Glossary of Catos First Exam
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- What are the 4 types of tissues?
- Nerve, muscle, connective tissue and epithelia
- Which parts of the cell control detox of alcohol vs. barbiturates?
- The peroxisome breaks down alcohol and the SER breaks down barbiturates.
- Which enzyme is used for diagnosis of a lysosome? What about a peroxisome?
- Acid phosphatase
- What do peroxisomes use catalase for?
- They use it to generate H2O2 to oxidize alcohol and other compounds.
- What is the most important property of the lipid bilayer?
- How would you make a membrane more or less fluid?
- Adding cholesterol makes the membrane less fluid.
Adding double bonds in the hydrocarbon tails of phospholipids makes the membrane more fluid.
- How much cholesterol is there in the membrane and what does it do to permeability?
- 1:1 Cholesterol to Phospholipids.
Cholesterol decreases the permeability by making the polar parts stiff and the hydrophobic tails fluid.
- What phospholipids are found on the E surface?
What about the P surface
Finally which surface is cholesterol found on?
- E surface is outside the cell so it contains PC and sphingomyelin.
P surface is inside and contains PE, PS and PI (PEPSPI).
Cholesterol is found equally in both layers.
- Where is the orientation for phospholipids in the membrane set and why is it like this?
- Phospholipids are added to the cytosolic side of the ER. Flippases are able to flip the PC and S to the inside of the ER so they end up outside the cell.
The reason this needs to happen is because there are no flippases in the PM and so lipids don't flip flop.
- Which phospholipid flips to the outside of the RBC when it is ready to die?
- Phosphatidylserine (PS)
- What is meant by patching and capping in the membrane fluidity experiments?
- The experiment involves applying an antibody to an integral membrane protein. Initially the antibody-protein is homogeneous but sometimes the proteins with ligand will join together in patches, this is a passive process.
Capping on the other hand is when the cell moves all the proteins to a part of the cell opposite the centrosome, THIS IS ACTIVE PROCESS.
- What are the 4 ways to create membrane domains?
- Bind phospholipids and proteins to ECM with fibronectin or laminin.
Bind them to the terminal web or cell cytoskeleton.
Create cell junctions between cells.
Tight junctions (ZO) will also create domains (Main way).
- What 3 types of receptors are there, what are good examples and what is their general structure?
- Ion-channel receptors are usually multipass proteins (Na+ channel)
Enzyme linked receptors are usually single pass (Receptor tyrosine kinases)
G-protein linked receptors are usually 7 transmembrane proteins (alpha or beta adrenergic receptors).
- What are the specifics of N-CAMS?
- They are cell adhesion molecules which exhibit homophillic binding and are Ca2+ independent.
They attach neurons to glial cells.
- What are the specifics of Cadherins?
- These exhibit homophillic interactions with Ca2+ dependence.
They are found in desmosomes and zonula adherens.
- What are the specifics of integrins?
- They are integral membrane proteins which bind the cell cortex to the ECM.
They bind to fibronectin (fibroblast) and laminin (epithelia).
They recognize the RGD sequence on laminin and fibronectin.
Integrins are Ca2+ dependent but also Mg2+ dependent.
- What are the specifics of selectins?
- Carbohydrate binding proteins which are also Ca2+ dependent. THESE EXHIBIT HETEROPHILLIC BINDING and the binding is transient and weak.
- Discuss the neutrophil diapedesis
- Infection causes tissue release of TNF-a and IL-1.
These two components cause endothelial cells to express p-selectins on their surface.
The p-selectins bind glycoproteins specifically on neutrophils but the binding is weak and transient. This causes the neutrophil to roll.
The binding of selectin to sugar on neutrophil causes Ca2+ increase in cytoplasm. This converts the cell from sol to gel state.
At this point, integrins on the neutrophil surface bind to ICAMS expressed on the endothelial surface.
This binding causes neutrophils to stop and turn into sol state.
At the same time, histamine and thrombin cause gaps to form in capillary. Now the neutrophil can diapedese out.
- What is the equation for the permeability coefficient and how does it relate to the Kp or permeability constant?
- Perm. coefficient = D/∆x
Perm. constant Kp = β*D/∆x
β = partition coefficient
- What is the equation for osmotic pressure and what does each thing account for?
- ∆π = RTφ[total S]
RT accounts for kinetic energy inherent in the concentration gradient.
φ is the osmotic coefficient which accounts for the effects of different solutes in water.
[total S] is the water concentration indirectly.
- What is Fick's Law equation?
- J = -DA*∆S/∆x
J = -KpA*∆S
Jv = LpA(∆P - σ∆π)
- How does Ohm's law relate to Fick's law?
- Ohm's Law V = IR
I = g*(∆Em-∆Ei). The g is conductance (1/R) and ∆Em is voltage.
In actual fact, g is equivalent to *mobility*area.
If you calculate (∆Em - ∆Ei), you are calculating the driving force and therefore current would be exactly equivalent to J or flow.
