phenotype chemical modifications that cause a phenotypic change Epigenetics

Phenotype chemical modifications that cause a

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phenotype; chemical modifications that cause a phenotypic change Epigenetics Familial Risks for Multifactorial Risks o Further down the line = less of a chance to inherit multifactorial genes
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Studying Complex Multifactorial Traits: Recurrence Risk – don’t memorize o Consanguity = related parents have higher risk of having a child with a complex disorder o Previous affected child will have a higher risk as well Phenotypic Variation o Derived from 2 places: Genetic variance – heritability is high = genetic variance will take most of effect Environmental variance – if heritability is low, environment will most likely have greater effect Twins and multifactorial traits o Closer the genetic relationship is, the closer their environment will be o Monozygotic twins – identical twins due to 1 zygote splitting; share 100% of genes and same environment o Dizygotic twins – fraternal twins produced by 2 embryos fertilized at the same time; share 50% genes and same environment Will be less similar than identical twins Concordant vs. discordant o Concordant – both members of a twin pair have the same trait o Discordant – one twin has it, one doesn’t GWAS & SNP o SNP = single nucleotide differences between sequences o GWAS = whole genomic sequencing; used to compare populations Haplotype – different SNPS are always together in 1 region of DNA o A block of SNPs Height o Involves many genes with high heritability Skin color is also a complex trait; can be affected by environment o Sun affects melanin production Is intelligence determined by genetics o It’s a complex trait;heritability of IQ is 0.6-0.8, so it’s a genetic component 2/12/2020 Test Review o What occurs in meiosis but not mitosis? Pairing of homologous chromosomes at metaphase plate o How many protein-encoding genes? 20,000-25,000 o What is the second leading cause of death in the US Cancer o LOH occurs in Tumor-suppressor genes
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Cytokinetics o Humans have 46 chromosomes (23 pairs) o Species vary in chromosome number Replicated Chromosomes o Telomere is the end unit of the chromosome – shorten after cell division (older chromosomes = shorter telomeres) o Telomeres 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 length o Telomeres can prevent chromosomes from sticking together Types of Chromosomes o 3 types of chromosomes – short arm (p), long arm (q); p for puny = short know which is which Metacentric – big telomere, typical chromosome shape Submetacentric – 1 short arm, 1 long arm Acrocentric – short arm is so small, you can barely see it Karyogram: Chromosome Banding Patterns o Staining chromosomes allows one to see all the banding on chromosomes to study them further Regions of Banding are Identified by a Descriptive Address o Ex: 1q2.4 Located in chrome 1, q arm (long arm), region 2, band 4 Karyotype o Arranging complete set of chromosomes to study for disease, mutation, etc.
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