Introduction to Genetics

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Introduction to Genetics

Inheritence is due to the passage of discrete particulate factors from one generation to the next in an unchanged form

Mendels first rule - The law of Segregation = two factors cannot enter the same gamete, they are separated from each other during mitosis

Factors - You have two factors, only 1 factor for each trait is used

Dominant factor - B

Recessive factor - b

If both factors the same - homozygous

if factors different - heterozygous

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Important genetic term

Mendels 2nd Law - Factors for each trait segregate into gametes Dihybrid cross

The genetic factor is a gene

Each factor is a gene, each gene describes one trait

Important genetic terms 

Gene - a genetic factor that determine a trait

Locus - Place on a chromosone

Genotype - set of Alleles of a person

46 Chromosones in each cells

23 chromosones from each parent

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Chromosomes and diseases

Karyotypes - 22 chromosome pairs are autosomal

1 pair are sex chromosomes

Females - XX  males - XY

Sex linked traits - mothers genes dominant in males

Heamophilia (X chromosomes) blood doesnt clot - cuts slow to heal

Autosomal recessive - two copies of an abnormal gene must be present

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Sickle cell disease and Cystic Fibrosis

Sickle cell disease

recessive allele causes amino acids substitution in heamoglobin

O2 conc - low   cells sickle

Cystic Fibrosis (autosomal recessive)

Faulty transport of Na and Chlorine

Autosomal dominant - one one copy of gene necessary

50 percent chance of inheritence

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Huntingtons disease

neurodegenerate disorder

affects muscle coordination

appears in middle age

Trisomy - (2n + 1) additional chromosome

Monsomy - (2n - 1) entire chromosome absent

Deletions - missing portion of chromosome

Inversions - genetic material is inverted

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Klinefelters syndrome and monosomy

XXY chromosome arrangement enlarged breast, rounded body taller, small testes, language impairment

Monosomy - one chromosome from a pair short stature, webbed stature, webbed neck lack of ovarian development, low hairline, heart problems, thyroid

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Mitrochondrial DNA Diseases

Mitochondria = 37 genes to encode proteins and RNA 

Diseases are very rare, always inherited from mother

Nuclear DNA errors

Do not cause symptoms early in life

arise from inheritence or mutation of a nuclear DNA mutation

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