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Cells
the structural units of all living things
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plasma membrane
the outer boundary of the cell
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cytoplasm
the intracellular fluid packed with organelles (small structures that perform specific cell functions)
the cellular material surrounding the nucleus and enclosed by the plasma membrane
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tight junction
series of integral protein molecules in the plasma membranes of adjacent cells fuse together, forming an impermeable junction that encircles the cell
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desmosomes
"binding bodies" anchoring functions - mechanical couplings scattered like rivets along the sides of abutting cells to prevent separation
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gap junction
"nexus" - communicating junction b/w adjacent cells. cells connected by hollow cylinders called connexons, composed of transmembrane proteins
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interstitial fluid
- extracellular fluid that is derived from the blood.
- contains 1000's of ingredients, including amino acids, sugars, fatty acids, vitamins, regulatory substances - hormones and neurotransmitters, salts, and waste products
- like a nutritious soup
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osmolarity
the measure of the total concentration of solute particles
*when solutions of different osmolarity are separated by a membrane, osmosis occurs until equilibrium is reached
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glycocalyx
the fuzzy, sticky, carbohydrate-rich area at the cell surface
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tonicity
the ability of a solution to cause a cell to shrink or swell by altering the cells internal water volume
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cytoplasm
- "cell forming material"
- cellular material b/w plasma membrane and nucleus, is the site of most cellular activities
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cytosol
- viscous, semitransparent fluid in which other cytoplasmic elements are suspended
- complex mixture w/properties of both a colloid and a true solution
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organelles
- metabolic machinery of the cell
- each type carries out specific function for the cell
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inclusions
- chemical substances that may or may not be present, depending on cell type
- eg-- stored nutrients, lipid droplets in fat cells, pigment (melanin) granules in certain skin and hair cells...
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free radical
highly reactive chemicals w/unpaired electrons that can scramble the structure of biological molecules
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centrioles
small tubes formed by microtubules
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chromatin
structures in the nucleus that carry the hereditary factors (genes)
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chromosomes
- barlike bodies of tightly coiled chromatin
- visible during cell division
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semiconservative replication
the mechanism of DNA replication
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gene
segment of DNA w/blueprint for one polypeptide
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genetic code
each 3-base sequence on DNA is represented by a codon
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codon
complementary 3-base sequence on mRNA
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anticodon
3-base sequence complementary to the mRNA codon
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triplet
each sequence of three-base
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transfer RNA (tRNA)
short-chain RNA molecules that transfer amino acids to the ribosome
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ribosomal RNA (rRNA)
constituent of ribosome, exists within the ribosomes of cytoplasm and assists in protein synthesis
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messenger RNA (mRNA)
long nucleotide strands that reflect the exact nucleotide sequences of the genetically active DNA and carry the DNA's message
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apoptosis
a process of controlled cellular suicide, eliminates cells that are unneeded, stressed, or aged
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anaplasia
an= without; plas= to grow
abnormalities in cell structure and loss of differentiation
example- cancer cells typically lose the appearance of parent cells and come to resemble undifferentiated or embryonic cells
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dysplasia
dys= abnormal
a change in cell size, shape, or arrangement due to chronic irritation or inflammation (infections, etc)
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hypertrophy
- growth of an organ or tissue due to an increase in the size of its cells
- normal response of skeletal muscle cells when they are challenged to lift excessive weight
- differs from hyperplasia, which is an increase in size due to an increase in cell #
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liposomes
- hollow microscopic sacs formed of phospholipids that can be filled w/a variety of drugs
- serve as multipurpose vehicles for drugs, genetic material, and cosmetics
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mutation
- a change in DNA base sequence that may lead to incorporation of incorrect amino acids in particular positions in the resulting protein
- the affected protein may remain unimpaired or may function abnormally or not at all, leading to disease
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necrosis
- death of a cell or group of cells due to injury or disease
- acute injury causes cells to swell and burst, and induces the inflammatory response (this is uncontrolled cell death, in contrast to apoptosis)
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osmosis
diffusion of a solvent through a membrane from a dilute solution into a more concentrated one
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