The Integumentary System
More Than Skin Deep
Mitosis
TAKS
• Objective 2 – The student will
demonstrate an understanding of
living systems and the environment.
TEKS
• The student knows the structures and
functions of nucleic acids in the
mechanisms of genetics. The student is
expected to
(C) compare the processes of mitosis and
meiosis and their significance to sexual
and asexual reproduction
Engage
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Grace’s Story
Explore 1: Onion Root Tip
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How many
anaphases can you
spot?
What phase is
represented by the
cells with the dark
circles?
Exploration 2: Onion/Whitefish Lab
Cells in Action
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Mitosis
Mitosis Animation
Explain:
Mitosis (Nuclear Division)
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Mitosis is considered nuclear division
since the steps only refer to the
contents of the nucleus.
There are 4 steps.
Prophase
P
Metaphase M
Anaphase A
Telophase T
Prophase
Early Metaphase
Late Metaphase
Anaphase
Telophase
Interphase Review (G1, S, G2)
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Chromosomes are replicated
Chromsomes appear as threadlike coils
(chromatin) at the start, but each
chromosome and its copy
(homologous chromosome) change to
sister chromatids at the end of this
phase
Prophase
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The nucleus disappears
DNA Condenses
The chromatid pairs
(sister chromatids)
are joined by a
centromere.
The thread-like spindle
fibers appear.
The centrioles move
toward the poles.
Metaphase
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The shortest stage of
mitosis.
Sister Chromatids
attach to spindle fibers
Chromatid pairs line up
along the equator
(middle) of the cell.
Why does this occur?
So that each new cell
will receive one
chromatid from the pair.
Anaphase
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The chromatid pairs
separate and the
separated
chromosomes move
in opposite
directions.
The spindle fibers
contract and
somehow pull them
toward the poles.
Telophase
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The cell begins to
separate.
Two new nuclei
begin to reappear.
Chromosomes
decondense to form
chromatin
The spindle fibers
disappear.
Cytokinesis
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Final separation into 2 new daughter cells.
Cells are identical in the type and number of
chromosomes it contains.
Each cell has its own nucleus with identical
DNA
If a cell containing 46 chromosomes undergoes
mitosis, how many chromosomes does each of its
daughter cells contain?
46
Where did the extra 46 chromosomes come from?
The S phase of the cell cycle.
Stages of Mitosis
Name Each
Anaphase
Early Metaphase
Prophase
Telophase
Late Metaphase
Questions
• What is all body tissue composed of?
• What is mitosis?
Elaborate
• Most common and preventable disease of the
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integument is skin cancer
Skin cancer - most common form of cancer in
the US
Cancer - general term for over 100 diseases our
body, including the skin
Cancer - uncontrolled growth of abnormal and
damaged cells.
What is skin cancer?
Skin Cancer
Skin Cancer
• One cell is damaged by the sun and is no
longer a normal skin cell.
• This cell continues to grow uncontrolled
and builds up in a location of the body
making a tumor.
• Malignant tumors can invade and destroy
other tissues and spread to other parts of
the body through the blood stream and
lymphatic system.
Lymphatic System
• Network of Vessels
• Carries Lymph-
•
Colorless Fluid
Lymph is carried to
organs including the
lymph nodes, spleen,
thymus, and to cells
throughout the body.
Metastasis
• When cancer spreads to other parts of the
body this is called metastasis
Types of Skin Cancer
• Basal cell carcinoma
• Squamous cell carcinoma
• Melanoma
Basal Cell and Squamous Cell
• These are the most common forms of
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skin cancers
Basal Cell – Most common type
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Starts in the basal cells
Slow Growing
If left untreated, invades cartilage and bone
causing disfigurement
• Squamous cell – Second most common
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Starts in the squamous cells
Most common form of skin cancer in those
with darker skin
Starts as a nodule or red patch with welldefined outline
May metastasize if left untreated
Melanoma
• Less common than Basal and Squamous
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cell cancers
MOST DEADLY
Starts in melanocytes
Linked to severe sunburns in childhood
and adolescence
Caused by short, intense, excessive,
exposure to ultraviolet light
Every blistering sunburn you get before
you turn 18 increases your chances of
developing melanoma
Questions
• What are the three types of skin cancer?
• Which types are the most common?
• Which skin cancer is most serious? Why
• Which cancer is caused by “short, intense,
excessive, exposure” to ultraviolet light?
• Which is the most common skin cancer in
people with darker skin?
Treatments
• Melanoma
– Surgery is most common, and the only certain cure
• Basal and Squamous
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Surgery
Freezing
Burning
Scraping
Creams and lotion-based chemotherapy
Radiation