Question 1

Which of the following statements best describes the inheritance pattern of mitochondrial DNA (mtDNA) in humans?

Accepted Answer

mtDNA is inherited exclusively from the mother because only egg cells contribute mitochondria to the zygote.

Question 2

A woman with a mitochondrial disorder has children with an unaffected man. What is the expected outcome for their children regarding the disorder?

Accepted Answer

All children will inherit the disorder because mitochondrial DNA is maternally inherited.

Question 3

Which of the following best explains why mitochondrial DNA accumulates mutations at a higher rate than nuclear DNA?

Accepted Answer

Mitochondria are exposed to reactive oxygen species (ROS) generated during ATP production and lack robust DNA repair enzymes.

Question 4

Which of the following is NOT a feature of the human mitochondrial genome?

Accepted Answer

It contains introns within its protein-coding genes.

Question 5

A cell contains a mixture of normal and mutated mitochondrial genomes. What is this condition called?

Accepted Answer

Heteroplasmy

Question 6

Which of the following best describes the endosymbiont theory as it relates to mitochondria?

Accepted Answer

Mitochondria evolved from free-living alpha proteobacteria that became symbiotic within early eukaryotic cells.

Question 7

Which of the following is a direct consequence of the lack of chromosomal crossover in mitochondrial DNA replication?

Accepted Answer

Mitochondrial DNA is ideal for tracing maternal ancestry over generations.

Question 8

Which of the following best explains why mitochondrial diseases can be inherited from either parent in some cases?

Accepted Answer

Some mitochondrial diseases are caused by mutations in nuclear genes that encode mitochondrial proteins.

Question 9

A researcher is analyzing the mitochondrial genome and finds 22 genes encoding tRNAs. What is the total number of genes in the human mitochondrial genome?

Accepted Answer

37

Question 10

Which of the following scenarios would most likely result in a mitochondrial disease developing spontaneously in an individual?

Accepted Answer

A mutation occurs in the mitochondrial DNA due to exposure to a toxic substance.

Question 11

Which of the following best describes the role of mitochondria in eukaryotic cells?

Accepted Answer

They produce ATP through cellular respiration, providing energy for cellular activities.

Question 12

Which of the following is a reason why mitochondrial DNA is useful for tracing maternal ancestry?

Accepted Answer

It accumulates mutations rapidly and is inherited only from the mother.

Question 13

A patient is diagnosed with a mitochondrial disorder. Genetic testing reveals the mutation is in a nuclear gene encoding a mitochondrial protein. Which inheritance pattern is possible?

Accepted Answer

Either maternal or paternal inheritance

Question 14

Which of the following cell types would you expect to have the highest number of mitochondria?

Accepted Answer

Muscle cells

Question 15

Which of the following is a plausible explanation for why mitochondrial diseases can present with a wide range of symptoms?

Accepted Answer

Mitochondrial function affects energy production in all cell types, so defects can impact multiple organ systems.

Question 16

Which of the following equations best represents the number of mitochondria in an average human cell?

Accepted Answer

$$1000 \u003c n \u003c 2000$$

Question 17

Which of the following is true regarding the protein-coding capacity of the mitochondrial genome?

Accepted Answer

Only 13 of the proteins involved in energy production are encoded by mitochondrial DNA; the rest are encoded by nuclear DNA.

Question 18

Which of the following best explains why a single cell can contain multiple types of mitochondrial genomes?

Accepted Answer

High mutation rates and random segregation during cell division lead to heteroplasmy.

Question 19

Which of the following is a correct statement about the structure of the mitochondrial genome?

Accepted Answer

It is circular and lacks introns.

Question 20

A mutation in which of the following would NOT be inherited in a strictly maternal pattern?

Accepted Answer

A gene located in the nuclear DNA encoding a mitochondrial protein

Mitochondrial Genetics: Structure, Inheritance, and Disease

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