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Intro, Cell Response, Toxins Flashcards

Block 1

1
Q

What is the function of miRNAs?

A

Never translated, regulate gene expression via post-transcriptional silencing

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2
Q

What is heterochromatin? Euchromatin?

A

Heterochromatin- dense, inactive
Euchromatin- disperse, active

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3
Q

What does histone methylation do? Where does it occur?

A

At lysines and arginines; activation or repression

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4
Q

What does histone acetylation do? Where does it occur?

A

At lysines; activate

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5
Q

What does histone phosphorylation do? Where does it occur?

A

At serines; activation or repression

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6
Q

What does DNA methylation do?

A

Transcriptional silencing

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7
Q

Order of products in post transcriptional silencing

A

DNA, primary miRNA processed into pre-miRNA, exits nucleus, DICER trims pre-miRNA to DS miRNA, forms RISC

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8
Q

What does long noncoding RNA do (3)?

A

Modulate gene expression by facilitating TF binding (gene activation), binding TFs to prevent binding (gene suppression), binding DNA to promote modification

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9
Q

What is XIST an example of?

A

Long noncoding RNA gene suppression- in females, cloaks the X chromosome to silence

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10
Q

What do peroxisomes contain? What do they generate through breakdown of fatty acids?

A

Catalase, peroxidase; ROS (hydrogen peroxide)

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11
Q

Where is cholesterol in the cell membrane?

A

Inner and outer faces

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12
Q

Where is phosphatidylinositol in the cell membrane? Phosphatidylserine?

A

Inner and outer; inner mostly

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13
Q

Role of phosphatidylserine (3)

A

Confers negative charge to inner membrane
Eat me signal during apoptosis
In platelets, cofactor in blood clotting

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14
Q

Where are glycolipids and sphingomyelin in the cell membrane; purpose?

A

Extracellular face; cell-cell interactions

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15
Q

Phosphatidylinositol is hydrolyzed by phospholipase C to form what? What receptor stimulates this?

A

Generates 2nd signals like DAG and IP3; G-protein coupled

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16
Q

What is potocytosis?

A

Caveolae mediated, non-coated

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17
Q

What is pinocytosis?

A

Receptor mediated, clathrin coated

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18
Q

Three types of filaments, examples, and their purpose

A

Microfilaments- actin, structure and movement
Intermediate filaments- keratin, desmin, IHCs, cytokeratins, tensile strength and shape
Microtubules- cilia, flagella, move things around cell

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19
Q

What are occluding/tight junctions attached to? Adherens junctions?

A

Actin; Actin

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20
Q

What are desmosome and hemidesmosome junctions attached to?

A

Desmosomes- Intermediate filaments to transmembrane desmoglein
Hemidesmosomes- intermediate filaments to ECM (transmembrane integrins)

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21
Q

What proteins form tight/occluding junctions?

A

Claudin, TAMP- transmembrane
Zonula occludens, cingulin- intracellular

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22
Q

What three categories make up anchoring junctions? What type of proteins form anchoring junctions?

A

Adherens, Desmosomes, hemidesmosomes
Cadherins (cell adhesion)

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23
Q

Where is the adherens junction in the cell? Classic cadherin

A

Next to tight junction; e-cadherin

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24
Q

What does the desmosome do? Cadherins?

