lesson overview lesson overview the process of cell division objectives 10.2 the process of cell...
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Lesson Overview The Process of Cell DivisionObjectives 10.2The Process of Cell Division
-Describe the role of chromosomes in cell division.-Name the main events of the cell cycle.-Describe what happens during the four phases of mitosis.-Describe the process of cytokinesis.
Lesson Overview The Process of Cell Division
The genetic information is carried by chromosomes.
Every cell must copy its genetic information before cell division begins.
Cells of every organism have a specific number of chromosomes. Humans have 46 chromosomes (or 23 pairs).
Chromosomes
Lesson Overview The Process of Cell Division
Prokaryotic Chromosomes
Prokaryotic cells lack nuclei. Their DNA molecules are in the cytoplasm.
Most prokaryotes contain a single, circular DNA molecule, or chromosome, that contains the cell’s genetic information.
Lesson Overview The Process of Cell Division
Eukaryotic Chromosomes
In eukaryotic cells, chromosomes are located in the nucleus, and are made up of chromatin.
Chromatin is composed of DNA and histones. The DNA supercoils around the histones (a type of protein).
Lesson Overview The Process of Cell Division
The Prokaryotic Cell Cycle
Prokaryotic cells begin to replicate, or copy, their DNA once they have grown to a certain size.
When DNA replication is complete, the cells divide through a process known as binary fission.
Binary fission is a form of asexual reproduction.
Cell Cycle The longest phase in the cell cycle is interphase.
The 3 stages of interphase are called G1, S, and G2.
M phase is mitosis or meiosis cell division
Phases of cell cycle & Mitosis - IPMATCImportant
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Lesson Overview The Process of Cell Division
The Phases of the Eukaryotic Cell Cycle:
1. Growth/Gap 1 (G1) - cell grows & carries out life functions.
2. Synthesis (S) – DNA is copied.
3. Growth/Gap 2 (G2) – cell continues growth preparing for mitosis & organelles are copied.
*Interphase is the time between cell divisions. It consists of the G1, S and G2 phases. LONGEST STEP IN THE CELL CYCLE!
4. Mitosis (M) – division of the nucleus.
5. Cytokinesis (C) – division of the cytoplasm.
Lesson Overview The Process of Cell Division
MitosisMitosis produces two
genetically identical cells.Mitosis is referred to in the
following stages: prophase, metaphase, anaphase, and telophase.
Lesson Overview The Process of Cell Division
ProphaseDuring prophase the duplicated chromosome become visible.
The nuclear envelope breaks down.
*Longest stage of mitosis
Lesson Overview The Process of Cell Division
Metaphase
During metaphase the chromosomes line up in the middle of the cell.
The spindle fibers connect to the centromere of each chromosome.
Lesson Overview The Process of Cell Division
Anaphase
During anaphase the centromeres are pulled apart and the chromatids separate into two groups near each pole.
*Shortest stage of mitosis.
Lesson Overview The Process of Cell Division
Telophase
During telophase the chromosomes spread out.
A nuclear envelope re-forms around each cluster of chromosomes.
The spindle breaks apart.
Lesson Overview The Process of Cell Division
Cytokinesis is the division of the cytoplasm.
The process of cytokinesis is different in animal and plant cells.
Cytokinesis
Lesson Overview The Process of Cell Division
Cytokinesis in Animal Cells
The cell membrane is drawn in until the cytoplasm is pinched into two equal parts.
Lesson Overview The Process of Cell Division
Cytokinesis in Plant CellsIn plants, the cell membrane is not flexible enough to draw inward because of the rigid cell wall.
Instead, a cell plate forms between the divided nuclei.