Drill #1
Jan. 23, 2013
• List the two parts that make up a
chromosome.
• How many chromosomes do human cells
contain?
Reviewing the Chromosome…
• Each chromosome
(coiled DNA)
consists of two
identical “sister”
chromatids.
• Each pair of
chromatids are
attached at an
area called the
centromere.
Sister chromatids
Centromere
Agenda
• Online Cell Cycle Lab
• Course recommendations
Homework
• Complete Cell Reproduction and Mitosis
WS – due Friday
Drill #2
1/24/13
• What is the difference between a
prokaryote and eukaryote?
Drill #3:
1/25/13
• Why does a cell need to go through cell
division?
• If a cell has 3 chromosomes, how many
chromosomes would there be at the end of
mitosis?
SWBAT
• Identify and draw the steps of cell division
in eukaryotes (cell cycle)
Agenda
• Turn in Cell Reproduction/Mitosis WS
• Notes on the Cell Cycle
• Course Recommendation
• Quiz – next week on DNA and the Cell
Cycle
Cell Division in Prokaryotes
• Asexual reproduction
• Binary fission-one cell divides into 2
offspring cells
Cell Division in Eukaryotes
• 2 types:
– Cell Cycle – Interphase & Mitosis-division
of the nucleus
• Takes place in body cells (somatic cells)
– Meiosis-reduces the number of
chromosomes by half in new cells
• Takes place in sex cells (sperm and egg
cells)
Your Turn !
Below are life spans of human cells:
Red blood cell – less than 120 days
Esophagus – 2-3 days
Cardiac muscle – long-lived
Neuron – long lived
Based on this information, how are injuries
to the heart and spinal cord similar to
each other?
Cell Cycle
– Cells grow, prepares for division, and
divides to form 2 daughter cells.
Your Turn!
• Based on the image,
what does a cell
spend most of its time
doing?
Phases of the Cell Cycle
Interphase:
• G1 phase-1st growth phase
– Cell grows
– Synthesize new proteins and organelles
• S phase-synthesis phase
– DNA replication
-- Chromosomes copied
• G2 phase- 2nd growth phase
– Cell continues to grow
– Prepares to divide
4 Phases of the Cell Cycle cont.
M – phase:
– Mitosis - division of the nucleus
– Cytokinesis – division of the cell
Cell Cycle cont.
• Cell spends 90% of its time in Interphase
which includes the first 3 phases G1, S, G2:
Mitosis
• The division of the nucleus
• 4 phases (PMAT)
– Prophase
– Metaphase
– Anaphase
– Telophase
Prophase
•
•
•
•
Start of mitosis
DNA coils into chromosomes
Nuclear membrane disappears
Spindle fibers form
Centrioles
between centrioles
Spindle fibers
Nuclear membrane
Chromosomes
(paired chromatids)
Metaphase
• Chromosomes line up in the middle of the
cell
• Spindle fibers attach at
the centromeres
Anaphase
• Spindle fibers pull chromatids away from
each other toward opposite poles of the
cell
Telophase
• Nuclear membrane forms around
chromatids
• Cytokinesis starts.
Cytokinesis
• The division of the cytoplasm
Cytokinesis in Animal and
Plant Cells
• In animal cells, the cell membrane pinches
in and separates the dividing cell into 2
cells
• In plant cells, vesicles line up in the middle
of the dividing cell
– The vesicles fuse and form the cell plate
– Cell plate separates the cell into 2 cells
Regulation of Cell Cycle
• Controlled by proteins to determine if the
cell should go into the next phase
• If a protein does not work, cell growth and
division will go out of control
– Ex. Cancer-uncontrolled growth of cells that
do not respond to the signals that regulate the
growth of most cells.
– Cancer Causes: DNA becomes damaged or
changed (mutated) from smoking tobacco,
radiation exposure, viral infections, etc.
Skin Cancer
Skin Cancer
CELL DIVISION
• AT THE CONCLUSION OF CELL
DIVISION, EACH OFFSPRING WILL
RECEIVE IDENTICAL COPIES OF THE
CELL’S CHROMOSOMES.
Your Turn!
• How many chromosomes are in a
human skin cell before mitosis?
After?
Name the following stages of
Mitosis:
Agenda
• DNA/Cell Division Concept Map
• Quiz
• Please hand in your cell division computer
game questions.
Drill #17:
Jan. 4 & 5, 2012
• ID each stage of the cell cycle:
– Sister chromatids line up on the midline
– Spindle fibers begin to form
– Sister chromatids separate and begin to move
towards the poles
– Cytoplasm division
– DNA makes a copy of itself
– Two new nuclei form
Drill #17:
Jan. 4 & 5, 2012
• ID each stage of the cell cycle:
– Sister chromatids line up on the midline metaphase
– Spindle fibers begin to form - prophase
– Sister chromatids separate and begin to move
towards the poles - anaphase
– Cytoplasm division - cytokinesis
– DNA makes a copy of itself – S phase
– Two new nuclei form - telophase
Agenda
•
•
•
•
•
Notes on Cell Division – prokaryotes
Notes on Cell Division - eukaryotes
Short clip on Mitosis
Cell cycle Worksheet
Control of Cell Cycle Computer Game
Steps of Binary Fission
1. Circular DNA makes a copy of itself
and attaches to the cell membrane
2. Cell grows and begins to divide
(pinches in the middle)
Splits into 2 new cells (each with
own DNA) that are genetically
identical.
Binary Fission