Bateman’s principle

In most cases, it is the male’s secondary sexual traits that are exaggerated.

This shows that sexual selection is more common and intense on males than females

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#Unit 4. Cell Communication and Cell Signaling

Tumors are detected only after they have reached 1cm3 in size.

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#Unit 4. Cell Communication and Cell Signaling

Precancerous cells have: 

lost contact inhibition

less adherent and more rounded than normal cells

continue to divide

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#Unit 4. Cell Communication and Cell Signaling

Malignant tumors are classified by their embryonic

tissue of origin:

Carcinomas -derive from epithelia such as endoderm

(gut epithelium) or ectoderm (skin and neural epithelia) 

Sarcomas - derive from mesoderm (muscle, blood, and

connective tissue precursors)

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#Unit 4. Cell Communication and Cell Signaling

Leukemias 

a class of sarcomas, grow as individual cells in the blood

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#Unit 4. Cell Communication and Cell Signaling

Melanoma 

Cancer that develops from the Pigment producing cells of skin

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#Unit 4. Cell Communication and Cell Signaling

Mutations in three broad classes of genes have been implicated in the onset of cancer. 

Protooncogenes

Tumor-suppressor genes

genome maintenance genes