CELL
CYCLE
How many
cells do we
begin with?
How do we
get more?
Cell Cycle
INTERPHASE
G1 PHASE
•“gap 1” Phase
• period when cell growth
and development occur
S PHASE
•“synthesis” Phase
• DNA replication /
synthesis occurs
G2 PHASE
• “gap 2” Phase
• when organelles needed
in cell division are
made (centrioles, spindle
fibers)
CHROMOSOME
structure that
contains genetic
information
(usually visible only in mitosis)
The set of 46 human chromosomes
CHROMATIDS
the two identical
parts on a
chromosome
CENTROMERE
The middle part of
the chromosome that
holds together the
sister chromatids
MITOSIS
GOAL OF THE
CELL CYCLE
to create a new somatic
cell exactly like the
parent
MITOSIS
process by which the
nucleus of a cell is
divided into two nuclei,
each with the same
number of chromosomes
as the parent cell
1. PROPHASE
• The longest phase
• Chromosomes appear
• Centrioles move to
opposite ends of the cell
• Chromosomes attach to
the spindle
• Nucleolus and nuclear
membrane breaks down
PROPHASE (cont…)
• The longest phase
• Chromosomes appear
• Centrioles move to
opposite ends of the cell
• Chromosomes attach to
the spindle
• Nucleolus and nuclear
membrane breaks down
2. METAPHASE
• Shortest phase of
mitosis
• Chromosomes line up at
center of the cell
3. ANAPHASE
• Centromeres split
• Sister chromotids
separate to form
individual chromosomes
• Anaphase ends when
the movement of
chromosomes stops
4. TELOPHASE
• Chromosomes uncoil
into chromatin
• Nuclear membrane
reforms
• Spindle breaks apart
CYTOKINESIS
•The cytoplasm of the cell divides
•Forms two daughter cells that are
exactly like the parent cell (each
have one complete set of
chromosomes)
Meiosis
The process of cell
division so that each new
cell has 1/2 the number of
chromosomes as the
original.