GENETICS

WHAT IS GENETICS??Thai branch of biology that deals with heredity, especially the mechanisms of hereditary transmission and the variation of inherited characteristics among similar or related organisms.

FATHER OF GENETICS

Gregory Mendel

Composed of 2 polymers of nucleotides.Polymers are oriented in antiparallel.Molecule resembles a spiral staircase of complementary base pairs.

DNA MOLECULE

“Double helix” proposed by Watson and Crick (1953).Antiparallel backbones.Complementary base pairing:

Adenine to ThymineCytosine to Guanine

STRUCTURE OF DNA

Abnormal number of chromosomes-Down’s syndrome, Edwards syndrome,

Deletion -Cri Du chat, Williams syndrome

Sex Chromosome Abnormalities-Turner syndrome, Klinferlter’s syndrome

Single Gene Mutations-Cystic Fibrosis, Sickle Cell anaemia

EXAMPLES OF CONDITIONS CAUSED BY DNA CHANGES

GENETIC TESTING AND PROFILING

Take a sample of cells (blood, hair root)

Extract the DNA from cells

Cut up the DNA

Separate the DNA fragments

Analyse the DNA fragments

CLASSIFICATION OF GENETIC DISEASES

Single gene defects/ Mendelian disorders Disorders with multifactorial or polygenic inheritance

Cytogenetic disorders

Disorders showing a typical patterns of inheritance

VARIOUS DISEASES ASSOCIATED

Diabetes mellitusHypertensionGoutCongenital heart diseaseNeural tube defectsSkeletal abnormalitiesCoronary artery diseaseBipolar disorder

DIAGNOSIS OF GENETIC DISEASE

FISH(Fluorescence in situ hybridisation)Conventional cytogenetic analysisMolecular analysis

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