Why do cells divide?
Agenda for Friday Dec 19th
1. Go over test
2. Mitosis notes & video
3. Mitosis worksheet
Grades on wall
Why does a cell divide?
• Too large to work efficiently
– Smaller the cell = quicker it can work
• Transport of Substances
• Cellular communication
– Ratio of surface area to volume
Other reasons for cellular division
• Growth
• Replace damaged cells
The Cell Cycle
• Cell reaches max size it stops growing or divides
– Cells reproduce by growing and dividing = cell cycle
• 3 main stages of cell cycle
1. Interphase – cell grows, replicates DNA
2. Mitosis – nucleus and nuclear material divide
3. Cytokinesis – cytoplasm divides
3 Stages of Interphase
Gap 1 (G1)
• Right after cell divides, normal functions,
prepares to replicate DNA
Synthesis (S)
• Cell copies DNA (contains genetic material)
– Chromatin is the relaxed form of DNA
– Chromosomes are the condensed form of DNA
Gap 2 (G2)
• Cell prepares for mitosis
Mitosis
• Cell’s DNA separates
– Creates 2 identical daughter cells
– Same DNA
– Same Number of Chromosomes in each cell
• 4 Stages – Prophase, Metaphase, Anaphase,
Telophase
1. Prophase
• Chromatin condenses into chromosomes
– X – shaped
– Consist of two chromatids – identical copies of DNA
– Chromatids are connected at a centromere
1. Prophase
• Nuclear membrane disappears
• Spindle apparatus appears
– Spindle fibers, centrioles, and aster fibers
– Helps move chromosomes
2. Metaphase
• Chromatids Line up at center of cell
3. Anaphase
• Chromatids pull apart
4. Telophase
•
•
•
•
Chromosomes arrive at the poles
Chromosomes unwind (back to chromatin)
Two nuclear membranes begin to form
Spindle apparatus disappears
Cytokinesis
• Divides cytoplasm
• Animal Cells
– Microfilaments constrict/pinch the cytoplasm
• Plant Cells
– Cell plate forms between two daughter nuclei
– Cell walls then form on either side of cell plate
Explain what happens in each step of mitosis.
Agenda for Monday Jan. 5th
1. Review mitosis (video)
2. Go over HW
3. Mitosis Cell Lab
• https://www.youtube.com/watch?v=L0kenzoeOM
If a cell has 150 chromosomes how
many daughter cells are created at the
end of mitosis? How many
chromosomes are in each cell?
Agenda for Tuesday Jan 6th
1. Finish mitosis onion cell lab
http://www.sumanasinc.com/webcontent/animations/content/mitosis.html
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__mitosis_and_cytok
inesis.html
What is cancer?
Agenda for Thursday Jan 8th
1. Cancer Notes
2. Cancer worksheet
Cancer Vocab
• Cancer – uncontrolled growth and spread of
abnormal cells
• Neoplasm – new growth of tissue that serves
no physiological function
• Tumor – clumping of neoplasmic cells
• Malignant - cancerous
• Benign - noncancerous
• Biopsy –examination of cell development
Skin Cancer
• The ABCD’s of melanoma (skin cancer):
–
–
–
–
A
B
C
D
Asymmetry: one half is not like the other
Border: the edges are jagged or irregular
Color: the color is varied, tan, red, black ect
Diameter: the diameter is larger than 8mm
(the top of a pencil eraser
Cancer
• Uncontrolled cell division
• Tumors begin with a single cell that reproduces
by mitosis
– Cells in tumors divide continuously
• Metastasis: Process in which cells are invasive
and move to other sites in the body
How does it happen?
• Two classes of genes: Oncogenes and tumor
suppressor genes
– Proto-oncogenes: control cell division
– Tumor suppressor genes turn off cell division
G2/M checkpoint
4
Cell
division
3
DNA
repair
1
Mitosis
G2
G1
• Checkpoints
in the cell
cycle
regulate cell
division 2
Cell
grows,
doubles
in size
S
Chromosome
duplication
G1/S
checkpoint
Stepped Art
p. 181
The Cell Cycle and Cancer
• Neoplasm- abnormal growth of cells
• Benign neoplasms are not cancerous
– Encapsulated; Do not invade neighboring tissue or
spread
• Malignant neoplasms are cancerous
– Not encapsulated; Readily invade neighboring
tissues
– May also detach and lodge in distant places –
metastasis
Stages of Cancer
• 4 stages,
– 1 = not so bad
– 4 = really bad
• Stage I – localized to one part of the body
Stage II - locally advanced
• Stage III - also locally advanced
• Stage IV - often metastasized, or spread
Causes of Cancer
• Mutation: change in genetic makeup
• A factor which brings about a mutation is
called a mutagen.
• Any agent that causes cancer is called a
carcinogen and is described as carcinogenic.
What Causes Cancer?
Family History
Lifestyle
Environment
Lifestyle Risks
• Smoking
• Diet high fat and low in
fruits and vegetables
• Lack of exercise
• Unprotected exposure to
the sun, (UV) rays
• Obesity
Environmental Risks
• Second hand smoke
• Air pollution
• Industrial pollution
• Chemical exposures
– tar from cigarettes
– some foods
Inherited Risks
• Less than 15% of cancers are inherited
• Gene mutations are linked to some inherited
cancers
• Cancers that may be caused by inherited gene
mutations are:
– Colon cancer
– Breast cancer
– Ovarian
– Prostate cancer
– Skin cancer
• Some families are more susceptible to getting
certain cancers.
– Remember you can’t inherit cancer its just that you
maybe more susceptible to getting it.
Stress
• There is connection between stress, immune
system and cancer, that is changing the
direction of research
– it now appears that cancer cells make proteins
that actually tell the immune system to let them
alone and even to help them grow.
Other ways
• Many forms of cancer related to:
– Physical surroundings
– Personal behavior
– Or both
• At least 50% of all cancer can be attributed to
some type of environmental factor
Treatment
Chemotherapy treatment
• uses medicine to weaken and destroy cancer
cells in the body, including cells at the original
cancer site and any cancer cells that may have
spread to another part of the body.
• a systemic therapy, which means it affects the
whole body by going through the
bloodstream.
Treatment
Radiation therapy (also called radiotherapy)
• high-energy rays are used to damage cancer
cells and stop them from growing and
dividing.
• A specialist in radiation therapy is called a
radiation oncologist
• Like surgery, radiation therapy is a local
treatment; it affects cancer cells only in the
treated area
Cancer Prevention
Healthy lifestyle
• Exercise and proper breathing
• Balanced diet
• Complete rest and sleep
• Water
• Eating Fruit
lab
How does one go about getting
cancer (name 2 ways)?
Agenda for Friday Jan 9th
1. Quiz
2. Cancer lab
Mitosis Foldable
Go to Page 243
Follow those directions
Homework
• Page 253 – 257
• Questions 1 – 7 on page 257