Content Standard 9

•Identify the process of chromosome reduction in the production of sperm and egg cells during meiosis

Eligible Content

• Describe and identify the process of chromosome reduction in the production of sperm and egg cells during meiosis

• Define haploid• Define diploid

MEIOSIS

• Meiosis – reduction division• Meiosis – reduces the chromosome number by ½ of

the parents cell’s chromosome number.• Meiosis – produces gametes (sex cells)• Meiosis – male = sperm eggs / female=egg cells• Meiosis – guarantees genetic diversity (variations)• Meiosis- Gametes or sex cells are called haploid• Haploid = ½ the original chromosome number• Humans (haploid number = 23)

• Egg cell (each have 23 chromosomes)• Sperm cells (each have 23 chromosomes)

Meiosis

• START One diploid cell • END Four haploid cells (1/2 of the parent cell’s

chromosome number)• Humans

• Diploid = 46• Interphase ( chromosome # doubles b/c of replication)

• 46 * 2 = 92 • Prophase 1• Metaphase 1• Anaphase 1 ( 92 separate two sets of 46)• Telophase 1

Meiosis contiunes

• Telophase 1 One cell divides = two cells each w/46• Prophase II No replication• Metaphase II• Anaphase II two cells each w/46 chromosomes / 46

chromosomes separate• Telophase II two cells complete division = four cells

• each cell has 23 chromsomes

MEIOSIS (1 diploid = 4 Haploid)

46

Diploid

23Haploid

23Haploid

23Haploid

23Haploid Egg or sperm

Egg or sperm

Egg or sperm

Egg or sperm

Meiosis ( Egg/Sperm)

A. Species has 4 chromosomes• What would the egg or sperm cell look like?

B. Species has 2 chromosomes• What would the egg or sperm cell look like?

C. Egg or sperm has 8 chromosomes• How many chromosomes would the organism or

body cells have?

Diploid = 4 chromosomes Chromosome• Which diagram represents the egg or sperm?

Cell (A)

Cell (A)

Cell (B)

Cell (C)

Cell (D)

• Diploid = 4 chromosomes

• Chromosome

Cell BDiploid = 4 chromosomesHaploid / egg or sperm = ½ = 2 chromosomes

Species has TWO chromosomes What would the egg or sperm cell look like?

• Cell C

• Cell D• Cell B

• Cell A

B. Species has 2 chromosomesWhat would the egg or sperm cell look like?

• CELL A

Cell ADiploid = 2 chromosomes Haploid /egg or sperm = ½ = 1 chromosome

HAPLOID CELLS

• HAPLOID

• Egg Cells• Sperm Cells• ONLY SEX cells• Gametes

DIPLOID CELLS = BODYor somatic Cells

• BODY Cells• Plant

• Leaf cells• Stem cells• Root cells

• NOT sex cells• NOT egg or sperm or gametes

Egg or sperm has 2 chromosomes.How many chromosomes in the organism?

• Cell A

• Cell B • Cell D

• Cell C

Egg or sperm has 2 chromosomes.How many chromosomes in the organism?

• Cell D

Egg or sperm = 2Organism or body cells = diploid # 2 (2) = 4