CGCC

name two examples of monogenic disorders

CF and sickle cell anaemia

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Name three examples of polygenic disorders

Type 2 diabetes, schizophrenia and rheumatoid arthiritis

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What mutation leads to you being immune to the HIV-1 virus

Lacking the chemokine CCR5 receptor

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Herceptin blocks the overexpression of what in breast cancer

Her2

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What is the human Karyotype

46 chromsomes, 22 pairs of autosomes and one pair of sex chromosomes

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Staining allows chromosome characteristics to be expressed due to

G-banding (stained in their metaphase spreads)

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What three things characterise a chromosome

G-banding, location of centromere and size

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Describe the three difference centromere locations

Metacentric (p and q arms are the same length) submetacentric (p arm is shorter than q) and acrocentric (p arm is a satellite and stalk)

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One round of DNA replication and one round of segregation is

Mitosis

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One round of DNA replication and recombination and 2 rounds of segregation

Meiosis

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What area of a chromosome determines maleness and why

The SRY region, encodes for testes determining factor

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50% of spontaneous abortions are due to

Trisomies

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Trisomy 21

Downs syndrome, 47 X or Y + 21. Retardation, single crease along palm, heart defects and increased risk of acute leukemia

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Trisomy 18

Edwards. Kidney malformations, heart defects, intenstines protruding outside the body. 95% die in utero, 50% of those who survive make it to 2 months and 5-10% first year

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Trisomy 13

Patau syndrome. Heart defects, incomplete brain development, small or missing eyes, spinal defects and seizures. Mean life expectancy = 130days

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Why are trisomy's 21, 18 and 13 the only trisomes to be born

They are small chromosomes and therefore fewer genes to be trireplicated

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XXY - Klinefetter

infertile (5% males in fertility clinics), small testes

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X - Turner

Short stature and amenorrhea. Infertile

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XYY - XYY syndrome

Increased growth

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Trisomys and Monosomies are examples of

Aneuploidys

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Aneuploidys are caused by

non-disjunction - failure to seperate homologous chromosome pairs

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Why does the chances of having a baby with downs increase with age

Aneuploidy in oogenesis. All eggs are suspended in meiosis one until fertilised where they undergo meisosis 2. Ova are as old as the mothers

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What four types of mendelian inheritance are there?

Autosomal recessive, Autosomal dominant, X-linked recessive, X-linked dominant

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Autosomal recessive

CFTR. 7th chromosome, 508th Codon. Rare. Affects males and females equally and transmitted by either sex.

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Autosomal dominant

HD. CAG repeat. Normal 28, >36 = aggregation of protein, cytoxicty and then neuronal cell death. Trait frequet in pedigree, males and females equally

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The development of HD increases as do the CAG repeats through the generations. This is an example of

Genetic anticipation

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X-linked recessive

Haemophilia A. Frequent in males, all daughters of affected fathers are carriers

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X-linked dominant

Vit D resistant rickets. all daughters of affected men are affected

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If a gene is more frequent in MZ twins than DZ the disease can be assumed to be

Caused by a genetic component more so than an environmental one

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