ch28ppt - 28-1Chapter 28The Reproductive Systems•Sexual...

Info iconThis preview shows pages 1–11. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 28-1Chapter 28The Reproductive Systems•Sexual reproduction produces new individuals–germ cells called gametes (sperm & 2nd oocyte) –fertilization produces one cell with one set of chromosomes from each parent•Gonads produce gametes & secrete sex hormones•Reproductive systems–gonads, ducts, glands & supporting structures–Gynecology is study of female reproductive system–Urology is study of urinary system & male reproductive system28-2Chromosomes in Somatic Cells & Gametes•Somatic cells (diploid cells)–23 pairs of chromosomes for a total of 46•each pair is homologous since contain similar genes in same order•one member of each pair is from each parent–22 autosomes & 1 pair of sex chromosomes•sex chromosomes are either X or Y•females have two X chromosomes•males have an X and a smaller Y chromosome•Gametes (haploid cells)–single set of chromosomes for a total of 23–produced by special type of division: meiosis28-3Meiosis I -- Prophase I•Chromosomes become visible, mitotic spindle appears, nuclear membrane & nucleoli disappear•Events not seen in prophase of Metaphase or Meiosis II–synapsis•all copies of homologous chromosomes pair off forming a tetrad–crossing-over•portions of chromatids are exchanged between any members of the tetrad•parts of maternal chromosomes may be exchanged with paternal ones–genetic recombination produces gametes unlike either parenttetrad28-4Exchange of Genetic Material•Chromosomes are exchanged between chromatids on homologous chromosomes28-5Meiosis I -- Metaphase I, Anaphase I & Telophase I•In metaphase I, homologous pairs of chromosomes line up along metaphase plate with attached microtubules•In anaphase I, each set of homologous chromatids held together by a centromere are pulled to opposite ends of the dividing cell•Telophase I and cytokinesis are similar to mitotic division•Result is 2 cells with haploid number of chromosomes28-6Meiosis II•Consists of 4 phases : prophase II, metaphase II, anaphase II and telophase II•Similar steps in this cellular process as in mitosis–centromeres split–sister chromatids separate and move toward opposite poles of the cell•Each of the daughter cells produced by meiosis I divides during meiosis II and the net result is 4 genetically unique haploid cells or gametes.28-7Male Reproductive System•Gonads, ducts, sex glands & supporting structures•Semen contains sperm plus glandular secretions28-8Scrotum•Sac of loose skin, fascia & smooth muscle divided into two pouches by septum•Skin contains dartos muscle causes wrinkling•Temperature regulation of testes–sperm survival requires 3 degrees lower temperature than core body temperature–cremaster muscle in spermatic cord•elevates testes on exposure to cold & during arousal•warmth reverses the process28-9Scrotal Sacs, Dartos & Cremaster Mm28-10Testes•Paired oval glands measuring 2 in. by 1in....
View Full Document

This note was uploaded on 04/10/2010 for the course BIO 222 taught by Professor Brooks during the Spring '10 term at Prairie State College .

Page1 / 103

ch28ppt - 28-1Chapter 28The Reproductive Systems•Sexual...

This preview shows document pages 1 - 11. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online