Download 1 Chapter 8: Cell Growth and Division

Chapter 8: Cell Growth and Division
Cell growth = change in size­ Controlled by the ratio of its volume to its surface area
When a cell becomes too large to function efficiently it will divide!
Cell division= increase in the number of cells (Organism growth)
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8.2 Cell Division
Cell Cycle­ refers to the period of a cell's life from its "birth" to its reproduction of offspring
Occurs in 4 Phases:
1. G1 Phase­ G=GAP
Normal cellular activity and cell growth
2. S Phase­ S=Synthesis
In order for an identical clone to be made, DNA (Chromosomes) must be Cloned/Copied/Synthesized
3. G2 Phase­ Gap 2 Phase
Cell conserves energy for the impending division
4. M Phase­ Mitosis (Cell Splitting)
Once we have obtained a duplicate of genetic information we can create a new identical daughter cell
The Cell Cycle
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Structure of a Chromosome
A chromosome contains DNA and packaging proteins called Histones
1 chromosome has two legs called Chromatid­ chromatid from the same chromosome are referred to as Sister Chromotid
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How we depict a chromosome depends on whether the organism we are studying is Haploid (n) or diploid (2n).
A Haploid organism contains one copy of genetic information After S Phase n= 2n or we have two copies of each chromosome
A Diploid Organism contains two copies
After S Phase 2n= 4n or we end up with 4 copies of each chromosome
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Phases of Mitosis
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Phases of Mitosis
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Phases of Cell Division
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Interphase
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Prophase
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Metaphase
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Anaphase
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Telophase and Cytokinesis
Cleavage­ Animal Cells only
Cell Plate­ Plant Cells only
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Onion Root Tip Mitosis
Interphase
Identify the Phases of Mitosis
Interphase
Interphase
Interphase
Interphase
Interphase
Interphase
Interphase
Interphase
Interphase
Interphase
Prophase
Interphase
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
Interphase
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8.8 Control of the Cell Cycle
A. Cells will remain in the G1 Phase of Interphase until they are signaled to divide
1. Anchorage dependence­ cells must be in contact with a solid surface in order to divide
2. Density Dependent inhibition­ cells will stop growing when they create one layer
and become crowded 3. Chemical Growth Factors 1. Growth Factors­ Proteins secreted by cells to cause other cells to divide
Controls Density Dependent Inhibition
Cyclins­ chemical messengers released by the cell that signal other cells as well as the cell itself to divide.
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8.9 Cancer
Genetic disease which alters the external portion of the Growth Factor Protein Receptors
1. Triggers constant by­passing of the G1 Checkpoint­constant cell reproduction
2. Also prevents APOPTOSIS­ normal programmed cell death in response to injury
Breast Cancer:
BRCA 1 and BRCA 2 Genes
p53 Tumor Suppressor Genes
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8.12 MEIOSIS and Sexual Reproduction
"Reduction Division"
"IPMAT PMAT"
Process of Gamete Formation­ Gametogenesis
Males­ Sperm, Pollen (Spermatogenesis)
Females­ egg or ovum (Oogenesis)
1 Diploid Cell Produces 4 Haploid Gametes
Human Karyotype= Diploid Organism
We have two copies of each chromosome called Homologous Chromosomes
Each Homologous Chromosome gets copied during the S Phase of Interphase
So in Humans:
46 Chromosomes become 92 Chromosomes by the end of Interphase
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Meiosis Diagram:
Meiosis I:
Meiosis II:
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Crossing Over­ Occurs during Metaphase I
"TETRAD FORMATION"
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Gametogenesis:
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CELL DIFFERENTIATION and SPECIALIZATION
Fertilization:
Development through MITOSIS­
Zygote
Blastocyst
Gastrula
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Week 4
Week 5
5 MONTHS
Week 8
Birth
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Attachments
chapter10.ppt
Chapter 10A.mpg