- True/False: The voltage required to open a voltage gated ion channel is the same as the Nernst potential for that ion?
- What are the 3 options for the structure of an ion channel?
- Heteromer - Different subunits make up the channel.
Homomer - Identical subunits make up the channel.
Single polypeptide with multi-pass membrane domains.
- What is the structure of a Na+ voltage-gated channel?
- It is a single polypeptide with 4 different subunits each having 6 transmembrane domains.
- Where is the voltage sensor in a Na+ channel?
- The S4 segment
- What are the kinetics of the Na+ channel?
- Fast open, fast inactivate.
- Why would you want Na+ channel inactivation?
- It ensures a transient flow of Na+ ions. It contributes to the refractory period of the AP. It prevents bidirectional movement of the AP.
- What is wrong with hyperkalemic periodic paralysis?
- A mutation in the alpha subunit of voltage gated Na+ channels prevents the channel from inactivating. As a result when hyperkalemia ensues, the resulting depolarization causes constant Na+ flux which causes paralysis.
- How does Tetrodotoxin work?
- It is a voltage gated Na channel blocker
- How do Lidocaine/Novacaine work?
- Both are selective voltage gated Na channel blockers
- What is the structure of the voltage gated Ca channel?
- Single polypeptide with 4 subunits and 6 transmembrane domains similar to Na channel. Also has auxillary subunits like Na channel.
- What are the kinetics of the voltage gated Ca channel?
- What is wrong in Lambert-Eaton Myasthenic syndrome?
- Autoantibodies against presynaptic Ca channels preventing release of Ach. This causes paralysis similar to myasthenia gravis.
- How do the drugs Nifedipine and Verapamil work?
- Both are L-type Ca channel blockers which decrease intracellular calcium to cause smooth muscle relaxation and a negative inotropic effect.
These drugs are antihypertensives.
- What is the structure of the voltage gated K channel?
- It is a single polypeptide with 4 IDENTICAL subunits (HOMOMER) which is different from Na/Ca2+ channel. Each subunit still has 6 transmembrane domains.
- What are the kinetics of the voltage gated K channel?
- Moderate/slow kinetics
- What is the problem in Benign familial neonatal convulsions?
- It is a mutated M-type K channel which normally hyperpolarizes the cell due to Ach binding to muscarinic receptor. In BFNC, the channel depolarizes causing hyperexcitability and convulsions.
- How would you treat benign familial neonatal convulsions?
- Retigabine which opens the defective M-type channel causing hyperpolarization.
- How does 3,4 Diaminopyridine work? What is it used to treat?
- It is a voltage gated K channel blocker which prolongs the AP.
Lambert-Eaton myasthenic syndrome by prolonging the AP allowing Ca to be released into the presynaptic terminal increasing Ach release.
- What is dofetilide?
- Anti-arrythmic drug used to treat Afib and flutter by blocking K current and therefore prolonging the refractory period of the cardiac AP.
- What is the structure of the nicotinic receptor? Include differences between adult and fetal forms and what happens as a result.
- It is a 5 subunit ligand gated channel that requires 2 Ach to bind to 2 alpha subunits. Adult version has an epsilon subunit whereas the fetal form has a gamma subunit. This results in larger conductance in the adult form and longer openings in the fetal form.
- What is the reversal potential for a nicotinic receptor? What does this mean for it does for the cell? What are the kinetics?
- Reversal potential is 0mV which means it is excitatory for the cell.
The kinetics are extremely fast.
- What is the nicotinic receptor selective for?
- Na and K ions.
- Name 2 diseases associated with the nicotinic receptor?
- Slow channel syndrome and Myasthenia gravis
- How does slow channel syndrome work?
- Mutated nicotinic receptor causes increased conductance of ions and longer channel open times.
It results in muscle fatigue, weakness and atrophy.
- How does myasthenia gravis work? How is it different from Lambert-Eaton myasthenic syndrome?
- It is auto-antibodies towards the nicotinic receptor resulting in paralysis and weakness.
Lambert-Eaton is an auto-antibody against the Ca2+ channel of the presynaptic neuron.
- List all the drugs that block the nicotinic receptor?
List all the agonists of the nicotinic receptor?
- What ions does the AMPA receptor allow to flow? What about NMDA?
- AMPA is Na+/K+
NMDA is Na+/K+/Ca2+
- Name the ligand-gated channel
Reversal potential 0mV
Opens Na+/K+ channels
Opens at both positive and negative potentials
- AMPA glutamate receptor
- Name the ligand-gated channel
Reversal potential 0mV
Opens Na+/K+/Ca2+ channels
Opens only at positive membrane potentials
Why does this receptor not open at negative potentials?
- NMDA glutamate receptor
When the interior of the cell is negative, it draws Mg2+ into the channel which blocks it. When the potential is positive, this Mg2+ is repelled.
- Name a blocker of AMPA receptors?
- Name all the things that bind to the NMDA receptor
- Mg2+, PCP, Zn, Glycine and Glutamate
Na+, K+ and Ca2+ go through it.
