Cell Growth Cell Growth and Division and Division Chapter 10
Dec 18, 2015
Cell Growth and Cell Growth and DivisionDivision
Chapter 10
By the time you finish reading this By the time you finish reading this sentence, 50 million of your cells sentence, 50 million of your cells will have died and been replaced will have died and been replaced by others. Some are lost through by others. Some are lost through 'wear and tear’, some just reach 'wear and tear’, some just reach the end of their life, and others the end of their life, and others deliberately self-destruct.deliberately self-destruct.
A. Importance of Cell A. Importance of Cell Growth and DivisionGrowth and Division
Allows for an organism’s growth
Replaces damaged cells
Allows cells to maintain the proper surface area-to-volume ratio
WHY CAN’T A CELL JUST KEEP GETTING WHY CAN’T A CELL JUST KEEP GETTING BIGGER?BIGGER?
HOWEVER>>>>The larger a cell becomes, the more demands it places on it’s DNA. It also has more trouble moving nutrients and wastes across the cell membrane.
Allows cells to maintain the proper Allows cells to maintain the proper surface area-to-volume ratiosurface area-to-volume ratio
1. Cells cannot simply grow by increasing in size.
Cells of adults and children of a species are the same size.
• The Cell membrane determines the surface area of the cell.
• The volume of a cell is determined by the amount of cytoplasm present with all its contents.
• As a cell’s size increases, its volume increases much faster than its surface area.
The cell overcomes these problems through the process of cell division.
Ratio of Surface Area to Ratio of Surface Area to Volume Volume
As the size of a cell increases, its volume increases faster than the surface area.
The decrease in the cell’s ratio of surface area to volume makes it more difficult for the cell to move needed materials in and waste products out quickly enough for the cell to survive.
Find surface area
Find surface area
Find surface area
Find surface area
Find Volume
Find Volume
Find Volume
Find Volume
Find Ratio
Find Ratio
Find Ratio
Find Ratio
How do little elephants grow up to be BIG elephants?
Why do animals shed their skin?
Cell Division!Cell Division!More next time!More next time!
Quiz over Ch 10.1 Cell Growth Next Time
Regulating Cell Division (Cell Regulating Cell Division (Cell Cycle)Cycle)
Cells stop growing when they come in contact with each other-such as when a wound is healing
Cyclins-proteins within the cell that regulate the timing of eukaryotic cell division
a. Internal Cyclins-usually controls cell division events inside the cell like the beginning and end of cell cycle stages.
b. External Cyclins -for events outside the cell. These usually speed up or slow down the cell cycle and heal wounds.
CANCERCANCEROccurs when cells do not respond to normal signals that regulate growth
*Most cancer cells have defect in the p53 gene
Benign Tumor-a tumor that only grows in one place. Noninvasive and usually treatable
Malignant Tumor-invasive uncontrolled growth of cells
Skin Cancer
Cell Division!Cell Division!
Ch 10.2Ch 10.2
Cell ReproductionCell Reproduction
ProkaryotesBacteria
EukaryotesPlants &
animals
ProkaryotesProkaryotes
Lack a nucleus Have a single chromosomeReproduce asexually by
binary fission Include bacteria
Steps in Binary FissionSteps in Binary Fission
1. Cells increase their cell mass slightly
2. DNA & cell components are replicated
3. Each cell divides into 2 daughter cells
Binary Fission of Bacterial Binary Fission of Bacterial CellCell
E. Coli E. Coli Dividing by Binary Dividing by Binary FissionFission
EukaryotesEukaryotes
Contain a nucleus & membrane bound organelles
Asexually reproduce cells by mitosis
VocabularyVocabularyMitosisMitosis = division of the cell nucleus and
its contentsCytokinesisCytokinesis = the division of cell
cytoplasm into two identical daughter cells
ChromatinChromatin = the combination of DNA and histone proteins
Chromosome-main organelle involved in Cell Cycle
DiploidDiploid = Two copies of each chromosome, one paternal, one maternal
ChromosomChromosomeses
in the in the Larger Larger SchemeScheme
Chromosome Chromosome StructureStructure
1 – Chromatid-because each has an identical half they are “sister” chromatids
2 – Centromere3 – Short arm4 – Long arm
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ChromosomesChromosomes
Made from DNA– Genetic material
directs activities determines characteristics
Formed from chromatin– Uncoiled DNA
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Chromosomes Chromosomes (cont.)(cont.)
