Mitochondrial DNA Structure and Function

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the typical consequence of either inherited or spontaneous mutations in nuclear or mitochondrial genes?

Improved muscle function

Enhanced vision

Increased ATP production

Mitochondrial dysfunction (correct)

What is the primary function of the 13 proteins encoded by the mtDNA genes?

Cell signaling

Cell division

Protein synthesis

Oxidative phosphorylation (correct)

Which of the following is a characteristic feature of Leber's hereditary optic neuropathy?

Diabetes and kidney failure

Heart disease and dementia

Mutations in four mitochondrial genes (correct)

Mutations in four nuclear genes

What is the primary source of energy for the cell?

ATP production Signup and view all the answers

Which of the following is NOT a symptom of mitochondrial disease?

Cystic fibrosis Signup and view all the answers

What is the typical pattern of inheritance for mitochondrial disease?

Variable inheritance Signup and view all the answers

What is the primary component of the enzyme complex involved in oxidative phosphorylation?

Proteins encoded by mitochondrial genes Signup and view all the answers

Which of the following optic atrophies is NOT a result of mutations in mitochondrial genes?

Sickle Cell Anaemia Signup and view all the answers

What is the prevalence range of autosomal dominant optic atrophy?

1 in 50 to 1 in 10,000 Signup and view all the answers

Why are mitochondria maternally inherited?

Because the paternal mitochondria are destroyed during fertilization Signup and view all the answers

What is the characteristic of cells with heteroplasmic mutations?

Having a mixture of mutated and normal mtDNA Signup and view all the answers

What determines the severity of disease presentation in offspring with heteroplasmic mutations?

The level of mutated mtDNA in the mother Signup and view all the answers

What is the term for the phenomenon where a cell can compensate for reduced normal mtDNA up to a certain threshold?

Threshold effect Signup and view all the answers

What is the consequence of having a high level of mutated mtDNA in the mtDNA of an offspring?

The offspring will likely present with severe disease Signup and view all the answers

What is the name of the disease associated with autosomal dominant optic atrophy?

Optic neuropathy Signup and view all the answers

How many copies of mtDNA are present in each cell at birth?

Thousands Signup and view all the answers

What is the primary function of the low-density lipoprotein (LDL) receptor in the context of familial hypercholesterolemia?

Regulating the removal of LDL from the blood Signup and view all the answers

What is the primary consequence of a defect in the phenylalanine hydroxylase enzyme?

Mental retardation Signup and view all the answers

What is the characteristic of lysosomal storage diseases?

Mutation in genes encoding lysosomal hydrolases Signup and view all the answers

What is the mode of inheritance of Haemophilia?

X-linked recessive (XR) Signup and view all the answers

What is the primary function of mitochondrial DNA (mtDNA)?

Encoding genes for mitochondrial function Signup and view all the answers

What is the characteristic of Neurofibromatosis?

Mutation in the neurofibromin 1 or 2 genes Signup and view all the answers

What is the primary consequence of a defect in the ATP production pathway?

Mitochondrial dysfunction Signup and view all the answers

What is the mode of inheritance of cystic fibrosis?

Autosomal recessive (AR) Signup and view all the answers

Study Notes

Mitochondria and Mitochondrial Disease

Mitochondria have 37 genes, encoding 13 proteins, 22 transfer RNAs, and 2 ribosomal RNAs, essential for normal mitochondrial function.
13 mt genes encode proteins responsible for or involved in oxidative phosphorylation to create ATP for the cell's source of energy.
Mitochondrial proteins are derived from both nDNA and mtDNA encoded genes.
mtDNA is more prone to mutation than nDNA, leading to mitochondrial disease.

Characteristics of Mitochondrial Disease

Mitochondrial disease refers to disorders caused by a reduction in ATP production.
Symptoms include muscle weakness, problems with movement, diabetes, kidney failure, heart disease, dementia, loss of hearing, and abnormalities involving the eyes and vision.
Visual component is often present, with features such as ptosis, external ophthalmoplegia, and retinitis pigmentosa.
Leber's hereditary optic neuropathy is a result of mutations in four mitochondrial genes, affecting the enzyme complex I necessary for oxidative phosphorylation.

Inheritance of Mitochondrial Disease

Mitochondrial disease is maternally inherited, as the mitochondria in the male sperm are lost during fertilization.
Each cell has 1000s of copies of mtDNA, which are the same at birth (homoplasmy).
Individuals with mutated mtDNA have a mixture of mutated and non-mutated mtDNA within a particular cell (heteroplasmy).
The level of mutation in mtDNA affects the severity of disease in offspring, with high levels of mutation leading to severe disease.

Other Genetic Disorders

Familial Hypercholesteremia is an autosomal dominant disorder due to a defect in the LDL receptor, leading to acceleration of atherosclerosis.
Phenylketonuria is an autosomal recessive disorder due to a defect in the enzyme phenylalanine hydroxylase, leading to mental retardation if left untreated.
Lysosomal storage disease is an autosomal recessive disorder resulting from a mutation in one of the genes encoding lysosomal hydrolases, leading to an accumulation of substrate within the lysosomes.
Neurofibromatosis is an autosomal dominant disorder resulting from a defect in the neurofibromin 1 or 2 genes, leading to growths in the nervous system and skin.
Haemophilia is an X-linked recessive disorder resulting from deficiencies in Factor VIII or IX, leading to impaired blood clotting and a risk of haemorrhaging.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers the structure and function of mitochondrial DNA, including the genes it encodes, the proteins involved in oxidative phosphorylation, and the differences between mtDNA and nDNA. Learn about the importance of mitochondrial function and the implications of mitochondrial disease.