Download Regular sequence of growth and division that cells undergo

1.27.11
Genetics
The Cell Cycle
What is the Cell Cycle?
The regular sequence of growth
and division that cells undergo is
known as the cell cycle.
Organisms grown and maintain
themselves by cell division (or
making new cells)
What is the Cell Cycle?
Regular sequence of growth
and division that cells
undergo.
CELL
CYCLE
Organisms grow and
maintain themselves by cell
division
Mitosis is the basic process
of cell division
For each new daughter cell,
the cycle begins again with
interphase.
STAGES OF THE CELL CYCLE
Interphase
Mitosis
Cytokenesis
TWO
DAUGHTER
CELLS
ONE
CELL
What’s a Chromosome?
Remember how DNA is found in
the nucleus of a cell?
When DNA condenses and coils
up really tight, it makes a
chromosome.
CHROMOSOMES
Body cells have a
full set of
chromosomes.
Full Set = Diploid #
Sex cells have a
half set.
Half Set = Haploid #
CHROMOSOMES
For Humans, the diploid number is 46.
For humans the haploid number is 23
Different organisms have different diploid and
haploid numbers because they have different
numbers of chromsomes.
Structure of Chromosomes
Chromatids: the 2 identical parts of a
chromosome
Centromere: the middle, round part of
the chromosome that holds the sister
chromatids together
Centromere
Sister chromatids
Sister
chromatids
CENTROMERE
It’s in the center!
INTERPHASE
Growing: The cell grows to its full size and produces structures it needs.
Copying DNA: Cells make an extra copy of the DNA in its nucleus in a
Process called replication.
Replication is important because each new cell, called
a daughter cell, must have a complete set of DNA to
survive (46 chromosomes)
Preparing for Division: Cells produce structures that it will use to divide
into 2 new cells.
Interphase
How many cells
does it take to
make a human?
EGG
SPERM
How do we
get more?
MITOSIS
MAIN IDEA
It’s Mitosis!
Cells Divide in 2
Each New
Daughter Cell Has
Identical
Chromosomes
2 Types of Cells
Body cells: all cells in the human body
except sex cells
•Have a full set of chromosomes
Ex: muscle cell, brain cell, skin cell
Sex cells: sperm and egg cells
•Have a half set of chromosomes
Mitosis
Mitosis: process in which a body
cell divides into 2 identical daughter
cells
•The goal is to make new body
cells
Phases of Mitosis
Interphase
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
Cytokinesis
Mitosis
daughter cells
Prophase (1st Phase of Mitosis)
Prophase (1st Phase of Mitosis)
Mitosis begins.
DNA
condenses
from stringy
DNA into
rodlike structures
Prophase (1st Phase of Mitosis)
• Mitosis begins.
• Chromosomes
condense from
stringy DNA
into rodlike
structures.
• Nuclear
membrane
disappears.
spindle
DNA
(chromosomes)
Metaphase (2nd Phase of Mitosis)
• The
chromosomes
line up across
the center of
the cell.
• Each
chromosome is
connected to a
spindle fiber at
its centromere.
Spindle
Anaphase (3rd Phase of Mitosis)
The sister
chromatids
separate and
move to
opposite
sides of the
cell.
Telophase (4th Phase of Mitosis)
• A nuclear
membrane
forms around
each set of
chromosomes.
Telophase (4th Step of Mitosis)
• A nucleus forms
on each side
• The
chromosomes
go back to
stringy shape.
Cytokinesis
• The cell
pinches in half.
• Each daughter
cell has an
identical set of
chromosomes.
CYTOKINESIS
(the cytoplasm
pinches and
splits in 2)
Prophase? Metaphase? Anaphase? Telophase?
1
3
2
4
5
6
Prophase? Metaphase? Anaphase? Telophase?
1
2
5
3
6
4
7
Mitosis Paper Plate Model
Groups of 2
Mitosis Microscope Lab
& Paper Plate Model
2 groups (rotating) –
20 minutes each