8.2 The Cell Cycle

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8.2 The Cell Cycle

• The sequence of growth and division of a cell
• Interphase
• Mitosis
• IPMAT

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Cell Size Limitations

• Materials must be able to pass through the
  cytoplasm quickly
• DNA material must be enough in the nucleus to
  control cell activities
• Volume increases faster than surface area as
  cells size increase

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Chromosomes

• Short, stringy, dark-staining structures
• Contains DNA
• Exist as chromatin (strands of DNA)
• Coils, shortens, thickens before cell division

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A. Interphase

• G-1- Cell growth occurs
• S - Chromosomes replicate
• G-2- More cell growth occurs
• G-o phase cells in this phase do not reproduce,
  most cells of the human body are in this phase

Animal cell in prophase
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Review of terms

• Sister chromatids
• Two halves of the doubled chromosomes

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B. Mitosis

• Division phase
• Results in two new cells
• Chromosome sets are identical to those of the
  parent cell

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Phases of Mitosis
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
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Prophase

• First, longest phase
• Sister chromatids held together by centromere
• Nucleus, nucleolus disappears
• Centrioles move to opposite ends of cells
• Spindle forms

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Metaphase

• Short phase
• Double chromosomes attach to spindle fibers at
  centromere
• Chromosomes line up at the equator

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Anaphase

• Sister chromatids separate
• Centromeres split apart

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Telophase

• Reverse of prophase occurs
• Chromosomes uncoil
• Spindle breaks down
• Nucleolus reappears
• New nuclear membrane forms around chromosomes
• Plasma membrane separate the two nuclei

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Cytokinesis

• Division of the cytoplasm
• Plants cell plate forms across cells
  equator
• Animals plasma membrane pinches along
  the equator

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8.3 Control of Cell Cycle

• DNA- Genetic Blueprint for Cells
• Gene- segment of DNA that controls production of
  a single protein
• Cancer- Uncontrolled cell division

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Cancer

• Mistake in cell cycle
• Uncontrolled cell division
• Cancerous cells forms tumors (masses of tissue)
• Tumors deprive normal cells with nutrients

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Factors that affect cancer

• Environmental
• Cigarette smoke
• UV radiation
• Air and water pollution
• Genetic
• Programmed in the genes

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