Slides cover Meiosis and Mendelian/ Nonmendelian outlines

Interphase

. Propase Duplicated chromosome (two sister chromatids) Chromosome replication 2n = 6 Parent cell (before chromosome replication) Chromosome replication MITOSISMEIOSIS Chiasma (site of crossing over) MEIOSIS I Prophase I Tetrad formed by synapsis of homologous chromosomes Tetrads positioned at the metaphase plate Metaphase I Chromosomes positioned at the metaphase plate Metaphase Anaphase Telophase Homologues separate during anaphase I; sister chromatids remain together Sister chromatids separate during anaphase Daughter cells of meiosis I Haploid n = 3 Anaphase I Telophase I MEIOSIS II Daughter cells of mitosis 2n2n 2n2n n Sister chromatids separate during anaphase II n nn Daughter cells of meiosis II

TWO Divisions (easy version – meiosis)

(First Division)

(Second Division)

Spermatogenesis Spermatogonium Primary spermatocyte (in prophase of meiosis I) Mitotic division, producing large numbers of spermatogonia Meiosis I completed Differentiation and onset of meiosis I Secondary spermatocyte Meiosis II Early spermatids Spermatids (at two stages of differentiation) Differentiation Sperm cells Neck Head Midpiece Tail Plasma membrane Mitochondria AcrosomeNucleus Sertoli cell nucleus Lumen of Seminiferous tubule Cross section of seminiferous tubule Testis Epididymis Seminiferous tubule

Oogenesis in the ovaries Primary germ cell in embryo Mitotic division Primary oocyte Ovary Oogonium Differentiation Oogonium in ovary Primary oocyte within follicle Growing follicle Secondary oocyte Completion of meiosis I and onset of meiosis II Ovulation First polar body Mature follicle Entry of sperm triggers completion of meiosis II Second polar body Ovum Ruptured follicle Ovulated secondary oocyte Corpus luteum Degen- erating corpus luteum

Crossover in Prophase I

Mitosis vs. Meiosis

Propase Duplicated chromosome (two sister chromatids) Chromosome replication 2n = 6 Parent cell (before chromosome replication) Chromosome replication MITOSISMEIOSIS Chiasma (site of crossing over) MEIOSIS I Prophase I Tetrad formed by synapsis of homologous chromosomes Tetrads positioned at the metaphase plate Metaphase I Chromosomes positioned at the metaphase plate Metaphase Anaphase Telophase Homologues separate during anaphase I; sister chromatids remain together Sister chromatids separate during anaphase Daughter cells of meiosis I Haploid n = 3 Anaphase I Telophase I MEIOSIS II Daughter cells of mitosis 2n2n 2n2n n Sister chromatids separate during anaphase II n nn Daughter cells of meiosis II

Independent Assortment Key Maternal set of chromosomes Paternal set of chromosomes Possibility 1 Possibility 2 Combination 2 Combination 1 Combination 3 Combination 4 Daughter cells Metaphase II Two equally probable arrangements of chromosomes at metaphase I

Locus (Gene locations on chromosomes)

Alleles for a gene

True breeds & Hybrids

Phenotype vs. Genotype Physical Trait vs. Gene allele type

Test Cross Dominant phenotype, unknown genotype: PP or Pp? If PP, then all offspring purple: pp P P Pp If Pp, then 1 2 offspring purple and 1 2 offspring white: pp P P pp Pp Recessive phenotype, known genotype: pp

Monohybrid

Dihybrid

Dihybrid – Normal 9:3:3:1 ratio

Law of Segregation - Anaphase

Independent Assortment Key Maternal set of chromosomes Paternal set of chromosomes Possibility 1 Possibility 2 Combination 2 Combination 1 Combination 3 Combination 4 Daughter cells Metaphase II Two equally probable arrangements of chromosomes at metaphase I

Complete Dominance

Incomplete Dominance

Codominance (AB) & Multiple Alleles

Pleiotropy (Sickle Cell)

Epistasis Sperm BC bCBc bc BbCcBBCcBbCCBBCC BbCC bbCCBbCc bbCc BbccBBcc BbCcBBCc BbCc bbCc Bbcc bbcc BC bC Bc bc BbCc

Polygenic Inheritance & Norm of the Reaction aabbccAabbccAaBbccAaBbCcAABbCcAABBCcAABBCC AaBbCc 20 / / 64 6 / 64 1 / 64 Fraction of progeny

Multifactorial example (Acid in soil changes the color)

. Wwww Ww wwWwww Ww WWww or Ww No widow’s peak Third generation (two sisters) Widow’s peak Second generation (parents plus aunts and uncles) First generation (grandparents) Dominant trait (widow’s peak)

. First generation (grandparents) Ff FF or Ffff Ff ff Ff Second generation (parents plus aunts and uncles) Third generation (two sisters) Attached earlobe Free earlobe ffFF or Ff Recessive trait (attached earlobe)

Genes on Chromosomes

Female (XX) Karyotype (Remember… “kary” means “nucleus”)

Autosomes and linked genes

Linkage Map based on Crossover frequency Recombination frequencies 9%9.5% 17% bcn vg Chromosome

Locus Gene Maps

Sex –Linked Female – TWO Xs

Sex-Linked Male – ONE X

One from EACH parent Sperm AND Egg

Pedigree of Color Blindness

Pedigree of Hemophila

Non-Disjunction

Trisomy 21

Chromosome Structure Errors

Extranuclear DNA (This DNA CAN can affect an organism)