THINK ABOUT IT
What role does cell division play in your life?
Does cell division stop when you are finished growing?
Lesson Overview
The Process of Cell Division
Chromosomes
What is the role of chromosomes in cell division?
Chromosomes make it possible to
separate DNA precisely during cell
division.
Every cell must copy its genetic information before cell division begins.
Each daughter cell gets its own copy of that genetic information.
Cells of every organism have a specific number of chromosomes.
Lesson Overview
The Process of Cell Division
Eukaryotic Chromosomes
In eukaryotic cells, chromosomes are located in the nucleus, and are made up of chromatin.
Lesson Overview
The Process of Cell Division
Chromatin is composed of DNA and histone proteins.
Lesson Overview
The Process of Cell Division
DNA coils around histone proteins to form nucleosomes.
Lesson Overview
The Process of Cell Division
The nucleosomes interact with one another to form coils and supercoils that make up chromosomes.
Lesson Overview
The Process of Cell Division
Prokaryotic Chromosomes
Prokaryotic cells lack nuclei. Instead, their DNA molecules are found in the cytoplasm.
Most prokaryotes contain a single, circular DNA molecule, or chromosome, that contains most of the cell’s genetic information.
Lesson Overview
The Process of Cell Division
The Prokaryotic Cell Cycle
The prokaryotic cell cycle is a regular pattern of growth, DNA replication, and cell division.
Most 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.
Lesson Overview
The Process of Cell Division
The Cell Cycle
What are the main events of the cell cycle?
During the cell cycle, a cell grows, prepares for division, and divides to form two daughter cells.
Lesson Overview
The Process of Cell Division
The Eukaryotic Cell Cycle
The eukaryotic cell cycle consists of four phases: G1, S, G2, and M.
Interphase is the time between cell divisions. It is a period of growth that consists of the G1, S, and G2 phases. The M phase is the period of cell division.
Lesson Overview
The Process of Cell Division
G1 Phase: Cell Growth
In the G1 phase, cells increase in size and synthesize new proteins and organelles.
Lesson Overview
The Process of Cell Division
S Phase: DNA Replication
In the S (or synthesis) phase, new DNA is synthesized when the “chromosomes” are replicated (chromatids become chromosomes).
Lesson Overview
The Process of Cell Division
G2 Phase: Preparing for Cell Division
In the G2 phase, many of the organelles and molecules required for cell division are produced.
The “mother cell” pushes the size limits.
Lesson Overview
The Process of Cell Division
M Phase: Cell Division
In eukaryotes, cell division occurs in two stages: mitosis and cytokinesis.
Mitosis is the division of the cell nucleus.
Cytokinesis is the division of the cytoplasm.
Lesson Overview
The Process of Cell Division
Concept Map
includes
is divided into
is divided into
Section 10-2
Cell Cycle
M phase
(Mitosis)
Interphase
G1 phase
S phase
Prophase
G2 phase
Metaphase
Telophase
Anaphase
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I P M A T
Lesson Overview
The Process of Cell Division
Mitosis
What events occur during each of the four phases of mitosis?
During prophase, the genetic material (chromatin) inside the nucleus condenses and the duplicated chromosomes become visible. Outside the nucleus, a spindle starts to form.
The centrioles move to opposite sides of nucleus and help organize the spindle.
The spindle forms and DNA strands attach at a point called their centromere.
The nucleolus disappears and nuclear envelope breaks down.
Lesson Overview
The Process of Cell Division
Mitosis
What events occur during each of the four phases of mitosis?
During metaphase, the centromeres of the duplicated chromosomes line up across the center of the cell. Spindle fibers connect the centromere of each chromosome to the two poles of the spindle.
Lesson Overview
The Process of Cell Division
Mitosis
What events occur during each of the four phases of mitosis?
During anaphase, the chromosomes separate and move along spindle fibers to opposite ends of the cell.
The centromeres are pulled apart and the chromatids separate to become individual “chromosomes”. The “chromosomes” congregate into two groups near the poles of the spindle.
Lesson Overview
The Process of Cell Division
Mitosis
What events occur during each of the four phases of mitosis?
During telophase, the chromosomes, which were distinct and condensed, begin to spread out into a tangle of chromatin.
A nuclear envelope re-forms around each cluster of chromosomes.
The spindle breaks apart, and a nucleolus becomes visible in each daughter nucleus.
Cytokinesis occurs
Lesson Overview
The Process of Cell Division
Cytokinesis
How do daughter cells split apart after mitosis?
Cytokinesis completes the process of cell division – it splits one cell into two.
Lesson Overview
The Process of Cell Division
The Stages of the Cell Cycle
Lesson Overview
The Process of Cell Division
Lesson Overview
The Process of Cell Division
Lesson Overview
The Process of Cell Division
Lesson Overview
The Process of Cell Division
Lesson Overview
The Process of Cell Division
Lesson Overview
The Process of Cell Division
Important C-words Involved in Mitosis
Chromosome – paired spooled up (organized) DNA
Chromatid – each strand of a duplicated chromosome
Centromere – the area where each pair of chromatids is joined
Centrioles – tiny structures located in the cytoplasm of animal cells that help organize the spindle
Cytokinesis – division of the cytoplasm.
cell plate – cytokinesis in plant cells
cleavage furrow – cytokinesis in animal cells
Cell cycle – life of a cell between divisions (G1,S,G2,M)
Lesson Overview
The Process of Cell Division