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Cell and tissue > Cell IV > Flashcards

Cell IV Flashcards

1
Q

Where is the principle site of phospholipid synthesis?

A

CYTOSOLIC layer of sER

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2
Q

How do phospholipids get from the sER to anywhere else in the cell?

A

Phospholipid translocators

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3
Q

What is the action of phospholipid translocators?

A

catalyze the flip-flop of phospholipids from one monolayer to the other

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4
Q

Where are phospholipid translocators found?

A

membrane-bound enzymes in the sER

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5
Q

Where is Ca stored?

A

sER

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6
Q

What is the function of atlastin?

A

a GTPase is involved in constructing and shaping the ER

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7
Q

What happens when there is over-expression of atlastin?

A

increased ER, lack of golgi

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8
Q

What happens where there is too little atlastin?

A

ER becomes fragmented

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9
Q

What disease has a deficiency of Atlastin been linked to?

A

Hereditary spastic paraplegia.

Symptoms include leg stiffness and gait disturbances such as stumbling and tripping. This is due to difficulty in hip flexion and dorsiflexion of the foot.

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10
Q

What are proteosomes?

A

Large proteases that require ATP

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11
Q

Where are proteosomes located?

A

In the cytoplasm and the nucleus

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12
Q

What are the three functions of proteosomes?

A

Proteolysis of:

  1. Regulating proteins in cell cycle
  2. Malformed, denatured and damaged proteins
  3. Antigenic proteins
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13
Q

What are the two major types of proteosomes?

A

Ubiqitin dependent and not (cytosolic is dependent)

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14
Q

True or false: prion proteins inhibit proteosomes?

A

True

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15
Q

Defective ubiquitination of proteins is implicated in what disease?

A

Parkinsons

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16
Q

How are proteosomes implicated in cystic fibrosis?

A

destroy a competent but slow to fold CFTR

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17
Q

How can proteosomes contribute to CA?

A

Inhibition of them decreases the degrading of pro-apoptotic factors

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18
Q

Partial inhibition of proetosomes by bortezomib has been effective against what disease? How does this work?

A

Multiple Myeloma

Inhibits the over destruction of pro-apoptotic factors

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19
Q

What is the main function of the Golgi complex?

A

Functions as a major sorting and distribution center

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20
Q

How are proteins sorted in the golgi?

A

By their ‘chemical zip code” (AA or carb attachments)

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21
Q

What are the five ways of protein modification in the Golgi?

A 
Glycosylation
Sulfation
Phosphorylation
Oligosaccharides added
Proteolytic cleavage of proteins
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22
Q

How are proteins sent out of the golgi?

A

In vesicles

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23
Q

Where is the golgi usually found?

A

Near the nucleus

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24
Q

How many cisternae usually comprise the Golgi?

A

3-10

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25
Q

What is the side of the golgi that faces the nucleus called?

A

Cis face

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26
Q

Where do most of the transport vesicles to the golgi come from?

A

from the ER

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27
Q

How do proteins get to one Golgi stack to the next?

A

vesicles

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28
Q

What is the side of the Golgi that faces the plasma membrane called?

A

The trans face

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29
Q

What is Wilson’s disease?

A

An autosomal recessive disorder caused by a mutation in a protein pump for copper in the trans-Golgi network of liver cells. This results in impaired biliary excretion of copper.
Kayser-Fleicher rings

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30
Q

How are proteins inserted into the membrane?

A

Via a start transfer and stop transfer sequence on the protein

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31
Q

Where is Ca stored in the cell?

A

sER

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32
Q

What are three deleterious effects of elevated Ca levels in the cell?

A

Membrane damage
Nuclear damage
Lower ATP

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33
Q

What is the enzymes that flips phospholipids from the cytosolic side to the ER lumen side?

A

Scramblase

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34
Q

What is the enzymes that is required for ER building?

A

Atlastin

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35
Q

Where are proteosomes found?

A

In the cytoplasm and nucleus

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36
Q

True or false: proteosomes are ATP dependent

A

True

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37
Q

What is the transporter of Cu in the Golgi?

A

ATP7B

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38
Q

how are microperforations of skeletal muscles sealed?

A

Via membrane protein from Golgi in-transporting vesicles containing dysferlin.

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39
Q

What is dysferlin transport dependent on?

