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58 Cards in this Set
- Front
- Back
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Histology
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the study of tissues, but in reality we’ll be studying
-cells |
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tissues
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an aggregation of similar cells and their products
performing a particular function |
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organs
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an aggregation of several tissues forming a functional
unit - |
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organ systems
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an aggregation of several organs forming a functional unit
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PREPARATION OF TISSUES FOR LIGHT MICROSCOPY
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FIXATION
– kills the tissue quickly, preserving physical and chemical relationships • DEHYDRATION – removes the water – uses a series of increasingly concentrated alcohols • CLEAR – immersed in organic solvent to replace the alcohol – becomes translucent as a byproduct • INFILTRATE AND EMBED – replace organic solvent with liquid wax (in heat) – let wax harden • SECTION – cut into thin sections using a microtome • MOUNT AND STAIN – put sections on glass slide, remove wax, and stain |
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FIXATION
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kills the tissue quickly, preserving physical and chemical relationships
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DEHYDRATION
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– removes the water
– uses a series of increasingly concentrated alcohols |
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CLEAR
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immersed in organic solvent to replace the alcohol
– becomes translucent as a byproduct |
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INFILTRATE AND EMBED
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replace organic solvent with liquid wax (in heat)
– let wax harden |
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SECTION
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cut into thin sections using a microtome
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MOUNT AND STAIN
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put sections on glass slide, remove wax, and stain
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MOST COMMON STAINS USED
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HEMATOXYLIN
EOSIN |
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is chemically a basic dye
-stains things blue -the structures stained are said to be basophilic -so that which is stained is chemically acidic |
HEMATOXYLIN
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-is chemically an acidic dye
-makes things pink -the structures stained are said to be acidophilic or eosinophilic -so that which is stained is chemically basic |
EOSIN
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CELLS HAVE TWO COMPARTMENTS
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CYTOPLASM
NUCLEUS |
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MICROSCOPES DO TWO THINGS
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- MAGNIFY
• RESOLVE |
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total mag=
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eyepiece x objective
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100X IS CALLED
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OIL IMMERSION OBJECTIVE
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resolving power
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expressed as a distance two objects
can be apart and still be seen as separate objects |
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THE FACTOR THAT DETERMINES THE
RESOLVING POWER OF A MICROSCOPE IS |
WAVE
LENGTH OF THE SOURCE THAT ILLUMINATES THE SPECIMEN |
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THE SHORTER THE WAVE LENGTH, THE BETTER THE
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RESOLVING POWER
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LIGHT MICROSCOPE IMAGES ARE COLORFUL
BECAUSE |
ORDINARY LIGHT USED TO ILLUMINATE
THE SPECIMEN CONTAINS MANY WAVE LENGTHS WHICH CAN BE BROKEN UP INTO A SPECTRUM OF COLORS |
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ELECTRONS ONLY HAVE _______ AND IT
IS ONE THAT PRODUCES ONLY VARIOUS SHADES OF _________ |
one wavelength
black |
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resolving power of the EM is 200 times better than
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light scope
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Contents of the cytoplasm
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inclusions (metabolic byproducts, products in storage etc.)
-secretion granules -pigment -glycogen -lipid -organelles (metabolically active structures that carry out specific functions) |
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The Plasma Membrane
-in EM seen as a __________ |
trilaminar structure (called a unit membrane)
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Plasma Membrane Structure
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1. Backbone: lipid bilayer of phospholipid and cholesterol
2. Proteins: drift in the lipid (like icebergs) or on it (like seagulls) -if on it: are peripheral proteins (loosely associated with inner or outer face- easily dissociated from the membrane -if in it: are integral proteins- inserted part or all the way through the lipid bilayer- must destroy the membrane to get them out |
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-functions of integral proteins
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pumps
-channels -receptors- built to bind to a specific other molecule (a ligand)- this may cause a message to be passed to the cell interior -linkers (may also act as receptors) -enzymes -structural proteins- example: for adhesion of adjacent cells |
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glycocalyx
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protects the cell from interacting
with inappropriate proteins and promoting the interaction with appropriate ones |
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Carbohydrates
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outer surface contains a heavy investment of carbohydrate
chains (collectively called the glycocalyx) -consists of chains of sugars attached to the proteins to form glycoproteins, or to the lipids, forming glycolipids -no carbohydrate on the side facing the cytoplasm |
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Existing ideas of membrane structure form THE
FLUID-MOSAIC MODEL: Fluid features |
peripheral proteins can change position
by floating on the lipid... integral proteins can move in the plane of the membrane -fluidity of the membrane is maintained by cholesterol |
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Existing ideas of membrane structure form THE
FLUID-MOSAIC MODEL: Mosaic features |
proteins are not homogeneously
distributed in the cell membrane- there are constraints to this mobility so that various parts of the membrane contain different proteins -attachment to adj cells is one such constraint-producing apical, lateral, and basal parts of the membrane |
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Endoplasmic Reticulum
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granular endoplasmic reticulum (aka rough ER)
-a system of unit membranes lined with ribosomes -very well developed in cells making protein for secretion, hence the cytop of these cells is basophilic (due to the ribosomes) -also makes proteins for insertion into the plasma membrane -and proteins destined for lysosomes -synthesized proteins go into the cisterns (or are threaded in and out) -first sugar linkage to glycoproteins added here |