- What are D-AP5 and D-AP7?
- Drugs that block the NMDA receptor
- When would you use Ketamine and how does it work?
- For analgesia, anticonvulsant or during ischemia to prevent glutamate excitotoxicity.
Ketamine is a non-competitive blocker of NMDA receptors.
- Name 3 non-competitive blockers of the NMDA receptor?
- Ketamine, MK-801 and PCP
- What is the structure of the GABA-A receptor?
- Similar to nicotinic receptor with 2α but has 2β and one γ. Benzodiazepines bind to the α subunit whereas GABA and barbiturates bind to the β subunit.
- Name 2 blockers of the GABA-A receptor?
- Picrotoxin is a competitive GABA-A blocker.
Bicuculline is a non-competitive blocker.
- What would I use Diazepam and Phenobarbital for?
- Diazepam is valium. It is used as an anxiolytic and activates the GABA-A receptor.
Phenobarbital is used as an anti-convulsant and sedative and also activates the GABA-A receptor.
- Where would glucose-6-phosphatase and glycogen phosphorylase be found and what do they do?
- Glucose-6-phosphatase is found on the RER P face in order to convert glucose-6-phosphate into glucose during gluconeogenesis in the cytosol of the liver.
Glycogen phosphorylase is also found on the P face of the RER for glycogenolysis (glycogen to G-6-P) in the liver cytosol.
- True/False Lipid droplets are surrounded by a bilayer membrane?
- False, no membrane around lipid droplet.
- What would you find in lipid droplets that give them their characteristic yellow color?
- Carotene which is derived from carrots and is the precursor to Vitamin A.
- Name the 3 exogenous pigments? Name the 3 endogenous pigments?
- Carotene, carbon and minerals (lead, mercury)
Hemoglobin, lipofuscin and melanin
- ATP or GTP?
- On which subunit do you find the mRNA binding site, P site and A site?
- The small subunit.
- How would I get a protein to be digested in a proteasome? What about a lysosome?
- Several ubiquitin added to lysine residue for proteasome.
Protein with KFERQ signal for lysosome.
- What protein is found selectively in the outer mitochondrial membrane?
- A β barrel called a porin, and these are aqueous pores.
- Why is the inner mitochondrial membrane so impermeable?
- Due to cardiolipin.
- What enzymes and proteins are stuck in the inner mitochondrial membrane?
- Succinate dehydrogenase, cytochrome C reductase, cytochrome C oxidase.
- Name the 2 organelles that undertake β oxidation?
- Mitochondria and peroxisomes.
- True/False: The mitochondrial DNA is attached to histones?
- FALSE. When thinking of mitochondria, think of bacteria.
- What enzyme does the peroxisome use to break down alcohol?
- What are the enzymes superoxide dismutase and peroxidase used for?
- Neutralizing free radicals.
- How do you move a protein into the mitochondrial matrix?
- Heat shock proteins bind the ribosome that has started translating the protein sequence with a 20-80 N-terminal signal sequence. The heat shock protein is a chaperone that takes the protein destined for the mitochondria to the contact sites which are connections between inner and outer mitochondrial membranes. The protein is then translated into the matrix where new chaperones meet it in the matrix.
- What is the signal sequence for mitochondria? Is it cleaved? How many signals do you need to insert the protein into the cristae?
- N-terminal 20-80 aa sequence.
The signal is cleaved.
1 signal to get into the matrix, another to get inserted into the cristae. BOTH are cleaved.
- What is the signal sequence for urate oxidase? What happens to the signal?
- Urate oxidase goes to the peroxisomes with a 3 aa C terminal signal sequence.
The signal is KEPT like the nucleus. NOTE: Could have asked catalase, superoxide dismutase or peroxidase
- What is the function of SER in these locations?
Most other cells
- Adrenal cortex - Steroid production
Hepatocytes - Detoxification of barbiturates
Skeletal muscle - Stores Ca2+
All other cells - Makes phospholipids.
- What is the signal sequence for the RER?
- 8-20aa N-terminal sequence
- Where is ribophorin found and what does it do?
- Ribophorin is found on the RER membrane and it binds to the large subunit of the ribosome so that the signal recognition particle can go off and attach to another mRNA.
- What is translocon?
- The protein channel in the ER membrane that the translated protein is fed through.
- How would you form a transmembrane protein while translating the protein into the ER lumen? When doing this, where would the N terminus be and where would the C terminus be?
- There is a STOP transfer sequence which tells the ribosome to push that piece of protein into the bilayer.
N-terminus would be within the lumen and C would be in the cytosol.
If you want to add more transmembrane domains there is a START transfer sequence which initiates the translation again.
- Discuss adding sugars to protein in the ER lumen?
- The 14 sugar polysaccharide is added en bloc (as a chunk) to the protein. It is added to an Asn residue. Before it is added, it is attached to dolichol in the lumen.
- What residue is the 14 sugar polysaccharide added to on a protein?
