2008 Genetics lecture

2008 Genetics lecture - Genes Units of inheritance. The...

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Genes • Units of inheritance. • The number of genes in humans is now estimated at about 30,000- lower than the initial estimate of >100,000, and similar to the number estimated for “simpler” animals, e.g., roundworm (20,000). • Can be switched on and off during development to cause cell specific properties to emerge--- long term expression. • Can be switched on and off in response to specific stimuli, e.g., painful stimuli can switch on the protooncogene c-fos- function is unknown.
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Central Dogma of Molecular Biology: DNA Makes Complementary mRNA. mRNA Codes for Strings of Amino Acids Called Proteins Each amino acid within a protein is coded by 3 base pairs of DNA/RNA DNA mRNA Protein Transcription Translation
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Alteration of gene function • Changes in sequence of nucleotides due to mutation • Action of transcription factors that turn gene function on and off • Alterations in nucleotide chemistry without changes in sequence , e.g., methylation of bases or alteration of protein molecules known as histones with which the DNA is associated (DNA + histones together are called chromatin). Such changes are known as epigenetic.
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Paired Human Chromosomes
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• 23 pairs of chromosomes (human): 22 paired structures + sex chromosomes- X and Y. • One from father, the other from mother. • If pairs of genes on the matched chromosomes are identical, they are said to be homozygous. • If not identical, they are
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This note was uploaded on 07/15/2009 for the course BIO 208 taught by Professor Lorne-mendell,s during the Fall '08 term at SUNY Stony Brook.

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2008 Genetics lecture - Genes Units of inheritance. The...

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