Question 1

Which of the following best explains why mitochondrial DNA is inherited maternally in most mammals?

Accepted Answer

Mitochondria from the sperm are selectively destroyed after fertilization.

Question 2

A plant cell contains both wild-type and mutant chloroplasts. What is the term for this condition?

Accepted Answer

Heteroplasmy

Question 3

In Correns’ experiments with the four o’clock plant, reciprocal crosses showed that leaf color was determined by the phenotype of which parent?

Accepted Answer

The female parent

Question 4

Which of the following is NOT evidence supporting the endosymbiosis theory for the origin of mitochondria and chloroplasts?

Accepted Answer

Organelle genomes are inherited in a Mendelian fashion.

Question 5

A heteroplasmic individual has a mitochondrial mutation associated with a disease. Which factor most directly determines whether the disease phenotype will be expressed in a particular tissue?

Accepted Answer

The proportion of mutant mitochondria in that tissue

Question 6

Which of the following best describes replicative segregation in organelle inheritance?

Accepted Answer

Random partitioning of organelles during cell division

Question 7

Which equation would you use to estimate the minimum divergence time between two species using mitochondrial DNA?

Accepted Answer

$$T = \frac{D}{2r}$$

Question 8

Which of the following is a consequence of the Recent African Origin (RAO) model supported by mitochondrial DNA analysis?

Accepted Answer

Genetic diversity is greatest in African populations.

Question 9

A woman with a mitochondrial disease has children with a healthy man. What is the probability that her children will inherit the disease, assuming complete penetrance?

Accepted Answer

100%

Question 10

Which of the following statements about organelle genome replication is correct?

Accepted Answer

Organelle genome replication is not tightly coupled to the cell cycle.

Question 11

Which of the following is a requirement for a gene transferred from an organelle to the nucleus to function properly?

Accepted Answer

It must acquire a sequence encoding an amino terminal signal for transport.

Question 12

Which of the following diseases is caused by a mutation in mitochondrial DNA and is characterized by late-onset blindness?

Accepted Answer

Leber’s hereditary optic neuropathy (LHON)

Question 13

In a population, a mutation arises in the mitochondrial genome. Which of the following best describes how this mutation can become homoplasmic in a lineage?

Accepted Answer

By chance through replicative segregation

Question 14

Which of the following statements about the targeting of organellar proteins is correct?

Accepted Answer

Most organellar proteins are encoded by nuclear genes and imported into the organelle.

Question 15

Which of the following is a real-world application of mitochondrial DNA analysis?

Accepted Answer

Reuniting kidnapped children with their biological families

Question 16

Which of the following best describes the genetic consequence of biparental inheritance of organelles?

Accepted Answer

Both parents contribute organelle genomes to the offspring.

Question 17

Which of the following is NOT a factor affecting the genetics of organelle transmission?

Accepted Answer

The division and segregation of nuclear chromosomes

Question 18

Which of the following statements about the evolutionary history of mitochondria is supported by the endosymbiosis theory?

Accepted Answer

Mitochondria are descendants of free-living bacteria that entered into a symbiotic relationship with ancestral eukaryotes.

Question 19

A heteroplasmic mother has 60% mutant mitochondria in her oocytes. If a tissue in her child contains 90% mutant mitochondria, what is the most likely explanation?

Accepted Answer

Replicative segregation during development

Organelle Inheritance and the Evolution of Organelle Genomes

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