurs via different mechanisms depending on the species

Question 4

Barr body

Answer 4

Highly condensed X chromosome in females, example of dosage compensation

Depends on X-inactivation center (Xic) and Xist gene

Question 5

Function of X-inactivation center

Answer 5

Nucleation: # of Xics is counted, one X chromosome remains active

Spreading: Begins at Xic, inactivation spreads across whole chromosome

Maintenence: Barr body remains through subsequent cell divisions

Question 6

Genomic imprinting

Answer 6

A segment of DNA is “marked” by methylation, maintained throughout life of organism

Offspring only express one allele

Question 7

Stages of imprinting

Answer 7

1. Establishment of imprint during gametogenesis
2. Maintenence of imprint during embryogenesis/in adult somatic cells
3. Erasure and reestablishment of imprint in germ cells

Question 8

Prader-Willi Syndrome (PWS)

Answer 8

Imprinting disease inherited from father, characterized by reduced motor function, obesity, and small hands and feet

Question 9

Angelman Syndrome (AS)

Answer 9

Imprinting disease inherited from mother, characterized by hyperactivity, thinness, seizures, repetitive symmetrical muscle movements, and mental deficiencies

Question 10

Extranuclear inheritance

Answer 10

Inheritance patterns involving genetic material outside nucleus (i.e., mitochondrial/chloroplast DNA)

Question 11

Maternal inheritance

Answer 11

Phenotype solely based on maternal parent mitochondrial genotype

(ex. four o’clock plant leaf color)

Question 12

Paternal leakage

Answer 12

Paternal parent may occasionally provide mitochondria via sperm

Question 13

Human ____ diseases occur either from ____ to ____ transmission or mutations in ____ cells (highly susceptible to degenerative diseases)

Answer 13

mitochondrial, mother to offspring, somatic

Question 14

____ is an important factor in mitochondrial disease

Answer 14

Heteroplasmy

Question 15

Endosymbiosis theory

Answer 15

Describes evolutionary origin of mitochondria and chloroplasts, endocytosis of bacteria by archaea formed primordial eukaryotes