Unit 4 –Reproduction and Genetics Lesson 13 - Gamete Production Colorado Agriscience Curriculum
Unit 4, Lesson 13 - Gamete Production
I: Production of Gametes A) Gametogenesis 1. Ovaries produce ova a) Oogenesis 2. Testicles produce sperm a) Spermatogenesis 3. Sex cells divide by meiosis a) Special cell division in which each new gamete(cell) carries only 1/2 the # of chromosomes a typical cell would in that species Unit 4, Lesson 13 - Gamete Production
I: Production of Gametes B) Initial steps are similar between male and female 1. Chromosomes replicate a) Each is doubled 2. Each pair comes together very accurately (synapsis) a) Now called a primary oocyte or b) Primary spermatocyte Unit 4, Lesson 13 - Gamete Production
Unit 4, Lesson 13 - Gamete Production II. Spermatogenesis A. Primary Spermatocyte 1. Contains 2 pair of chromosomes a) Two bodies containing 4 structures 2 rapid cell divisions produce 4 cells a) Each ontain 2 chromosomes b) Spermatid cells lose much of their cytoplasm & develop a tail Unit 4, Lesson 13 - Gamete Production
Unit 4, Lesson 13 - Gamete Production
Unit 4, Lesson 13 - Gamete Production III: OOGENESIS A. 1st maturation division 1. Produce 1 large oocyte (secondary) & 1 small (1st Polar Body) a) Unequal size results from body wanting one rich in nutrients @ the expense of the other B. 2nd maturation division 1. Produces the ovum a) Polar bodies may divide but will soon die and be reabsorbed by the body Unit 4, Lesson 13 - Gamete Production
Unit 4, Lesson 13 - Gamete Production
Unit 4, Lesson 13 - Gamete Production IV: Fertilization A) Fertilization is the union of sperm and ovum and the establishment of paired chromosomes 1. Zygote is a diploid (Double) because chromosomes are in pairs a) 1 member of each pair came from the sire and 1 from the dam Unit 4, Lesson 13 - Gamete Production
Unit 4, Lesson 13 - Gamete Production IV: Fertilization B) Gametes have only one member of each pair. 1. Haploid (Half) 2. Gametogenesis reduces the # of chromosomes in a cell to 1/2 the diploid # 3. Each gamete carries a random sampling 1/2 of each parents genetic code. 4. Which sperm fertilizes the ovum is also random a) This insures genetic diversity Unit 4, Lesson 13 - Gamete Production
Unit 4, Lesson 13 - Gamete Production