Mitosis Reference

7/28/2019 Mitosis Reference

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BIOLOGYCONCEPTS & CONNECTIONS

Fourth Edition

Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Neil A. Campbell Jane B. Reece Lawrence G. Mitchell Martha R. Taylor

From PowerPoint Lectures forBiology: Concepts & Connections

CHAPTER 8The Cellular Basis of

Reproduction and Inheritance

Modules 8.48.11


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A eukaryotic cell has many more genes than aprokaryotic cell

The genes are grouped intomultiple chromosomes,found in the nucleus

The chromosomes of thisplant cell are staineddark purple

8.4 The large, complex chromosomes of eukaryotes

duplicate with each cell division

THE EUKARYOTIC CELL CYCLE ANDMITOSIS

Figure 8.4A


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Chromosomes contain a very long DNA

molecule with thousands of genes Individual chromosomes are only visible

during cell division

They are packaged as chromatin


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Before a cell startsdividing, the

chromosomes areduplicated

This process

produces sisterchromatids

Centromere

Sister chromatids

Figure 8.4B


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When the celldivides, the sister

chromatids separateTwo daughter

cells are produced

Each has acomplete andidentical set ofchromosomes

CentromereSisterchromatids

Figure 8.4C

Chromosomeduplication

Chromosomedistribution

todaughter

cells


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The cell cycle consists of two major phases: Interphase, where chromosomes duplicate

and cell partsare made

The mitoticphase, whencell divisionoccurs

8.5 The cell cycle multiplies cells

Figure 8.5


7/23Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Eukaryotic cell division consists of two stages:Mitosis

Cytokinesis

8.6 Cell division is a continuum of dynamicchanges



In mitosis, the duplicated chromosomes aredistributed into two daughter nuclei

After the chromosomes coil up, a mitotic spindlemoves them to the middle of the cell



INTERPHASE PROPHASE

Centrosomes(with centriole pairs)

Chromatin

Nucleolus Nuclearenvelope

Plasmamembrane

Early mitoticspindle

Centrosome

CentrosomeChromosome,consisting of twosister chromatids

Fragmentsof nuclearenvelope

Kinetochore

Spindlemicrotubules

Figure 8.6



The sister chromatids then separate and moveto opposite poles of the cell

The process of cytokinesis divides the cell intotwo genetically identical cells



METAPHASE TELOPHASE AND CYTOKINESIS

Metaphaseplate

Spindle Daughterchromosomes

Cleavagefurrow

Nucleolusforming

Nuclearenvelopeforming

ANAPHASE

Figure 8.6 (continued)



In animals, cytokinesisoccurs by cleavage

This process pinchesthe cell apart

8.7 Cytokinesis differs for plant and animal cells

Figure 8.7A

Cleavagefurrow

Cleavagefurrow

Contracting ring ofmicrofilaments

Daughter cells



In plants, amembranous cell

plate splits the cell intwo

Vesicles containing

cell wall material

Cell plateforming

Figure 8.7BCell plate Daughter

cells

Wall ofparent cell

Daughternucleus

Cell wall New cell wall


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Most animal cells divide only when stimulated,and others not at all

In laboratory cultures, most normal cells divide

only when attached to a surface

They are anchorage dependent

8.8 Anchorage, cell density, and chemical growthfactors affect cell division


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Cells continue dividing until they touch oneanother

This is called density-dependent inhibition

Cells anchor to dish surface anddivide.

Figure 8.8A

When cells have formed acomplete single layer, they stopdividing (density-dependentinhibition).

If some cells are scraped away,the remaining cells divide to fillthe dish with a single layer andthen stop (density-dependentinhibition).


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Growth factors are proteins secreted by cellsthat stimulate other cells to divide

After forming a single layer, cellshave stopped dividing.

Figure 8.8B

Providing an additional supply ofgrowth factors stimulates furthercell division.


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Proteins within the cell control the cell cycleSignals affecting critical checkpoints determine

whether the cell will go through a complete cycleand divide

8.9 Growth factors signal the cell cycle controlsystem

G1 checkpoint

M checkpoint

G2 checkpoint

Control

system

Figure 8.9A


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The binding of growth factors to specificreceptors on the plasma membrane is usually

necessary for cell divisionGrowth factor

Figure 8.8B

Cell cycle

controlsystem

Plasma membrane

Receptorprotein

Signaltransduction

pathway

G1 checkpointRelayproteins


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Cancer cells have abnormal cell cyclesThey divide excessively and can form abnormal

masses called tumors

Radiation and chemotherapy are effective ascancer treatments because they interfere withcell division

8.10 Connection: Growing out of control, cancercells produce malignant tumors


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Malignant tumors can invade other tissues andmay kill the organism

Tumor

Figure 8.10

Glandulartissue

1 2 3A tumor growsfrom a singlecancer cell.

Cancer cells invadeneighboring tissue.

Lymphvessels

Cancer cells spreadthrough lymph andblood vessels to otherparts of the body.

Metastasis


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When the cell cycle operates normally, mitoticcell division functions in:

Growth (seen here in an onion root)

8.11 Review of the functions of mitosis: Growth,cell replacement, and asexual reproduction

Figure 8.11A


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Cell replacement (seen here in skin)

Deadcells

Figure 8.11B

Dividingcells

Epidermis,the outerlayer of theskin

Dermis


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Copyright 2003 Pearson Education Inc publishing as Benjamin Cummings

Asexual reproduction (seen here in a hydra)

Figure 8.11C

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