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First Aid STEP 1 - Biochemistry > Biochemistry - Cellular > Flashcards

Biochemistry - Cellular Flashcards

1
Q

What regulates the cell cycle phases?

A

cyclins, cyclin-depenent kinases (CDKs), and tumor suppressors

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2
Q

What is the shortest phase of the cell cycle?

A

mitosis

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3
Q

What are cyclins?

A

regulatory proteins that control cell cycle events

phase specific

active CDKs

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4
Q

What is the role of a tumor suppressor? What are two examples of tumor suppressors?

A
  1. inhibit G1 to S progression in the cell cycle

2. p53 and hypophosphorylated RB protein

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5
Q

What happens if there is a mutation in a tumor suppressor gene?

A

Unrestrained cell division (e.g. Li-Fraumeni Syndrome)

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6
Q

What are the three cell types?

Give examples of each.

A
  1. Permanent- remain in G0, regenerate from stem cells (neurons, skeletal and cardiac muscle, RBCs
  2. Stable (quiescent) - Enter G1 from G0 when stimulated (hepatocytes, lymphocytes)
  3. Labile - Never go to G0, divide rapidly with a short G1. Most affected by chemotherapy (bone marrow, gut epithelium, skin, hair follicles, germ cells)
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7
Q

What is the purpose of the rough endoplasmic reticulum?

A

synthesizes secretory proteins and N-linked oligosaccharide additions to many proteins

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8
Q

Where are peptide neurotransmitters for secretion from neurons made?

A

Nissl bodies

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9
Q

What cells are rich in RER?

A

mucus-secreting goblet cells and Ab-secreting plasma cells (makes lots of proteins!)

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10
Q

What is the purpose of the smooth ER? How is the SER different from the rough ER?

A

steroid synthesis and detoxification of drugs and poisons

LACKS ribosomes

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11
Q

What cells are rich in SER?

A

hepatocytes (detoxification)

steroid-hormone producing cells of the adrenal cortex

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12
Q

What is the purpose of the Golgi body?

A

Distribution center for proteins and lipids from the ER to the vesicles and plasma membrane

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13
Q

What is the matching amino acid to…

  1. N-oligosaccharide
  2. O-oligosaccharide
  3. mannose-6-phosphate
A
  1. asparagine
  2. serine and threonine
  3. proteins for trafficking to lysosomes
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14
Q

What disease is related to cell trafficking?

A

I- Cell Disease (Inclusion Cell Disease)

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15
Q

What is the pathogenesis of I-Cell Disease?

A

inherited LYSOSOMAL STORAGE DISORDER

Defect in phosphotransferase –> failure of the Golgi to phosphorylate mannose residues on glycoproteins –> proteins secreted extracellularly rather than delivered to lysosomes

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16
Q

What are the symptoms of I- Cell Disease?

A

Coarse facial features
Clouded corneas
Restricted joint movement
High plasma levels of lysosomal enzymes

*Often fatal in childhood

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17
Q

What direction does COP I traffic proteins?

A

Golgi –> Golgi (retrograde)

Golgi –> ER

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18
Q

What direction does COP II traffic proteins?

A

Golgi –> Golgi (anterograde)

ER –> Golgi

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19
Q

What direction does clathrin traffic proteins?

A

trans-golgi –> lysosomes

plasma membrane –> endosomes

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20
Q

What is the purpose of a peroxisome?

A

catabolism of very long chain fatty acids, branched chain fatty acids, and amino acids

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21
Q

What is the purpose of a proteasome?

A

degradation of damaged or ubiquitin-tagged proteins

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22
Q

What disease is associated with a defect in ubiquitin-proteasome system?

A

Parkinson disease

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23
Q

What is the purpose of a microtubule? Where are they found?

A

MOVEMENT

Found in flagella, cilia, mitotic spindles, axonal trafficking, centrioles

Cyclindrical structure composed of helical array of heterodimers of alph and beta tubular

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24
Q

What are the molecular motor proteins and what direction do they move cargo towards?

A

Dynein - retrograde (+ –> -)

Kinesin - anterograde (- –> +)

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25
Q

What are cilia?

A

9 + 2 arrangement of microtubules

Axonemal dynein - ATPase links peripheral 9 doublets and causes bending of cilium by different sliding of doublets

26
Q

What disease is associated with ciliary dyskinesia?

A

Kartagener Syndrome (Primary Ciliary Dyskinesia)

Immotile cilia d/t a dynein arm defect

Symptoms
male and female infertility d/t immotile sperm and dysfunctional fallopian tube cilia

Increased risk of ectopic pregnancy

Other risks: bronchiectasis, recurrent sinusitis, and situs inversus

27
Q

What is the purpose of actin and myosin?

A

Muscle contraction, microvilli, cytokinesis, adherens junctions

Actins are long, structural polymers

Myosins are dimeric, ATP driven motor proteins that move along actins

28
Q

What is the purpose of intermediate filaments?

