handout 3.31.11 - 3/31/11 1. LOD score LOD stands for log...

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3/31/11 1. LOD score – LOD stands for log of odds ratio. The LOD score is designed to test whether the gene for a trait is linked or not linked to a known mapped genetic marker 2. Pseudogene – Gene that was once functional in the past, but is currently nonfunctional (i.e., “dead”) due to disabling mutations 3. Resistance (R) plasmid – As for other plasmids, double-stranded, circular DNA that is capable of autonomous (independent) replication and transfer across cells. However, R plasmids are special, because they carry multiple, antibiotic resistance genes 4. Cancer – Malignant growth of cells that no longer respond to normal controls on cell division, cell death (apoptosis), and cell-to-cell communication (signal transduction); invade surrounding tissue and may also metastasize into distant ones by the blood or lymphatic systems 5. Apoptosis – Programmed cell death; occurs to prevent the spread of defective (e.g., mutated or infected) cells and to generate structures during development (e.g., the formation of fingers during hand development) --------------------------------------------------------------------------------------------------------------------------------------------------- HUMAN GENOME: SUMMARY A. Total size 3.1 gb (gb = billion base pairs) Euchromatin 2.9 gb Constituitive heterochromatin 0.2 gb Euchromatin, A+T 59% (thus, 41% G+C) B. Genes, total number >26,000 Structural RNA genes (e.g., rRNA and tRNA) >6,000 Protein-coding genes >20,000 Average length 53.6 kb (kb = 1000 base pairs) % genome, protein-coding DNA ~1.1% % without reasonably well-known function <40% Number of different proteins >200,000 Number of pseudogenes >12,000 C. % genome, repetitive DNA 54% Satellite DNA (e.g., highly repetitive DNA, microsatellites, and minisatellites) 7% DNA transposable elements 3% Retroelements (RNA-based transposable elements) 44% SINEs 14% LINEs 21% Endogenous retroviruses 9% E. Human variation (polymorphism) and interspecific differences (divergence) Human individuals share 99.9% of their DNA sequences with each other Humans and chimpanzees share ~99% of their DNA sequences with each other HUMAN GENOME: MOST REMARKABLE FINDINGS 1. Only ~1% of total DNA codes for protein (or conversely, ~99% doesn’t code for protein) 2. >50% of total DNA constitutes repetitive DNA, much of which represents ancient transposable elements and retroviruses 3. Human genome has surprisingly few genes --------------------------------------------------------------------------------------------------------------------------------------------------- SPECIES GENE NUMBER Human ( Homo sapiens ) >26,000 Weed ( Arabidopsis thaliana ) 26,000 Nematode worm ( Caenorhabditis elegans ) 18,000 Fruit fly (
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handout 3.31.11 - 3/31/11 1. LOD score LOD stands for log...

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