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Biochemestry > Cellular > Flashcards

Cellular Flashcards

1
Q

Defining characteristics of Ehlers Danlos syndrome (type 1 and 2)

A
  1. Joint hypermobility
  2. Hyperextensible, fragile skin
  3. Most common cause of EDS
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2
Q

Defining characteristics of osteogenesis imperfecta

A
  1. Spontaneous fractures
  2. Bone and tooth malformation
  3. Blue sclerae
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3
Q

Impairment in osteogenesis imperfecta

A

Mutation in type 1 collagen

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4
Q

Impairment in scurvy

A

Lack of vitamin C impairs collagen hydroxylation

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5
Q

Name the steps in collagen synthesis

A
  1. Synthesis
  2. Hydroxylation of proline and lysine
  3. Glycosylation of pro-a-chain hydroxyproline residues and formation of procollagen via hydrogen and disulfide bonds (triple helix!)
  4. Exocytosis of procollagen
  5. Proteolytic processing (cleavage of disulfide-rich terminal regions leads to insoluble tropocollagen)
  6. Cross linking (lysine-hydroxylysine by copper containing lysyl oxidase)
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6
Q

Pathogenesis of Menkes disease

A

Defective ATP7A protein (Menkes protein), which is a copper transporter, results in impaired copper absorption and transport - Therefore, enzymes that use copper will function inapropiately

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7
Q

Affected enzymes in Menkes disease

A
  1. Lysyl oxidase (crosslinking of collagen fibers) - leads to “kinky”, brittle hair
  2. Cytochrome C oxidase (neurologic abnormalities)
  3. Tyrosinase (hypopigmentation)
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8
Q

Hereditary mode of transmission of Menkes disease

A

X-linked recessive

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9
Q

Name the 2 main divisions of the M phase of the cell cycle

A
  1. Mitosis

2. Cytokinesis

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10
Q

Name the 5 subdivision of mitosis

A
  1. Prophase
  2. Prometaphase
  3. Metaphase
  4. Anaphase
  5. Telophase
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11
Q

Function of p53 protein

A

Induces p21, which in turn inhibits CDKs, leading to hypophosphorylation of Rb (activating it) and inhibition of G1-S progression

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12
Q

Function of the smooth endoplasmic reticulum

A

Steroid synthesis and detoxification of drugs and poisons

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13
Q

Cells that are rich in SER

A
  • Liver hepatocytes

* Steroid hormone-producing cells of the adrenal cortex and gonads

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14
Q

Cdk that phosphorylates Rb and promotes progress to S phase

A

Cdk4

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15
Q

Protein modification done on the Golgi apparatus to proteins that are transported to lysosomes

A

Addition of mannose-6-phosphate

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16
Q

Deficient/defective enzyme in I-cell disease

A

N-acetylglucosaminyl-1-phosphotransferase

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17
Q

Pathogenesis of I-cell disease

A

Failure of the Golgi to phosphorylate mannose residues leads to a decrease in mannose-6-phosphate, therefore proteins are secreted extracellularly rather than delivered to lysosomes

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18
Q

Signs and symptoms of I-cell disease

A
  • Corse facial features
  • Clouded corneas
  • Restricted joint movement
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19
Q

Characteristic laboratory finding in I-cell disease

A

High plasma levels of lysosomal proteins

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20
Q

Abundant, cytosolic protein that traffics proteins from the ribosome to the RER

A

Signal recognition particle (SRP)

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21
Q

Absent or dysfunctional signal recognition particle (SRP) leads to…

A

Accumulation of proteins in the cytosol

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22
Q

Traffic direction of COP1 proteins

A
  • Golgi to Golgi (retrograde)

* cis-Golgi to ER

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23
Q

Traffic direction of COP2 proteins

A

*ER to cis-Golgi (anterograde)

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24
Q

Traffic direction of Clathrin

A
  • trans-Golgi to lysosomes

* Plasma membrane to endosomes (receptor-mediated endocytosis)

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25
Q

Protein modification done on the Golgi apparatus to proteins that are destined for secretion

A

Adding of sialic acid

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26
Q

Function of the peroxisome

A

Catabolism of:

  • Very-long-chain fatty acids (beta oxidation)
  • Branched-chain fatty acids
  • Aminoacids
  • Ethanol

And synthesis of PLASMALOGENS, important phospholipids in myelin

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27
Q

Signs and symptoms of Zellweger syndrome (peroxisomal disease)

A
  • Hypotonia
  • Seizures
  • Hepatomegaly
  • Early death
28
Q

Signs and symptoms of Refsum disease (peroxisomal disease)

A
  • Scaly skin
  • Ataxia
  • Cataracts/night blindness
  • Shortening of the 4th toe
  • Epiphyseal dysplasia
29
Q

Actin and microvilli are examples of what type of cytoskeletsl filaments

A

Microfilaments

30
Q

Cilia, flagella, the mitotic spindle, and the centrioles are examples of what type of cytoskeletal filament

A

Microtubules

31
Q

Identified cell type by staining GFAP intermediate filaments

A

Neuroglia (eg, astrocytes, Schwann cells, oligodendrocytes)

*Identifies astrocytomas and glioblastomas

32
Q

Identified cell type staining Vimentin intermediate filaments

A

Mesenchymal tissue (eg, fibroblasts, endothelial cells, macrophages)

