Transcript Bio392-Chapter 10-2 - Cell Division- this one!!

Friday Feb 10th
Day E
• Collect remaining Wequests
• Begin 10.2
– Notes
– Video Clip
– Handout
HW – Study for 10.1 Quiz
Chapter 10 Vocabulary
Surface area/volume problems
Chapter 10.2
Cell Division
Cell Division
• Before a cell gets too large, a
growing cell divides forming two
“daughter cells”
• Cell division  process by
which a cell divides into two new
daughter cells
• Before cell division begins,
 DNA replicates (copies) itself
One copy for each new cell
Division in Prokaryotes
• After DNA is copied, cell splits in two
Each new cell contains a copy of the DNA called
binary fission
– Example of  asexual reproduction
Binary Fission in a Paramecium
Division in Eukaryotes
• Occurs in two main stages
– 1st stage division of the nucleus = mitosis
– 2nd stage  division of the cytoplasm = cytokinesis
• Helps multicellular organisms  grow and develop
Chromosomes
•  Structures that carry genetic information
– Made up of  DNA and protein (histones)
• Humans have  46 total (23 pairs)
(other organisms have different numbers)
Chromosomes
• While the cell is “resting”, you cannot see the
chromosomes.
 It is unwound
Called chromatin
(1) Double-stranded DNA. (2) Chromatin strand (DNA with histones). (3)
Chromatin during interphase with centromere. (4) Condensed chromatin during
prophase. (Two copies of the DNA molecule are now present) (5) Chromosome
chromosome
during metaphase.
chromatin
Chromosomes
• While the cell is dividing, you can see the
chromosomes
 It is wound up
Made of two sister chromatids connected by a
centromere
Chromosomes
Sister
Chromatid
Centromere
The Cell Cycle
• Occurs in  eukaryotic
cells
G1 phase
It is the period of time from
the beginning of one cell M phase
division to the beginning
of the next
S
phase
G2 phase
• Cell doubles its contents
so that it is ready to divide
into two completely
independent cells
The Cell Cycle
G1 phase
M phase
S
phase
G2 phase
Consists of 4 phases
– 1. M phase – mitosis  the division of the cell nucleus and cytokinesis
– 2. G1  intense growth and activity; new proteins and organelles are made
– 3. S phase  copying of chromosomes
– 4. G2  intense growth and activity; new proteins and organelles are made
• Shortest of the four phases
M phase
• Cell division
– Process in which the cell divides
into two independent cells
 daughter cells
– Process is called  mitosis in
eukaryotes and  binary fission
in prokaryotes
Cell Cycle Rates
Cells do not move through the cell cycle at
the same rate
– Average rate of a human cell is once every 20
hours
Mitosis
• Time of cell division
• Divided into four main phases
– 1. Prophase
– 2. Metaphase
– 3. Anaphase
– 4. Telophase
Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
1. Prophase
• 1. Appearance of chromosomes
– 2 sister chromatids attached at the
centromere
Spindle
forming
• 2. Nuclear membrane begins to
breakdown
• 3. Spindle begins to form
– Purpose is to pull chromatids apart
Centromere
• 4. Spindle attaches to the chromosomes
at the centromere
– In animals, spindle is made by the centriole
Plants lack centrioles
Chromosomes
(paired chromatids)
2. Metaphase
• 1. Chromosomes line up in the middle of the cell
Centriole
Spindle
Centriole
3. Anaphase
• 1. Centromeres split
• 2. Sister chromatids are pulled to the opposite
ends of the cell by the spindle
Individual
chromosomes
4. Telophase
• 1. Spindle breaks down
• 2. Nuclear envelope
reforms around the
chromosomes
• 3. Chromosomes unwind
to chromatin again
Nuclear
envelope
reforming
Cytokinesis
• Division of the cytoplasm
• In animals the cell
pinches in at the middle
to create two new cells
• In plants  a cell plate is
created in the middle of
the cell
Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Videos
• Animal Cell Mitosis
• Animal Cell Cytokinesis
• Animal Cell Mitosis: Interactive
• How the Cell Cycle Works
Friday Feb 10th
Day E
• Collect remaining Wequests
• Begin 10.2
– Notes
– Video Clip
– Handout
HW – Study for 10.1 Quiz
Chapter 10 Vocabulary
Surface area/volume problems