Question 1

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

Accepted Answer

It is inherited exclusively from the mother.

Question 2

A cell contains both wild-type and mutant mitochondrial DNA. This condition is known as:

Accepted Answer

Heteroplasmy

Question 3

Which effect describes the reduction in the number of mitochondria during oocyte maturation, leading to a small pool of mitochondria in the mature egg?

Accepted Answer

Bottleneck effect

Question 4

A patient presents with symptoms of a mitochondrial disease. Which tissue is most likely to be affected first?

Accepted Answer

Muscle

Question 5

Which of the following statements about replicative segregation is correct?

Accepted Answer

Mitochondria and their genomes are randomly distributed to daughter cells during cell division.

Question 6

The threshold effect in mitochondrial diseases refers to:

Accepted Answer

The critical proportion of mutant mtDNA required before a phenotype is expressed.

Question 7

Which equation best represents the probability $$P of a $$child inheriting a mitochondrial disorder from a heteroplasmic mother, assuming random segregation of mitochondria?

Accepted Answer

$$P = \frac{n_{mut}}{n_{total}}$$

Question 8

Genomic imprinting is best described as:

Accepted Answer

An epigenetic form of gene regulation where only one allele is expressed depending on its parental origin.

Question 9

Prader-Willi syndrome is caused by a deletion in which chromosome region, and from which parent?

Accepted Answer

15q11-q13, paternal chromosome

Question 10

Angelman syndrome is caused by a deletion in the same chromosomal region as Prader-Willi syndrome, but differs in that:

Accepted Answer

The deletion is on the maternal chromosome.

Question 11

Which of the following is NOT a feature of mitochondrial diseases?

Accepted Answer

Strict Mendelian inheritance

Question 12

Which of the following best explains why mitochondrial DNA has a higher mutation rate than nuclear DNA?

Accepted Answer

Mitochondria lack efficient DNA repair systems.

Question 13

A child is diagnosed with a disease caused by uniparental disomy. Which of the following best describes this genetic event?

Accepted Answer

The child inherited both homologs of a chromosome from one parent.

Question 14

Which gene is involved in Angelman syndrome and what is its function?

Accepted Answer

UBE3A, codes for a protein involved in ubiquitin-mediated protein degradation

Question 15

Which of the following is a consequence of genomic imprinting?

Accepted Answer

An individual is genetically haploid for imprinted genes.

Question 16

Which process is responsible for the random distribution of mitochondria and their genomes to daughter cells during cell division?

Accepted Answer

Replicative segregation

Question 17

A patient with Leber Hereditary Optic Neuropathy (LHON) is most likely to have a mutation in which mitochondrial gene?

Accepted Answer

ND4

Question 18

Which of the following best describes the parental conflict theory of genomic imprinting?

Accepted Answer

Imprinting arises from evolutionary conflict between maternal and paternal interests in offspring resource allocation.

Question 19

Which of the following is true regarding the epigenetic marks on imprinted genes?

Accepted Answer

They are erased during gametogenesis and re-established in the developing gametes.

Question 20

If a cell contains $$n$$ mitochondria, and $$k of $$them carry a mutant allele, what is the proportion $$p of $$mutant mtDNA in the cell?

Accepted Answer

$$p = \frac{k}{n}$$

Nonclassical Patterns of Inheritance: Mitochondrial Inheritance, Genomic Imprinting, and Uniparental Disomy

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