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Modern Cell Theory
- 1. All organisms are composed of cells and cell products
- 2. A cell is the simplest structural and functional unit of life. There are no smaller subdivision of a cell organism that, in themselves , are alive.
- 3. An organisms structure and all of its functions are ultimately due to the activities of its cells.
- 4. cells come only from preexisting cells, not from nonliving matter. all life, therefore, traces its ancestry to the same original cells.
- 5.Because of this common ancestry, the cells of all species have many fundamental similarities in their chemical composition and metabolic mechanisms.
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all cells in the body except germ cells
somatic cells
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somatic cells use____number
diploid
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Somatic cells reproduce by_____
mitosis
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germ cells reproduce by_____________
meiosis
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germ cells use_____number
haploid
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all fluid within the plasma membrane
intracellular fluid
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all fluid outside the plasma membrane
extracellular fluid
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extracellular fluid in the tissues, usaully between the cells
interstitial fluid
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explain the limitation on cell surface area and volume and why cells must be small
as cell enlarges, volume increases faster than surface area so the need for increased nutrients and waste removal exceeds abillity of membrane surface to exchange
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lateral part of cell
apical cell surface
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median part of cell--attached to some membrane of cell
basal cell surface
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film of lipids with proteins and other molecules embedded in it
plasma membrane
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defines the boundaries of the cell, governs its interactions with other cells, and controls the passage of materials into and out of the cell
plasma membrane
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arrangement of mobile globular proteins embedded in an oily film of phospholipids
plasma membrane
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what are the components of the phosolipid bilayer
75% lipids with hydrophobic heads on each side and hydrophobic tails in the center
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keeps the membrane fluid
phospholipids
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Name the protiens found in the phoshoplipid bilayer
- transmembrane proteins
- peripheral protiens
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protein that passes through membrane
transmembrane protein
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protein that adheres to intracellular surface of membrane
peripheral proteins
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anchors integral proteins to cytoskeleton
peripheral proteins
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most are glycoproteins, conjugated with oligosaccharides on the extracellular sid of membrane
transmembrane proteins
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may cross the plasma membrane once or multiple times
transmembrane proteins
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membrane protein functions list
- receptors
- second messenger systems
- ezymes
- channel proteins
- carriers and pumps
- cell identity markers
- cell adhesion molecules
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functions of receptors
- 1.cells communicate with chemical signals that cannot enter target cells
- 2. receptors bind these messengers
- 3. each receptor is usually specific for one messenger
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allows the cell to respond to extracellular substances such as hormaones
second messengers
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break down chemical messengers to stop their effects
enzymes
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formed by transmembrane proteins, allows water and hydrophillic solutes in and out
channel proteins
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channel proteins that open and close are
Gates
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control passage of electrolytes
gated channels
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integral proteins that bind to solutes and transfer them accross membrane
carriers
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carrier that consume ATP are called
pumps
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enables our bodies to tell which cells belong to it and which are invaders
cell identity markers
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allow cells to adhere to one another or to extracellular material
cell adhesion molecoules
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Three types of intercelluar junctions
- desmosomes
- tight junction
- gap junction
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Location of desmosomes
- epidermis of skin
- cardiac muscle
- cervix of uterus
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hold adjacent cells together
desmosomes
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completely encircles cell and holds it tightly to neighboring cell
tight junction
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location of tight junctions and how it works in this location
- intestinal tract and stomach
- keeps nutrients from leaking between cells
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completely encircles cell and holds it tightly to neighboring cell
tight junctions
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allows passage of ions, gluclose, amino acids, and other small solutes
gap junction
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location of gap junction and what they do
- intercalated discs in cardiac muscle and in smooth muscle
- allows electrical excitation to pass from cell to cell
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connection between cells
gap connections
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