CancerAbnormal Cell divisionMedical technologies

Cell Cycle

• The cell cycle regulates how long a cell lives

Cell Lifespan

Cell Type LifespanLining of gut 5 days

Skin 14 daysRed blood cell 120 days

Liver cell 300-500 daysBone 10 years

Neurons From birth

Cell DeathNecrosis•Death due to unexpected and accidental cell damage/injury that cannot be repaired•Causes: toxins, radiation, lack of oxygen due to the blockage of blood flow

Apoptosis•Programmed cell death – Regulated and controlled cell death•A way of removing unwanted cells

Cell Death

Cell Damage

Specific Signal

Apoptosis – Regulated cell death

• Cells programs itself to die after it has done its job

• Example: white blood cells after repaired the injury

Out of control cell division• What happens when a cell doesn’t destroy itself?

• What happens when a cell doesn‘t stop dividing?

Cancer• Cancer: a group of diseases in which cells undergo uncontrolled division

• Tumour: mass of cells that grow and divide without any obvious function in the body

• Benign tumour: cells stay together having no effect on surrounding tissue other than physical crowding

• Malignant tumour: cells interfere with the function of surrounding cells

Characteristics of Cancer Cells

• Rapid cell division• Uses energy and resources of other cells• Does no useful work of its own• May undergo metastasis: cancer cells that break away from the original location and move through the blood stream to a secondary location

http://www.sciencephoto.com/media/247272/view

Cancer animation• http://www.youtube.com/watch?v=LEpTTolebqo

Cause of Cancer: Mutations

• Genetic mutations in the parts of the DNA responsible for regulating the cell cycle

• Loss of 1 or more cell cycle checkpoints

http://train-srv.manipalu.com/wpress/wp-content/uploads/2010/01/clip-image004137.gif

Results of Mutation

• Cell spends less time in interphase

• Continuous mitosis• Rapid cell division

Cause of Cancer: Carcinogens Environmental factors that cause cancer

• Viral: • hepatitis B (liver cancer)• HPV (cervical cancer)

• Ionizing radiation: • nuclear fallout• x-rays• sun (skin cancer)

• Mutagenic chemicals: • cigarette (lung cancer)

Cause of Cancer: Carcinogens• Development of cancer is unpredictable when people are exposed to a carcinogens

Diagnosing Cancer: Imaging technologies• Endoscopy• X-ray• Ultrasound• CT/CAT scan (computerized axial tomography)

• MRI (magnetic resonance imaging)

CT scan animation

Endoscopy

X-ray

Lung cancer in smokers

Note: X-ray can also cause DNA damage

Ultrasound

Ovarian Cancer

CT/CAT scan (computerized axial tomography)CT scan of healthy lung•http://www.youtube.com/watch?v=j3Plfdmg2P8

MRI (magnetic resonance imaging)

Brain tumor

Diagnosing Cancer: Biopsy

• A sample of tissue is removed and analyzed to determine what it is

CT scan animation

Diagnosing Cancer: Biopsy

CT scan animation

Reducing Risk: Screening• Important for those with a family history of cancer• Does not prevent cancer but increase the chance of detecting it early to treat it

• Examples: self-examination, blood tests etc.• Some common screening:

• Breast exam for breast cancer• Pap smear for cervical cancer

Reducing Risk: Lifestyle Choice• Healthy diet• “super foods”• Reduce body fat• Not smoking

Cancer Treatments• Surgery – physical removal of the tumour• Chemotherapy – a combination of drugs that kill rapidly dividing cells like cancer cells but can also affect normal rapidly dividing cells (e.g. hair follicle, intestinal cells)

• Radiation therapy – high energy radiation to kill cancer cells but can damage normal cells

Specialized cellsCells differentiate into different types of cells for their specific function

The “typical” animal cell

Fig. 7.7 Campbell

The “typical” plant cell

Fig. 7.8 Campbell

What actual cells look like• Cells in organisms are specialized• Differentiation not only affects function but also STRUCTURE• Example: red blood cells is flat for easier diffusion of

oxygen• Cells physically look different from each other

Specialized Cells

• Complex organisms contain many different types of cells that perform different functions

• Specialized cells have physical and chemical differences that allow them to perform one job very well

Specialized Plant Cells:transport cells (xylem in orange, phloem in green)

Specialized Plant Cells:storage cells (amyloplasts)

Specialized Plant Cells:photosynthetic cells (contain many chloroplasts)

Specialized Plant Cells:root hair cells (epidermal)

Specialized Plant Cells:guard cells (stomata)

Specialized Animal Cells:blood cells (red erythrocytes & white leukocytes)

Specialized Animal Cells:skin cells

Specialized Animal Cells:bone cells (osteoclasts and osteoblasts)

Specialized Animal Cells:muscle cells

Specialized Animal Cells:muscle cells

• Cross-section: bundles of muscle fibres

• Longitudinal section: striations

http://cellbio.utmb.edu/microanatomy/muscle/striated_skeletal_muscle.htm

Specialized Animal Cells:gametes (sperm & egg)

http://www.bbc.co.uk/schools/gcsebitesize/img/bieggsperm2.jpg

Specialized Animal Cells:gametes (sperm & egg)

Specialized Animal Cells:fat cells (adipocytes)

Specialized Animal Cells:fat cells (adipocytes)

• Large, central droplet of fat pushes the nucleus to one side.

http://www.mhhe.com/biosci/ap/histology_mh/adipos2.jpg

Specialized Animal Cells:nerve cell (neurons)

Specialized Animal Cells:nerve cell (neurons)

http://www.loria.fr/~rougier/artwork/neuro/img/neuron-SEM-2.png

Specialized Animal Cells:rod & cone cells (retina)

Specialized Animal Cells:lung cells

Specialized Animal Cells:figure 2 & 3 on p.59-60 of Nelson Perspective 10