Each chromosome (at this point) is made up of 2 identical chromatids
– Joined strands of identical duplicated genetic material
Joined at centromere
– Chromatids separate and each cell has identical information
Formed in S phase of cell cycle
From: http://www.rothamsted.bbsrc.ac.uk/notebook/courses/guide/chromo.htm
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From: http://www.accessexcellence.org/RC/VL/GG/nucleosome.html
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Sets of chromosomesSets of chromosomes
Each human somatic (body) cell – 23 pairs of chromosomes (46 total)
Homologous chromosomes– Each pair is called homologous
Similar in size, shape and genetic content Not identical! One from each parent
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Cell Cycle Interphase
– G1 - growth and normal cell activity G0 – never divides again
– S - Synthesis of DNA DNA replication
– G2 - Growth for division, organelles double
Mitosis - Division of the nucleus Cytokinesis - Division of the cytoplasm (cell)
Cell CycleCell Cycle
Stages in growth & division
G1 Phase S Phase G2 Phase M Phase Cytokinesis
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1/ 25/ 01
Page: 5
Cell cycleCell cycle
G0
Growth & normal cell activity
DNA replication
Growth for divisionOrganelles double
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Length of cell cycleLength of cell cycle
Ranges from 20 minutes to 20 hoursSome cells divide constantly and others
never divide– Muscle cells– Red Blood cells– Skin cells– Bone cells– Nerve cells
G1 PhaseG1 Phase
First growth stageCell increases in sizeCell prepares to copy its DNA
Synthesis (S) PhaseSynthesis (S) Phase
Copying of all of DNA’s instructions
Chromosomes duplicated
G2 PhaseG2 Phase
Time between DNA synthesis & mitosis
Cell continues growingNeeded proteins produced
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MitosisMitosisA process in which eukaryotic cells form
two identical nuclei.– Each cell receives a complete set of
chromosomes– division of the nucleus
Cytokinesis– division of the cytoplasm
2 independent cells (genetically identical)
– Different in plant and animals
Significance of the process of mitosis
M PhaseM Phase
Cell growth & protein production stop
Cell’s energy used to make 2 daughter cells
Called mitosis or karyokinesis (nuclear division)
Life Cycle of a CellLife Cycle of a Cell
Mitosis is a cycle with no beginning or end.
Interphase – Resting StageInterphase – Resting Stage
Cells carrying on normal activities
Chromosomes aren’t visibleCell metabolism is occurringOccurs before mitosis
InterphaseInterphase
D. Stages of MitosisD. Stages of Mitosis
ProphaseMetaphaseAnaphaseTelophase
Major Events in MitosisMajor Events in Mitosis
Cells Undergoing MitosisCells Undergoing Mitosis
Steps in ProphaseSteps in Prophase1. DNA coils tightly & becomes
visible as chromosomes2. Nuclear membrane disappears3. Nuceolus disappears4. Centrioles migrate to poles5. Spindle fibers begin to form
and the chromosomes attach
Eukaryotic ChromosomeEukaryotic Chromosome
Spindles attach here
ProphaseProphase
Animal Cell Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Spindle fibers
Centrioles
Steps in MetaphaseSteps in Metaphase
Spindle fibers from centrioles attach to each chromosome
Cell preparing to separate its chromosomes
Cell aligns its chromosomes in the middle of the cell
MetaphaseMetaphase
MetaphaseMetaphase
Animal Cell Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Steps in AnaphaseSteps in Anaphase
Cell chromosomes are separated
Spindle fibers shorten so chromosomes pulled to ends of cell
Mitotic SpindleMitotic Spindle
AnaphaseAnaphase
AnaphaseAnaphase
Animal Cell Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Steps in TelophaseSteps in Telophase Separation of
chromosomes completed
Cell Plate forms (plants)
Cleavage furrow forms(animals)
Nucleus & nucleolus reform
Chromosomes uncoil
TelophaseTelophase
Plant Animal
TelophaseTelophase
Animal Cell Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
CytokinesisCytokinesis
Occurs after chromosomes separate
Forms two, identical daughter cells
CytokinesisCytokinesis
Cell Plate Forming in Plant Cells
Animal Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
Plant Mitosis -- ReviewInterphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
04/18/23 Page: 75From: http://www.kumc.edu/instruction/medicine/anatomy/histoweb/cytology/large/Cyt001.JPG
04/18/23 Page: 76http://virtual.yosemite.cc.ca.us/randerson/Lynn's%20Bioslides/45.jpg
04/18/23 Page: 77http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/Bio%20101/Bio%20101%20Laboratory/Mitosis/Photographs/whitefish_mitosis_prophase_metaphase_anaphaseX400.jpg
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http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/Bio%20101/Bio%20101%20Laboratory/
Mitosis/Photographs/whitefish_mitosis_anaphaseX400.jpg
http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/Bio%20101/Bio%20101%20Laboratory/Mitosis/Photographs/whitefish_mitosis_telophaseX400.jpg
QuizQuiz Next time!Next time!
Regulating Cell Division (Cell Regulating Cell Division (Cell Cycle)Cycle)
Cells stop growing when they come in contact with each other-such as when a wound is healing
Cyclins-proteins within the cell that regulate the timing of eukaryotic cell division
a. Internal Cyclins-usually controls cell division events inside the cell like the beginning and end of cell cycle stages.
b. External Cyclins -for events outside the cell. These usually speed up or slow down the cell cycle and heal wounds.
Benign Tumor-a tumor that only grows in one place. Noninvasive and usually treatable
Malignant Tumor-invasive uncontrolled growth of cells
Skin Cancer
CANCERCANCEROccurs when cells do not respond to normal signals that regulate growth
*Most cancer cells have defect in the p53 gene
Make a little bookMake a little book
Page one – TitlePage two – interphase including G1, S, G2Page three – prophasePage four – metaphasePage five – anaphasePage six – telephasePage seven – cytokinesisPage eight – the end
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Test informationTest information Cell Cycle
– Order– S phase– Cancer– Interphase
Mitosis completed– What does each cell have?
Chromosomes Mitosis
– Prophase– Metaphase– Anaphase– Telophase
Cytokinesis