week 1 histology ultra structure Flashcards
steps for making histology slide
- specimen acquisition
- fixation
- dehydration
- embedding
- section
- stain
why do we do fixation?
to preserve the structure
why do we do embedding?
to stiffen it so we can cut
why do we do sectioning?
to improve resolution
why do we stain?
to produce contrast
what is the maximum resolution, magnification and section thickness of a light microscope ?
0.2um, 2000x , 1-100 um
what is the max resolution and magnification of the TEM microscope? and then sectioning thickness
3nm , 500,000 x, 0.025 um
how thick is plasma membrane?
9nm
Nucleus of non-dividing cells contains?
Chromatin
Nucleus of dividing cells contains? (mitosis)
Chromosomes
What is chromatin comprised of?
DNA + Histones
What is Euchromatin?
DNA wraps around histones forming NUCLEOSOMES. light areas.
What is Heterochromatin?
Multiple nucleosomes wrap to form a 30nm CHROMATIN FIBRE.
Euchromatin features?
Pale areas, active, extended
Heterochromatin features?
Dark areas, condensed, inactive.
Cytoskeleton functions?
Structural support, intracellular movement of organelles & metabolites
What are non-membranous organelles?
Microtubules, microfilaments, intermediate filaments
What is the function of Microtubules?
Intracellular transport, cell shape, cilia movement, chromosome arrangement
T or F: Microtubules are stable and do not continuously change shape.
F: Continually forming & disassembling
What disrupts microtubules?
Drugs, decrease temp, increase hydrostatic pressure
What is the structure of Microtubules?
Tubulin protein, hollow cylinders, 22n, diameter, 5nm thick walls, dynamic
What is the structure of microfilaments?
Actin, helical array, 6nm diameter, flexible
T or F: Microtubules are arranged in a helical structure.
False: arranged in hollow cylinders.
Function of microfilaments?
Microvilli structure, extension of cell processes
Which organelle initiates apoptosis via release of cytochrome c into the cell cytoplasm?
Mitochondria
