All the DNA in a cell 

Can consist of a single DNA molecule (common in prokaryotic cells) ot a number of DNA molecules (common in eukaryotic cells)

Reproductive cells 

Have hals as many chromosomes as somatic cells 

A complex of DNA and protein that condenses during cell division 

Make up the chromosomes 

An apparatus of microtubules that controls chromosome movement during mitosis 

Assembly begins in the centrosome during prophase 

The narrow "waist" of duplicated chromosomes where two chromatids are most closely attached

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The division of the cytoplasm 

Is well under way by late telophase 

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A variation of cell division that produces gametes 

Yields nonidentical daughter cells that only habe one set of chromosomes, half as many as the parent cell

A section of the cell cycle during which cell growth and copying of chromosomes in preperation of cell division takes place

Takes up approximately 90% of the cell cycle 

Can be divided into 3 subphases:

G1 Phase (first gap) - 

S Phase (synthesis) - 

G2 phase (second gap)

The cell grows during all three phases, but chromosomes are duplicated only during the S phase

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-Prophase 

-Prometaphase - spindle microtubules attach to the kinetochores of the chromosomes and begin to move the chromosomes

-Metaphase - A stage of mitosis at which the chromosomes are all lined up at the metaphase plate

-Anaphase A stage of mitosis during which sister chromatids seperate and move along the kinetochore microtubules toward the opposite ends of the cell 

-Telophase A stage of mitosis during which genetically identical daughter nuclei form at opposite ends of the cell (Cytokinesis is well underway at this point)

The microtubule organizing center 

Replicates, forming two centrosomes that migrate to opposite ends of the cell, as spindles of microtubules grow out of them

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A radial array of short microtubules that extends from each centrosome

Is included in the spindle, along with the centrosomes and sprindle microtubules 

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A stage of mitosis at which the chromosomes are all lined up at the metaphase plate

Def: The midway point between the spindles two poles[image]

A stage of mitosis during which sister chromatids seperate and move along the kinetochore microtubules toward the opposite ends of the cell 

The microtubules shorten by depolymerizing their kinetochore ends

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The midway point between the spindle's two poles at which the chromosomes are lined up during metaphase 

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The process of cytonikesis in animal cells

Forms a cleavage furrow 

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What is grown between sperating plant cells in cytokinesis 

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A type of cell duvision used by prokaryotes in which chromosomes replicate (beginning at the origin of replication) and the two daughter cells actively move apart 

Def: The particular location in a genome from which synthesis begins 

Since prokaryotes evolved before eukaryotes, mitosis probably evolved from binary fission 

Certain protists exhibit types of cell division that seem intermediate between binary fission and mitosis[image]

Cell Cycle Control System 

The system that regulates the sequential events of the cell cycle 

Regulated by both internal and external controls

Would appear to be driven by specific chemical signals present in the cytoplasm 

Has specific checkpoints where the cell cycle stops until a go-ahead signal is received 

For many cells, the G1 checkpoint seems to be the most important one

If a cell receives a go-ahead signal at G1, it will usually complete S, G2 and M phases and divide

If a cell does not receive the go-ahead signal, it will exit the cycle, switching into a nondivided state called the G0 phase 

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a family of proteins that control the progression of cells through the cell cycle by activating cyclin-dependent kinase (Cdk) enzymes.

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An external signal that prompts crowded cells to stop growing 

Cancer cells do not exhibit this

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Cells must be attached to a substratum in order to divide

Cancer cells do not exhibit this

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