Download - Ch6a CellDiv Mitosis and Cancer F14s
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Cell Division: Overview
The Cell Cycle and Mitosis
Cancer
Cell Division, Mitosis, and
Cancer (Ch. 6 part 1)
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Learning Objectives: Overview
Identify the three different types of celldivisionand the functions of each
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Cell Division: Three Types
Binary fission
Used for asexual reproduction
Mitosis, Meiosis
Asexual reproduction:
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Prokaryotes reproduce by binary fission
Circular parent
chromosome
Parent cell
divides;
duplicate
chromosomes
separate
Duplicate
chromosomes
Genetically
identical
daughter cells
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FUNCTIONS OF MITOSIS
Early human embryo
LM
ColorizedTEM
Red blood cells
Mitosis produces duplicate cells
Used for many functions in eukaryotes
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Sea starsLM
Amoeba African Violet
FUNCTIONS OF MITOSIS, continued
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Meiosis:
Two
parents
FERTILIZATION
Sperm cell
Offspring
(has mixture
of genes from
2 parents)
Egg cellGametes
MEIOSIS
Each gamete
has only half the
parents DNA
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Learning Objectives:
Cell Cycle and Mitosis
Name the 2 main phases of the cell cycleand describe the events that occur in each
Distinguish between the terms chromatin,
sister chromatid, centromere, chromosome List the 4 main stages of mitosisin order,
and describe the events that occur in each
Distinguish mitosis from cytokinesis
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G1
S
G2
M
The Cell Cycle regulates the
growth and mitotic division
of eukaryotic cellsInterphase:
Mitotic (M)
phase:
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DNA replication during Interphase
produces identical sister chromat ids
one DNA molecule
two identical DNA molecules(= )
The chromatids stayjoined together at the:
repl icat ion
one chromosome Still have only one
chromosome!
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The M Phase includes two distinct
events: mitosis & cytokinesis
Mitosis:
4 subphases
G2
M
Cytokinesis:
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Duplicated chromosome
(sister chromatids
joined at centromere) TEM
Coiled fiber
Looped regions
Centromere
DNA in
condensed form
DNA in form
of chromatinDuring the
M phase, the
chromosomes
are condensed
and visible
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Distinct chromosomes
seen during cell division
LM
DNA in form of chromatin
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Mitosis begins with Prophase
Nuclear
envelope
Plasma
membrane
Chromosome consisting
of two sister chromatids
Spindle
microtubules
Fragments of
nuclear envelopecentrosome
Centromere
centrosomes
Chromatin
PROPHASEINTERPHASE
1)
2)
3)
Mitotic spindle: cage of
microtubulesradiating
from centrosomesat
opposite poles of cell
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Metaphase and Anaphase ensure an
orderly division of chromosomes
Anaphase:
ANAPHASEMETAPHASE
Spindle Daughter chromosomes
Metaphase:
Spindle fibers aid chromosome movements
sister
chromatids
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Telophase is the last stage of Mitosis
and overlaps with Cytokinesis
Cytokinesis: two new daughter cells formed through
division of cytoplasm and other organelles
Telophase:
1)
2)
3)
Cleavage
furrowNuclear
envelope
forming
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Learning Objectives: Cancer
Define cancer, and explain how cancer isrelated to the cell cycle and mutations
Explain how age and inherited cancer
genes increase a persons cancer risk Describe several ways in which personal
habits and individual choices can affect a
persons risk of developing cancers Explain why chemotherapyoften has
unpleasant side effects
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Cancer
Leading causes of
death in the U.S.:
1. Heart disease (25%)
2. Cancer (23%)
Lifetime risk of cancer (U.S.):
Uncontrolled celldivision produces
tumorsthat can disrupt
vital organ functions
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Conversion to a cancerous cell
usually requires multiple mutations
Explains:
1mutation
Normal cell Cancerous cell
4mutations
3mutations
2mutations
Chromosomes
New cancer diagnoses per year (U.S.):
Age 50+ : 15 per 1000 people
Age
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Inherited cancer genes
1mutation
Gamete-
producing
cell (normal)
Chromosomes
gamete
(e.g., egg cell)
All cells in offspring
will have the mutation
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Many environmental and lifestyle
factors increase cancer risk
Carcinogens
UV and other high-energy radiation
Tobacco chemicals
Alcohol (liver cancer) Viruses
Disrupt cell cycle regulator
genes or proteins
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Many cancer treatments act to
inhibit cell division
Side effects of
chemotherapy
hair root cells
cells lining
digestive tract
bone marrow cells(give rise to red and
white blood cells)