Cell Growth Cell Growth and Divisionand Division

Chapter 10Chapter 10

Limits to cell growth 10-1Limits to cell growth 10-1

1. The larger a cell becomes, 1. The larger a cell becomes, the more demands the cell the more demands the cell

places on its DNA.places on its DNA.

2. The more trouble the cell 2. The more trouble the cell has moving enough nutrients has moving enough nutrients

and wastes across the cell and wastes across the cell membrane.membrane.

DNA overloadDNA overload

• DNA controls the cell’s functionDNA controls the cell’s function

• When a cell is small, the information stored When a cell is small, the information stored in that DNA is able to meet all of the cell’s in that DNA is able to meet all of the cell’s needs.needs.

• As the cell increases in size, it does not As the cell increases in size, it does not make extra DNA and is no longer able to make extra DNA and is no longer able to serve the needs of the growing cell.serve the needs of the growing cell.

Exchanging Exchanging materialsmaterials• Cells must obtain all of their food, oxygen Cells must obtain all of their food, oxygen

and water through their membraneand water through their membrane

• The rate at which food and oxygen are The rate at which food and oxygen are used up and waste produced depends on used up and waste produced depends on the cell’s volumethe cell’s volume

• As cells grow large their ability to obtain As cells grow large their ability to obtain materials through their membrane goes materials through their membrane goes downdown

• Surface area to volume ratioSurface area to volume ratio

Cell Size

Surface Area (length x width x 6)

Volume (length x width x height)

Ratio of Surface Area to Volume

Ratio of Surface Area to Volume in CellsSection 10-1

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As cell volume increases, surface area decreases!

How does the cellhandle overload??

Cell Division 10-2Cell Division 10-2

• DNA is stored in the form of DNA is stored in the form of chromosomeschromosomes– Human cells contain 46 chromosomesHuman cells contain 46 chromosomes– Fruit flies contain 8 chromosomesFruit flies contain 8 chromosomes– C. not visible except during cell divisionC. not visible except during cell division– Each C. is replicated prior to divisionEach C. is replicated prior to division– What you see is identical “sister” chromatidsWhat you see is identical “sister” chromatids– Chromatids are attached in the center by a Chromatids are attached in the center by a

centromerecentromere

Chromosomes

Cell CycleCell Cycle

• Period of time from the beginning of one cell Period of time from the beginning of one cell division to the beginning of the next.division to the beginning of the next.

• G1 phase – cell growth and activityG1 phase – cell growth and activity• S phase – replicationS phase – replication• G2 – time gapG2 – time gap• M phase – mitosisM phase – mitosis

• Interphase – G1, S, G2Interphase – G1, S, G2

M phase

G2 phase

S phase

G1 phase

Figure 10–4 The Cell CycleSection 10-2

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Mitosis

• The process by which the chromosome’s in a cell duplicate themselves and then separates into two identical cells.

• Mitosis is the division of body cells (somatic cells)

• 4 stages of mitosis

InterphaseInterphase Normal cellular Normal cellular

functionfunction DNA get replicatedDNA get replicated Cell prepares for Cell prepares for

cell divisioncell division Chromosomes are Chromosomes are

not visiblenot visible

ProphaseProphase DNA begins to coil DNA begins to coil

upup Chromosomes Chromosomes

become visiblebecome visible Nuclear membrane Nuclear membrane

dissolvesdissolves Centrioles move to Centrioles move to

opposite endsopposite ends

Metaphase Metaphase

Chromosomes Chromosomes meet in the middlemeet in the middle

AnaphaseAnaphase

Chromosomes pull apartChromosomes pull apart

TelophaseTelophase

Cell membrane pinches in (animal cell)Cell membrane pinches in (animal cell) Cell wall begins to form in (plant cells)Cell wall begins to form in (plant cells) Cytokinesis Cytokinesis

Centrioles

Chromatin

Interphase

Nuclear envelope

Cytokinesis

Nuclear envelope reforming

Telophase

Anaphase

Individual chromosomes

Metaphase

Centriole

Spindle

CentrioleChromosomes

(paired chromatids)

Prophase

Centromere

Spindle forming

Section 10-2

Figure 10–5 Mitosis and Cytokinesis

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Centrioles

Chromatin

Interphase

Nuclear envelope

Cytokinesis

Nuclear envelope reforming

Telophase

Anaphase

Individual chromosomes

Metaphase

Centriole

Spindle

CentrioleChromosomes

(paired chromatids)

Prophase

Centromere

Spindle forming

Section 10-2

Figure 10–5 Mitosis and Cytokinesis

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Centrioles

Chromatin

Interphase

Nuclear envelope

Cytokinesis

Nuclear envelope reforming

Telophase

Anaphase

Individual chromosomes

Metaphase

Centriole

Spindle

CentrioleChromosomes

(paired chromatids)

Prophase

Centromere

Spindle forming

Section 10-2

Figure 10–5 Mitosis and Cytokinesis

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Centrioles

Chromatin

Interphase

Nuclear envelope

Cytokinesis

Nuclear envelope reforming

Telophase

Anaphase

Individual chromosomes

Metaphase

Centriole

Spindle

CentrioleChromosomes

(paired chromatids)

Prophase

Centromere

Spindle forming

Section 10-2

Figure 10–5 Mitosis and Cytokinesis

Go to Section:

Centrioles

Chromatin

Interphase

Nuclear envelope

Cytokinesis

Nuclear envelope reforming

Telophase

Anaphase

Individual chromosomes

Metaphase

Centriole

Spindle

CentrioleChromosomes

(paired chromatids)

Prophase

Centromere

Spindle forming

Section 10-2

Figure 10–5 Mitosis and Cytokinesis

Go to Section:

Centrioles

Chromatin

Interphase

Nuclear envelope

Cytokinesis

Nuclear envelope reforming

Telophase

Anaphase

Individual chromosomes

Metaphase

Centriole

Spindle

CentrioleChromosomes

(paired chromatids)

Prophase

Centromere

Spindle forming

Section 10-2

Figure 10–5 Mitosis and Cytokinesis

Go to Section:

InterphaseInterphase

ProphaseProphase

Metaphase Metaphase

AnaphaseAnaphase

TelophaseTelophase

Telophase Telophase

Prophase Prophase

Metaphase Metaphase

Anaphase Anaphase

Telophase Telophase