Transcript Cell Division: Mitosis and Cytokinesis

The Cell Cycle:
Interphase, Mitosis and
Cytokinesis
Gridlock Rules
Introduction:
You should be able to:
• Define interphase, mitosis and
cytokinesis
• Describe the cell cycle
• Discuss the events and
significance of mitosis.
Definitions:
• Interphase: the period during the
cell cycle between cell divisions,
during which DNA replication and
protein synthesis take place.
More...
Definitions (cont).
• Mitosis: is the process by which the
nucleus of a cell is divided into two
nuclei, each with the same number
and kinds of chromosomes as the
parent cell.
• Cytokinesis: is the process by which
the cytoplasm divides forming two
distinct cells.
Review:
• Chromosomes: are
structures in the cell
that contain genetic
information that is
passed from one
generation to the
next.
Chromosomes:
• Only visible during mitosis
• Made up of chromatin
(DNA and proteins)
• Cells of every organism have a
specific number of chromosomes.
(Goldfish=94, Humans=46)
Chromosome Structure
• Each chromosome is
made up of two
identical chromatids
joined at a specific
site called the
centromere.
The Cell Cycle
Interphase
Cytokinesis
Mitosis
Interphase
• Period “in between” cell divisions
• Usually longer than other phases
• Chromosomes are unraveled, the
DNA is at work
• 3 main parts of interphase
– G1 , S , G2
Interphase (cont.)
• G1- Cell growth and
development
• S- DNA replication & Protein
Synthesis
• G2- Organelle replication
Interphase
Animal
Plant
Mitosis
•Prophase
•Metaphase
•Anaphase
•Telophase
Prophase
• Longest phase of mitosis
• Chromosomes begin to form visible
coils
• Centrioles move to opposite ends of
the cell (no centrioles in plant cells)
• Spindle fibers form
• Nucleolus disappears
• Nuclear envelope breaks down
Prophase
Animal
Plant
Metaphase
• Shortest phase of mitosis
• Chromosomes are fully coiled
• Chromosomes line up at the
middle of the cell
• Spindle fibers form star-like
patterns around the
centrioles called asters
Metaphase
Animal
Plant
Anaphase
• Begins when the sister
chromatids begin to separate
• Chromatids move to opposite
ends of the cell
• Anaphase ends when the
chromatids stop moving
Anaphase
Animal
Plant
Telophase
• Chromatids uncoil
• Two nuclear envelopes form
• Spindle fibers disappear
• Nucleoli become visible
• Telophase is the end of mitosis,
but not the end of cell division.
Telophase
Animal
Plant
Animal Cell Mitosis
I
A
P
M
T
Plant Cell Mitosis
I
P
A
M
T
Cytokinesis
• Immediately following mitosis
• Cytoplasm divides
• Two separate cells are formed
Cytokinesis
Animal
Cell Cycle Summary
• Interphase
• Mitosis:
•Prophase
•Metaphase
•Anaphase
•Telophase
• Cytokinesis
Plant Vs. Animal
Cellular Division
• Animal Cells have centrioles,
Plant cells do not
Plant Vs. Animal
Cellular Division
•Animal cells form a
cleavage furrow during
cytokinesis (cell membrane
pinches in the middle)
Plant Vs. Animal
Cellular Division
•Plants generate a cell plate
at the equator during
anaphase.
•Cell plate is filled with
cellulose to make a new cell
wall.
Animal Cell
Cleavage Furrow
Plant Cell
Cell Plate
Prokaryote Vs. Eukaryote
Cell Division
• Prokaryotes divide by process
called Binary Fission
• They only have one
chromosome called a nucleoid
• Nucleoid is copied and
separated during division
Prokaryote Vs. Eukaryote
Cell Division
• Binary fission produces 2
identical daughter cells
• Can happen as fast as every 20
minutes.
Nucleoid
Prokaryote Vs. Eukaryote
Cell Division
• Eukaryotes produces 2 or more
chromosomes
• Organelles must be evenly
separated into the new cells
• Slower process (Human cells
take over 16 hours to divide)
Cancer
• Cancer is the uncontrolled
growth and division of cells
• group of cancer cells is a
tumor
• As the tumor grows, it destroys
neighboring cells and tissues
Cancer
• Two types of tumors
1. Benign- cells grow in a ball,
does not invade other cells.
2. Malignant- unorganized
growth that can spread to
other parts of the body or
tissues.
Cancer Cells