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How many stages of cell division do you see in this image?
Genetics Unit: Mitosis
)
Cell Cycle
Mitosis will be our main focus.
First, we will look at Interphase…
Interphase
)
• Longest stage of cell division (90% of cell cycle)
• Nucleus is visible
• Cell is growing and DNA is being replicated.
Interphase:3 Phases
)
1. G1: Cell is Growing
2. S: DNA is Synthesized (DNA Replication)
3. G2: Organelles duplicate in preparation for division
Most of these cells are in Interphase
Key Vocabulary
• DNA molecules are packaged into .– Human (body cells)
have 46 – Human (sperm or eggs)
have 23
• Chromosomes are made of a material called .
chromosomessomatic cells
gametes
chromosomes.
chromosomes.
chromatin
Key Vocabulary
• Chromatin is composed of and .
• It is supercoiled around proteins, called .
• Together the DNA and histone molecules form bead-like structures called
DNAproteins
histones
nucleosomes
Key Vocabulary
sisterchromatids
centromere
• The chromosome is duplicated.
• Each duplicated chromosome consists of two
.
• These are connected by a .
Mitosis (M Phase)
The M Phase consists of:• Mitosis and Cytokinesis
Four Stages of Mitosis:
• Prophase
• Metaphase
• Anaphase
• TelophaseFor Homework: Left-side IntNB assignment: Write an Acrostic Poem for the four stages of Mitosis
Late Interphase: GLate Interphase: G22
Centrosomes (with centriole pairs)Centrosomes (with centriole pairs)
Preparing for Division
Nuclear membrane still visibleNuclear membrane still visible
Nucleolus Nucleolus
Chromatin has been replicatedChromatin has been replicated
Late Interphase: GLate Interphase: G22
Preparing for Division
Chromosome consisting of two sister chromatidsChromosome consisting of two sister chromatids
CentromereCentromereEarly Spindle ApparatusEarly Spindle Apparatus
ProphaseProphase
Nuclear Nuclear membrane membrane disappearsdisappears
MetaphaseMetaphase
Chromosomes line upChromosomes line up at an at an imaginary line between the imaginary line between the centrosomes at opposite ends centrosomes at opposite ends of the cell.of the cell.
The spindle attaches to The spindle attaches to the centromeres.the centromeres.
AnaphaseAnaphase
Spindles pull the Spindles pull the “daughter” “daughter” chromosomes appart chromosomes appart
Telophase & CytokinesisTelophase & CytokinesisTelophaseTwo nuclei become visible
In animal cells, a Cleavage Furrow is visible
In plant cells, a cell plate is now visible
CytokinesisThe cytoplasm and organelles divide.
What’s the end product?
• Two identical daughter cells ready to start the cycle again… or not.
• Some cells (like your nerve and muscle cells) do not undergo division.
• For those that do (your skin and the lining of your intestinal tract) how would you know how quickly division takes place?