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Nutrition > Repair > Flashcards

Repair Flashcards

1
Q

Heterochromatin vs euchromatin

A

Heterochromatin = dense, inactive
Euchromatin = disperse, active

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2
Q

Epigenetic alterations :
1. Methylation
2. Acetylation
3. Phosphorylation
4. DNA methylation

A
  1. Methylation = lysine, argine = transcription activation or repression
  2. Acetylation = lysine by HATs = open chromatine = increase transcription
  3. Phosphorylation = serine = opened or condensed
  4. DNA methylation = transcriptional silencing
    REVERSIBLE
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3
Q

Role of miRNA
Transcription

A

Modulate translation of target mRNA
MiRNA transcription ->pri-miRNA trimmed by DICER -> mature miRNA associated with RISC (RNA induced silencing complex) -> induce or repress translation

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4
Q

What is siRNA?

A

Small interfering RNA = substrate for DICER, interacts with RISC = study gene fct

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5
Q

4 roles of lncRNA

A
  1. Facilitate transcription factor binding = gene activation
  2. Preemptively bind transcription factor = inhibe transcription
  3. Directs acetylases and methylases
  4. Acts as scaffold to stabilize 2nd or 3 structures that influence chromatin architecture and gene activity
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6
Q

Role of CRISPR (Cas9)

A

Endow bacteria acquired immunity to phages and plasmids = efficient and highly Sp cleavage of target sequence
CRISPR transcribe to guideRNA -> gRNA constant region binds to Cas9 -> Cas9 cleaves bound DNA -> double stranded DNA break

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7
Q

Role of RER and golgi

A

Assembly of new proteins ans secretion to plasma membrane
RER = translate mRNA into proteins = directed by N-termini of nascent proteins
Golgi = shuttle from trans to cis

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8
Q

Role of free ribosomes

A

Proteins for cytosol

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9
Q

Role of SER

A

Synthesis of steroids hormones and lipoproteins
Role ion Ca2+ sequestration (muscle contraction)

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10
Q

Role of proteasome

A

Degrade/denature tagged cytosolic proteins (CMH)

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11
Q

Role of peroxisomes

A

Role in break down of long chain fatty acids

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12
Q

Location and role of :
1. Phosphatidylinositol
2. Phosphatidylserine
3. Glycolipids

A
  1. Phosphatidylinositol = inner membrane = electrostatic scaffold for IC proteins
  2. Phosphatidylserine = inner face, negative charge = when flipped EC leaflet send eat me signal (apoptosis)
  3. Glycolipids = outer face = contribute to EC glycocalyx
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13
Q

Mechanism of endocytosis

A
  1. Caalveolae-mediated
  2. Receptor-mediated -> clathrin coated pit -> coated vesicle -> early endosome (low pH) release ligand to plasma membrane for recycling -> late endosome -> fusion with lysosome
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14
Q

Filaments composign the cytoskeleton

A
  1. Actin microfilaments = G-actin polymerize in F-actin = defines polarity (myosine = motor proteins)
  2. Intermediate filaments (keratin prots) = tensil strenght (desmosomes)
  3. Microtubules (noncovalent polymerized a-B-tubulin dimers) = très dynamique
    Negative end = embedded in microtubule (MTOC ou centrosome)
    Positive end = elongates or recedes with stimuli
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15
Q

What cells express these intermediate filaments :
1. Vimentin
2. Desmin
3. Neurofilaments
4. Glial fibrillary acidic protein
5. Cytokeratin
6. Lamins

A
  1. Vimentin = mesenchymal cells
  2. Desmin = muscle cells
  3. Neurofilaments = neuronal axon structure
  4. Glial fibrillary acidic protein = glial cells
  5. Cytokeratin = epithelial cells
  6. Lamins = nuclear lamina, regulate transcription
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16
Q

Localisation and role of tight junctions (occluding)

