Questions and Answers
Where does mtDNA replication begin?
Which of the following is NOT encoded in mtDNA?
What type of genetic variation describes all mtDNA sequences being different?
Which gene is associated with MELAS syndrome?
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What is a common symptom of MELAS syndrome?
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Which statement about homoplasmy is true?
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Which condition is characterized by the widening of blood vessels in the eye?
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Which gene is associated with Leber's Hereditary Optic Neuropathy?
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Study Notes
mtDNA Overview
- Mitochondrial DNA (mtDNA) replication initiates at the D loop.
- Replication occurs on one strand first followed by the other after two-thirds completion.
Encoded Components of mtDNA
- Contains 2 ribosomal RNA (rRNA) molecules.
- Includes 22 transfer RNA (tRNA) molecules.
- Encodes 13 proteins involved in three respiratory complexes.
- Also encodes ATPase.
Content Characteristics of mtDNA
- Lacks introns and features one D loop comprised of non-coding DNA.
- Consists of two strands: the heavy chain (H) and light chain (L).
Structure of the D Loop
- Comprises three promoter regions:
- LSP: Promotes synthesis of the light chain (L).
- HSP1: Promotes synthesis of the heavy chain (H).
- HSP2: Also promotes heavy chain (H).
- LSP and HSP2 are consistently present, while HSP1 is situated at tRNA Leu.
Homoplasmy vs. Heteroplasmy
- Homoplasmy indicates all mtDNA shares the same sequence.
- Heteroplasmy signifies variations in mtDNA sequences.
Leber's Hereditary Optic Neuropathy (LHON)
- Genes implicated include MT-ND1, MT-ND4, and MT-ND6.
- MT-ND genes encode NADH dehydrogenase.
- Symptoms include loss of optic nerve and telangiectasia (blood vessel dilation in the eye).
- Affects males significantly more than females, with a 50% penetration rate in males compared to low in females.
MELAS Syndrome
- Associated gene: MT-TL1.
- MT-TL1 gene encodes tRNA.
- Symptoms of MELAS include:
- Encephalopathy (brain damage)
- Lactic acidosis
- Stroke-like episodes (temporary loss of movement or sensation)
- Absence of leucine in the blood.
Diseases Linked to MT-TL1 Mutations
- MELAS syndrome.
- Miopathy leading to muscle weakness.
- Diabetes.
- Deafness (type II).
MERRF Syndrome
- Associated gene yet to be specified in provided information.
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Description
This quiz delves into the fundamental aspects of mitochondrial DNA (mtDNA), covering replication origins, encoded components, and structural features. Explore the importance of mtDNA in cellular functions and the specific roles of various RNA and proteins it encodes.
