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Step One Prep > Biochemistry-Cellular > Flashcards

Biochemistry-Cellular Flashcards

1
Q

CDKs

A

Constitutive and inactive

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2
Q

Cyclin

A

Regulatory proteins that control cell cycle events; phase specific; activate CDKs

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3
Q

Cyclin-CDK complexes

A

Must be both activated and inactivated for cell cycle to progress

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4
Q

Tumor suppressors

A

p53 and hypophosphorylated Rb normally inhibit G1-to-S progression; mutations in these genes result in unrestrained cell division

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5
Q

Cell Types- Permanent

A

Remain in G0, regenerate from stem cells

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6
Q

Give an example of a permanent cell

A

Neurons, skeletal and cardiac muscle, RBC

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7
Q

Cell Types- Stable (quiescent)

A

Engter G1 from G0 when stimulated

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8
Q

Give an example of a stable (quiescent) cell

A

Hepatocytes and lymphocytes

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9
Q

Cell Type- Labile

A

Never go to G0, divide rapidly witha short G1. Most affected by chemotherapy

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10
Q

Give an example of a labile cell

A

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

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11
Q

Cell Type- Rough endoplasmic reticulum

A 
Site of synthesis of secretory (exported) proteins and of N-linked oligosaccharide addition to many proteins. 
Nissl bodies (RER in neurons)- synthesize peptide neurotransmitters for secretion. 
Free ribosomes- unattached to any membrane; site of synthesis of cytosolic and organellar proteins.
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12
Q

Give an example of a rough endoplasmic reticulum cells

A

Mucus-secreting goblet cells of the small intestine and antibody-secreting plasma cells are rich in RER

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13
Q

Cell Type- Smooth endoplasmic reticulum

A

Site of steroid synthesis and detoxification of drugs and poisons. Lack surface ribosomes

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14
Q

Give an example of a smooth endoplasmic reticulum cell

A

Liver hepatocytes and steroid hormone- producing cells of the adrenal cortex and gonads are rich in SER

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15
Q

The golgi apparatus adds N-oligosaccharides to what amino acid?

A

Asparagine

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16
Q

The golgi apparatus adds O-oligosaccharides to which amino acids?

A

Serine and Threonine

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17
Q

What compound is added to the proteins destined for destruction by the lysosome? (Added by the golgi apparatus)

A

mannos-6-phosphate

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18
Q

What is the function of endosomes?

A

They are sorting centers for material from outside the cell or from the Golgi, sending it to the lysosomes for destruction or back to the membrane/Golgi for further use.

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19
Q

What is I-cell disease (inclusion cell disease)?

A

It is an inherited lysosomal storage disorder caused by a defect in phophotransferase which decreases mannose-6-phosphate on glycoproteins. Proteins are secreted extracellularly as opposed to tagged for the lysosome.

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20
Q

What is the likely diagnosis for a patient born with coarse facial features, clouded corneas, restricted joint movement, and high plasma levels of lysosomal enzymes?

A

I-Cell Disease. Often fatal in childhood.

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21
Q

What is a signal recognition particle (SRP)?

A

Abundant, cytosolic ribonucleoprotein that traffics proteins from the ribosome to the RER. Absent or dysfunctional SRP leads to proteins accumulatinng in the cytosol.

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22
Q

What is COPI?

A

Retrograde trafficking of protein from Golgi to ER

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23
Q

What is COPII?

A

Anterograde trafficking of protein from ER to Golgi

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24
Q

What is Clathrin?

A

A vesicular trafficking protein that traffics proteins from golgi to lysosomes, plasma membrane and endosomes (receptor mediated endocytosis)

25
Q

What are peroxisomes?

A

Membrane-enclosed organelle involved in catabolism of very -long-chain fatty acids, branched-chain fatty acid, and amino acids.

26
Q

What are proteasomes?

A

Barrel-shaped protein complex that degrades damaged or ubiquitin-tagged proteins. Defects in the ubiquitin-proteasome system have been implicated in some cases of Parkinson’s disease.

27
Q

What are microtubules?

A

Cylindrical structure composed of a helical array of polymerized heterodimers of alpha- and beta-tubulin. Each dimer has 2 GTP bound. Incorporated into flagella, cilia, mitotic spindles, Grows slowly, collapses quickly. Also involved in slow axoplasmic transport in neurons.

28
Q

What are molecular motor proteins?

A

Proteins that transport cellular cargo toward opposite ends of microtubule tracks

29
Q

In which direction does dynein travel?

