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phenotype; chemical modifications that cause a phenotypic changeEpigeneticsFamilial Risks for Multifactorial RisksoFurther down the line = less of a chance to inherit multifactorial genes
Studying Complex Multifactorial Traits: Recurrence Risk – don’t memorizeoConsanguity = related parents have higher risk of having a child with a complex disorderoPrevious affected child will have a higher risk as wellPhenotypic VariationoDerived from 2 places:Genetic variance – heritability is high = genetic variance will take most of effectEnvironmental variance – if heritability is low, environment will most likely have greater effectTwins and multifactorial traitsoCloser the genetic relationship is, the closer their environment will beoMonozygotic twins – identical twins due to 1 zygote splitting; share 100% of genes and same environmentoDizygotic twins – fraternal twins produced by 2 embryos fertilized at the same time; share 50% genes and same environmentWill be less similar than identical twinsConcordant vs. discordantoConcordant – both members of a twin pair have the same traitoDiscordant – one twin has it, one doesn’tGWAS & SNPoSNP = single nucleotide differences between sequencesoGWAS = whole genomic sequencing; used to compare populationsHaplotype – different SNPS are always together in 1 region of DNAoA block of SNPsHeightoInvolves many genes with high heritabilitySkin color is also a complex trait; can be affected by environmentoSun affects melanin productionIs intelligence determined by geneticsoIt’s a complex trait;heritability of IQ is 0.6-0.8, so it’s a genetic component2/12/2020Test ReviewoWhat occurs in meiosis but not mitosis?Pairing of homologous chromosomes at metaphase plateoHow many protein-encoding genes?20,000-25,000oWhat is the second leading cause of death in the USCanceroLOH occurs inTumor-suppressor genes
CytokineticsoHumans have 46 chromosomes (23 pairs)oSpecies vary in chromosome numberReplicated ChromosomesoTelomere is the end unit of the chromosome – shorten after cell division (older chromosomes = shorter telomeres)oTelomeres don’t shorten in cancer cells bc those cells have high levels of enzymes that make more repetitive sequences on the end of the telomere, maintaining its lengthoTelomeres can prevent chromosomes from sticking togetherTypes of Chromosomeso3 types of chromosomes – short arm (p), long arm (q); p for puny = short know which is whichMetacentric – big telomere, typical chromosome shapeSubmetacentric – 1 short arm, 1 long armAcrocentric – short arm is so small, you can barely see itKaryogram: Chromosome Banding Patterns oStaining chromosomes allows one to see all the banding on chromosomes to study them furtherRegions of Banding are Identified by a Descriptive AddressoEx: 1q2.4Located in chrome 1, q arm (long arm), region 2, band 4KaryotypeoArranging complete set of chromosomes to study for disease, mutation, etc.