Quarter 2, Lesson 1

Division of cells and its contents into two or more cells

Cell Division

“Cells come from pre-existing cell”

RUDOLF VIRCHOW

Two types of Cell Division

Mitosis and Meiosis

Stages of Mitosis

Prophase

Metaphase

Anaphase

Telophase

Stages of Meiosis

PMAT I

PMAT II

Why is it important for cell division to occur?

1. Replace

2. Repair

3. Reproduce

Stages of Cell Cycle (Mitotic Phases)

1. Interphase

2. Mitosis

3. Cytokinesis

Preparatory stage before cell division

Interphase

Resting phase

G0 Phase

Cell death

Apoptosis

Rapid growth of newly produced cells. Creation of copies of organelles and molecular building blocks

G1 Phase (First Gap)

Centrioles Replicate. DNA replicates producing 2 (DNA REPLICATION) identical chromatids.

S Phase (Synthesis)

Grows more. Makes more proteins and organelles. Reorganization of cell contents

G2 Phase (Second Gap)

Cell Checkpoints

1. G1 Checkpoint

2. G2 Checkpoint

3. M or Spindle Checkpoint

Cell Checkpoints (2)

G1 → S Phase

G2 → Mitosis

Metaphase → Anaphase

❖Cell Size

❖Nutrients

❖DNA Integrity

G1 Checkpoint

❖DNA Integrity

❖Complete DNA Replication

G2 Checkpoint

❖Chromosome alignment and attachment to spindle fibers

M Checkpoint or spindle checkpoint

A form of cell/nuclear division in which one parent cell divides to produce two new cells (daughter cells)

Mitosis

Produces 2 daughter cells containing the same number of chromosomes as the parent cell.

Mitosis

Diploid

2n

The 2 daughter cells are genetically ________

Identical

➢Chromatin threads condense to become chromosomes ➢Formation of spindle fibers

➢Nucleolus disappears

Early Prophase

➢ Two pairs of centrioles move apart to opposite poles of the cell ➢ Nuclear membrane disappears

➢ Spindle fibers bind to chromosomes at the kinetochore

Early Prophase

➢Alignment of chromosomes along the EQUATORIAL PLANE

Metaphase

➢Spindle fibers shorten and pull the sister chromatids apart to opposite poles of the cell

Anaphase

➢Spindle fibers break down

➢Nuclear envelope forms

➢Nucleolus form

➢Chromosomes start to uncoil

Telophase

➢Division of the cytoplasm

Cytokinesis

Cytokinesis ➢In animals: ________ is formed

CLEAVAGE FURROW

Cytokinesis ➢In plants: _____ is formed instead of cleavage furrows.

CELL PLATE

Type of cell division involved in the production of GAMETES.

Meiosis

Reproductive/sex/germ cells

Gametes

Contain half number of chromosomes as the normal body cells (haploid)

Gametes

Produces 4 daughter cells that have half the number of chromosomes as the parent cell.

Meiosis

Meiosis produces FOUR _______ daughter cells.

Unidentical

Two Divisions of Meiosis

Meiosis I (Reductional)

Meiosis II (Equational)

Meiosis I

PMAT I

MEIOSIS II

PMAT II