A

STRUCTURE

Found in vimentin, desmin, cytokeratin, lamins, glial fibrillary acid proteins (GFAP), neurofilaments

29
Q

Types of Immunohistochemical stains for intermediate filaments

A 
Vimentin - Connective Tissue
DesMin - Muscle
Cytokeratin - Epithelial cells
GFAP - NeuroGlia
Neurofilaments - Neurons
30
Q

Where is the sodium potassium pump located? How many sodium and potassium are moved across the membrane?

A

plasma membrane

3 Na+ move out and 2 K+ move in

31
Q

What is the most abundant protein in the body?

A

collagen

32
Q

What is the most common type of collagen?

A

Type I collagen

33
Q

What tissue is made from Type I collagen?

A 
Bone (made by osteoblasts)
Skin
Tendon
Dentin 
Fascia
Cornea
Late wound repair
34
Q

What disease is associated with Type I collagen deficiency?

A

Osteogenesis imperfecta type I

35
Q

What tissue is made from Type II collagen?

A

Cartilage (including hyaline)
Vitreous body
Nucleus pulposus

36
Q

What tissue is made from Type III collagen?

A

Reticulin - skin, BLOOD VESSELS, uterus, fetal tissue, granulation tissue

37
Q

What disease is associated with Type III collagen deficiency?

A

Vascular type of Ehlers-Danlos Syndrome

38
Q

What tissue is made from Type IV collagen?

A

Basement membrane
basal lamina
lens

39
Q

What disease is associated with defective Type IV collagen or Ab attack?

A

Defective - Alport syndrome

Ab attack - Goodpasture Syndrome

40
Q

What type of cells produce collagen?

A

fibroblasts

41
Q

What are the 6 steps to collagen synthesis and structure?

A

INSIDE fibroblast

  1. Synthesis (RER) - collagen is ⅓ glycine
  2. Hydroxylation (RER) - hydroxylation of proline and lysine residues (requires vitamin C)
  3. Glycosylation (RER) - glycosylation and formation of pro collagen via hydrogen and disulfide bonds (triple helix of 3 collagen alpha chains)
  4. Exocytosis into extracellular matrix

OUTSIDE fibroblast

  1. Proteolytic processing - cleave disulfide-rich terrine regions of pro collagen –> now an insoluble tropocollagen
  2. Cross-linking - reinforcement of many staggered tropocollagen molecules by covalent lysine- hydroxylyxine cross-linkage to make COLLAGEN FIBRILS
42
Q

A deficiency in Vitamin C will result in inhibition of what step of the collagen synthesis process?

A

Hydroxylation (RER) - Step 2

43
Q

Osteogenesis imperfecta causes problems in what step of the collagen synthesis process?

A

Glycosylation - Step 3

Problems forming triple helix

44
Q

Ehlers-Danlos is associated with what step of the collagen synthesis process?

A

Cross-linking - Step 6

45
Q

What is the pathogenesis of osteogenesis imperfecta?

A

Genetic bone disorder (brittle bone disease) caused by a variety of gene defects that inhibit proper forming of the triple helix of collagen

46
Q

What are symptoms of osteogenesis imperfecta?

A

Multiple fractures with minimal trauma (may occur during birth process)

Blue sclerae d/t translucency of the CT over the choroidal veins

Hearing loss (abnormal ossicles)

Dental imperfections d/t lack of dentin

47
Q

What is the inheritance pattern of osteogenesis imperfecta?

A

AD

48
Q

What is the pathogenesis of Ehlers-Danlos Syndrome (EDS)?

A

Defect Type III collagen synthesis

49
Q

What are the symptoms of Ehlers-Danlos Syndrome?

A

hyper extensible skin

tendency to bleed (easy bruising)

Hypermobile joints

May be associated with joint dislocation, berry and aortic aneurysms, organ rupture

50
Q

What is the inheritance pattern of Ehlers-Danlos Syndrome?

A

AD or AR

51
Q

What is the most common type of EDS?

A

hypermobility type (joint instability)

52
Q

Classical type of EDS is associated with what type of collagen?

A

Type V collagen

53
Q

What type of EDS is associated with vascular and organ rupture?

A

Vascular type –> aneurysms

54
Q

What is the pathogenesis of Menkes disease and what are the Sx of the disease?

A

Impaired copper absorption and transport –> decreased activity of lysol oxidase (copper is a necessary cofactor)

Sx: brittle, “kinky” hair, growth retardation, and hypotonia

55
Q

What is the purpose of elastin and where is it found?

A

Stretchy protein w/in in skin, lungs, large arteries, elastic ligaments, vocal cords, ligamenta flava

56
Q

What amino acids is elastin rich in?

A

proline and glycine

57
Q

What enzyme breaks down elastin and what inhibits this enzyme?

A

Elastase breaks down elastin

This enzyme is inhibited by alpha1- antitrypsin

58
Q

What is the pathogenesis of Marfan Syndome?

A

defect in fibrillin (a glycoprotein that forms a sheath around elastin)

59
Q

What is the pathogenesis of emphysema d/t an enzyme deficiency?

A

A1AT deficiency –> excess elastase activity

60
Q

What causes wrinkles?

A

decrease in collagen and elastin production

First Aid STEP 1 - Biochemistry (8 decks)

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