- How many core sugars are there on a glycoprotein and what is their significance?
- There are 5 core sugars which can survive the Golgi trimming.
- What is the KDEL sequence? Where is it recognized?
- It is the C-terminal signal sequence that tells proteins that have gone to the Golgi to go back to the ER.
It is recognized in the cis golgi network (forming face)
- What is the sequence to go to lysosomes? Where is it added?
- Phosphorylation of mannose residues occurs in the CGN and the signal sequence becomes mannose-6-phosphate.
- What are the differences between sugars added at the Golgi and those added at the ER?
- Sugars are added one monomer at a time in the Golgi whereas in the ER it is en bloc. The sugars added in the Golgi are O-linked sugars added to serine and threonine residues and those added in the ER are N-linked added to asparagine residues.
- True/False Transcytosis does not involve the Golgi or ER?
- True. It is just movement of vesicles from one surface to the other.
- What enzyme adds O-linked sugars in the Golgi?
- When would I need to use the constitutive pathway? What signal do I need? What vesicle coat would I need?
- When adding proteins to the E surface of membranes or extruding them from the cell.
There is no sorting signal.
Coatomer coated vesicles are used in the constitutive pathway.
- Which pathway would I use to add P surface proteins to the membrane, Constitutive or Regulated?
- Neither, P surface proteins are just added directly from free ribosomes.
- When would I use the regulated pathway? What signal do I need? What coat would be covering the vesicles?
- When I need to store a secretory product near the PM to be released when a ligand binds.
- What do I need to release secretory granules?
- You need Ca2+ to increase inside the cell which causes the vesicle to release from the cytoskeleton.
- What are the 4 differences between the vesicles of the constitutive pathway vs. regulated pathway?
- Coatomer coat vs. clathrin coat.
pH normal vs. pH = 6 (cause release of receptor)
Ca2+ independent vs. Ca2+ dependent release from spectrin II.
No sorting signal vs. sorting signal for regulated
- What type of secretion is a lactating mammary gland?
- Apocrine secretion
- What type of secretion is a sebaceous gland?
- Holocrine (sebum)
- What enzyme would I look for to identify a lysosome?
- Acid phosphatase
- What is the pH of a lysosome?
- pH = 5
- True/False Clathrin is required to move acid phosphatase to lysosomes?
- Why does the pH drop in a late endosome and what does it drop to?
- The pH drops to 6 so that the enzyme with M-6-P attached to receptor will release the receptor and the receptor can go back to the Golgi. The pH drop also allows the M-6-P to be cleaved.
- What is the difference between a primary and secondary lysosome?
- Primary only has enzymes, secondary has the stuff that needs to be digested.
- What is a residual body?
- It is the undigested product of a secondary lysosome.
- Discuss the process of taking LDL up into the cell?
- It is receptor mediated endocytosis whereby the LDL binds to the coated pit where receptors are found.
Adaptin then binds to the cytoplasmic side of the receptor and clathrin binds to the adaptin. This causes a clathrin coated vesicle to form within cell.
- True/False Energy is required to form a clathrin vesicle?
- False, energy is required for clathrin to release, not form.
- True/False The pH of the early endosome is higher than that of the late endosome?
- False. The only difference between them is that the early endosome is found near the PM surface, the late is found near the Golgi. Both have a pH = 6.
- What are the 3 options for the receptors found in early endosomes?
- 1) The pH will drop causing the release of the receptor which is recycled.
2) The receptor doesn't let go with pH drop and is degraded in the late endosome/lysosome.
3) The receptor moves to a different membrane through transcytosis.
- Name 4 uses for lysosomes?
- 1) Heterophagy - break down of extracellular material.
2) Autophagy - break down of cell components
3) Autolysis - lysosome bursts causing cell to die.
4) Extrusion to degrade other membranes (sperm head and osteoclast)
- Name 3 pathways clathrin is found in?
- Receptor mediated endocytosis
Enzymes to lysosomes
- True/False COP proteins require ATP to assemble?
- True, unlike clathrin, COP proteins do need energy to assemble.
- If a protein has the KDEL sequence, what coat will the vesicle taking it back to the ER have?
- To move from Golgi to ER, COP-I is needed.
To move anterograde from ER to Golgi, COP-II is needed.
- What 2 things do I need to get a vesicle to fuse with the membrane? What proteins are associated?
- You need V-snares (vesicle) to meet with T-snares (membrane) and this will allow docking.
You then need NSF and SNAPs to allow the membranes to come close enough to fuse.
- What is treadmilling?
- When G-actin monomers are added to the plus end of a microfilament at an equal rate to that of F-actin being degraded from minus end.
- What accounts for the lag phase of microfilament formation?
- The nucleation seed (trimer) of G-actin subunits takes a lot of time to form.
- Name the 2 gel forming microfilament associated proteins?
- Filamin and spectrin are both found in the terminal web where they tie the cell cortex (actin) to the PM.
- Name the 2 bundling actin associated proteins? Where are these found respectively?
