Reproductive Biology: An Overview

Biology 2: Reproductio Cell Cycle Mitosis G1: Make mRNA and proteins to prep for mitosis Prophase: G0: A cell will enter G0 if it DOES NOT need to divide G1 Checkpoint: Cell decides if it should divide. P53 in charge Anaphase: S: DNA replicated G2: Cell growth. Make organelles G2 Checkpoint: Check cell size & organelles M: Mitosis and cytokinesis DNA condenses. Centrioles migrate to opposite poles and microtubules form. Nuclear envelope disappears. “Meet in the middle”. Chromosomes meet in middle. “Apart”. Sister chromatids separate and move to opposite poles. Telophase: Chromosomes decondense. Nuclear membrane forms. Cytokinesis occurs. Meiosis - PMAT x 2 Nondisjunction: When sister chromatids don’t separate properly during anaphase. Results in aneuploidy. Prophase I: Chromosomes condense, nuclear membrane dissolves, homologous chromosomes form bivalents, crossing over occurs. Growth Signals Positive Growth Signals: 1) 2) 3) 4) Negative Growth Signals: 1) 2) 3) Metaphase: - PMAT - Ploidy of 2n throughout CDK + Cyclin create a complex Phosphorylate Rb to Rb + P Rb changes shape, releases E2F Cell division continues CDK inhibitors block phosphorylation of Rb So, E2F stays attached Cell cycle halts Sex Chromosomes Sex determined by 23rd pair of chromosomes. XX = female. XY = Male. X-Linked Disorders: Males express, females can be carriers Y-Chromosome: Little genetic info. SRY gene = “Sorry you’re a male” Male Reproductive System Metaphase I: Spindle fibers from opposing centrosomes connect to bivalents (at centromeres) and align them along the middle of the cell. Anaphase I: Homologous pairs move to opposite poles of the cell. This is disjunction and it accounts for the Law of Segregation. Telophase I: Chromosomes decondense, nuclear membrane MAY reform, cell divides (cytokinesis), forms two haploid daughter cells of unequal sizes. Prophase II: Chromosomes condense, nuclear membrane dissolves, centrosomes move to opposite poles (perpendicular to before). Metaphase II: Spindle fibers from opposing centrosomes attach to chromosomes (at centromere) and align them along the cell equator. Anaphase II: Spindle fibers contract and separate the sister chromatids, chromatids (now called chromosomes) move to opposite poles. Telophase II: Chromosomes decondense, nuclear membrane reforms, cells divide (cytokinesis) to form four haploid daughter cells. Semen: Sperm + seminal fluid. Bulbourethral Glands: Makes viscous fluid to clean out urethra. SEVE(N) UP sperm pathway mnemonic Seminiferous tubules: Site of spermatogenesis . Nourished by Sertoli Cells. Epididymis: Stores sperm. Sperm gain motility. Vans deferens: Raise / lower testes . Ejaculatory duct: Urethra: Meiosis Diagram Seminal Vesicles & Make alkaline fluid to help sperm survive acidic Prostate Gland: environment of female reproductive tract. Penis: The Menstrual Cycle Female Reproductive System Ovaries: Have follicles that produce ova. Controlled by FSH and LH. Oogenesis: Production of female gametes. Estrogen: Response to FSH. Develops rep tract, thickens uterine wall. Progesterone: Response to LH. Maintains / protects endometrium. “Estrogen establishes; progesterone protects the endometrium”. Pathway: Egg ® peritoneal sac ® fallopian tube / oviduct Gonadotropin-Releasing Hormone (GnRH) FSH: Follicle Stimulating Hormone. Males: Triggers spermatogenesis, stimulates Sertoli Cells. Females: Stimulates development of ovarian follicles. LH: Luteinizing Hormone. Males: Causes interstitial cells to make testosterone. Females: Induces ovulation.