mitosis notes. 2 cell division all cells are derived from pre-existing cells all cells are derived...
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Mitosis Notes
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Cell DivisionCell Division All cells are derived from All cells are derived from pre-pre-
existingexisting cells cells New cells are produced for New cells are produced for
growthgrowth and to and to replace damaged replace damaged or or old cellsold cells
Differs in Differs in prokaryotes (bacteriaprokaryotes (bacteria) ) and and eukaryotes (protists, fungi, eukaryotes (protists, fungi, plants, & animals)plants, & animals)
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Keeping Cells Keeping Cells IdenticalIdentical
The instructions for The instructions for making cell parts making cell parts are encoded in are encoded in the DNA, so each the DNA, so each new cell must get new cell must get a complete set of a complete set of the DNA the DNA moleculesmolecules
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DNA ReplicationDNA Replication DNA must be DNA must be
copied or copied or replicated before replicated before cell division cell division
Each new cell Each new cell will then have an will then have an identical copy of identical copy of the the DNADNA
Original DNA Original DNA strandstrand
Two new, Two new, identical DNA identical DNA strandsstrands
Mitosis NotesCells divide to make more cells…
this is called mitosis. All organisms start as just one
cell and continue to divide and make more. Humans have over 50,000,000,000,000 cells.
Mitosis Mitosis is the division of the nucleus in
eukaryotic cells. Mitosis has 6 steps. In mitosis the DNA is copied so that each
cell gets a copy. The DNA is condensed into a
chromosome. Humans have 46 chromosomes.
Chromosomes Notes Each of the cells in your body have the
same 46 chromosomes. You get 23 chromosomes from each parent.
Not all species have the same number of chromosomes. Corn has 20, flies have 10, chimpanzees have 48.
Chromosome Notes Each chromosomes has a central region
called a centromere that is an important attachment point for mitosis.
Chromosome Notes The cell providing the
DNA to be copied is the “parent cell,” the cells that are created are identical “daughter cell.”
Chromosome A chromosome contains
the DNA for the organism.
During mitosis the chromosome divides into two chromatids that are copied during mitosis.
These chromatids are “sister chromatids”
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KaryotypeKaryotype First 22 pairs are
called autosomes Last pair are the sex
chromosomes XX female or XY male
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Boy or Girl?Boy or Girl?
Y - ChromosomeY - Chromosome
X - ChromosomeX - Chromosome
The Y Chromosome DecidesThe Y Chromosome Decides
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Prokaryotic Prokaryotic ChromosomeChromosome
The DNA of The DNA of prokaryotes prokaryotes (bacteria) is (bacteria) is one, circular one, circular chromosome chromosome attached to the attached to the inside of the inside of the cell membranecell membrane
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Cell Division in Cell Division in ProkaryotesProkaryotes Prokaryotes such as
bacteria divide into 2 identical cells by the process of binary fission
Single chromosome makes a copy of itself
Cell wall forms between the chromosomes dividing the cell
Parent cellParent cell
2 identical daughter cells2 identical daughter cells
Chromosome Chromosome doublesdoubles
Cell splitsCell splits
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Types of Cell Types of Cell ReproductionReproduction
Asexual reproduction Asexual reproduction involves a involves a single cell single cell dividing to make dividing to make 2 new, identical daughter 2 new, identical daughter cellscells
MitosisMitosis & & binary fission binary fission are examples of are examples of asexual reproductionasexual reproduction
Sexual reproduction Sexual reproduction involves involves two cells two cells ((egg egg & sperm& sperm) joining to make a new cell ) joining to make a new cell ((zygotezygote) that is ) that is NOT identical NOT identical to the original to the original cellscells
MeiosisMeiosis is an example is an example
The cell cycle Some cells divide constantly like skin cells
and stomach cells. Some cells divide only every 10 years. Actively dividing cells go through the cell cycle. The cell cycle has four parts.
The Cell Cycle G1- (GAP) Each chromosome has 1
chromatid. Cells spend most of their time here if they are not dividing.
S- (Synthesis) this is when DNA is copied. The chromosome goes from one chromatid to 2 chromatids.
G2- Is the period between S and mitosis. The cell prepares for Mitosis
M- is Mitosis
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Daughter Daughter CellsCells
DNA CopiedDNA Copied
Cells Cells MatureMature
Cells prepare for DivisionCells prepare for Division
Cell Divides into Identical cellsCell Divides into Identical cells
Interphase During Interphase chromosomes are
copied (sister chromosome) but remain in loose structures called chromatin.
All the organelles are copied. Interphase is not technically part of mitosis
because mitosis is division of the nucleus and Interphase involves division of other organelles.
Prophase Prophase means “the before stage.”
Prophase is the start of mitosis. Chromatin condenses into chromosomes. The microtubules condense into
centrisomes which move to opposite poles of the cell.
The nuclear membrane starts to dissolve. Spindle fibers begin to form to help line the
chromosomes up.
Metaphase Chromosomes line up on the equator of the
cell. Spindle fibers attach to the centromeres of the chromatids.
Everything is now aligned for the rest of division to occur.
Anaphase Chromatids (or pairs of chromosomes)
separate and move to opposite ends of the cell.
The spindle fibers contract and the chromosomes are pulled towards the centrioles.
Telophase In telophase the cell divides. Two new
nuclei begin to form. The chromosomes are at the poles and the
spindle fibers disintegrate. Chromosomes begin to appear as
chromatin (the threads not the rods). This is the end of mitosis.
Cytokinesis The organelles get divided evenly into each
(daughter cell). Each cell has identical chromosomes in their own nucleus.
Plant and animal cells divide differently. Plants form a new cell wall that cuts the two cells apart. Animal cells form actin fibers around the equator of the cell and this pinches the cell in half.
Cytokinesis isn’t part of mitosis (doesn’t involve the nucleus). After Cytokinesis we go back to G1 and start over.
White Board Mitosis Review
What part of mitosis is shown?
What part of mitosis is shown?
What part of mitosis is shown?
What part of mitosis is shown?
What part of mitosis is shown?
In what part of mitosis do chromosomes double?
In what part of mitosis do chromosomes attach to spindle
fibers?
In what part of mitosis does the nuclear membrane start to re-form?
In what part of mitosis do the chromosomes line up at the cell
equator?
When do the copied chromosomes move to opposite ends of the cell?
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