- Fimbrin and α-actinin.
Fimbrin is found in filopodia of fibroblasts and microvilli along with villin.
α-actinin is found in stress fibers attached fibroblasts to the ECM.
- What does gelsolin do to actin microfilaments and what does it require?
- It fragments them but NEEDS Ca2+ to do this. It actually also caps one end.
- What do profillin and Cap-Z do?
- Profillin binds to G-actin monomers preventing them from aggregating.
Cap-Z caps microfilaments on the PLUS END.
- Name 1 drug that blocks the polymerization of actin?
- Cytochalasians produced by molds.
- What are the steps in focal contact formation?
- 1) The integrins of the fibroblast recognize fibronectin.
2) This activates FAK (focal adhesion kinase) which phosphorylates vinculin and talin and causes them to aggregate.
3) Vinculin binds talin, α-actinin and actin into the stress fiber.
4) We use α-actinin because the actin fibers have to be far enough apart to fit vinculin and talin.
5) Cap-Z caps the actin of the stress fiber.
- What proteins bind the cell cortex to the PM?
- Band 3, an integral membrane protein binds to ankyrin. Ankyrin binds to spectrin which has formed cross-links of actin in the cortex.
Band 4.1 just attaches the actin in the cortex to the PM directly.
- Discuss the formation of pseudopods?
- 1) Antigens of bacteria bind to a Gq receptor on the macrophage surface.
2) The Gq activates phospholipase C which converts PIP2 into DAG and IP3.
3) The IP3 goes to the ER where is causes release of Ca2+.
4) Ca2+ activates gelsolin which chews up the actin cytoskeleton being held together by spectrin and filamin.
5) Profillin also comes in and binds free G-actin monomers.
6) The increase in solute draws water into the cell and that region swells. Pseudopod is formed.
- What actin associated protein is found in filopodia?
- Fimbrin, like they are microvilli.
- What are the 3 stages to cell locomotion?
- 1) Protrusion - Lamellipodia form from actin and filamin interactions.
2) Adhere - Focal contacts are made to surface with stress fibers.
3) Traction - Myosin 1 causes pulling on stress fibers.
- True/False The plus end of a microtubule is the α monomer?
- False, remember α bind to the γ of the MOC in which case they are at the negative end.
- Which organelle is more associate with dynein?
- Golgi is more associated with dynein because it is found by the nucleus and dynein moves stuff from periphery to nucleus (plus end to minus end)
- Which organelle is more associated with kinesin?
- ER because kinesin moves stuff from nucleus out to the periphery (minus end to plus end). ER is out in the periphery.
- What 2 drugs should you know for microtubules?
- Colchicine prevents polymerization of microtubules.
Taxol prevents depolymerization of microtubules.
- Why can't microtubules form anywhere like microfilaments?
- Microtubules require a nucleation site which is in the MOC or centrosome
- What is the significance of the GTP cap?
- Microtubules grow out from the centrosome because the tip tubulin subunits are bound to a GTP cap which is stable. When this cap gets hydrolyzed, the microtubule shrinks.
- What is the ultrastructure of the centriole?
- 9+0 which means 9 triplet microtubules on the outside and none in the middle.
- True/False A centriole is made of triplet microtubules labelled A,B and C. A is the subunit closest to the middle.
- What region does a centriole divide from?
- The procentriole
- What is the ultrastructure of the basal body?
- Same as centriole 9+0
- What are the 3 locations that you find cilia?
- Conducting airways of respiratory system.
Efferent ducts of testes
- What is the ultrastructure of a cilium?
- 9+2 DOUBLET microtubules.
- Which subunit is the ciliary dynein attached to? What other protein is found connecting A subunits to B?
- The A subunit.
Nexin connects the outer microtubules in a cilium.
- What is the difference between metachronal and isochronal rhythm?
- Metachronal is wave-like movement of cilia whereas isochronal is all together.
- What are the differences between cilia and flagella?
- Only 1 flagellum per cell
Only found in sperm
Have quasi-sinusoidal waves as opposed to metachronal.
- Name 4 things unique to intermediate filaments?
- No energy is required for polymerization
They have no polarity
They are the toughest cytoskeletal filaments
They are the only ones found in the nucleus
- What is the ultrastructure of intermediate filaments?
- α Helices which are put together in a rope like configuration.
- What intermediate filament do you find in epithelia?
- What intermediate filament do you find in connective tissue?
- Vimentin (Fibroblasts have vimentin)
- What intermediate filament do you find in muscle?
- What intermediate filament do you find in glia?
- Glial fibrillary acidic protein (GFAP)
- What intermediate filament do you find in neurons?
- What intermediate filament do you find in the nucleus of all cells?
- Nuclear lamins which remember are in sheet formation not rope formation.
- What is the only protein that we talked about associated with intermediate filaments?
- Fillagrin binds tonofilaments together.
- Name the actin associated protein only found in microvilli? What anchors the microvillus into the terminal web?
