Download CELLS

CELLS
the basic living, structural, and
functional unit of all organisms
CELLS IN THE BODY
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Nucleus
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the “Control Center” of
the cell
Contains DNA
Chromatin: threadlike
strands of DNA &
protein
Chromosome:
condensed DNA
Nucleolus makes RNA
Cytosol
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Semi-fluid portion of the cytoplasm
Mostly water
Contains cell organelles
Aka as intracellular fluid.
Cell organelles “little organs” Highly
specialized
Review notes on cell organelles—cards
The Cell (Plasma) Membrane
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Protective barrier of the cell
Structure of the Cell Membrane
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phospholipid bilayer--bi means two LAYERS
Phospholipids - phosphate & fatty acid lipids
Hydrophilic phosphate heads face outward
Hydrophobic fatty acid tails face inward
Structure of the Cell Membrane
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Cholesterol -lipid made by liver
Stabilizes membrane –gives strength
prevents fatty acid tails from sticking to each other
Carbohydrate chains -extend from surface and aid in cell
identity
Cell Membrane Proteins
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Integral Proteins -through the phospholipid bilayer --gates, channels,
transport proteins, receptor sites for hormones, enzymes, and cell
identity markers
Peripheral Proteins
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loosely bound on the inside or outside of the
plasma membrane--Function in structure or
identity
Functions of the cell membrane
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Selective permeability help
maintain cell’s homeostasis
THESE EFFECT PASSAGE:
Size of molecule
Ion charge – or +
Inside cell mostly neg and
outside mostly pos
Lipid soluble passes easily -(O2, CO2)
Intracellular(ICF) vs Extracellular (ECF) Fluid
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ICF makes up > 66% of
body’s total water
mostly water, but may
also contain ions
ECF found in several
places–
between cells, - interstitial
fluid
ECF is also plasma, lymph,
CSF (cerebrospinal fluid),
synovial fluid, serous fluid,
aqueous humor in eye and
perilymph and endolymph in
the ear.
Cell Division
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How cells reproduce themselves
– somatic cell - (MITOSIS)--46 chromosomes
– sex cell - (MEIOSIS)--23 chromosomes
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Cytoplasmic Division = Cytokinesis
Movement Across the Cell Membrane
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Passive Processes-no energy --moves down a concentration
gradient
– high ---> low concentration
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Active Processes--requires energy
– moves against a concentration gradient
– low ---> high concentration
– may utilize 40% of cells ATP supply
Examples of Passive Transport
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Simple Diffusion – High to low
Facilitated Diffusion
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Proteins in the
membrane are
carriers of molecules
Molecules cannot
pass through on
their own
Dialysis
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Diffusion of small solute particles, but not larger ones
It goes through a semi-permeable membrane
Filtration
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Process whereby dialysis works
Particles are removed and replaced in the blood as it
passes through nephrons in kidneys
Controlled by gravity or hydrostatic pressure
Osmosis
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Movement of water across a selectively permeable
membrane
Effects of Osmosis
Cell in:
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Isotonic state –same amount of water and particles in ICF
and ECF
Hypotonic state--low concentration particles in ECF—More
water in ECF than ICF. May cause lysis
Hypertonic State--high concentration of particles in ECF.
More water in ICF than ECF. May cause crenation
Active Transport
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Active Transport
– uses energy
– against a concentration gradient
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Example: Na+/K+ pump
– estimated 40% ATP use in the body
Active Transport
Exocytosis
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Bulk Transport to outside of cell
Usually uses vesicles
Active Transport
Endocytosis
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– going into cell
Ex. : phagocytocis cell
eating
Pinocytosis – cell
drinking
Receptor mediated
endocytosis