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Bio Exam II
Human Genetics
| Term | Definition |
|---|---|
| intro | - study of inherited variance in humans - difficulties in studying human genetics (few offspring, long gen. times, cant experiment) |
| How to study human genetics | - pop. studies of large extended families - analyze matings that already occurred - medical attention to human genetic diseases |
| Use DNA Sequencing | DNA sequencing- many generations, extended relatives= genetic basis |
| Pedigree Analysis | - pedigree: family tree/ shows inheritance patterns over several gen. - determine inheritance patterns over several gen. - determine inheritance patterns "based in prevalence & distribution of trait"; used by genetic counselors |
| Recessively Inherited Disorders | - autosomal recessive - Dom. Allele makes enough proteins |
| Everybody Carries Something | - most human genetic disorders are single- locus autosomal recessive traits |
| 2 Outcomes | - cell destroyed immediately/ cells clump together |
| Sickle Cell Heterozygotes | - normal & above normal hemoglobin - no phenotypic diff. usually in human homozygotes & heterozygotes |
| Sickle Cell & Malaria Resistance | - malaria: intracellular parasite of RBC's - heterozygotes resistant - sickle- cell allele favored in regions w/ malaria |
| Dominant Inherited Disorders | - Autosomal Dominant: rare; only one defective allele required ex. Achondroplasia: dwarfism; dom. allele |
| Human Traits w/ non- mendelian inheritance | - changes to chromosome # - difference in # of chromosome can cause disease - typical state: disomy (2 copies of eacg chromosome) |
| Aneuploidy | - abnormal # of a partial chromosome (extra or missing copy) |
| Trisomy | - having 3 of a chromosome - 2n+1 |
| Monosomy | - lacking 1 member of a pair of chromosomes - 2n-1 |
| Nondisjunction | - all abnormalities in chromosome # due to nondisjunction; chromosomes aren't pulled apart properly |
| Aneuploidy Viability | - in humans, monosomes for all autosomes inviable - most trisomies also inviable - estimated that over 50% of pregnancies end by 8 weeks |
| Trisomy 21 | - down syndrome; named after Langdon Down - extra 21st chromosome, complete or partial - frequency increases w/ maternal age |
| Symptoms of Trisomy 21 | - abnormalities of face, hands, tongue, eyelids -slow physical &mental development -short structure - prone to heart malformations, respiratory disease, leukemia |
| Aneuploidy of sex chromosome | - diff. # of sex chromosomes relatively common - many sex chromosome aneuploidies are viable but infertile |
| Turner Syndrome- XO | - 44 autosome 1X chromosomes - "XO" or "45, XO" - Common symptoms: short stature, webbed neck, sterile, no barr bodies |
| Klinefelter Syndrome- XXY (XXY or 47,XXY) | - 44 autosomes 1 X chromosomes, 24 - no specific phenotype - usually fertile (don't transmit extra Y) |
| Changes to Chromosome Structure | - errors in meiosis, radiation, other mutagens |
| 4 Types | deletion, duplication, inversion (backwards), translocation ex. Philadelphia chromosomes: translocation: splits a gene, high change of leukemia |
| Genomic Imprinting | - variation in phenotype dependent on parent- specific expression of each allele - occurs during gamete formation |
| Genomic Imprinting pt.2 | - sperm & egg imprinted differently - maternal & paternal copies expressed at diff. levels - often involves DNA methylation= 1 allele silenced= 1 allele expressed |
| Genetic Testing and Counseling | - cancer diagnosis= better change of prevention or alleviation |
| Fetal testing & Genetic tests done before birth methods | - amniocentesis - Chronic villus sampling (CVS) - non-invasive parental screening/testing |
| Amniocentesis | - takes weeks to grow before taking sample |
| CVS | - several hours; takes rapidly growing cells |
| Newborn Screening | - some genetic disorders detected @ birth |
| Phenylketonuria (PKU) | - every newborn tested @ birth in us - normally: phenylalanine= tyrosine - PKU: phenylalanine = phenylketones (toxic) - phenylketones accumulate= damage to nervous system= mental impairment |
| Managing PKU | done eat PKU (anything with amino acids in it) |
Created by:
tennadeleta.
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