- True/False Myosin I is found in the tip of a microvillus?
- True, but doesn't provide motor function because a microvillus can't move.
- If I see striated border microvilli where am I?
- Small or Large intestine
- If I see brush border microvilli where am I?
- Proximal tubule of nephron
- If I see stereocilia where am I?
- Epididymis or inner ear.
- If I see basal infoldings, where am I? What integral membrane protein and organelle will be abundant?
- Probably in the proximal tubule of the nephron
Na+/K+ ATPase and mitochondrion
- What are the 2 functions of the tight junction (ZO)?
- Create membrane domains and a tight seal so there is no para-cellular flow between cells.
- If you are looking at a pentalaminar structure, what are you looking at?
- The tight junction or ZO
- What proteins comprise the tight junction?
- Claudins are the major transmembrane protein.
Occludins are the 2nd transmembrane protein
ZO1, ZO2 and ZO3 attach actin of the terminal web to the occludins. AF6 is also in there somewhere.
- If you are looking at a junction of a continuous capillary what structure do you see?
- The fascia occludens
- What is the primary transmembrane protein of a zonula adherens?
- Cadherins which are tissue specific and require calcium
- What does δ catenin do?
- It attaches the actin microfilaments to the cadherins of the zonula adherens
- What makes up the terminal bar? What about a junctional complex? Where do you find terminal bars?
- ZO and ZA
ZO, ZA and MA (desmosome)
In cuboidal and columnar epithelia
- Where do you find terminal web?
- Striated and brush border microvilli areas.
- What is another name for the intercalated disc? If you see this then where are you?
- Fascia adherens
- What are the protein components of the macula adherens (desmosome)?
- Desmoplakin and plakoglobin make up plaques on either cytosolic side.
Desmoglein and desmocolin make up the cadherins that hold the thing together.
Tonofilaments are intermediate filaments that attach to the plaques.
- True/False Without Ca2+, the desmosome and zonula adherens would fall apart?
- True, both use cadherins which are calcium dependent.
- What are the proteins associated with the hemidesmosome?
- There are plaques which aren't labelled but these plaques attach to the basement membrane through integrins which bind to laminin (epithelial cells).
The plaques are also attached to intermediate filaments, in this case keratin
- What does laminin do for an epithelial cell?
- It binds the integrin of the cell to the type IV collagen
- What protein comprises the gap junction?
- What are the particles found in the nuclear matrix?
- snRNPs which are cutting introns from hnRNA.
- What do the following represent?
- 45s rRNA being transcribed
Inactive DNA but also the NORs of chromosomes 13,14,15,21,22
Pre-ribosomal particles being adding to rRNA
- True/False The secondary constrictions on chromosomes 13,14,15,21 and 22 are where the nucleolus will reform?
- True, these are the nucleolar organizing regions (NORs) of the cell. The secondary constrictions are actually the rRNA for the cell.
- Which do you normally have more of? Heterochromatin or Euchromatin
- Normal cells have 90% heterochromatin
- What are the centromere and satellite DNA examples of?
- Constitutive heterochromatin, DNA with no genes that is never transcribed.
- What is facultative chromatin?
- Chromatin that can be unfolded to be transcribed or that has genes that code for stuff but is never transcribed (barr body)
- What are the 5 regulators of cell division?
- Nutrients, contact with ECM and neighbouring cells, hormones and growth factors.
- What is MPF and what does it do for you?
- M-phase promoting factor. It is Cyclin B with Cdc2
1) MPF phosphorylates the nuclear lamins to cause breakdown of the nucleus
2) It phosphorylates H1 histones to cause DNA to condense into chromosomes
3) It phosphorylates microtubule associated proteins to cause spindle microtubules to form.
- Give me the best examples of a submetacentric and acrocentric chromosome?
- X - submetacentric
Y - acrocentric
- List 2 locations where telomerase is found?
- Embryonic stem cells and cancer
- What rRNA is associated with the large subunit of the ribosome? What about the small subunit?
- 28, 5.8 and 5s with the large subunit
18s with the small subunit
- List 3 things happening in prophase?
- MPF is phosphorylating stuff.
Centrioles go to opposite side of the cell and are called spindle poles
DNA condenses and polar microtubules form.
- List 3 things happening in prometaphase?
- Nuclear lamina is phosphorylated and nuclear membrane breaks down
Kinetochores associate with centromeres and chromosomal microtubules attach
Nucleoli are gone
- List 1 thing happening in metaphase?
- Chromosomes pair up at the equator
- List 3 things happening in anaphase?
- Cyclin and MPF are degraded
Proteases cut the connection between kinetochore and centromere.
Chromosomes are pulled apart
- List 3 things happening in telophase?
- Chromosomes decondense, nucleoli reform and nuclear envelope reforms.
- What makes up the contractile ring of the cell?
- Actin microfilaments
- What is cell fusion? Example
- It is polyploidy where cells like skeletal muscle cells or osteoclasts fuse to form one giant cell with multiple nuclei
- What is amitosis? Example
- It is when the nucleus divides but the cytoplasm doesn't so you get multiple nuclei in one cell.
