Transcript Document 7398151

The Cell Cycle
Chapter 2, Lesson 1
Modified from L. Gilmore 2012
Big questions for something so small
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You start life as a single cell!!
You will have a trillion cells!!
SO . . .
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How are all these cells made?
How long does a cell live?
The Cell cycle
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Cell cycle = the life cycle of a cell
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Just like all living things, our CELLS have a cycle of
life.
Write this on page 1 of your notebook
Prediction 1: How long does it take to make a
new cell? Explain.
Length of Cell Cycle
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Different for different cells.
Humans may have as many as 500 different
types of cells in your bodies.
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Skin cells = new cells every 24 hours
Liver cells = 1 year or more
Brain = never makes new cells, you get one chance.
Most our cells are like skin and take 24 hours
Length of Cell Cycle
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Other organisms have
cycles that are shorter
Zebra Fish:
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Sea Urchin
From 1 cell to 4 in 2
hours.
http://www.exploratorium.e
du/imaging_station/gallery.p
hp?Category=Mitosis&Secti
on=Introduction
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From 1 cell to hatching
in 48 hours.
We will now begin the Cell Cycle
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Main Phases of cell cycle
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Interphase
Mitosis
Cytokinesis
Birth/Childhood
Teenager
Leaving your parents
Beginning the Cell Cycle
Interphase
Interphase
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When a cell is getting ready to reproduce
The longest phase.
The chromosomes in the nucleus look like a
bunch of thin spaghetti because they are
getting ready to be copied.
The Phases of Interphase
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To summarize look at Textbook pg 91
Now what do you think Interphase does?
Talk with a partner.
Answer
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Growth and regular cell functions.
NUCLEUS makes chromatids
Organelles make copies of themselves.
The Phases of Interphase
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Do ALL cells go finish interphase?
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Answer: Some do not!
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Muscles, nerve, brain. Injuries to these can be
permanent. The cells don’t leave interphase.
Drugs literally kill brain cells. . . You can’t get
them back once they have been damaged.
Time for a
Vocabulary lesson
DNA vs. Chromosomes
What is DNA?
A macro molecule that
makes proteins.
What is a chromosome?
DNA tightly coiled
around some proteins
into a smaller package.
Humans have 46
chromosomes.
http://learn.genetics.utah.edu/content/begin/tour
What is a homologous chromosome?
From mom
From dad
/
Homologous
chromosomes are the
matched set.
You get one from mom
and one from dad. So
we have 23 pairs of
homologous
chromosomes.
What is a chromatid?
• Chromatid: copy of
chromosome
• Centromere: a region
near middle of each
chromatid that holds
together homologous
chromosomes
Page 1
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Prediction 2: Why do we need chromatids?
Prediction 3: Why do we need centromeres?
Talk with your partner.
Answer:
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The cell needs to make copies of EVERY
chromosome so the new cell has EVERY
chromosome.
Centromeres hold the copy to the original for a
while.
For later
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More about this later.
But what are some
things you notice?
Now we move on the to . . .
Mitosis
Different cells at different times
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Four main
phases
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Prophase
Metaphase
Anaphase
Telephase
1
What phase is this?
Anaphase
How do we know?
The chromosomes are not lined up in the
center or all the way at the ends.
Name the Phase and defend
3
1
2
4
1 = Metaphase
2 = Telophase
3 = Prophase
4 = Interphase
Now to the end of the
cycle
Cytokinesis
Cytokinesis
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The final stage
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Cytoplasm divides
Organelles divide up
Occurs very quickly – like you “splitting” off this
campus on a Friday.
The results of cell division
 NO
parent cell exists
anymore!
 The TWO daughter cells are
identical!
One Cell Interphase Zshhooop
Prophase Metaphase Anaphase
In your face! Telophase Cytokinesis