Welcome to Class What is probability? What is the probability of pulling an Ace out of a deck of cards?

Agenda Finish probability Mitosis and Meiosis

Chromosomes Chromosome – cell structure that contains DNA (Bio A) Gene – on DNA, controls protein synthesis Homologous chromosomes - Chromosomes that make a pair – 1 from each parent Humans have 46 chromosomes

How do we maintain 46 Chromosomes? Produce gametes – sex cells that have half the number of chromosomes Humans have 23 chromosomes per gamete Cell with ½ the number of regular chromosomes (n) is called haploid Cell with all chromosome (2n) is called diploid

6 Stages of Mitosis Interphase – DNA replicates Prophase – Chromosomes condense, spindles appear, nuclear membrane disappears Metaphase – chromosomes attach to spindles, align in center of cell Anaphase – chromosomes move to opposite ends of cells Telophase – nuclear envelope reappears, chromosome decondense Cytokinesis – Cells divide into two cells

Meiosis I Interphase – Chromosomes replicate – Similar to Mitosis! Prophase I – homologous chromosomes pair 1 from mom, 1 from dad – Nuclear envelope breaks down, spindles form – Crossing over!

Meiosis I Metaphase I – Homologous chromosomes line up at center Anaphase I – Homologous pairs move to opposite sides of cell Telophase I – Chromosomes uncoil – Cell divides

Meiosis II Prophase II - no DNA replication!!! – Chromosomes condense – Spindle fibers appear Metaphase II – Chromosomes line up at center Anaphase II – Chromosomes split and move to opposite sides Telophase II – Nuclei form around chromosomes – Cells divide

MeiosisMitosis Chromosome Number: Reduced by half (homologous pairs separate) Remains the same Pairing of Homologues:YesNo Function:sexual reproduction Cellular (asexual) Reproduction (cell division during which the cell nucleus divides); general growth and repair of the body Number of Divisions: 2 nuclear and 2 cytoplasmic divisions 1 division of the nucleus and 1 Cytokinesis Number of Cells produced:42 Creates: Sex cells only: Female egg cells or Male sperm cells Makes everything other than sex cells (Somatic Cells) Occurrence of Crossing Over: YesNo Produces:four haploid daughter cellstwo diploid daughter cells Genetically:differentidentical

MeiosisMitosis Two cell divisions Centrioles appear Half the original chromosomes Homologous Chromosomes pair up Spindle fibers form Cytokinesis Four daughter cells 46 Chromosomes at end X X X X X X X X X X X

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Welcome to Class Define diploid and haploid.

Agenda Review mitosis and meiosis Compare and contrast mitosis and meiosis CH. 10 Study guide

Cytokinesis

MeiosisMitosis Chromosome Number: Reduced by half (homologous pairs separate) Remains the same Pairing of Homologues:YesNo Function:sexual reproduction Cellular (asexual) Reproduction (cell division during which the cell nucleus divides); general growth and repair of the body Number of Divisions:21 Number of Cells produced:42 Creates: Sex cells (GAMETES): Female egg cells or Male sperm cells Makes “normal” cells(Somatic Cells) Occurrence of Crossing Over: YesNo Produces:four haploid daughter cellstwo diploid daughter cells Genetically:differentidentical

MeiosisMitosis Two cell divisions Centrioles appear Half the original chromosomes Homologous Chromosomes pair up Spindle fibers form Cytokinesis Four daughter cells 46 Chromosomes at end X X X X X X X X X X X

Welcome to Class What are three main differences between mitosis and meiosis?

Agenda Quiz Finish Study guide Traits survey Mendel

Online Bio Books Access Code: CCF Glencoe.com

Welcome to Class What is a trait?

Agenda Mitosis/Meiosis Review – Drawing Traits survey Mendel

Mitosis/Meiosis Review 1. Number of Cells – Mitosis creates 2 identical cells – Meiosis creates 4 individual cells 2. Number of chromosomes – Mitosis creates cells with 46 chromosomes (2n – diploid) – Meiosis creates cells with 23 chromosomes (n – haploid) 3. Locations – Mitosis – somatic (“normal”) cells – Meiosis – gametes (sex) cells

Drawing Mitosis and Meiosis

1. Interphase 2. Prophase 3. Metaphase4. Anaphase 5. Telophase/Cytokinesis

1. Prophase I 2. Metaphase I 3. Anaphase I 4. Telophase/Cytokinesis I

1.Prophase II Cells from Meiosis I 2. Metaphase II 3. Anaphase II 4. Telophase II /Cytokinesis II

Importance of Meiosis Genetic Variation

Sexual vs. Asexual Reproduction Asexual Organisms inherit all chromosomes from single parent Genetically identical Sexual Chromosomes from 2 parents Genetic variation