- What is endomitosis? Example
- When the nucleus divides but becomes lobulated instead of having multiple nuclei
- What enzyme causes apoptosis and what activates it?
- TNF-α activates caspase enzymes which destroy cell.
- What are the 4 ultrastructural features of apoptosis?
- Pyknotic nucleus
Cell shrinkage and adhesion junction loss
Apoptotic bodies form
Neighbouring cells phagocytose apoptotic bodies
- What is karyorrhexis?
- The nucleus splits up into lots of pyknotic pieces
- What is karyolysis?
- The nucleus goes poof (disappears)
- What facilitates the binding of the steroid receptor to the DNA transcription start site?
- A zinc finger
- What tissues have HRE's for the androgen-androgen receptor?
- Laryngeal muscle and prostate specific antigen
- Where are the HRE's for Vitamin D in the intestines?
- On the calbindin gene.
- Which subunit of the G-protein activates adenylate cyclase?
- α subunit
- How does the B1 receptor in skeletal muscle differ from that of cardiac muscle?
- B1's are Gs receptors. In skeletal muscle, the activation of PKA causes phosphorylation of glycogen phosphorylase and causes glycogen breakdown.
In cardiac muscle, the PKA phosphorylates L-type Ca2+ channels which increases cytosolic Ca2+, thereby increasing inotropic effect.
- Where is the L-type Ca2+ in cardiac muscle and how does it affect the Ryanodine receptor?
- Phosphorylating the L-type Ca2+ channel in the PM causes influx of Ca2+ which stimulates Ryanodine receptor on the SER to release more Ca2+. The ryanodine receptor is a Ca activated Ca channel.
- Name a drug that blocks phosphodiesterase?
- How does vasoconstriction from α1 stimulation occur?
- α1 receptor is a Gq which activates PLC which increases IP3 which opens Ca2+ channels on SER thereby causing vasoconstriction.
- What is phenylephrine, what is it used for?
- Phenylephrine is an α receptor agonist used as a decongestant, vasoconstrictor and pupillary dilator
- What is isoproterenol, what is it used for?
- It is a β agonist used as an anti-asthmatic and increases HR and SV
- What is albuterol, what is it used for?
- Selective β2 agonist used to treat asthma
- What is phenoxybenzamine, what is it used for?
- It is an α antagonist used to treat high BP
- What is phentolamine, what is it used for?
- It is an α antagonist, used to increase blood flow and treat high BP
- What is prazosin, what is it used for?
- It is a selective α1 blocker used to treat high BP
- What is Propranolol, what is it used for?
- It is a β blocker used to treat high BP by lowering HR, SV and CO. It also treats migraines, relieves angina and treats arrythmias
- What is Metoprolol, what is it used for?
- Selective β1 antagonist which means it can treat heart failure, decrease BP and treats angina.
- How does Cholera toxin do it's damage?
- It stimulates Gs receptors increasing cAMP which causes phosphorylation of the CFTR receptor and causes massive loss of Cl in the GI tract. This induces water movement and severe diarrhea
- How does Pertussis toxin do it's damage?
- It inhibits the Gi receptor causing an increase in cAMP which causes whooping cough and other problems.
- What causes desensitization of the G-protein receptors?
- G-protein receptor kinase (GRK) phosphorylates the G-protein receptor thereby desensitizing it.
- What causes internalization of the G-protein receptors?
- Once the G-protein receptor has been phosphorylated, B arrestin is recruited to the site as well as AP2. This recruits clathrin which causes an endocytic vesicle to form.
- Run through the big picture of receptor tyrosine kinase mechanism?
- Ligand binds to receptor, causes the receptor to dimerize which allows self-phosphorylation of receptor. This recruits Grb2 which activates SOS to transfer GTP to Ras and replace the GDP bound.
Ras is active with GTP bound and it activates MAP kinases.
- What do the MAP kinases do after activation through receptor tyrosine kinases?
- They phosphorylate protein products to cause activation of early genes (myc, fos and jun). They then cause production of the late genes which are the cyclins. The cyclins can then interact with the Cdks.
- What phase of the cell cycle is responsive to growth factors and what is the restriction point?
- Only the G1 phase
The restriction point is the point of the cycle where the cell no longer needs growth factors to complete cell division.
- Name the 4 ways that growth factors can increase the functioning of cyclin D?
- 1) They increase transcription of D
2) They stabilize it, preventing the breakdown
3) They translocate it to the nucleus.
4) They help it attach to Cdk4 and Cdk6.
- What is the main point of cyclin D binding to Cdk4/6?
- Once this complex forms, the Rb protein is phosphorylated. Rb in the dephosphorylated form binds the E2F transcription factor required for gene transcription of Cyclin E and other genes needed for cell cycling.
The phosphorylated Rb lets go of E2F so that gene transcription of cyclin E and other genes can occur.
