BIO 1201 1nd Edition Lecture 15 Outline of Last Lecture I.Problems during meiosisII.Comparing meiosis and mitosisOutline of Current Lecture III.Meiosis 2IV.GeneticsCurrent LectureI. Meiosis 2: makes 4 cells with 23 chromosomes eacha. Required to make gametesb. Must cut ploidy in halfc. Strictly used to make babiesd. Germ cells are only cells that can undergo meiosise. In males each of these becomes sperm—men are always going through meiosisf. In females on of these cells becomes an egg—females go through meiosis maybe once a monthg. When sex happens, sperm combines with egg to make 46 chromosomesh. A human germ cell containing 46 chromosomes undergoes meiosis to produce 4 cells containing 23 chromosomes because the DNA replicates before the cells divideII. Genetics: a mechanism to follow traitsa. Traits=phenotypes/appearancesb. Genetics follows these from generation to generationc. Mendel: monk who performed hybridizations by using pea plantsi. Crossed (mated) pea plants of different phenotypes and observed outcomesii. Took flowers of pea plants that he knew had certain traits (yellow seeds, etc.)iii. Took male parts of flower with paint brush and painted different female parts of other pea plantsiv. Mendel’s hypotheses:1. There are alternate forms of genes that determine traits2. For each inherited characteristic, an organism has two genes, one from each parent3. A gamete carries only one allele for each inherited characteristicThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.4. When two genes of a pair are different alleles, the one that determines the trait is dominant and the one that has no noticeable effect is recessived. Monohybrid crosses look at one traite. Dihybrid crosses look at 2 traitsf. Most genes come in slightly different molecular forms called allelesg. Gene: the heritable instructions for producing a traith. Gene Locus: the location of a specific gene on a specific
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