Aim #51: How do organisms create offspring through sexual reproduction?

What is Sexual Reproduction? It involves the joining of two cells to begin the development of a new individual. These special cells are called: Sex Cells (Gametes)

What are the names of these sex cells? Sperm Cell (Male) Egg cell (Female) The joining of a sperm cell with an egg cell is called fertilization.

1) How many chromosomes do we have in our cells? We have 46 chromosomes in each our body cells. We can also say that we have 23 pairs of chromosomes Karyotype

2) Why do we have 2 of each chromosome? We get one chromosome from each parent 3) Each pair of chromosomes are called: Homologous Chromosomes

4) Homologous Chromosomes: Eye Color Hair Color MomDad BG B R Have genes that code for the same trait, but may have different versions of that trait Gene Part of a chromosome that codes for a trait

5) How are chromatids different than homologous chromosomes? Chromatids are exact duplicates of each other Homologous chromosomes have genes that code for the same trait, but they may code for different versions of that trait

6) How many chromosomes do the offspring have after mitosis? 46X Mitosis

7) Do our sex cells have 46 chromosomes? NO!!!

8) What would happen if our sex cells did have 46 chromosomes? Egg Offspring Sperm The offspring would have 92 chromosomes

9) Sexual Reproduction: Sperm Egg Offspring A fertilized egg cell is called a Zygote 10) Characteristics of Sexual Reproduction: 1) Is the creation of a new individual from parents.2 2) Offspring are not genetically to the parents.identical

Date: February 3, 2016 Aim #51: How do organisms create offspring through sexual reproduction? HW: 1)Read Chapter 11-4 (Meiosis) pages and complete Cornell Notes Outline due Friday –Consider Section Assessment Questions (p. 278) in your summary 2)Yarn Lab due Friday! Do Now: Warm-Up Notebook DateTitle of Activity Page # 2/3Asexual vs. Sexual Reproduction 89

Sex Cells: SPERM and EGG Sex cells should have 1/2 the normal number of chromosomes 11) Sex Cells (Gametes)

12) Chromosome Number Diploid cells: (2n) normal number of chromosomes (Body Cells) Haploid cells: (n) ½ the normal number of chromosomes (Sex Cells)

Diploid vs Haploid Diploid Cells Haploid Cells and Fertilization

13) Meiosis The process by which haploid (sex) cells are produced with half the number of chromosomes.

14) What is the end result of meiosis? 46X 23X Meiosis

15) Where does meiosis occur? Gonads – Ovaries and Testis

16) Why is meiosis important? Maintains the number of chromosomes from generation to generation Provides genetic variation Only during fertilization (union of sperm and egg) is the full (diploid) set of chromosomes restored.

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