A

Cu

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40
Q

Deficiency of dysferlin are found in what three diseases?

A

three types of muscular dystrophy: Miyoshi myopathy, limb-girdle muscular dystrophy type 2b, and distal myopathy tibialis anterior muscle onset

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41
Q

What is the protein in the Golgi that holds the Cu?

A

Ceruloplasm (apoceruloplasm if not bound to Cu)

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42
Q

How is Cu excreted from cells

A

Via transport vesicles that are filled from ATP7B action

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43
Q

A defective Cu transporter (ATP7B) leads to what disease?

A

Wilson’s disease

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44
Q

What are Kayser-Fleisher rings?

A

Cu rings around the eye found in Wilson’s disease

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45
Q

Where is ceruloplasm found?

A

Golgi

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46
Q

What happens to ceruloplasm levels when there is a defective Cu transporter?

A

Decrease

47
Q

What is the protein that is used in microtears of muscles? What type of diseases are defects of this protein implicated in?

A

Dysferlin

Muscular dystrophy

48
Q

How is insulin made/secreted? (3 steps)

A

First made into preproinsulin in the ER, and shipped to golgi.

Golgi forms vesicle with enz to cleave pro part inside.

These vesicles are held in the regulated pathway.

49
Q

What is proinsulinemia?

A

A disease where mutated proinsulin is sent into the constitutive pathway, but prohormone secreting enzymes are secreted in the regulated pathway. (no insulin produced)

50
Q

What stain is used to show a negative of the Golgi? Why does this work?

A

A basophilic stain (hematoxylin). Golgi is not charged.

51
Q

How do you get a positive stain of the Golgi?

A

Use metals

52
Q

Where are the golgi found in nerve cells?

A

Completely surround the nucleus

53
Q

You see a nucleus that is relatively clear on the EM. What can you infer based on this?

A

Transcription is taking place at high rates

54
Q

What are endosomes?

A

dynamic membrane-limited compartments that exist in the cell’s cytoplasm. The organelles are involved in sorting and identifying molecules for recycling or degradation in lysosomes.

55
Q

What are the four types of endsomes?

A
  1. Early endosomes
  2. Recycling endosomes
  3. Multivesicular bodies
  4. Late endosomes
56
Q

Where are early endosomes located?

A

the cell’s periphery

57
Q

What is the pH of early endosomes?

A

6.2 - 6.5

58
Q

How are endosomes acidified?

A

H+ ATPases

59
Q

What are multivesicular bodies (MVBs)?

A

Small membrane bound structures from the early endosome located between the early and late endosome (transporter)

60
Q

What is the pH of the multivesicular bodies?

A

5-6.2

61
Q

How do MVBs get from the early to late endosome?

A

Via a microtuble

62
Q

Where do the MVBs eventually go?

A

Mere with a late endosome or excreted (=exosomes!!)

63
Q

What are late endosomes?

A

A permature lysosome that receives components for degradtaion from the early endosome.

64
Q

Where are the late endosomes located?

A

Near the golgi

65
Q

What is the pH of the elate endosomes?

A

5

66
Q

What is the fate of a late endosome?

A

become a lysosome or merge with one

67
Q

What is the function of the recyling endosome?

A

Bring transport molecules (like GLUT4) to the surface plasma membrane in response to a signal (insulin)

68
Q

LDL receptor are endocytozed via clatharin coated pits and turned into what?

A

Endosomes

69
Q

What happens to the LDL and receptors that are endocytozed (2)?

A
  1. both brought to the early endosome where receptor is taken off of LDL and recycled back.
  2. LDL goes to lysosome
70
Q

What is the binding protein for Fe? What is the receptor? What process of endocytosis does the receptor/ligand go through?

A
  1. Transferrin
  2. transferrin receptor
  3. Clatharin-mediated endocytosis
71
Q

What causes the abnormal bone growth in achondroplasia

A

lysosomal targeting is disturbed due to a mutation of FGFR3 (fibroblast growth factor receptor). This causes FGFR3 to be recycled to the membrane rather than degraded

72
Q

Why do you want to degrade receptor molecules after they have bound their ligand?

A

Stop over signalling

73
Q

What is transcytosis?

A

Receptor and ligand are transported across the cell via endosomes

74
Q

What cells use transcytosis?