A

Retrograde to microtubule (+ to -)

30
Q

In which direction does kinesin travel?

A

anterograde to microtubule (-to +)

31
Q

Name the drugs that act on microtubules. (Hint: Microtubules Get Constructed Very Poorly)

A 
Mebendazole (anti-helminthic)
Griseofulvin (anti-fungal)
Colchicine (anti-gout)
Vincristine/Vinblastine (anti-cancer)
Paclitaxel (anti-cancer)
32
Q

Describe the arrangement of cilia.

A

9+2 arrangement

33
Q

What is axonemal dynein?

A

An ATPase that links peripheral 9 doublets and causes bending of cilium by differential sliding of doublets

34
Q

What causes Kartagener Syndrome (Primary ciliary dyskinesia)?

A

Immotile cilia due to a dynein arm defect

35
Q

Are individuals with Kartagener syndrome fertile?

A

No. Males are infertile due to immotile sperm and females are immotile due to dysfunctional fallopian tube cilia with a increased risk of ectopic pregnancy.

36
Q

What are common symptoms of Kartagener syndrome?

A

Bronchiectasis, recurrent sinusitis, and situs inversus

37
Q

Describe actin and myosin

A

Muscle contraction, microbvilli, cytokinesis, adherens junctions. Actins are long, structural polymers, myosins are dimeric, ATP-driven motor proteins that move along actins.

38
Q

Describe microtubules

A

Movement. Cilia, flagella, mitotic spindle, axonal trafficking, centrioles.

39
Q

Describe intermediate filaments

A

Structure. Vimentin, desmin, cytokeratin, lamin, glial fibrillary acid proteins (GFAP), neurofilaments.

40
Q

Describe plasma membrane composition

A

Asymmetric lipid bilayer. Contains cholesterol, phopholipids, sphingolipids, glycolipids, and proteins. Fungal membranes contain ergosterol.

41
Q

Describe sodium-potassium pumps

A

Sodium-potassium ATPase is located int eh plasma membrane with ATP site on cytosolic side. For each ATP consumed, 3 sodiums go out and two potassiums come in

42
Q

What does Ouabain do?

A

Inhibits sodium-potassium pump by binding to potassium site

43
Q

What do cardiac glycosides do? (digoxin and digitoxin)

A

They directl inhibit the sodium-potassium ATPase, which leads to indirect inhibition of sodium/calcium exchange which leads to increase calcium in the cell and increased cardiac contractility.

44
Q

What is collagen?

A

Most abundant protein in the human body. Extensibely modified by posttranslational modification. Organizes and strengthens extracellular matrix

45
Q

Where is type I collagen found?

A

Most common (90%)- Bone, Skin, Tendon, dentin, fascia, cornea, late wound repair

46
Q

Where is type II collagen found?

A

Cartilage (including hyaline), vitreous body, nucleus pulposus.

47
Q

Where is type III collagen found?

A

Reticulin-skin, blood vessels, uterus, fetal tissue, granulation tissue.

48
Q

Where is type IV collagen found?

A

Basement membrane, basal lamina, lens

49
Q

Where are collagen alpha chains synthesized?

A

Rough ER

50
Q

Which amino acid is hydroxylated in collagen?

A

Proline and lysine. Requires vitamin C; deficiency is scurvy

51
Q

Glycosylation and formation of procollagen via hydrogen and disulfide bonds creates what structure?

A

Triple helix

52
Q

An error in glycosylation of pro-alpha-chain hydroxylysine residues results in what disorder

A

osteogenesis imperfecta

53
Q

What processing transforms procollagen into insolube tropocollagen?

A

Proteolytic cleavage of disulfide-rich terminal regions

54
Q

Cross-linking reinforces many staggered tropocollagen molecules by covalently cross-linking lysine-hydroxylysine to make collagen fibrils. A deficiency in cross-linking will cause what disorder?

A

Ehlers-Danlos

55
Q

Describe elastin

A

It is a stretchy protein within skin, lungs, large arteries, elastic ligaments, vocal cords, ligamenta flava. It is rich in proline and glycine, nonhydroxylated forms. tropoelastin with fibrillin scaffolding.
Cross-linking takes place extracellularly and gives elastin its elastic properties.

56
Q

What enzyme breakes down elastin?

A

Elastase

57
Q

What inhibits elastase?

A

alpha-antitrypsin

58
Q

Defects in ubiquitin-proteasome system have been implicated in some cases of which disorder?

A

Parkinson disease

Step One Prep (11 decks)

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