Cell V Flashcards
What is vesicular transport?
a mechanism that uses membrane-bound structures, called transport vesicles, to ferry proteins from the donor compartment to the target membrane
How is vesicular transport selective (2)?
Transport vesicles must dock with correct target on membrane
Transport vesicle must package appropriate proteins for delivery
What is the protein that coats vesicles and directs them from the ER to the golgi?
COP II
What is the protein that coats vesicles, and directs the from the golgi back to the ER?
COP I
What is clatharin used for?
Coating incoming vesicles from the plasma membrane
Helps form secretory vesicles and directs to endosomes
What are the role of SNARE proteins?
allow the vesicle to recognize its target domain.
What are v-SNAREs?
SNARE proteins on vesicles
what are t-SNAREs?
SNARE proteins on target membranes
Why would you want to have equal flow of vesicles from the ER to the Golgi (3)?
- Maintain membrane balance
- Recycle SNAREs
- Send back misdelivered proteins
How do the neurotoxins of tetanus and botulism exert their effects?
enter nerve terminals and proteolyse SNARE proteins
(This prevents vesicles containing neurotransmitters from docking with the pre-synaptic membrane of the nerve cell.
Tetanus toxins enter inhibitory neurons thereby releasing the braking effect on motoneurons)
Is the mitochondria acidophilic or basophilic?
Acidophilic
What are the only two organelles that have two membranes?
Nucleus and mitochondria
What does the term pleomorphic mean? Which organelle does it describe?
ovoid or elongated threadlike structures: are motile and change their shape
Mitochondria
How big are mitochondria?
0.5-1 um in length
What type of cells have numerous mitochondria?
Cells that have high metabolic activity
What are the striations of the plasmalemma? Where can these be seen?
Region
What is the characteristic feature that can by used to compare two mitochondria when trying to determine which one is more involved in energy metabolism?
Number of crista
What type of cell does not require mitochondria?
RBCs
What is the space that the cristie project?
Matrix
Which membrane is more selective the inner or outer mitochondiral membrane?
Inner
What is the length of the mitchondira?
10 um
How many mitochondria do lympocytes have (relatively)?
Few
How many mitochondria do hepatocytes have?
1000 (22% of total cell volume)
How many mitochondria do cardiac muscle cells have?
40% of cells volume
True or false: the number of mitochondira in muscle cells are relatively set and do not change unless as a part of a disease process
False–change with exercise vs sedentary lifestyle
True or false: mitochondira are easy to pick out via light microscopy due to their characteristic shape
False–very hard to see them at all with light microscopy unless you used tagged succinate dehydrogenase
What are the three components of mitochondira?
Proteins (mainly)
Lipids
RNA and mtDNA
Where are most of the mt proteins synthesized? What synthesizes them?
cytoplasm by free polyribosomes
About how long do mt last?
short time–some only 10 days
How do mts reproduce?
fission or fusion with one another.
What are the two outer mt membrane transporters?
TOM complex
SAM complex
What are the three inner mt membrane transporters?
TIM 23
TIM 22
OXA complex
What causes the decreased permeability of the inner mt membrane?
due to the presence of a high conc. of a phospholipid called cardiolipin
Why are mitochondria located next to the tuble in kidneys?
Support energy dependent ion gradient
Mitochondria in palisades confer what when stained?
Acidophilic striations
mt with tubular criste are involved in what process? What if they are shelf-like?
Cholesterol/steroid synthesis if tubular
ATP generation if shelf like
If you see a mitochondria with tubular cristae, what else are you likely to see in the cell nearby?
Deposits of lipids
Would you expect to find mitochondria with tubular or shelf-like cristae in hepatocytes?
Shelf-like
Would you expect to find mt with tubular or shelf-like cristae in Cardiac/skeltal muscle?
Shelf-like
Would you expect to find mt with tubular or shelf-like christae in steroid secreting cells?
Tubular
What is released from mitochondria to initiate apoptosis?
Cytochrome C
What is MERRF? HOw is it recognized?
At the electron microscopic level, affected mitochondria harbor “parking lot” inclusions. Mitochondria are also observed to assume peculiar shapes and cristal disruption.
What is the ping pong process of hormone synthesis?
Cholesterol go to mt to sER, back to mt, secreted
What are parking lot inclusions in mt that are seen at the EM level diagnostic of?
MERRF
Odd shape mt are diagnostic of what?
Substance abuse (like EtOH)
What are the five functions of peroxisomes?
Regulate H2O2 Kill pathogens Oxidize EtOH Plasmalogen Beta FA oxidation
Zwellweger syndrome is the result of what?
impaired import of enzymes into the peroxisomes –no ether linkages in plamsa membrane lipids
True or false: cytoskeleton elements are considered to be organelles?
True
What are the three filaments?
Actin (thin)
Intermediate filaments
Myosin (thick)
What are microtubules made up of?
Tublin subunits
What are the structural elements that are hallow in cytoplasm?
Microtubules
What is Dynein?
ATPase attached to microtubules
What is the function of kinesin?
move vesicles on microtubule tracts frmo negative to positive end
Why is it important that microtubules are charged?
direct movement of vesicles
In what disease do lipids accumulate in the cerebellum?
Zellweger syndrome
How do peroxisomes get their enzymes?
From free polyribosome protein synthesis in the cytoplasm
What does the enzyme catalase do?
Forms water and oxygen from H2O2
True or false: Peroxisomal β-oxidation may equal that of mitochondria in some cell types.
True
How do peroxisomes maintain their phospholipid bilayer?
Phospholipid exchange proteins from sER maintain it
What is the defect that causes Zellweger syndrome?
Peroxisomal enzymes are not transported into the peroxisome. This is due to a defective import protein on the unit membrane of the peroxisome.
What are the four components of the cytoskeleton?
Microtubules
Actin (microfilaments)
Myosin (thick filaments)
Intermediate filaments
What is the diameter of microtubules?
24 nm
What is the composition of microtubules?
13 longitudinally arranged protofilaments made of tubulin dimers
What are the two molecules necessary for microtubule polymerization?
Mg ions and GTP
Where does microtubule synthesis occur?
From a ring of γ-tubulin within a microtubule-organizing center possessing many capping proteins.
What are three drugs that inhibit microtubule polymerization?
Colchicine, vinblastine, and vincristine
What is a drug that inhibits microtubule depolymerization?
Taxol
What is the function of inhibiting microtubule synthesis/depolymerization?
Anti-mitotic (CA)
What are the five major functions of microtubules?
- Support cytoplasm
- Organelle support
- Cell division
- Motility of cilia and flagella
- Long range transport of vesicles by microtubule motor proteins
What are the two types of motor proteins used in microtubular transport? Which way does each move along the microtubule?
Kinesin -toward the periphery (neg to pos)
Dynein - toward the nucleus (positive to negative)
A sample of cells taken from a 5 mo show an accumulation of VLCFAs, and a biopsy of the cerebellum show lipdi deposits. What is your diagnosis?
Zellweger syndrome
