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Step 1 biochemistry > Cellular > Flashcards

Cellular Flashcards

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1
Q

Checkpoints in cell cycle regulated by….

A
  1. Cyclins
  2. CDKs
  3. Tumor supppresors
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2
Q

M phase includes what processes?

A
  1. Mitosis (prophase, prometphase, metaphase, anaphase, telophase)
  2. Cytokinesis ( cytoplasm splits in 2)
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3
Q

Cyclins

A
  • Regulatory protein cell cycle
  • phase specific
  • activate CDKs
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4
Q

CDKs

A
  • regulate cell cycle

- Constitutive and inactive

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5
Q

Cyclin-CDK complexes

A

Phosphorylate proteins to coordinate cell cycle progression

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6
Q

Tumor suppressors do what to cell cycle

A

-Restrict cell cycle

Example: p53 induces p21 -> inhibit CDKs -> hypophosphorlyation Rb (activates) -> restrict at G1 phase

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7
Q

Is phosphorylated Rb active or inactive?

A

Inactive

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8
Q

Hypohosphorylated Rb does what?

A
  • Bind to transcription factor E2F and inactivates it

- inhibit cell cycle in G1 phase

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9
Q

Li-Fraumeni syndrome is caused by a mutation in what kind of gene?

A

Tumor suppressor

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10
Q

Permanent cells are in what phase of cell cycle?

A
  • Remian in Go

- regenerate from stem cells

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11
Q

Examples of permanent cells are?

A

Neurons, skeletal and cardiac muscle, RBCs

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12
Q

Stable (quiescent) cells are in what phase of cell cycle?

A

Enter G1 from Go when stimulated

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13
Q

Examples of stable cells?

A

Lymphocytes and hepatocytes

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14
Q

What phase in cell cycle are labile cells?

A
  • Never go to Go
  • divide rapidly with short G1 phase
  • (most effected by chemo)
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15
Q

Examples of labile cells?

A

Bone marrow, gut epithelium, skin, hair follicles, germ cells

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16
Q

Areas rich in Rough ER

A

Goblet cells of small intestine and Ab secreting plasma cells

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17
Q

RER

A

Synthesize secretory (export) proteins

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18
Q

RER in neurons- Nissl bodies

A

Synthesize peptide neurotransmitters for secretion

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19
Q

RER free ribosomes

A
  • Unattached to membrane

- site synthesis cytosolic and organellar proteins

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20
Q

SER

A

Site steroid synthesis and detoxification of drugs and poisons

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21
Q

Areas rich in SER

A

Gonads, adrenal cortex, liver hepatocytes

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22
Q

Types of vesicular trafficking proteins

A
  1. COPI: Golgi -> Golgi (retrograde); cis-Golgi -> ER
  2. COPII: ER -> cis-Golgi (anterograde)
  3. Clathrin: trans-Golgi -> lysosomes; plasma membrane -> endosome (receptor mediated endocytosis {LDL receptor activity})
    * the 3 C’s
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23
Q

Inclusion cell disease symptoms (I cell disease/mucolipidosis type II)