A

Links cells through intermediate filaments; desmoglein and desmocollin

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25
What does the hemidesmosome do? Cadherin?
Links cells to ECM through intermediate filaments; integrins
26
What are gap junctions? Example?
Allow communication between cells; connexons
27
What cells have a lot of SER?
Steroid producing cells- gonads, adrenals Hepatocytes (CYP450)
28
What is the unfolded protein response?
If excess abnormally folded proteins, cell reduces protein synthesis and increases chaperone proteins, then autophagy
29
What is the double membrane vacuole of autophagy derived from? what is it tagged with?
ER; LC3
30
What attaches ubiquitin to misfolded proteins?
E1, E2, E3 ubiquitin ligases
31
What are the membrane permeability transition pores?
Toxic or ischemic injury induces them, dissipates proton gradient (H+ leaves mitochondria), so ATP generation declines, Na/K pumps stop working, intracellular Na increases, cell swelling, necrosis
32
G protein coupled receptor pathway
receptor associates with GTP binding protein , exchanges GDP for GTP, activates phospholipase C, which generates 2nd messengers cAMP, IP3, DAG, IP3 triggers release of calcium from ER
33
Wnt ligands bind to __________, then....
Frizzled receptors (GPCR). recruits Dishevelled proteinthat disrupts beta catenin degradation complex, allowing it to go to nucleus and transcribe
34
Tyrosine kinase receptor (GF receptor) pathway)
Receptor dimerizes, autophosphorylates tyrosine residues, bridging proteins attach receptor to GDP bound (inactive) RAS, GDP replaced by GTP to activate RAS, which then activates RAF-->MAPK, or PI3K-->Akt-->mTOR
35
Pro-apoptotic proteins
BAX, BAK, BOK
36
Calcium storage in decreasing order
Mitochondria>ER>Cytosol
37
Examples of antioxidants
Vitamins A, C, E, and glutathione
38
Location and function of catalase
Peroxisomes, breaks down peroxide (H2O2)
39
Location and function of Superoxide Dismutase (SOD)
Cytosol and mitochondria; converts superoxide to H2O2
40
Location and function of glutathione peroxidase
Cytosol and mitochondria; converts H2O2 to H2O
41
Three ROS effects
Lipid peroxidation in membranes, forming peroxides Oxidative modification of proteins DNA lesions
42
What enzymes are activated by increased cytosolic Ca?
Phospholipases (membrane damage) Proteases Endonucleases ATPases
43
Other antioxidants in the cytosol?
Vitamin C, ferritin, cerruloplasmin
44
Antioxidants in membranes
Vitamin E, A, and beta-carotene
45
Features of reversible cell injury
Swelling, loss of microvilli, membrane blebs, clumped chromatin, lipid, myelin figures
46
Features of irreversible cell injury
Pyknosis, karyorrhexis, karyolysis, absence of nuclei, cytoplasmic eosinophilia
47
Ultrastructural features of necrosis; what changes are reversible? Irreversible?
Swollen, rounded, detached Swollen mitochondria with electron dense deposits Swollen ER Myelin figures (ceroid) Reversible: small mitochondrial densities, detachment of ribosomes, clumping of chromatin Only in irreversible cell injury: Large mitochondrial densities, loss of ribosomes, profound nuclear changes
48
AL amyloidosis is? Example? Made of
Primary; immune dyscrasias; lambda light chain of immunoglobulin
49
AA amyloidosis is? Example? Made of
Secondary; reactive or familial; serum amyloid A (IL1 and IL6 stimulate production)
50
Who gets AA amyloid in their glomeruli? Liver? medullary interstitium?
Abyssinians; siamese; shar-peis
51
What amyloidosis causes neurodegeneration? Made of
Abeta; amyloid precursor protein (APP)
52
What amyloidosis causes localized endocrine amyloid?
IAPP
53
Best stain for amyloid in cats
Thioflavin T
54
Which amyloid type retains congophilia after potassium permanganate? Which one loses congophilia?
AL; AA
55
What is the most common amyloidosis in animals?
AA
56
What causes lipofuscin? What does it stain with?
Lipid peroxidation of cell membranes; ORO, Sudan black, PAS+
57
What does melanin production require?
Tyrosine, tyrosinase (contains copper)
58
How does cyanide cause toxicity? How does this change the color of blood?
Binds and inhibits cytochrome C oxidase, so no oxidative phosphorylation; Oxygen remains on hemoglobin, so venous blood bright red
59
How does carbon monoxide cause toxicity? How does this change the color of blood?
Binds hemoglobin, replacing oxygen, forming carboxyhemoglobin, so blood cherry red
60
What is methemoglobin?
