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Medicine Sem 1 > Genetics week 6 + clinical info > Flashcards

Genetics week 6 + clinical info Flashcards

1
Q

What is another way to write mitochondrial DNA

A
  • mtDNA
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2
Q

Where is mitochondrial DNA inheritied from

A
  • Maternal line
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3
Q

What does the mitochondrial encode and why

A
  • 13 polypeptides
  • 2 rRNAS
    -22 tRNAs
    For oxidative phosphorylation
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4
Q

What are key features of mtDNA(mitochondrial DNA)

A
  • lacks introns
  • Has mutation rate 10x higher than nucler DNA
    -Susceptible to damage
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5
Q

Why is the mitochondrial DNA susceptible to damage?

A
  • Due to repair mechanisms
  • Exposure to free radicals during oxidative phosphorylation
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6
Q

What is heteroplasmy? (in relation to mitochondrial DNA)

A
  • Where cells may contain a mix of normal and mutant mTDNA molecules
  • The amount/porportion of mutant mtDNA detrmines the severity of mitochondrial diseases
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7
Q

What type of organs are more severly affected by mtDNA molecules

A
  • Organs with high ATP demands
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8
Q

Name the types of mitochindrial mutations

A
  • Misense mutations
  • Single base mutations in tRNA genes
    -Duplication and deletions
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9
Q

What does misense mutations lead to

A

LHON

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10
Q

What does LHON lead to

A
  • Rapid loss of vision in the central field
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11
Q

What does single base mutations lead to

A
  • MERRF
  • MELAS
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12
Q

What does duplications and deletions lead to

A

-Kearns-sayre disease
- Pearson syndrome
- CPEO

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13
Q

What does kearns-sayre disease lead to

A
  • Muscle weakness and heart failure
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14
Q

What is genetic imprinting?

A
  • It is a form of gene silencing, where only 1 allele of a gene is transcriptionally active, depending on the parent of origin
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15
Q

Describe the mechanism for geneomic imprinting

A

-The transcriptionally inactive alleles is refered to as imprinted.
-The imprinted genes are transcriptionally silent due to epigenetic modifications such as:
- DNA methylation
- Histone hypoacetylation
- Chromatin condensation(preventing transcription factor binding)

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16
Q

What does chromatin condensation do

A
  • Prevent trasncription fators from binding
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17
Q

What is prader willi and angelman syndrome caused by

A

-Deletion of several megabases(Mb) on the long arm of chromosome 15

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18
Q

How is prader willi syndrome inherited

A

-Deletion inhertied from the father

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19
Q

How is Angelman syndrome inherited

A
  • Deletion inherited from the mother
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20
Q

What are features of someone with Prader willi syndrome

A
  • Obesity,
  • small hands and feet
  • Short stature
  • poor muscle tissue(hyptonia)
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21
Q

What are the features of someone with Angelman syndrome

A
  • Seizures
  • Intelectual disability
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22
Q

What is Mosaicism

A
  • Refers to the presence of 2 or more genetically distinct cell lines within an individual.This can occur do to several mechanism
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23
Q

What are the mechanisms that can cause mosaicism

A
  • Chromosomal nondisjunctions during mitosis
  • Gene mutations during development
  • Chromosome inactivation in females
24
Q

What happens in chromosomal nondisjunction during mitosis

A
  • When a chromosome does not separate properly during cell division therefore the daughter cell will have an abnormal number of chromosomes
25
Q

What are the types of mosaicism?

A
  • Germaline
  • Somatic
  • Confined placental mosaicism
26
Q

When does germlin mosaicism occur

A
  • Occurs when a mutation is present in the germ cells(sperm and egg) but not the somatic cells
27
Q

When does somatic mosaicims occur

A

= Occurs when there is mutations in some of the body cells but not the germline cells

28
Q

When does confined placental mosaicism occur

A

When chromosomal abnormalities are present in the plasma

29
Q

What are triplet repeats

A

Sequences of 3 nucleotides that are repeated in tandem within a gene

30
Q

Explain the concept of normal variation in triplet repeats

A
  • A certain number of triplet repeats is considered normal , but expansions beyond this range can lead to disease
31
Q

Explain the concept of disease mechanisms in triplet repeats

A
  • The expansion of triplet repeats can disrupt gene function in several ways depending on the location of the repeats within the gene
32
Q

What is osteogensis imperfecta caused by

A
  • Defects in Type 1 collagen
    which leads to weakened bone strength
33
Q

Whats the most common substitution leading to OI

A

Sub of glycine in the collagen triple helix

34
Q

What are they symptoms of OI

A
  • Short stature
  • Blue sclerae
  • Hearing loss
  • Bone deformitites
  • Dental issues
35
Q

What is the most severe type of OI
What is the midelst type of OI

A
  • Type 2
  • Type 1
36
Q

How many different types of OI are there

A

1,2,3,4,5,6,7,

37
Q

What is cystic Fibrosis(CF) caused by

A
  • Mutations in the CFTR gene, which encodes chlorine ion channels involved in fluid transport
38
Q

Whats the most common mutation in CF
and its effect

A

-F508
- Deletion of 3 nucleotides
resulting in the loss of the amino acid phenylalanine

39
Q

What type of disorder is cystic fibrosis

A
  • Autosmal recessive disorder
40
Q

What is retinoblastoma

A
  • Malignant tumor of the retina
41
Q

What is retinblastoma caused by?

A
  • Mutations in the RB1 gene which is a tumor suppressor gene located on chromosome 13
42
Q

What is the function of the TSG

A

regulates cell growth

43
Q

What type of inheritance pattern is Huntingtons disease

A
  • Autosomal dominant
44
Q

What is the role of the HTT gene in Huntington’s disease

A

It encodes for the Huntington protein

45
Q

What is Huntington’s disease?

A
  • Neurodegenerative disorder characterised by motor, cognitive and psychiatric
46
Q

What is huntingtions disease caused by

A
  • Expansions of a CAG trinucleotide repeat in the HTT gene that codes for Huntington protein
47
Q

What does neurofibromatosis effect

A
  • Effects the development and growth of nerve cells
48
Q

What is neurofibromatosis caused by?

A
  • Caused by mutations in the NF1 gene which encodes a protein called neurofibromin that acts as a tumor suppressor gene
49
Q

What is Marfan syndrome

A
  • A connective tissue disorder, that affects multiple organ systems
50
Q

What is the most common form of marfan syndrome

A
  • Marfan syndrome type 1
51
Q

What is marfan syndrome caused by

A
  • Mutations in the FBN1 gene which encodes the protein fibrillin-1 . This weakens the connective tissues
52
Q

What are symptoms of marfan syndrome

A
  • Tall stature
  • Long limbs
  • Scoliosis
  • Cardiovascular abnormalities
53
Q

What are the symptoms of duchenne muscular dystrophy

A
  • leads to muscle weakness and degradation
54
Q

What is duchenne muscular dystrophy caused by

A
  • Mutation in the DMD gene which encodes dystrophin, which is a protein that is essential for the structure of the muscle fibers
55
Q

What is Hemophilia A

A
  • A bleeding disorder in the f8 gene which encodes clotting factor V111
56
Q

What are the symptoms of the Hemophilia A

A
  • Severe bleeding
  • Blood clots
  • Easy bruising

Medicine Sem 1 (33 decks)

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