A

Junction between epithelial cells = restricts the flow and maintain polarity
Composed of transmembrane protein associated with MARVEL protein (TAMP) and scaffold proteins (cingulin)

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17
Q

Localisation and role of anchoring junctions (adherens and desmosomes)

A

Attach cytoskeleton to other cells or ECM
Adherens = with IC actin microfilaments (shape, mouvement) : loss of E-cadherin = loss of cohesion
Desmosomes = cadherin linked to IC intermediate filament = dissipate force over multiple cells
Hemidesmosomes = attached to ECM = integrin attached to intermediate

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18
Q

Localisation and role of communicating junction (gap jct)

A

Composed of connexons (pores) = diffusion of chemical or electrical signals

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19
Q

Steps for lysosomal degradation

A

AUTOPHAGY
1. Senescent organs/proteins
2. Encircled by double membrane derived from RE and marked by LC3 protein
3. Fuse with lysosome
4. Exocytosis or stay in cell for nutrients
HETEROPHAGY
Endocytosis or phagocytosis

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20
Q

Steps for proteasomal degradation

A
  1. Cytosolic proteins destined for turnover, senescent proteins, denatured proteins (age, UV, ROS) tagged by ubiquitin molecules via E1, E2, E3 ubiquitin ligase
  2. Proteins marked for degradation by proteasome in peptides fragments
    High levels of misfold prots in ER trigger protective unfolded protein response
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21
Q

What is the protective unfolded protein response?

A

Reduction in protein synthesis
Specific increase in chaperone proteins for protein refolding
If inadequate = apoptosis

22
Q

Structure of mitochondria

A

Inner membrane = enzyme for respiratory chain folded in cristae
Intermembrane space = site of nucleotide phosphorylation
Outer membrane = voltage dependant anion channels

23
Q

What is the Warburg effect?

A

Switch to aerobic glycolysis
Glucose catabolized to lactic acid = 2 ATP but +++ intermediates for conversion to new lipids, aa, prots, an
CELLULAR ENERGY VS PROLIFERATION

24
Q

Impact of toxic or ischemic injury on mitochondria?

A

Induce membrane permeability transition that dissipates intermembrane proton gradient = death through loss of ATP generation

25
Q

What does the MOMP do?

A

Release cytochrome C to cytoplasm to stabilize apoptosome = promote caspase activation -> apoptosis

26
Q

Impact of G-protein coupled-R (GPCR)

A

Traverse plasma membrane 7 times
Generation of cAMP, IP3, release Ca in ER

27
Q

Impact of nuclear hormone-R

A

Lipid solubles ligand = traverse directement + binds with nuclear DNA = gene activation or repression

28
Q

Notch-ligand activity

A

Cleave IC notch and can enter nucleus = influence transcription of target gene

29
Q

Action of Wnt/frizzled pathway

A

Forms multi-subunit complex = activation release IC B-catenin from protein complex that normally drives its degradation
Release B-catenin migrate to nucleus = acts as transcription factor

30
Q

Genes regulating cell division

A

MYC
JUN
TP53

31
Q

Epidermal growth factor (EGF)
1. Source
2. Function

A
  1. Source = activated macro, salivary glands, keratinocytes and other
  2. Function = mitogenic for many cell types, stimule epithelial cell aggregates, stimule formation of granulation tissue
32
Q

Hepatocyte growth factor (HGF) = scatter factor
1. Source
2. Function

A
  1. Source = fibroblasts, stromal cells in liver, endothelial cells
  2. Function = enhance proliferation of hepatocytes and other epithelial cells, increase motility
33
Q

Transforming growth-factor-a (TGFa)

  1. Source
  2. Function
A
  1. Source = activated macrophages, keratinocytes and other
  2. Function = stimule proliferation of hepatocytes and many other epithelial cells
34
Q

Vascular endothelial growth factor (VEGF)
1. Source
2. Function

A
  1. Source = mesenchymal cells
  2. Function = stimule prolif of endo cells, increase vascular permeability, vasoD
35
Q

