8.3 - Control of Cell Cycle

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8.3 - Control of Cell Cycle

• The speed of cell division varies with
• tissue type and organism
• Intestine lining----24 to 48 hours
• Frog embryo------less than 60 minutes
• Adult liver----------once a year

2. Cell division is still not completely
understood
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Cell Enzymes Control Cell Cycle Cancer
uncontrolled dividing of cells
1. Enzymes normally start and/or stop the cell
cycle
2. Cancer results from cells a. failing to
produce enzymes that inhibit or stop the cell
cycle b. producing too much of enzymes that
continue cell division c. producing enzymes at
the wrong time
3. Enzyme production is directed by cell DNA
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Contact Inhibition -when cells stop dividing
after they completely cover an area
1. Normal cells produce or secrete chemical
signals that stop cell division and growth
when cells come in contact each other
2. Cancer cells will ignore these signals and
continue to grow and divide unchecked 3.
Cancer cells can move from one organ/area to
another spreading the cancer
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Cancer A mistake in the cell cycle
Cancer can be caused by

• Random mutations or changes in one or more genes
• in the DNA that control enzyme production.

2. Environmental factors. Ex. nicotine alcohol
toxic chemicals metal pollutants UV
radiation 3. Inherited potential for certain
cancers 4. Viral infections
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Cancer Growth
1. Cancer cells can grow slowly over many years
(benign tumors). These are more easily treated.
2. Cancer can grow very rapidly and spread
(metastasize) to other body tissues. This is
also called a malignant tumor. Usually treated
with a combination of surgery, radiation and/or
chemotherapy
Since cancer is of the body your white blood
cells cannot protect you from the cancer.
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Basal cell carcinoma is the most common form of
skin cancer worldwide, accounting for 80 of
all diagnosed skin cancer cases. Where it
Occurs Basal cell carcinoma appears most often
on sun-exposed areas, such as the as the
face, scalp, ears, neck, chest, hands, back, and
legs. Though rare, basal cell carcinoma can
occur on skin that has been protected from the
sun.
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• Warning Signs
• Basal cell carcinoma can take several forms
• Small, translucent growth with rolled edges that
  may be
• pigmented (brown) or have small blood vessels
  on
• the surface
• 2. Open sore that bleeds, heals, and then repeats
  the cycle
• 3. Cluster of slow-growing, shiny pink or red
  lesions that are
• slightly scaly and bleed easily
• 4. Flat or slightly depressed lesion that feels
  hard to the
• touch may be white or yellow and have
  indistinct borders
• 5. Waxy scar that is skin-colored, white, or
  yellow

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Basal Cell Carcinoma
This type of basal cell carcinoma is called
sclerosing basal cell carcinoma, which typically
appears as a thickened, skin-colored scar.
This elderly patient has superficial basal cell
carcinoma, a type of basal cell carcinoma that
usually appears as multiple, slow-growing, shiny
pink or red, slightly scaly lesions that most
often develop on the trunk and shoulders.
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Basal Cell Carcinoma
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Squamous Cell Carcinoma  about 16 of new skin
cancer cases in the United States. Where
Occurs- commonly found on sun-exposed areas of
the body, however, it may occur anywhere even
inside of the mouth, on a lip, or on genitals.
Warning SignsSigns of squamous cell carcinoma
include Crusted or scaly area on the skin with a
red, inflamed base Persistent, non-healing,
ulcerated (skin not covering) bump or thickened
skin on the lower lip Wart-like growth or
plaque Sore that does not heal Red, scaly patches
or bumps
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This tumor developed rapidly over a six-month
period on the patients scalp.
This tumor appeared as a persistent,
non-healing lesion on the patients lower
lip.
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The patient said that this lesion, which
appears as a well-defined plaque, had
been slowly growing for years.
Advanced squamous cell carcinoma on the hands
and forearms of an elderly patient.
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Melanoma  What it Looks Like While only 4 of
diagnosed skin cancer is melanoma, melanoma is
the most serious form of skin cancer because
of its ability to spread. This is why it is so
important to catch melanoma early when the cure
rate with dermatological surgery is about 95.
Where OccursMelanoma can appear anywhere on
the body soles, palms, inside the mouth,
genitalia, and underneath nails. However, it is
most commonly found on the back, buttocks,
legs, scalp, neck, and behind the ears. Warning
signs Melanoma often develops in a pre-existing
mole that begins to change or a new mole. It is
estimated that 20 to 40 of melanomas arise from
an atypical mole. This is why it is so
important to be familiar with the moles on
your body and perform regular self-examinations
of your skin. When looking at moles, keep in
mind the ABCDs of Melanoma Detection
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• Asymmetry. If you could fold the lesion in
  two,
• the two halves would not match.

2. Border. Melanomas often have uneven or
blurred borders.
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3. Color. Melanoma typically is not one solid
color rather it contains mixed shads of
tan, brown, and black.  It can also show
traces of red, blue or white.
4. Diameter. While melanomas are usually greater
than 6 millimeters (about the size of a pencil
eraser), they can be smaller. If you notice a
mole different from others, or which changes,
itches, or bleeds even if it is smaller than 6
millimeters, you should see a dermatologist.
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Melanomas
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Lungs and Lung Cancer
Healthy Lungs
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Lungs with Cancer
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Smokers Lungs
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Mouth cancers
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