How Cells Reproduce
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Transcript of How Cells Reproduce
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How Cells Reproduce
Chapter 8
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Have you ever wondered…
How you grow from one cell to billions?
How your cuts heal? Hair grows?
How some animals regenerate lost parts?
The Answer Is _______!!!
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FUN FACT: ___________________ ______________________Rudolph Virchow
came up with this great idea in 1858.
Its importance is hugeIf you start as one cell
and end up with millions… that means there is a lot of cellular division happening…
In that case lets study it!
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The process of division depends on who you are and what you want…
Prokaryote: All are unicellular so any _________ is __________
and all reproduction is asexual (called binary fission)
Eukaryote: Unicellular ones… all reproduction is asexual but
they use mitosis Multicellular
________ for repair, increasing size, and replacement of damaged cells
______ for sexual reproduction… making egg and sperm
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Asexual Reproduction
Like a Xerox machine.DNA comes only from
one parent making variation dependent on ______ _______and __________
Organisms can be only asexual or both depending on the circumstanceRegenerationBudding (cactus)Mitosis (we’ll come
back to it)
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Before we can get to Mitosis we need to start with the chromosome…
For the majority of DNA’s life it exists as _______… chromosomes + protein associated, loosely packed
When a cell is going to divide the DNA packs up tightly into ______________.
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Cell cycle… INTERPHASEA cell is undergoing
changes at all timesEvery moment of a cells life
________ ________ is called INTERPHASE
In this time it gets prepared to divideMakes proteins, lipids,
carbohydrates and organelles. Grows, metabolizes etc (___ or gap 1)
____________ its DNA (S phase)
Prepares for mitosis(__ or gap 2)
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Not all cells are destined to divideSome cells, like adult
_______ will _____ _____ __ living life but not ready to divide
Some cells, like skin cells, are _____ _______ though the cell cycle
At the end of G1, G2, and during division there are _________, like stop lights, that must be ‘green’ for the cell to continue though the cycle.
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Duplicating DNA (S-Phase)
Before it divides it has to duplicate…
Each chromosome makes a Xerox so that it has a _____ of chromatids (we call them _______ _________)
They are joined by a __________ and when the cell divides each new cell grabs its chromatid by the centromere
** NOTE… it’s a chromosome before and after division… when its doubled its called sister chromatids
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M phase-- MITOSISAfter interphase…Nuclear Division
P__________ (one and two) M__________ A__________ T__________
Before cytoplasm division (c____________)
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Prophase
Early prophaseTime when chromosomes appearNucleolus disappears
Late prophaseNuclear membrane breaks apartMicrotubules grab the centromere
making a structure called the kinetochore
Chromosomes begin to move
Centriole
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Metaphase
Spindle fibers line the chromosomes up at the metaphase plate… all ready to break apart
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Anaphase
Sister chromatids break apart and move to opposite poles (sides)
Make little A looking things… remember A for Anaphase!
The other spindle fibers (that are not forming kinetochores push apart to elongate the cell)
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TelophaseReversal of prophase… the nuclear
membrane, then nucleolus reappearThe chromosomes go back to chromatinAs the cell begins cytokinesis a cleavage
furrow forms
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BUT WE’RE NOT DONE… cytokinesisOnce nuclear division
is over the cytoplasm must be divided
This splits up the _________, _______, _____ and _______… everything but the DNA
Accomplished by the spindle fibers
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Affecting cell division
Cells will grow more or less based on their surroundings_________ _______ is
when cells won’t grow unless with other cells that are the same.
________ ______ is when cells stop dividing once they reach their max capacity (like a full room)
Growth factor: when one cell makes and secretes a protein that tells other cells to divide
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Check-points of Mitosis What happens if cell division gets out of
control? So what do we do to stop it? Cell cycle
control system 3 major check points
G1G2 M
Each go ahead sends the cell further into dividing
Non- dividing cells such as muscle and nerve receive stop signals at the _____ phase.
If a cell is damaged it will not have the proper signal to divide and thus will abort its reproduction… the mechanism of this is called signal transduction
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When Mitosis gets out of control
Cells that undergo uncontrolled division are tumor cells
Their divisions cause them to pile up making a tumor
The tumor can be malignant or benignbenign means the cells are
okay… like a molemalignant means the cells kill
the good tissue as they go and can break off or metastasize to other cells
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Cancer Nomenclature
Each cancer is named from where it originatedCarcinoma: from the covering
or lining (epithelium) either in the gut or on the skin (includes lung)
Sarcoma: supportive tissue, bone or muscle
Leukemia: of the blood or blood forming tissues
Lymphoma: lymph or lymphatic organs (spleen)
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Cancer Treatments
Treatments:Surgery: cut out as much
of the tumor as possibleRadiation therapy exposes
a localized area to large amounts of radiation which halt cell division in the area
Chemotherapy supplies a poison to the whole individual slowing cell divisionit works better…but it
also effects many normal cells