Platelet derived growth factor (PDGF)
1. Source
2. Function

A
  1. Source = platelets, macro, endothelial cells, smooth muscle cells, keratinocytes
  2. Function = chemotactic for neutrophils, macro, fibroblasts and smooth muscle cells, active/stimule prolif of fibroblasts, endo cells and other, stimule ECM protein synthesis
36
Q

Fibroblasts growth factor (FGF)

  1. Source
  2. Function
A
  1. Source = macro, masto, endo cells and other
  2. Function = chemotactic and mitogenic for fibroblasts, stimule angiogenesis and ECM protein synthesis
37
Q

Transforming growth-factor-B (TGFB)

  1. Source
  2. Function
A
  1. Source = platelets, LT, macro, endo, epith, smooth muscle cells, fibroblast
  2. Function = chemotactic for leucocytes and fibroblasts, stimule ECM prot synthesis, suppress acute inflamm, scar formation
38
Q

Keratinocytes growth factor (KGF)

  1. Source
  2. Function
A
  1. Source = fibroblasts
  2. Function = stimulates keratinocyte migration, proliferation and differenciation
39
Q

Components of ECM

A
  1. Interstitial matrix = amorphous semi-fluid gel (PG, hyaluronate, collagen, fibronectin, elastin)
  2. Basement membrane = highly organized (non fibrillar type 4 collagen and laminin)
40
Q

With what do integrin in ECM interact in the cell?

A

Interact with cytoskelet adhesion complexes = vinculin, actinin, talin
Adhesion complexes are attached to actin cytoskelet = recruit + active kinases (IC signaling)

41
Q

What are the different types of collagen?

A

Fibrillar = 1-2-3-5 = tensile strength from lateral cross linking + covalent bonds by lysine hydroxylation (vitC dependant)
Non-fibrillar = 4 = basement membrane, collagen interactions

42
Q

Composition of proteoglycan and hyaluronan

A

Negatively charged = attract Na+ = attract H2O = gel (resist compressive force)
Reservoir for FGF, HGF

43
Q

What allows elastic fibers to stretch?

A

Elastin molecules are cross linked with large hydrophobic segments = opened when stretched

44
Q

Synthesis of collagen

A
  1. DNA -> mRNA -> splicing -> mature mRNA -> translation -> proline and lysine hydroxylation and lysine glycosylation in ER -> 3 procollagen chains align -> triple helix
    Fibrillary collagen = carboxyl end of propeptide removed by endoproteinase after secretion in EC space = triple helix polymerize to form fibrils
    N-terminus propeptide processing: 1-2 (complete), 5-11 (incomplete)
  2. After secretion = lateral stability by crosslinking with lysyl oxidase
45
Q

What is checked at G1/S and G2/M checkpoint in cell cycle?

A

G1/S = DNA integrity before DNA replication
G2/M = accurate replication before division

46
Q

Labile tissue
Stable tissue
Permanent tissue

A

Labile = epiderme, TGI = division continue
Stable = hepatocytes = quiescent
Permanent = neurons, heart = no proliferation

47
Q

Steps in the cell cycle

A
  1. G0 (quiescent)
  2. G1 restriction point (cell enters cycle w/o more growth signal), centrosome duplication
  3. G1/S = check DNA damage
  4. S = chromosome duplication
  5. G2/M = check for damage DNA
  6. M = mitosis
  7. Cell division
48
Q

What can become pluripotent stem cells?

A

Division asymétrique
- Multipotent stem cells
- Embryonal stem cells (pancreas, hematopoietic, cardiomyocytes, neurons, hepatocytes)

49
Q

Location of stem cells

A

Skin = bulge stem cells
Intestin = intestinal crypt base between Paneth cells
Liver = in canal of Hering

50
Q

What are the 3 potential differenciation of cells?

A

Ectoderm
Mesoderm
Endoderm

Nutrition (13 decks)

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