A

Clouded cornea, restricted joint movement, high plasma levels lysosomal enzymes

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24
Q

Golgi function

Study These Flashcards
A
  • Distribute proteins and lipids from ER to vesicles and plasma membrane
  • adds mannose-6-phosphate to proteins for trafficking to lysosomes
25
Endosomes function
- Sorting center for material from outside the cell or from the Golgi - send to lysosome for destruction or back to Golgi for further use
26
Inclusion cell disease/mucolipidosis type II pathology
- Lysosomal storage disorder - failure of Golgi to phosphorylate mannose residues = decrease mannose-6-phosphate - proteins secreted extracellularly instead of to lysosome
27
Peroxisome function
Catabolism of very long chain fatty acids through beta oxidation, AA and ethanol
28
Proteasome function
Degrade damaged or ubiquitin tagged proteins
29
Signal recognition particle function
Traffic proteins from ribosomes RER
30
Signal recognition particle (SRP) dysfunction leads to what?
Protein accumulate in cytosol
31
Microfilament function
Muscle contraction, cytokinesis
32
Microfilament examples
Actin and microvilli
33
Intermediate filament function
Maintain cell structure
34
Intermediate filament examples
Fine tin, desmin, cytokeratin, lamins, glial fibrillary acid proteins (GFAP), neurofilaments
35
Microtubules function
Movement, cell division
36
Microtuble example
Cilia, flagella, mitotic spindle, axonal trafficking centrioles
37
Immunohistochemical stains for intermediate filaments and what they identify
Vimentin =mesenchymal tumors (sarcoma) - DesMin = Muscle tumors (rhabdomyosarcoma) - cytokeratin = epithelial tumors (squamous cell carcinoma) - GFAP= neuroGlia(astrocytoma, glioblastoma) - Nuerofilaments= neuron tumors (neuroblastoma)
38
Microtubule composition
- cylindrical - heterodimers alpha and beta tubulin - each diner has2 GTP bound
39
What are the Molecular motor proteins for microtubules?
- Dynein - retrograde (+ to -) | - kinesin- anterograde (- to +)
40
Drugs that act on microtubules
Microtubules Get Constructed Very Poorly - Mebendazole (antihelminthic) - Griseofulvin (anti-fungal) - Colchicine (anti-gout) - Vincristine/Vinblastine (anti-cancer) - Paclitaxel (anti-cancer)
41
Cilia structure
9+2 microtubule doublet arrangement
42
How cilia move proteins?
Axonemal dynein- uses ATPase
43
Kartagener syndrome pathology and symptoms
AKA 1o ciliary dyskinesia - immobile cilia due to dynein arm defect - Sxs= 1. male and female infertility (immobile sperm and dysfunction Fallopian tube cilia) 2. Bronchiectasis 3. Recurrent sinusitis 4. Situs inversus (dextrocardia on CXR)
44
Ouabain inhibits what?
Bind and then inhibit K+ site of Na+/K+ pump
45
Cardiac glycosides (digoxin and digitoxin) inhibit what?
Directly inhibit Na+-K+ ATPase = indirect inhibit Na+/Ca2+ exchange = increased Ca2+ = increased cardiac contractility
46
Collagen types
Be (So Totally) Cool, Read Books Type I: Bone, Skin, Tendon, dentin, cornea, late wound repair, fascia Type II: Cartilage Type III: Recticulin-skin, blood vessels fetal tissue Type IV: Basement membrane
47
Type III collagen defect
Vascular type of Ehlers-Danlos syndrome (ThreE D)
48
Alport syndrome results in what type of defect in collagen?
Type IV ( basement membrane)
49
Goodpasture syndrome causes what?
Autoantibodies target type IV collagen (BM and basal lamina, lens)
50
Osteogenesis imperfecta symptoms and mutation
-Mutation autosomal dominant-COL1A1 and COL1A2 - decrease production type1 collagen Symptoms: 1. Multiple fractures w/o trauma 2. Blue sclerae: translucent connective tissue 3. Hearing loss: abnormal ossicles 4. Tooth abnormality: lack dentin = wear easily
51
Ehlers-Danlos syndrome symptoms and types
Symptoms: 1. Hyperextensible skin 2. Easy bruising 3. Hyper mobile joints 4. Joint dislocation 5. Berry and aortic aneurysm 6. Organ rupture - Classical type: joint symptoms; type V collagen mutation - Vascular type: vascular and organ rupture; deficient type III collagen * autosomal recessive or dominant
52
Menkes disease
- X linked recessive - connective tissue disease (defective ATP7A) - impaired copper absorption and transport = decreased activity lysyl oxidase (copper is cofactor) - symptoms: 1. Brittle 2. Kinky hair 3. Growth retardation 4. Hypotonia
53
Collagen synthesis steps
1. Synthesis: alpha chains (preprocollagen) 2. Hydroxylation: lysine and proline, requires vit c 3. Glycosylation: procollagen formed via hydrogen and disulfide bonds (triple helix) 4. Exocytosis: procollagen into extra cellular space 5. Proteolytic processing: cleave disulfide rich terminal regions of procollagen forming insoluble tropocollagen 6. Cross linking: tropocollagen covalent lysine-hydroxylysone cross link (lysyl oxidase) making collagen fibrils
54
Marian syndrome is a defect in what?
Defect in fibrillin- which forms sheath around elastin
55
Emphysema can be caused by what kind of deficiency?
Alpha1 anti-trypsin deficiency = excess elastase activity
56
Elastin is what and found where?
-Stretchy protein in skin, lungs, large arteries, elastic ligaments, vocal cords, ligamenta flava (connect vertebrae)
57
Elastin is rich in what AAs?
Nonhydroxylated proline, glycine, and lysine residues
58
Elastin is broken down by what?
Elastase
59
Elastase is inhibited by what?
Alpha1-anti-trypsin

Step 1 biochemistry (6 decks)

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