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Bell Ringer. Cell Division Review. Units 5 & 6. Prokaryotic Cell Division. Prokaryotic Cell Division = Binary Fission After DNA replication occurs, the cytoplasm divides. There is NO nucleus, so mitosis does NOT happen. DNA Replication. Cytokinesis.

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prokaryotic cell division
Prokaryotic Cell Division
  • Prokaryotic Cell Division = Binary Fission
  • After DNA replication occurs, the cytoplasm divides. There is NO nucleus, so mitosis does NOT happen.
slide4

DNA Replication

Cytokinesis

This process is called Binary Fission

eukaryotic somatic body cell division mitosis
Eukaryotic Somatic (Body) Cell Division = Mitosis

Stages of Cell Cycle

  • Interphase
    • G1 = Growth
    • S = DNA replication
    • G2 = Prepare for Mitosis
  • M Phase
    • Mitosis = Division of Nucleus
      • Prophase
      • Metaphase
      • Anaphase
      • Telophase
    • Cytokinesis = Division of Cytoplasm
mitosis

MITOSIS

REPRODUCTION OF BODY CELLS

PRODUCES

2 IDENTICAL DIPLOID CELLS

interphase
Interphase
  • Cell Grows & Divides
  • DNA is Replicated
prophase
Prophase
  • Chromosomesbecome visible
  • Nuclear Membrane & Nucleolus Disappear

EARLY

LATE

metaphase
Metaphase
  • Spindle Fibers attach to the Centromeres
  • Chromosomes Line up in the Middle/ Equator
anaphase
Anaphase
  • Sister Chromatids are Pulled Apart (separated) to opposite poles of the cell
telophase
Telophase
  • Nuclear Membrane & Nucleolus Reform
  • Chromosomes Unwind into Chromatin
cytokinesis
Cytokinesis
  • Cytoplasm Divides
  • 2 Identical daughter cells form with the SAMEnumber of chromosomes as parent cell

Occurs during Telophase

mitosis1
MITOSIS

END RESULT:

Produces 2 Genetically Identical Diploid Body (Somatic) Cells

cytokinesis1
Cytokinesis
  • ANIMAL CELL
  • PLANT CELL
meiosis

MEIOSIS

REPRODUCTION OF SEX CELLS

PRODUCES

4 GENETICALLY DIFFERENT HAPLOID GAMETES

interphase1
Interphase
  • Cell Grows & Divides
  • DNA is Replicated
meiosis i
Meiosis I

Anaphase I

Telophase I

Prophase I

Metaphase I

meiosis i i

2 Stages of Division

Meiosis II

Prophase II

Metaphase II

Anaphase II

Telophase II

crossing over
Crossing Over

Synapsis/Tetrad = Homologous Chromosomes Pair Up & Cross Over

  • Crossing Over begins during Prophase I& ends during Anaphase I
  • Crossing Over is important because
    • It increases Genetic Diversity
    • It ensures that all cells produced during meiosis are Different
    • It Unlinksgenes
slide22

Homologous Chromosomes Pair Up & Cross Over

Homologous Chromosomes Line Up In The Middle (double line)

meiosis i1
Meiosis I

Homologous Chromosomes Separate

slide24

Spindle Reforms & Chromosomes Attach

Chromosomes Line Up

in the Middle

(single line)

Sister Chromatids Separate

meiosis ii
Meiosis II

Produces 4 Genetically Different Haploid Gametes (Sex Cells)

slide26

1ovum (egg) produced

4 sperm produced

Fertilization

Zygote

slide29

Human Gametes normally have 23chromosomes.

Human Body Cells normally have 46chromosomes (23pairs).

slide30

What is this disorder called? Down’s SyndromeOR Trisomy 21

This is caused by Nondisjunction.

Nondisjunction can occur during Anaphase IOR Anaphase II of meiosis if the chromosomes do not SEPARATEcorrectly.

slide31

Stage of Meiosis = Anaphase II

Stage of Meiosis = Anaphase I

Too Many Chromosomes

slide32

Crossing Over

Homologous Chromosomes Line Up in the Middle/Equator

Chromosomes Line Up in the Middle/Equator

Homologous Chromosomes Separate

Sister Chromatids Separate

Diploid

Haploid

4

2

Identical Body Cells

Genetically Different Gametes (sex cells)