Cell II Flashcards by tcarlso 3

Proteins constitute how much mass of the membrane?

25-75%

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How do you remove peripheral proteins from the membrane?

salt solutions

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Abnormal cleavage of beta-APP form what?

A-beta peptides that aggregate as amyloid fibrils. This is Alzheimer’s disease

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The precursor to the prion protein in Creutzfeldt-Jakob disease is found where in the cell? What conformation is it in?

GPI anchored to the cell membrane within lipid raft

Alpha helix

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What does the prion protein in Creutzfeldt-Jakob disease turn into?

Beta-pleated sheets, and amyloid fibrils

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What does the cerebrum of a patient with cruetfeld jakob disease look like

Spongiform (Swiss cheese)

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What substance will identify the amyloid plaques in Alzheimer’s and cruetzfeld jakob disease?

Congo red

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What type of protein is the beta-amyloid protein? What are its functional attributes?

Intergral (transmembrane) protein

neuronal migration during development, synapse formation/repair

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What are the functions of membrane proteins? (6)

Receptors
Pumps
Channels
Linker proteins
Structural proteins (ECM)
Enzymes

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What is the medical relevance of receptors?

Pharmacological agents may act as agonists or antagonists

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How do receptors regulate their response?

[C] of receptors

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What is the clinical significance of estrogen receptors?

target for CA (tamoxifen)

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What is the function of Na/K transporters? Are the energy dependent?

Moves 3 Na ions out of the cell and exchanges 2 K ions.

This can regulate cell volume

ATP driven

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Digoxin is used in the treatment of heart failure, and inhibits Na/K pumps. This leads to an increase in intracellular [Na]. What is the purpose of doing this?

Since Ca is exchanged for Na in its pump, the Ca pump will also slow down, increasing sacroplasmic [Ca]

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What type of transporter is GLUT5?

Secondary active synporter with Na

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Where is the Na/K pump that is used in transporting glucose?

On the interface of the intestinal epithelial cell, and the extra cellular fluid

(NOT on the intestinal lumen side with the Glu transporter)

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Where is MDR-1 expressed? (4) In what disease can it be a problem?

kidney, intestine, liver, and blood brain barrier

Will pump out antineoplastic agents if overexpressed in CA cells

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What is the function of MDR-2?

Transports bilirubin

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What is the function of MDR-3?

Expressed in liver where it functions as a flipase of phosphatidylcholine so that is may be excreted into bile

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What is Dubin-Johnson syndrome?

Defective MDR-2 transporter, leading to the accumulation of bilirubin

How do you overcome MDR-1 overexpression in CA cells

RNA interference (silence the gene for MDR-1 by eliminate its RNA)

How many isoforms of Aquaporin are there?

How is aquaporin 2 induced in kidney cells?

Vasopressin or ADH (its receptor), causes translocation of aquaporin receptors to the plasma membrane of collecting tubule, increasing water re-absorption

What disease involves defective aquaporins in the kidney?

Nephrogenic Diabetes insipidus

How does EtOH affect ADH receptor?

Inhibits it

What ion is symported with Cl in CFTR channels?

Why do cystic fibrosis patients taste salty?

Dysfunctional Cl transport = build up of Na/Cl on skin

Why do cystic fibrosis patients have thick mucus secretions?

Lack of export of Cl causes increase of [Cl]. Na and H20 transported back into the cell for balance.

What other areas are obstructed in cystic fibrosis?

bile duct, intestines, ductus deferens

Where is lactase found?

On the cell wall of intestinal epithelium

Duchenne's muscular dystrophy is the result of a defect in what protein?

Dystrophin

What is the function of Dystrophin?

Links to dystroglycans that are in the plasma membrane, which in turn link to ECM proteins

Where are glycolipids found?

The extracellular side of the plasma membrane

What is the receptor for the cholera toxin (hint" it's a glyolipid)

Gm1 ganglioside

What is the effect of cholera toxin?

Ramps up adenylate cyclase activity to increase CFTR transporters to push out H2O

What is the function of glycolipids on RBCs?

Have negative charges to keep RBCs apart

What are the roles of glycolipids/proteins?

Protection cell-cell adhesion signalling

What are the four processes of vesicular transport across the membrane

1. Endocytosis 2. Exocytosis 3. Porocytosis 4. Exosomes

How many different pathways are there for endocytosis? What is needed?

5 | ATP and Ca

Where does macropinocytosis take place?

thyroid cells taking up thryoglobulin Dendritic cells for immune surveillance

What is the type of molecule needed for macropinocytosis?

Actin

How specific is macropinocytosis?

Not at all

What is the normal function of beta-amyloid precursor protein (5)?

neuronal migration during development, synaptic formation/repair, cell signalling, long-term potentiation of memory, cell adhesion

What is the function of the normal prion protein found in creutzfeldt-Jakob disease (3)?

1. may be neuroprotective against ischemia 2. control circadian rhythms 3. may serve serve to organize the myelin sheath

Kuru disease stained with congo red will show what? PAS?

Large red amyloid aggregations with congo, black dots with PAS

Water follows what ion? How can the cell manipulate this to regulate the water content of the cytoplasm?

Na Na/K pump can shift Na out of cell, to lose water

What is the effect of increased Ca in cardiac muscle?

Increased contractile force

In the glucose/Na pump, where does Na travel (starting from the intestinal lumen)?

symport with Glucose down [C] gradient, and is pumped into the ECF by Na/K pump.

What technique would you use to identify Duchenne's muscluar dystrophy?

Immunocytochemistry