Genetics Flashcards
What happens in mitosis?
1 diploid parent cell –> 2 identical diploid daughter cells
What happen in meiosis?
1 diploid parent cell –> 4 haploid daughter cells
What is a polymorphism?
Any variation in the human genome that has a population frequency of greater than 1% (does not cause disease in its own right)
What does aneuploidy mean?
Whole extra or missing chromosome
What is translocation?
Rearrangement of chromosomes
What is Down’s syndrome?
Extra chromosome 21
What are the chances of a woman who already has a child with Down’s syndrome having another?
1%
What are the stages of the cell cycle?
G1 - cell grows in prep for DNA replication
S - DNA replication
G2 - make sure DNA replication occurred properly
M - mitosis - cell division
What is trisomy 18 called?
Edwards syndrome
What is trisomy 13 called?
Patau syndrome
What is 47XXY called?
Klinefelter syndrome
2 main types of translocation
Balanced
Unbalanced
What is robertsonian translocation?
An entire chromosome has attached to another at the centromere
What is a reciprocal translocation?
Where segments from 2 different chromosomes have been exchanged
Syndromes caused by deletion
DiGeorge’s syndrome
William’s syndrome
Cri du chat syndrome
What is amniocentesis?
Needle used to obtain sample from unborn child in utero
Treatment for Philadelphia chromosome?
Tyrosine kinase inhibitor: imatinib
What does autosomal dominant mean?
1 faulty copy of gene causes disease
50% risk
What does autosomal recessive mean?
2 faulty copies of the gene are needed to cause disease
25% risk if parents are carriers
What does x linked mean?
Disease carried on X chromosome
Female carrier - 1/2 male kids affected, 1/2 female kids carriers
Make affected - male kids normal, female kids carriers
What does mitochondrial inheritance mean?
Mitochondria always come from mother
What are single nucleotide polymorphisms?
Any variation in the human genome that does not cause a disease in its own right but may predispose to a common disease
What are copy number variations?
Extra or missing stretches of DJA
What is penetrance?
The likelihood of having the disease if you have the mutation
What is expression?
The variation in disease severity if you have the mutation
What is mosaicism?
When different cells have a different genetic constitution within one individual
When does somatic mosaicism occur?
When the somatic cells of the badly are of more than one genotype
What is gonadal mosaicism?
A special form of mosaicism where some gametes (i.e. Either sperm or oocytes) carry a mutation but the rest are normal
3 outcomes if the cell cycle is arrested
DNA repair
Apoptosis
Cancer
What is DNA methylation?
Epicene tic mechanism that cells use to control gene expression
What is Angelman’s syndrome?
Neuro genetic disorder
What is myotonic dystrophy?,
I a chronic, slow progressing, inherited multi systemic disease
Clinical features of myotonic dystrophy
Muscular dystrophy Cataracts Heart conduction defects Endocrine changes Myotonia (slow relaxation of muscles after contraction)
What is huntingtons disease?
Neurodegenerative genetic disorder that afters muscle coordination and leads to cognitive decline and psychiatric problems
What is anticipation?
Where disease symptoms become more severe from generation to generation and may become onset at a much earlier age
What is heteroplasmy?
Different daughter cells contain different proportions of mutant mitochondria (similar to mosaicism)
What are the symptoms of mitochondrial disease?
Myopathy Diabetes Deafness Optic atrophy Stroke-like episodes Encephalitis (inflammation of the brain)
4 methods by which oncogenes are activated?
Duplication of the gene
Activation of the gene promoter
Change in amino acid sequence
Phosphorylation of the gene