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free ribosomes
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these make proteins destined for the cytoplasm, nucleus, and
mitochondria ex: keratin, hemoglobin |
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smooth ER
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usually tubular
-may or may not be interconnected with rough ER -generally involved with lipid and glycogen metabolism -in liver contains a variety of detoxifying enzymes |
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-in nearly all eukaryotic cells
-very well developed in secretory cells where it lies between the nucleus and the apical cell membrane -in H and E will show as a negative image (due to absence of staining) -consists of a stack of flattened membranous sacs with dilated ends |
Golgi Apparatus
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Golgi Apparatus
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receives proteins from the rough ER via transport vesicles
-the side where these transport vesicles dock is the forming face -delivered proteins move from cistern to cistern via vesicles budding off the lateral part of each sac -modified proteins emerge from the maturing face packaged in one of several structures |
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functions of the Golgi
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concentrate and package protein into secretion granules, lysosomes, or a
class of structures hard to identify (all are membrane-bounded) -secretion granules release their contents from the cell -lysosomes contain digestive enzymes for use within the cell -HTI structures (my term)- carry membrane proteins to the plasma membrane --finish the glycosylation of glycoproteins (trimming and addition of sugars) -phosphorylate and sulfate glycoproteins |
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Lysosomes
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a membrane-bounded sac containing
many hydrolytic enzymes -involved in digestion of: worn out organelles, certain other cell constituents, and material brought into the cell via endocytosis |
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secretion granules
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release their contents outside the cell via exocytosis
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release their contents outside the cell via exocytosis
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defined as any process whereby the cell engulfs material from its
environment -there are different kinds |
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receptor mediated endocytosis
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ingestion of large molecules
-involves specific receptors and ligands for those receptors --in some forms of this, the ingested material is degraded by lysosomes (the receptors may be recycled or also degraded by lysosomes) |
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phagocytosis- (another kind of endocytosis
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-involves ingestion of particulate matter (ie bacteria, carbon, dead cells)
-also involves receptor recognition of some ligand on the particle (for bacteria the ligand might be an antibody) -this recognition causes the cell to extend processes to engulf the particle (not shown) -no clathrin used -lysososomes eventually fuse with the phagosome |
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Mitochondria
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-have a double unit membrane with the inner one folded to form
cristae -contain the enzymes for oxidative metabolism- make huge amts of ATP -contain ribosomes and DNA- can replicate w/o the cell nucleus -were once free-living organisms |
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Cytoskeleton
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involved in maintaining cell shape, shifting organelles around
inside the cell, and moving the cell or extensions of the cell |
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(solid elongated structures of cytoskeleton
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filaments
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composed of polymers of the protein, actin
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thin filaments
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basis of muscle contraction but present in most other cells
-also participate in nonmuscle contractile events such as: cleavage furrow of dividing cells, movement of cells from place to place etc. (need myosin for this) -provide mechanical support for the cell membrane thru a network just inside the cell and via connections with proteins in the cell membrane |
thin filaments (aka microfilaments
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-intermediate filaments
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-mostly structural in function
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tonofilaments
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(made of the protein keratin)
involved in certain cell adhesion structures and make the surface of skin hard and scaly |
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m i c r o t u b ules (another component of the cytoskeleton
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-made of polymers of tubulin dimers
-arranged to form a hollow structure with a wall consisting of 13 protofilaments -can assemble and disassemble quickly -colchicine binds to free dimers causing existing microtubules to disappear and preventing the formation of new ones -located in areas of organelle movement- where molecular motor proteins move organelles along the tubules like a hand truck on railroad tracks -also involved in cell division (form the mitotic spindle) |
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Centrosome (aka cell center, microtubule organizing center
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-consists of two centrioles and an amorphous, dense pericentriolar
material containing many ring-shaped microtubule-nucleation sites |
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-without the centrioles
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entire centrosome disappears
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functions of the centrosome
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-acts as the center from which microtubules form and which
directs their destination |
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specific functions of the centrioles
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during cell division they duplicate and move so that each
end of the dividing cell has a pair. In that location they regulate the polarity of the mitotic spindle (spindle microtubules come from the chromosomes) -also play a role in cilia formation replicate many times then migrate to the cell surface where they line up as basal bodies and each one initiates formation of a single cilium -cilia are motile cell surface structures that have a core of microtubules |
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Nucleus
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-single or multiple
-is basophilic (because of all the DNA) -surrounded by a double unit membrane -outer one continuous with rough ER -the double membrane has pores in it -contain a cluster of proteins that function in transporting things bi-directionally thru the pore |
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contents of the nucleus
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chromatin- chromosomal material- DNA plus other material
-euchromatin- uncoiled, active, pale staining -heterochromatin- coiled, inactive, dark staining |
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-nucleolus
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-very large and often multiple in cells growing and dividing
-composed of RNA plus protein -where ribosomes are made -may stain pink or blue -made up of pars fibrosa and pars granulosa (together form the nucleonema |
