Senogles 1

Senogles 1
Why is genetics in curriculum?
Design of course- human and Mendelian genetics and basis of disease. We need to be able to read a pedigree for following lectures. Friday- looking at positional cloning of genetic disease genes. She means her learning objectives. Know what she says.
Also know pseudoautosomal or Y-linked.
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Definitions she will use. Email her if you have questions.
Marker is known DNA sequence- not a gene enecessarily. Locus usually refers to a gene.
Dominant and recessive refers to traits, Not genes.
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44 of our chromosomes are autosomes. 2 sex chromosomes.
Somatic cell is anything nongonadal. Germ cells are haploid.
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G bands are reproducible.
Upper arm is P, lower Q. Centromere in middle. Number corresponds to nomenclature shown here when you look up a genetic mutation or deletion for a disease.
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Mitosis- how somatic cells reproduce. Same complement of chromosomes results in the end.
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Meiosis- haploid complement.
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Recombination between nonsister chromaids occurs at metaphase 1.
2 points: reduces to haploid state, and recombination in metaphase 1 scrambles information between maternal and paternal alleles.
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Standard
Open symbol- person not affected by disease. Fillled in affected.
Proband- where pedigree begins.
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Principle of independent segregation- each offspring independently has probability of inheriting a gene.
Each offspring independent.
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Autosomal dominant- can be caused by new mutation, but otherwise appears every generation. No gender bias.
18 Sometimes normal mates are not shown. Proband is first person identified.
Pedigree may not show exact 50/50 segregation.
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Phenotype may not show up until later.
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Autosomal recessive option often left to end. Often sproadic
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X-linked is trickier. Females compensate for gene dosage by inactivating one X chromosome in somatic tissue. Females are X mosaics.
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X-linked dominant- affected male- affected daughters, not sons. No male to male transmission. Follow pattern- connected through female. No male to male.
29X-linked recessive- transmitted from affected male through daughters. No male to male transmission. Carrier females show in pedigree.
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Half males affected, 25% of females carrier.
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Obligate heterozygote is carrier. (synonym)
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Y linked traits do occur. X and Y line up- only recombine on end portions. Not a gene dense region. Rest of chromosome cannot recombine X-Y.
34 Only males affected. See it in every generation, but only males affected. Rare pedigrees.
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Atypical- genomic imprinting is difference in gene expression between allele from mom and one from Dad. Only a few of these. Mice have more than we do. Not completely understood- thought to be differential methylation of DNA. Imprinting- which parent the chromosome is from determines outcome.