Notes 23 February (25th was a Snow Day)
Notes 23 February (25th was a Snow Day) BIO 151
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This 2 page Class Notes was uploaded by Chelsea Notetaker on Sunday February 28, 2016. The Class Notes belongs to BIO 151 at Central Michigan University taught by Professor Learman in Winter 2016. Since its upload, it has received 30 views. For similar materials see Human Biology in Biology at Central Michigan University.
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Date Created: 02/28/16
23 February 2016 Genetic Variation >The 46 chromosomes we inherit include genetic information from our grandparents. >During meiosis DNA is crossed over; chunks of DNA swapped between homologous chromosomes -Independent Assortment: Mom’s and Dad’s chromosomes separate randomly from each other -Random Fertilization: Any sperm can meet any egg >Exception: identical twins -Monozygotic – twins formed after fertilization, the embryo dividing. 100% identical. -Fraternal twins – dizygotic – two eggs released by the mother, fertilized by two different sperm. Share the same fifty percent of DNAas regular siblings. Class Activity List three ways sexual reproduction causes genetic variation. > Crossing over, random fertilization, independent assortment. Name the fourth mechanism that results in genetic variation. > Mutations. >Mendelian Inheritance patterns – Mendel was the first person to study inheritance, and his conclusions are the basis for our understanding of inheritance today. >Character – a heritable feature: eye or hair color, earlobe shape >Trait – specific representation of a character: red hair, green eyes >Locus – specific place on the chromosome for a certain gene >Allele – different versions of a given gene -You inherit only one gene/allele of each kind from each Mom and Dad -The expression of the genes depends on the type of allele. >Homozygous – when the alleles for a particular gene are identical on both chromosomes of the pair >Heterozygous – the mentioned alleles are different -Only one allele typically gets expressed -the expressed allele is dominant – written in uppercase -the non-expressed allele is recessive – written in lowercase Class Activity Classify and identify the gene expressed: PP: homozygous – dominant aa: homozygous – recessive Bb: heterozygous – dominant >Genotype – specific genes present: Ff >Phenotype – physical appearance of a gene’s espression: freckles -observing an individual’s phenotype doesn’t always identify the genotype – with freckles it could be FF or Ff. >Genes are not necessarily inherited together, but genes located close toe ach other on the chromosome are more likely to be inherited together >Punnett Square: helps determine likely gene/phenotypes Class Activity What is the phenotype of someone homozygous R for tongue-rolling? >RR What is the genotype for a man heterozygous for it? >Rr What is his phenotype? >Tongue-roller What would be the expected genotype and phenotype for their offspring? >50% Rr tongue-rollers and 50% RR tongue-rollers.
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