Transcript Cell Division

CELL CYCLE
The Cell Cycle
• Cells undergo an orderly sequence of
events as they grow and divide.
• The sequence in the following slides show
a typical cell cycle of an animal cell.
• The end result are two “daughter cells.”
• Each will then begin the cell cycle again.
Length of the
Human Liver Cell Cycle
Chromosomes and DNA
• Chromosome
structures of DNA and
proteins
• Gene
a section on a
chromosome that has
genetic information for
a trait
• DNA
deoxyribonucleic acidgenetic material
Phase One
INTERPHASE
The period during the cell cycle of a
cell’s growth and development. Most
cells go through three stages:
1. Rapid growth and replication
2. Copying DNA
3. Preparation for cell division
During Interphase, the cell grows, makes a copy
of its DNA, and prepares to divide into two cells.
Phase 2
MITOSIS
BEGINS
Chromatin in the nucleus condenses to form chromosomes. The
pairs of centrioles move to opposite sides of the nucleus. Spindle
fibers form a bridge between the ends of the cell. The nuclear
envelope breaks down.
The chromosomes line up across the center of the cell.
Each chromosome attaches to a spindle fiber at its
centromere.
The centromeres split. The two chromatids separate, and each
chromatid becomes a new chromosome. The new chromosomes
move to opposite ends of the cell. The cell stretches out as the
opposite ends are pushed apart.
The chromosomes begin to stretch out and lose their
rod-like appearance. A new nuclear envelope forms
around each region of chromosomes.
Stage 3
CYTOKINESIS
The cell membrane pinches in around the middle of the cell. The
cell splits in two. Each daughter cell ends up with an identical set
of chromosomes and about half the organelles.
The Cell Cycle
Results of Cell Division
• Reproduction
– Unicellular reproduction
• Growth
– Multicellular organism
• Replacement
– Replaces worn out cells
• Repair
– Repairing damage to most cells