- Name the 2 ways that the Rb protein prevents cell division?
- It binds to early genes myc and fos preventing them from being expressed.
It binds to E2F which is a transcription factor required to produce cyclin E and other products needed for cell division.
- What does Cyclin E do when it is active?
- It phosphorylates the Rb protein allowing more cyclin E to be made and other genes to be expressed.
- Name an inhibitor of Cdk2-cyclin E complex? How does this work and how can you get rid of it?
Cip/Kip normally binds to Cdk2 preventing it from joining with cyclin E. When the cyclin D-Cdk4/6 complex forms, Cip can bind to it, thereby releasing Cyclin E to bind with Cdk2.
- How does p53 inhibit cell cycle division?
- p53 is a tumor suppressor gene and it codes for the Cdk inhibitor Cip. Cip normally binds to Cdk2 preventing it from associating with cyclin E and thereby stopping cell division.
- Name 3 ways you can get cancer?
- Constitutive expression of Ras, myc, fos or jun.
Loss of either Rb or p53
Constitutive activation of growth factor, tyrosine kinase receptor
- What are TrkA, TrkB, TrkC and p75?
- They are all receptors for the neurotrophic growth factors (NGF, NT-3, BDNF)
- Name 3 ways that neurotrophins effect neuronal growth?
- Increase MAP kinase which promotes axon elongation.
Increase Ca2+ through IP3 to potentiate synaptic transmission.
Increase PI3K activity which activates Akt preventing neuron apoptosis.
- What are the 2 subunits of PI3K and how are they activated?
- The 2 subunits are P85 and P110. P110 is the catalytic subunit and P85 is the inhibitory subunit.
GAB1 which is activated like SOS via Grb2 is the protein that causes PI3K activity by causing P85 to let go of P110.
- Name the 3 components of the ECM?
- Gags/proteoglycans provide gel formation
Collagen and elastin provide tensile strength
Glycoproteins - fibronectin and laminin provide adhesion to cells
- Why does ground substance contain water?
- Because GAGs are negatively charged due to having amino sugars every 2nd residue. These have COO groups that attract Na+ which attracts water.
- Name 2 proteoglycans, their components and where they are found?
- Perlecan is made of heparan sulfate and is found in the basal lamina.
Aggrecan is made of chondroitin and keratan sulfate and is found in cartilage
- What is special about hyaluronic acid?
- It is a non-sulfated GAG.
- What sequence is required for fibronectin/laminin to bind to integrins?
- RGD sequence (arg, gly, asp)
- What are the 3 things that fibronectin binds to?
- Perlecan (heparan sulfate)
Type IV collagen
Integrin of cell.
- Name 4 things laminin binds to?
- Perlecan (heparan sulfate)
Type IV collagen
- What is the job of entactin?
- It binds laminin to the type IV collagen of the basal lamina
- What is special about Type III collagen?
- Reticular fibers are very highly glycosylated.
- What 5 places are reticular fibers found in?
- Capillaries, nerves and muscles.
Myeloid and lymphoid gland tissue.
- What should you know about Type VII collagen?
- It has a 67 nm banding pattern and it connects type IV collagen to the underlying CT.
- Name the 4 aa rich in collagen?
- Glycine, proline, hydroxyproline and hydroxylysine.
- Lysyl hydroxylase is required for what reaction? Why do you need to do this and what cofactor is required?
- To hydroxylate proline and lysine residues.
You need to do this so that hydroxylysine can be glycosylated and the cofactor required is Vitamin C.
- True/False Release of procollagen is the constitutive pathway?
- What is the secretory product of a fibroblast?
- How would I convert procollagen into tropocollagen?
- Procollagen peptidases cut off the registration peptides on procollagen.
- What enzyme is missing in Ehlers Danlos syndrome and what does it do?
- Lysyl oxidase and it forms Aldol linkages between the tropocollagen strands to strengthen collagen.
- True/False Elastin is highly glycosylated?
- False, it is non-glycosylated. Reticular fibers are heavily glycosylated.
- What 4 aa's are found in elastin?
- Proline, glycine, Desmosine and Isodesmosine.
- Marfan's syndrome is a defect in what component?
- Fibrillin part of elastic fibers
- What are the locations of elastic fibers?
- Vocal cords, ligamentum nuchae, pinna, auditory tube, epiglottis, all blood vessels except capillaries.
- Where do you find basal lamina?
- All epithelial cells, surrounding muscle cells, fat cells and Schwann cells.
- Who makes the basal lamina?
- The cells that sit on it.
- What do you find in the lamina rara?
- In a fibroblast you find fibronectin, in an epithelial cell you find laminin
- What do you find in the lamina densa?
- Type IV collagen
Perlecan (heparan sulfate) on both sides of the densa in rara and reticularis
- What is the difference between the basal lamina and the basement membrane?
- The basal lamina is lamina rara and densa and is not resolvable with LM.
The basement membrane is basal lamina and lamina reticularis and is resolvable with LM because the reticularis is usually thick.
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