BIOL 1107 1nd Edition Lecture 26Outline of Last Lecture I. MitosisII. Chromosome MappingIII. Karyotype IV. InterphaseV. Phases of MitosisOutline of Current Lecture I. Asexual v. Sexual ReproductionII. Mitosis v. Meiosis III. Meiosis IIV. Meiosis IICurrent LectureI. Asexual v. Sexual Reproduction- Asexual reproduction- mode of reproduction by which offspring arise from a single organism, and inherit the genes of that parent only; it is reproduction which almost never involves ploidy or reduction. The offspring will be exact genetic copies of the parent, except in the specific caseof automixis.- Sexual reproduction- Sperm + Egg -> zygoteII. Mitosis v. MeiosisMitosis Meiosis Identical cells Different cellsCell division is over cells divide againSister chromatids line up Occurs in all organisms Occurs is humans, animals, plants, fungiMakes everything other than sex cells Creates: sex cells onlyIII. Meiosis I- Prophase I: o this is the phase where chromosomes condenseo mitotic spindle forms These 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.o homologous chromosomes form chiasmata o two chromosomes from sister chromatids - Metaphase I: o Chromosomes line up on metaphase plateo Instead of individual chromosomes lining up, we have pairs (4 chromatids) lining up - Anaphase I:o Phase where chromosomes get pulled apart - Telophase I & Cytokinesiso Chromosomes condense o Haploid cells form o Decreased chromosomal content by half IV. Meiosis II- very similar to Meoisis I except with haploid cells - Q: How many unique gametes can a cell with two pair of chromosomes make? 4 unique gametes - Law of independent Assortment (Mendel’s)- chromosomes don’t have preference as to where they line up - Why bother? Helps diversify population which helps in survival of population - Q: How can a cell end up with an incorrect # of chromosomes? Chromosomesdo not separate correctly during mitosis or meiosis (would be worse!)- The older you get, the higher the risk of getting child with down syndrome - The different copies of chromosome 21 in a couple are shown to right - How is Down syndrome detected? o Karyotyping-> isolate chromosomes during cell division - When would the best time be to isolate chromosomes for a karyotype? Prophase - Why would this be the best time? Because you want them to be condensed but not
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