33
Q

Identified cell type staining Desmin intermediate filaments

34
Q

Direction of dynein movement in microtubules

A

Retrograde to microtubules (towards the negative end, Negative Near Nucleus)

*Di NO (negativo)

35
Q

Direction of movement of kinesin in microtubules

A

Anterograde to microtubules (towards the positive end, Positive Points to Periphery)

36
Q

Drugs that act on microtubules

A

“Microtubules Get Constructed Very Poorly”

  • Mebendazole
  • Griseofulvin
  • Colchicine
  • Vincristine/Vinblastine
  • Paclitaxel
37
Q

Microtubular structure of cilia

A

9 doublet + 2 singlet arrangement of microtubules

*Basal body consists of 9 microtubule triplets

38
Q

Pathogenesis of Kartagener syndrome

A

Immotile cilia due to a dynein arm defect

39
Q

Signs and symptoms of Kartagener syndrome

A
  • Decrease in fertility
  • Increased risk of ectopic pregnancy
  • Bronquiectasis
  • Recurrent sinusitis
  • Chronic ear infections
  • Conductive hearing loss
  • Situs inversus
40
Q

Number of Na and K molecules transported through the Na-K ATPase

A

For each ATP consumed, 3 Na go out (phosphorylated pump) and 2 K go in (dephosphorylated pump)

41
Q

Site of the Na-K ATPase that is inhibiten by ouabain

A

The K site (dephosphorylated state of the pump)

42
Q

Most common type of collagen

43
Q

Structures with predominantly type 1 collagen

A
  • Bone
  • Skin
  • Tendon
  • Dentin
  • Fascia
  • Cornea
  • Late wound repair
44
Q

Structures with predominantly type 2 collagen

A
  • Cartilage (including hyaline)
  • Vitreous body
  • Nucleus pulposus
45
Q

Structures with predominantly type 3 collagen (reticulin)

A
  • Skin
  • Blood vessels
  • Uterus
  • Fetal tissue
  • GRANULATION TISSUE and KELOID FORMATION
46
Q

Structures with predominantly type 4 collagen

A
  • Basement membrane
  • Basal lamina
  • Lens
47
Q

Type of collagen found in the epiphyseal growth plate

48
Q

Most abundant aminoacid in collagen

A

Glycine (1/3)

*Structure is Gly-X-Y, where X and Y are proline or lysine

49
Q

Cofactor required for hydroxylation of proline and lysine residues during collagen synthesis

50
Q

Residue that gets glycosylated during the third step of collagen synthesis

A

Hydroxylysine residues

51
Q

Types of bonds that form procollagen (triple helix of 3 collagen alpha chains)

A

Hydrogen and disulfide bonds

52
Q

Collagen synthesis steps that take place in the RER

A
  1. Synthesis (translation of preprocollagen)
  2. Hydroxylation of proline and lysine
  3. Glycosylation of hydroxylysine residues
53
Q

Function of procollagen peptidase

A

Cleavage of procollagen C- and N- terminals (disulfide-rich) to form insoluble tropocollagen

54
Q

Cofactor required by lysyl oxidase to form covalent lysine-hydroxylysine cross-linkage

55
Q

Collagen synthesis steps that take place extracellularly

A
  1. Cleavage of procollagen

2. Cross-linkage

56
Q

Deficient/defective enzyme in Menkes disease

A

Lysyl oxidase

57
Q

Mutations in which genes can lead to osteogenesis imperfecta

A

COL1A1 (chromosome 17) and COL1A2 (chromosome 7)

58
Q

Decreased production of what type of collagen leads to osteogenesis imperfecta

A

Type 1 collagen

59
Q

Signs and symptoms of osteogenesis imperfecta

A

Patients can’t BITE

  • Bones = multiple fractures
  • I (eye) = blue sclerae
  • Teeth = dental imperfections
  • Ear = hearing loss
60
Q

Signs and symptoms of Ehlers-Danlos syndrome

A
  • Hyperextensible skin
  • Tendency to bleed
  • Hypermobile joints

Associated with joint dislocation, berry and aortic aneurysms, organ rupture

61
Q

Type of collagen mutated in classical Ehlers-Danlos syndrome

A

Type 5 collagen

62
Q

Main structural difference between collagen and elastin

A

Elastin is rich in NONHYDROXYLATED proline, lysine, and glycine residues

63
Q

Protein modification that gives elastin its elastic properties

A

Cross-linking

64
Q

Elastase, the enzyme that degrades elastin, is inhibited by what other enzyme

A

alpha1-antitrypsin

65
Q

Pathogenesis of Marfan syndrome

A

Autosomal dominant connective tissue disorder due to a mutation in the FBN1 gene on chromosome 15 that results in defective fibrillin

*Fibrillin forms a sheath around elastin

66
Q

Signs and symptoms of Marfan syndrome

A
  • Tall with long extremities
  • Pectus carinatum or excavatum
  • Hypermobile joints
  • Aracnodactyly
  • Cystic medial necrosis of the aorta
  • Aortic incompetence and dissecting aortic aneurysms
  • Floppy mitral valve
  • Subluxation of lenses (upward and temporally)
67
Q

Pathogenesis of achondroplasia

A

Missense mutation in the FGFR3 gene (chromosome 4) that leads to irreversible activation of fibroblast growth factor receptor 3, thereby inhibitin chondrocyte proliferation

Biochemestry (7 decks)

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