پاورپوینت Molecular Genetics and Otolaryngology (pptx) 38 اسلاید
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Molecular Genetics and Otolaryngology
Michael E. Prater, MD
Shawn D. Newlands, MD
Introduction
Chromosomal analysis
Cytogenetics
Molecular biology and genetics
Biochemical genetics
Clinical genetics
Population genetics
Genetic epidemiology
Developmental genetics
Immunogenetics
Genetic counseling
Fetal genetics
History
Gregor Mendel, 1865
“Mendel’s Laws” of autosomal inheritence
Work “lost” until early 1900’s
Charles Darwin, 1859
“The Origin of Species”
Jean Baptiste Lemarck
History, continued
Francis Galton (Charles Darwin’s cousin)
The “father” of modern genetics
rediscovered Mendel’s laws
“nature versus nurture”
“inborn errors of metabolism” responsible for biological abnormalities
History, Continued
James Watson and Francis Crick
DNA discovered in 1940’s
Determined double helix in 1953
Nobel Prize in 1962
Human Genome Project
Begun in 1990
Goal is to identify every human gene by 2005
9% completed as of 1999
Classification of Disorders
Single Gene Defects
Usually single critical error in the genetic code
Usually phenotypically obvious
Examples: NF I and II, osteogenesis imperfecta, cystic fibrosis
Classification, continued
Chromosomal disorders
not due to single defect
usually due to deficiency in number of genes within chromosome
classic example is Down Syndrome (Trisomy 21)
other examples: Trimsomies 13, 18, Klinefelter’s Syndrome, Turner’s Syndrome
phenotypically obvious
usually incompatible with life
Classification, continued
Multifactorial inheritance
multiple single code defects
usually form a pattern
classic examples: cleft lip/palate, neural tube defects
possible example: head and neck cancer?
Chromosomal Structure
23 pairs of chromosomes
approximately 7 million base pairs
100,000 genes
DNA:
five carbon sugar (deoxyribose; ribose in RNA)
nitrogen base (purines, pyrimidines)
3’5’ phosphate linkage
hydrogen bonded double strand