When ferrous iron is converted to ferric iron, does not bind oxygen as well
61
What is hemosiderin
Free iron bound by ferritin is converted to hemosiderin after accumulating in macrophages
62
How is hematoidin different?
Bright yellow, polarizes light, derived from hemosiderin, contains no iron, closely related to bilirubin
63
Where does bilirubin come from?
heme from hemoglobin, no iron, first converted to biliverdin, then to bilirubin
64
Which CDK inhibitors contribute to cellular senescence?
CDKN2A- p16 aka INK4a
65
Ultrastructural changes with apoptosis
Chromatin condensation into caps/crescents Cell surface blebbing (apoptotic bodies)
66
Initiator caspases
2, 8, 9, 10
67
Executioner caspases
3, 6, 7
68
What caspase causes pyroptosis? via what?
Caspase 1; inflammasome Also 4 and 5 (all inflammatory caspases)
69
What caspase is activated by p53 after DNA damage?
Caspase 2
70
What else stimulates caspase 3, 6, and 7?
Granzyme B from WBCs
71
What does caspase 8 do?
In extrinsic necrosis, forms death induced signal complex
72
What redirects cell to necroptosis? Outcome?
Inhibition of caspase 8; Necrosome forms from RIPK1, RIPK3, and FADD, which then phosphorylates MLKL
73
What does caspase 9 do?
In intrinsic necrosis, forms apoptosome in response to MOMP releasing cytochrome C
74
What does caspase 11 do?
Triggered by LPS and sepsis
75
How does apoptosis lead to phagocytosis? Name of process?
Phosphatidylserine flipped out, may become coated with antibodies and C1q; Efferocytosis
76
Triggers of necroptosis
TNF, FasL, DNA damage, LPS, interferon gamma via death receptors or TLR 3 and 4
77
Three possible responses to TNF binding TNFR1; what decides which fate?
1. Survival through NFkappB signaling 2. Extrinsic apoptosis through DISC formation 3. Necroptosis Ubiquitination of RIPK1
78
What is necroptosis?
Resembles necrosis morphologically, but occurs similarly to extrinsic apoptosis Pro-inflammatory Caspase-independent
79
What does MLKL do?
Polymerizes to form amyloid-like structure that disrupts cell membrane
80
What can inhibit necroptosis?
Caspase 8 cleavage of RIPK Necrostatin
81
What triggers ferroptosis? What inhibits it? Why does it happen?
Excessive intracellular iron or ROS; Glutathione peroxidase 4; fenton reaction overwhelms glutathione, leading to ROS and lipid peroxidation
82
Ferroptosis morphologically resembles ___________.
Necrosis
83
Cause and result of pyroptosis; Initiated by ____________
Intracellular pathogens, pyrexia; caspase 1 (activates IL1)
84
Parthanatos is initiated by what? In response to what?
PARP1 in response to severe damage or stress
85
Entosis is
Detached epithelial cells enguled by autophagy
86
Chaperone proteins in cytoplasm? In mitochondria?
HSP 70 HSP 60
87
What happens if unfolded protein response is unsuccessful?
Apoptosis
88
What allows initiation of autophagy? How?
Inhibition of mTOR; mTOR inhibits ULK1 complex
89
Where is the isolation membrane derived from in autophagy? What drives its formation?
ER; ULK1 complex (initiation complex)
90
What does the ULK1 complex activate? What is this complex also called?
Phosphorylates AMBRA1, activating PI3K complex (nucleation complex)
91
What happens during elongation?
Vesicle forms (autophagosome) marked with LC3
92
What happens during maturation?
Autophagosome fuses with lysosomes via SNARE-like protein docking to form autophagolysosome
93
Deletion of what gene increases susceptibility of macrophages to tuberculosis due to defect in autophagy
Atg5
94
What factors promote autophagy?
BAD, BID (bind BCL-2, preventing binding of Beclin) Caspase 9 Sirtuins (anti-aging) p53 in nucleus
95
What factors inhibit autophagy?
Binding Beclin BCL-2 (bind Beclin) FLIP p53 in cytoplasm
96
What molecules signal via G-protein coupled receptors?
Eicosanoids, chemokines, some growth factors, thrombin, N-formylmethionyl (bacterial peptides), PTH
97
What causes Niemann Pick Dz?
Lysosomal Storage Disease- Mutations in enzyme involved in cholesterol trafficking--> cholesterol accumulation in multiple organs
98
Major trigger and pathway for physiologic myocardial hypertrophy; Two triggers and the pathway for pathologic myocardial hypertrophy?
Mechanical stretch receptors-->PI3K-AKT pathway; Agonists, growth factors-->GPCR
99
Genes that encode muscle proteins (myocardial hypertrophy)
GATA4, NFAT, MEF2

Gen Path (14 decks)

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