Transcript Cell Division

How do we get new
cells and new living
things?
Cell Division
Cell Division
Meiosis
Mitosis
• Mitosis, the process • Meiosis occurs during
the formation of
by which the body
gametes in animals.
grows and replaces
cells, is divided into
five phases.
Interphase
Prophase
Metaphase
Anaphase
Mitosis
Overview
Telophase
Interphase
Interphase
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•
•
•
G1 phase- Cell growth
S phase- DNA Replication
G2 phase- Preparation for mitosis
This is the longest phase of all
Prophase
• Nucleus Condenses
• DNA is compacted into movable packages
called Chromosomes
Metaphase
• Aligning chromosomes at cell equator
• Attaching spindle fibers from each new
daughter cell pole to each chromosome at
the centromere
Anaphase
• Spindle fibers pull chromosomes apart
• Half of the chromosomes (chromatid)
moves to a new daughter cell
Telophase & Cytokinesis
• DNA gathers and two nuclei form
• new cell wall and membrane appears
between the two nuclei to form two new
daughter cells and cytoplasm pinches in half
Cell Plate
Interphase
• From new cell formation into rest phase
again
Meiosis
Gamete Formation and
Recombination
Meiosis Definition
cell division that produces reproductive cells in
sexually reproducing organisms; the nucleus
divides into four nuclei each containing half
the chromosome number leading to gametes.
Division 1
• Interphase 1: DNA replication
• Prophase 1: Each chromosome forms and
remains closely associated. These are called
sister chromatids.
• Metaphase 1: Homologous chromosomes
align at the equatorial plate.
• Anaphase 1: Homologous pairs separate with
sister chromatids remaining together.
• Telophase 1: Two daughter cells are formed
with each daughter containing only one
chromosome of the homologous pair.
Division 2
• Prophase 2: DNA does not replicate.
• Metaphase 2: Chromosomes align at the
equatorial plate.
• Anaphase 2: Centromeres divide and sister
chromatids migrate separately to each pole.
• Telophase 2: Cell division is complete.
Four haploid daughter cells are obtained.
Web Link to animated Meiosis
http://www.sumanasinc.com/webcontent/anisamples/majorsbiolo
gy/meiosis.html
Who can Explain Each Step?
Step 4
Step 3
Step 1
Step 2