Essential Lecture Questions After lecture you should be able to answer

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Essential Lecture QuestionsAfter lecture you
should be able to answer

• 1. What are the reasons cells undergo mitosis?
• 2. What are the parts of the cell cycle?
• In which part does DNA duplicate?
• In which part does mitosis occur?
• 3. What are the 4 stages of mitosis? What happens
  in each stage?
• 4. What is the end result of mitosis?

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The Cell Cycle

• The Cell Cycle-  During the cell cycle, the cell
  grows, replicates its DNA, and divides into two
  daughter cells. G1, S, G2, M
• Interphase- Cell is growing and preparing for
  cell division
• G1 phase
• S phase DNA Replication
• G2 phase
• Cell Division- (M phase) process of one cell
  forming two daughter cells.
• Mitosis- Nuclear division
• Cytokinesis- cytoplasm division

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Figure 12.4 The cell cycle
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Interphase (94 of a Cells Life)

• G1 phase
• Cell increases in size
• Synthesize new proteins and organelles
• S phase
• Chromosomes are replicated here
• DNA/protein complex
• G2 phase
• Many organelles and molecules required for cell
  division are produced

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Definition of Mitosis

• What is mitosis?
• Mitosis is the nuclear division and
  cytokinesis, in eukaryotic cells, producing 2
  daughter cells with the same diploid (2n) number
  of chromosomes (somatic cells).

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Types of Cells

• Somatic Cells- regular body cells (skin, muscle,
  etc)
• Diploid (2n)- have two kinds of each chromosome
• Somatic cells undergo mitosis
• Gamete (germ) Cells- sex cells (sperm and egg)
• Haploid (n)- have one kind of each chromosome.
• Haploid cells will fuse to form a diploid zygote
• Cells undergo meiosis to form germ cells

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Why a Somatic Cell Divides

• The larger a cell grows, the more demands the
  cell places on its DNA and the more trouble the
  cell has moving enough nutrients and wastes
  across the cell membrane
• Specific issues a cell has
• DNA Overload
• Trouble Exchanging Material Surface area/to
  volume ratio
• Damage to tissues repair
• Growth of organism signals mitosis HGF, steroids

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Figure 12.1c The functions of cell division
Tissue renewal
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Why a Somatic Cell Divides

• DNA Overload
• Information is stored in DNA
• As a cell grows it usually does not make copies
  of DNA
• If a cell grew too large an information crisis
  would occur (not enough DNA to instruct the cell
  as needed)

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Why a Somatic Cell Divides

• Cellular Transport needs
• The larger the cell volume
• the more food, water, and oxygen needed
• The more wastes produced
• Less efficient transport

The bigger the cell the greater the distance and
more material to get out and in more volume,
less surface area (plasma membrane)
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Why a Somatic Cell Divides

• Surface Area to Volume
• Cell volume grows quicker than cell surface
• At some point in time there is not enough surface
  area for material exchange (ex. food and waste)

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Key to cell division is the copying and equal
separation of chromosomes.

• Chromatin hazy loose DNA becomes condensed and
  coiled ? chromosomes
• Chromosome- DNA and proteins that contain genetic
  information
• 46 human chromosomes or 23 pairs
• Sister Chromatids- when chromosomes are
  replicated and there are 2 identical parts
• Centromere- part where sister chromatids are
  attached

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Figure 12.3 Chromosome duplication and
distribution during mitosis
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M phase MitosisPMAT

• Prophase
• Metaphase
• Anaphase
• Telophase
• PMAT C Cell Division

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Cell Division (mitosis and cytokinesis)

• Mitosis (P M A T) ?C
• Prophase
• Metaphase
• Anaphase
• Telophase

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Mitosis

• Prophase- 1st and longest phase of mitosis

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Mitosis

• Metaphase- 2nd stage of mitosis

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Mitosis

• Anaphase- 3rd stage of mitosis

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Mitosis

• Telophase- 4th stage of mitosis

In animal cells, a cleavage furrow forms
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Cell Division (mitosis and cytokinesis)

• Cytokinesis- usually occurs at the same time as
  telophase of mitosis

In animal cells, a cleavage furrow forms
In plants cytoplasm is divided by a cell plate
being formed
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Cytokinesis

• Division of the cytoplasm itself
• Plants lack centrioles
• Can take place in a number of ways
• in animal cells draw-string effect
• in plant cells cell plate forms from inside
  out, and cell wall begins to appear

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Figure 12.8 Cytokinesis in animal and plant cells
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Concept Map of all events of Cell Cycle
Section 10-2
Cell Cycle
includes
is divided into
is divided into
Go to Section
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Prokaryote vs. Eukaryote Result

• Multicellular Eukaryotes Results include
  growth, repair of specialized cells in a
  multicellular organism
• Unicellular Eukaryotes and Prokaryotes called
  Cell Division is called Binary Fission
• What is the result?

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http//www.bozemanscience.com/mitosis
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Why do some human cells divide often and others
not at all?
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When cells come into contact with other cells,
they stop growing..
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Regulating Cell Division

• Internal regulators
• Proteins that respond to events inside the cell
• Cyclins- regulate the timing of the cell cycle in
  eukaryotic cells
• External regulators
• Closeness of neighboring cells slows growth (no
  contact inhibition)
• Protein hormones
• Ex. Growth factors stimulate growth

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Effect of Cyclin on the cell cycle
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Role of proto-oncogenes and oncogenes

• Proto-oncogenes (unmutated oncogenes) stimulate
  cell division in a regulated manner.
  Proto-oncogenes include growth factors, growth
  factor receptors, and cyclins.
• Oncogenes are mutated forms of these genes that
  result in unregulated stimulation of cell
  division.

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Cancer
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Uncontrolled Cell Growth

• If growth is not controlled, then crowding and
  even tissue damage may result
• Ex. Cancer disorder where bodys own cells lose
  the ability to control growth can crowd and even
  damage tissue in surrounding area forms tumor
• Benign vs. malignant tumors benign are
  localized and not spreading malignant tumors
  become invasive enough to impair normal function
  of other organs
• Also, malignancies are capable of breaking off
  and starting up in another location -- metastasis

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How do malignancies form?

• Angiogenesis

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Cancer Formation

• DNA Mutations Carcingens, mutagens - oncogenes
• Excessive hormones genetic, environmental
• Heritable mutations mutations in cell cycle
  control genes (Ex p53)
• Viral infections Can insert in DNA and disrupt
  control over cell cycle (HPV)
• Mutated receptor proteins bind hormones too
  tightly (HER2 Receptor)

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HPV Cervical Cancer
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Treatment

• Surgery mastectomy (breast cancer),
  prostatectomy (prostate cancer) etc./can allow
  staging of the cancer
• Radiation therapy use of ionizing radiation that
  damages genetic material so much that cell can no
  further divide (normal cells can be affected by
  radiation as well but can recover)
• Chemotherapy cytotoxic drugs targeting all
  rapidly dividing cells by interfering with
  phases of the cell cycle
• Immunotherapy stimulation of own immune system
  to destroy cancerous cells alpha interferon

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