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Genetics. Vicky “Bio-lover” Atzl Farah “Bird-hater” Momen. Meiosis. a. Meiosis 1 separates homologous pairs (known as reduction division) crossing over occurs in Prophase 1 resulting in genetic variation (not in mitosis)
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Genetics Vicky “Bio-lover” Atzl Farah “Bird-hater” Momen
Meiosis • a. Meiosis 1 separates homologous pairs (known as reduction division) • crossing over occurs in Prophase 1 resulting in genetic variation (not in mitosis) • b. Meiosis 2 separates homologous pairs into sister chromatids: produces 4 haploid gametes (meiosis 2 resembles mitosis)
Alleles • a. dominant vs. recessive • Dominant allele is expressed over recessive • b. homozygous vs. heterozygous • Homozygous has two of the same allele (AA or aa); heterozygous has two different alleles (Aa) and therefore has dominant phenotype • c. phenotype vs. genotype • Phenotype is the physical appearance of an expressed allele; genotype is the genetic makeup of an organism
Non-Mendelian inheritance • a. incomplete dominance (pink flower color) • When a heterozygote’s two alleles blend b. co-dominance (blood type) When a heterozygote’s two alleles are expressed equally. c. sex linked (mainly X-linked: color blindness, hemophilia) • epistasis (coat color) presence of certain alleles on one locus mask the expression of alleles on another locus and express their own phenotype instead. • pleiotropy (dwarfism, giantism) one allele affects various phenotypes in an organism. • polygenic (skin color) multiple alleles are required for the expression of a characteristic
Chi-square analysis • a. used to determine if observed results are significantly different from expected results • b. know how to use formula when given & how to interpret results • • degrees freedom (1 less than number of classes of results) • • if x^2 less than p=.05, then difference can be due to random chance and hypothesis accepted
DNA & RNA a. DNA: ACTG nitrogen based nucleotides in double helix formation • • A pairs with T, C pairs with G • b. RNA: ACUG nitrogen based nucleotides in single helix formation
Central Dogma DNA is transcribed into RNA; that is further translated into proteins that code for traits. Transcription: RNA polymerase copies template strand and makes mRNA Translation: ribosomes in cytoplasm match tRNA codons to mRNA codons; amino acids carried to P site of ribosome and forms polypeptide chain. Chain ends at one of stop codons.
Gene regulation • Operons • Inducible: lac operon • I DIDN’T FINISH!
Mendelian inheritance • a. monohybrid crosses • • Aa x Aa = 3:1 ratio • • Law of Segregation