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© Cengage Learning 2015 Biology Concepts and Applications | 9e Starr | Evers | Starr © Cengage Learning 2015 Chapter 11 How Cells Reproduce
© Cengage Learning 2015
Biology Concepts and Applications | 9e
Starr | Evers | Starr
© Cengage Learning 2015
Chapter 11
How Cells Reproduce
© Cengage Learning 2015
Mitosis – Nucleus of a cell divides to create
2 new nuclei, each containing an identical
copy of DNA
Why does mitosis occur?
• Cell Replacement
• Growth via cell division
• Reproduction (asexual)
Figure 8.1
• Chromatin = DNA
and associated
proteins, before
condensing into
chromosomes
Figure 8.4
DNA double helix
Histones
“Beads on a string”
Nucleosome
Tight helical fiber Supercoil
Sister chromatids
Centromere
The Cell Cycle
Figure 11-4a p180
Interphase
Figure 11-4b p180
Prophase
Figure 11-4d p180
Metaphase
Anaphase
Figure 11-4f p180
Telophase
Cytokinesis: Cytoplasmic Division
Cleavage
furrow
Cell plate
Mitosis rap
• http://www.sciencemusicvideos.com/mitosi
s-cell-division-rap/
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Homologous Chromosomes
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Control Over the Cell Cycle:
Checkpoint Genes
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Factors Affecting Cell Division
• Anchorage
• Cell density
• Growth factors
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Cancer: A Disease of the Cell Cycle
T-cells attacking cancer cell
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Types of mutations that affect cell cycle
• Checkpoint genes
mutate causing the loss
of function of protein
products
• When enough fail, a cell
loses control over its cell
cycle
• Checkpoint malfunctions
passed along to cell’s
descendants
Lung cancer cell dividing
© Cengage Learning 2015
• Neoplasm (tumor)
– Accumulation of
abnormally dividing
cells
– Benign
– Malignant
• Metastasis
Terminology
Breast cancer cell
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Benign tumor
(neoplasm)
Cells of a malignant
neoplasm can break
free, enter blood or
lymph vessels and
migrate
(metastasis)
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Skin Cancers
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Some Good News
• Mutations in multiple checkpoint genes are
required to transform a normal cell into a
malignant one
– Such mutations may take a lifetime to
accumulate
• Lifestyle choices can reduce one’s risk of
acquiring mutations:
– Do not smoke
– Avoid sun exposure
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Cancer Treatment
• Surgery
– To remove the tumor
• Radiation Therapy
– Beams of high energy radiation are used to destroy the cancer cells
• Chemotherapy
– Drugs that disrupt the cell cycle
– See examples on next slide
Chemotherapy
Drugs
• Taxol
– Stops mitosis after formation of the mitotic
spindle
– Made from the Pacific Yew Tree in the Pacific
Northwest
• Vinblastine
– Prevents the mitotic spindle from forming
– From the Periwinkle plant from Madagascar
