cellular reproduction. cellular growth cells grow until they reach their size limit, then they...

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Cellular Reproduction Cellular Reproduction

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Page 1: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

Cellular ReproductionCellular Reproduction

Page 2: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

Cellular GrowthCellular GrowthCells grow until they reach their size limit,

then they either stop growing or divide.

A cells size is limited by the surface area-to-volume ratio

Page 3: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

• As cell size INCREASES, its volume INCREASES much faster than its surface area

• Two Formulas -Surface Area (SA) & Volume (V)

SA = length+ width+ # of sides

V = length x width x height

Cellular GrowthCellular Growth

Page 4: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited
Page 5: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

The cell might have difficulty supplying nutrients and expelling enough waste products if its surface area is too small compared to its volume.

The need for a surfacesurface sufficiently large to accommodate the volumevolume explains the microscopic size of most cells.

Importance of Surface AreaImportance of Surface Area

Page 6: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

• Substances move by diffusion or by motor proteins.Diffusion over large distances is slow and inefficient.Small cells maintain more efficient transport systems.

• Cell size affects the ability of the cell to communicate instructions for cellular functions.

Importance of Surface AreaImportance of Surface Area

Page 7: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

• Cells must reproduce themselves at some point in their life. They do this by dividing in half to produce two new cells.

• Our entire body is made of cells-these are called body cells (somatic cells)

Cellular GrowthCellular Growth

Page 8: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

• Cell division prevents the cell from becoming too large.

• It is also the way the cell reproduces so that you grow and heal certain injuries.

• Cells reproduce by a cycle of growing and dividing called the cell cycle.

The Cell CycleThe Cell Cycle

Page 9: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

Cellular Organization of Genetic MaterialCellular Organization of Genetic Material

Chromatin-◦Found in nucleus of

cell◦Made up of DNA &

proteins◦Between cell

divisions the chromatin strands are loosely coiled in the nucleus

Page 10: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

Cellular Organization of Genetic MaterialCellular Organization of Genetic Material

◦Chromatin strands become tightly coiled during cell division and are then called chromosomes

◦The DNA in cells wraps tightly around proteins to maintain shape of a chromosome

Page 11: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

ChromosomesChromosomes

• The number of chromosomes in different species may be the same or significantly different

How many chromosomes are there in humans?

In a plant?

In a carrot? In a dog?

46

18

78

1,262

Page 12: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

• Interphase is the stage during which the cell grows, carries out cellular functions, and replicates.

• Mitosis is the stage of the cell cycle during which the cell’s nucleus and nuclear material divide.

• Cytokinesis is the method by which a cell’s cytoplasm divides, creating a new cell.

The Cell CycleThe Cell Cycle

Page 13: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

The first stage of interphase, G1

• The cell is growing, carrying out normal cell functions, and preparing to replicate DNA.

• Cells are performing their assigned tasks, metabolizing, synthesizing, etc.

The Stages of InterphaseThe Stages of Interphase

Page 14: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

The second stage of interphase, S• The cell copies its DNA in preparation for cell division.

(DNA synthesizes)• DNA goes from 2 arms to 4 arms

The Stages of InterphaseThe Stages of Interphase

Page 15: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

The third stage of interphase, G2

• 2nd growth stage• The cell prepares for the division of its nucleus.

The Stages of InterphaseThe Stages of Interphase

Page 16: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited
Page 17: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

Mitosis•Body cell reproduction•A cell divides into 2 new “daughter” cells and the cell cycle starts over•Four Stages of Mitosis = PMAT

Mitosis and CytokinesisMitosis and Cytokinesis

Page 18: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

Prophase◦ Chromatin shortens and coils into

chromosomes

◦ Nuclear membrane breaks down◦ Centrioles appear & begin to move

to opposite ends

◦ Spindle fibers form

Stages of MitosisStages of Mitosis

Page 19: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

Stages of MitosisStages of Mitosis

Metaphase◦Sister chromatids

attach to spindle fibers

◦Chromatids pulled to the middle of the cell

Page 20: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

Stages of MitosisStages of Mitosis

Anaphase◦The microtubules of the

spindle apparatus begin to shorten.

◦Chromatids of each chromosome separate at centromere

◦Chromatids move toward opposite poles of cell, centromere first

Page 21: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

Stages of MitosisStages of Mitosis

Telophase◦ Once chromosomes reach

the poles, spindle fibers disassemble

◦ Chromosomes return to chromatin

◦ Two new nuclear membranes begin to form and the nucleoli reappear.

Page 22: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited
Page 23: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

• Cytokinesis- process where cytoplasm of cell begins dividing, this occurs during telophase stage

• Cell membrane moves inward to create TWO daughter cells- each with its own nucleus and identical chromosomes• In humans each cell would have 46 chromosomes

(diploid amount)

CytokinesisCytokinesis

Page 24: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

Cleavage furrow- area of cell membrane that pinches in and divides animal cell

Cell plate- midline of dividing plant cell, eventually forms into a cell wall

CytokinesisCytokinesis

Page 25: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited
Page 26: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

Cell Cycle RegulationCell Cycle Regulation

Normal Cell Cycle Proteins called cyclins bind to enzymes called cyclin-

dependent kinases(CDK) in stages of interphase and mitosis to start various activities in the cell cycle.

Quality Control Checkpoints◦The cell cycle has built-in checkpoints that

monitor the cycle and can stop it if something goes wrong.

Page 27: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

SG1

M checkpoint

G2M

Controlsystem

G1 checkpoint

G2 checkpoint

Signals DNA replication

Drives protein synthesis

Starts mitosis

Signals preparation for cell cycle

Page 28: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

Cell Cycle RegulationCell Cycle Regulation

Abnormal Cell Cycle: Cancer Cancer is the uncontrolled growth and division of

cells. Cancer cells can kill an organism by crowding out

normal cells, resulting in the loss of tissue function.

Page 29: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited
Page 30: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited
Page 31: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

Cell Cycle RegulationCell Cycle Regulation

Causes of Cancer The changes that occur in the regulation of cell

growth and division of cancer cells are due to mutations.

Various environmental factors can affect the occurrence of cancer cells.

Substances and agents known to cause cancer are called carcinogens.

Page 32: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

Cell Cycle RegulationCell Cycle Regulation

Apoptosis• Programmed cell death• Cells going through apoptosis actually shrink and

shrivel in a controlled process• Apoptosis can help to protect organisms from

developing cancerous growths.

Page 33: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

Cell Cycle RegulationCell Cycle Regulation

Stem Cells• Unspecialized cells that can develop into

specialized cells when under the right conditions

Page 34: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

Cell Cycle RegulationCell Cycle RegulationEmbryonic Stem Cells• An embryo is an organism’s early prebirth stage of

development

• After fertilization, the resulting mass of cells divides repeatedly until there are about 100–150 cells. These cells have not become specialized.

• If separated, cells can develop into specialized cells. If left alone, embryo will continue to develop.

Page 35: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

Cell Cycle RegulationCell Cycle Regulation

Adult Stem Cells• Found in various tissues in the body and might be

used to maintain and repair the same kind of tissue

• Less controversial because the adult stem cells can be obtained with the consent of their donor

Page 36: Cellular Reproduction. Cellular Growth Cells grow until they reach their size limit, then they either stop growing or divide. A cells size is limited

Importance of Stem CellsImportance of Stem Cells

Stem cells are not locked into being one type of cell, they might be the key to curing medical conditions and genetic defects if they can be developed into specific cells that are needed.