2.1 (Lecture 2) - Ultrastructure Flashcards
P-face
- protoplasmic face of the lipid bilayer
- intracellular
E-face
- ectoplasmic face of the lipid bilayer
- extracellular
freez-fracture technique
- method allowing a split of the middle of the lipid bilayer through the middle of the hydrophobic tails from each side
glycocalyx
- an important functional extension of the cell - fromed of the extracellular glycosylations associated with other extracellular molecules
rough endoplasmic reticulum
- has a phospholipid membrane
- site of protein production
ribosomes
translation of mRNA into proteins
smooth endoplasmic reticulum
site of lipid + steroid production
golgi apparatus
site of protein packaging and addressing
mitchondria
- responsible for producing energy from ATP
- highly sterotypical and recognizable structure with outer membrane + inner cistae
- high density of mitochondria can make a cytoplasm appear more eosinophilic (pink in H&E stain)
basal striations
- folds of a membrane in cells where mitochondria provide energy to basally located ion pumps or other transmembrane pore proteins
- (may be barely visable under LM - because of spatial constraints the folds place on eosinophilic mitochondria)
endocytosis
uptake of substances from the extracellular space
pinocytosis
uptake of small substances
phagocytosis
uptake of substances followed by their digestion
endosome
= the containing vesicle during phagocytosis
lysosomes
- a special type of endosome?
- specialized vesicle for phagocytosis that contains hydrolase enzymes
perioxisomes
vesicle designed to breakdown FAs through oxygenation
residual bodies
- undigestable remnants of metabolic processes that accumulate in cells
- are more prevalent in long lived cells
exocytosis
process of removing substances out to the extracellular space
regulated exocytosis
- primarily by Ca++ and SNARE proteins
- they control fusion with the cell membrane
constitutive exocytosis
release without any specific signal
thin filaments (actin)
- 1 of 3 long-chain molecules comprising the cytoskeleton
- generally sit beneath the cell membrane
intermediate filaments
- 1 of 3 long-chain molecules comprising the cytoskeleton
- keratins, desmin, vimentin, others
- form a scaffolding
microtubules
- 1 of 3 long-chain molecules comprising the cytoskeleton
- form a transport network radiating outward from the MTOC
centriole
- organizes the microtubules as they radiate outward from the MTOC
centrosomes
The name for MTOCs during cell division
Desmosomes
- also called Macula Adherens (adhering spot)
- comprised of cadherin proteins
- intracellularly bind with cytoskeletal keratin
- Appears in Em as a roundish density centered over the membranes of the two adjacent cells
hemidesmosome
- when a desmosome is used to bind a connective tissue = hemidesmosome
gap-junctions
- create an electrically conductive channel between neighboring cells through transmembrane connexin proteins
- do not bind the cytoskeleton
adhering junction
- also called the Zonula Adherens
- connects with cytoskeletal actin (thin filaments?)
tight junction
- also called Zonula Occludens
- consists of transport membrane proteins (claudins + occludins)
- they are arranged in multiple linear structures
- special because: form a barrier between cells that is largely impermeable even to water and ions
junctional complex
- often connects epithelial cells at their lateral surfaces in simple epithelia
- consists of tight junctions(zonula occludens), adhering junctions (zonula adherens), desmosomes (macula adherens)
- will be clustered in a distinct band-shaped region at the most apical portion of the lateral cell membrane
cilia
- long, motile, membrane-bound structures
- protrude from cell membrane
- in epithelia = apical surface specializations
- normal FXN: move material along the epithelial surface
axoneme
- the core of the cilium
- highly recognizable in EM by its characteristic “9 doublet plus 2 central” arrangement of modified microtubules
- insert within the cell into basal bodies
basal bodies
- microtubule structures that have a “9 triplets plus zero” arrangement
- are the location where the axoneme of cilia insert into the cell membrane
microvillus
- membrane-bound apical surface specialization
- consists of longitudinally-arranged f-actin (filamentous actin)
- inserts into the actin of the cytoskeleton (thin filaments?)
terminal web
- if the longitudinally arrange f-actin microvilli are numerous –> they form an area of the cell known as the terminal web
nucleus
contains cell’s DNA
nuclear membrane
- membrane of the nucleus that contains the cells DNA
- is continuous with the rER
- contains nuclear pores
nuclear pores
nuclear membrane proteins that allow the transport of RNA and small molecules
euchromatin
- DNA complex in LM when it is largely unpacked
- appears light
heterochromatin
- DNA complex in LM when it is tightly packed
- appears dark
nucleolus
- site of rRNA production
centromere
- organizes chromosomes during cell division
- binds homologous chromosomes at their center
telomeres
- cap the ends of chromosomes during cell division
mitosis
- equal division of a cell
- cells go from 2n1x –> 2n2x –> 2n1x
(n=chromosome #; x=copy #)
prophase
chromosomal replication during mitosis
metaphase
chromosomal alignment during mitosis
anaphase
chromosomal separation during mitosis
telophase
cell division during mitosis
meiosis
- unequal division of germ cells
- cells divide twice
- 2n1x –> 2n2x –> 1n2x (division 1) –> 1n1x (division 2)
apoptosis
- process of controlled cell death
1) dissolution of the chromosomal material
2) autodigestion
3) lysing of the cell - Important for controlling: cell #, cell quality, responsiveness of growth processes to environmental cues
- designed to minimize exposure of the lysed cell to the immune system
MTOC
- referred to as a centrosome during cell division
- the center of the transport network of microtubules within a cell