A

Glandular cells

75
Q

What is the signal that is attached to the lysosomal hydrolase precursor?

A

Mannose

76
Q

How are lysosoms directed to the early endosome?

A

Mannose phosphate receptor on the last part of the golgi accepts and clatharin coats the vesicle. Now a receptor driven vesicle

77
Q

What are inside of lysosomes?

A

Lysosomal hydrolases

ions/molecules

78
Q

True or false: enzymes are able to only able to destroy a tiny fraction of biological molecules?

A

False–most are able to be digested

79
Q

In what type of cells are lysosomes primarily found?

A

professional phagocytic cells such as neutrophils and macrophages

80
Q

How is the acidic nature of the lysosomes maintained?

A

H+ pumps

81
Q

What is the autophagic pathway?

A

Pathway where lysosomes degrade defective organelles

82
Q

What are the three types of autophagy?

A

Macroautophagy
Microautophagy
Chaperone-mediated direct transport

83
Q

True or false: organelles destined for destruction are delivered to the lysoosome inside a membrane?

A

True

84
Q

What is the term that describes the degradation of outside material such as bacteria?

A

Heterophagocytosis

85
Q

What happens when sER is no longer needed?

A

Autophagy of the sER

86
Q

What type of structure are eliminated via macroautophagy?

A

Organelles

87
Q

What type of structure are eliminated via MICROautophagy?

A

Proteins, small molecules

88
Q

What molecules are needed to direct proteins to the lysosome?

A

Chaperones

89
Q

What is a heterophagosome?

A

Phagosome what has foreign material in it

90
Q

What are residual bodies?

A

Material that lysosomes cannot digest and leaves undegraded –accumulates

91
Q

What is lipofuscin?

A

Build up of residual bodies

92
Q

Are lysosomes acidophilic or basophilic?

A

Acidophilic (H+ in it)

93
Q

What are Heterophagolysosomes?

A

primary lysosome + heterophagosome

94
Q

What are the two destinies for digested material by lysosomes?

A

Residual bodies

exocytozed

95
Q

A lysosome that has consistent coloration throughout (on EM) is of what type?

A

Primary (homogeneous)

96
Q

A lysosome that has inconsistent coloration and a large, darker area (on EM) is of what type?

A

Secondary (heterogeneous)

97
Q

What is Pompe disease?

A

Glycogen storage disease due to M6P receptor

98
Q

What is Tay-Sach’s disease?

A

Problem with the breakdown of lipids

99
Q

You’re looking at a lysosome through EM and see a whorl effect. You also see a sample from the same tissue using light microscopy and E&M staining, that shows a very large, rounded area in the cell that appears white. What is your diagnosis?

A

Tay-Sach’s disease

100
Q

How do integral membrane proteins establish themselves in the membrane?

A
  1. There are start and stop sequences on the protein that are recognized by a translocator protein that starts and stops translocation of the protein as necessary.
  2. a signal peptidase again cuts off the signal sequence
101
Q

What are the four possible fates of endocytozed receptor and ligands? (Give examples of each)

A
  1. Receptor is recycled and ligand is degraded (LDL)
  2. Receptor and ligand are recycled (Fe)
  3. Receptor and ligand are degraded (EGF)
  4. Transcytosis [Receptor and ligand transported across the cell] (IgA)
102
Q

Why would the cell want to degrade receptors? What happens in achondroplasia?

A
  1. To stop signalling

2. FGFR3 is recycled instead of degraded

103
Q

What is the sorting place for all of the receptor/ligands that are endocytozed?

A

Early endosome

104
Q

What is the enzyme deficiency in Pompe’s disease? What accumulates?

A

alpha-1,4 Glucosidase

Glycogen accumulates

105
Q

What is the enzyme defciency in GM1 gangliosidosis?

A

GM1 ganglioside beta-galactosidase

106
Q

What is the enzyme that is deficient in Tay-Sach’s disease? What accumulates?

A

Hexosaminidase a subunit

GM2 gangliosides accumulate

107
Q

What is the enzyme that is deficient in Sandhoff (GM2 sphingolipidosis)? What accumulates?

A

Hexosaminidase beta

GM2 gangliosides globosides

108
Q

What is the defective enzyme in metachromatic leukodystropy? What accumulates?

A

Arylsulfatase A.

Sulfatide accumulates

109
Q

What is the defective enzyme in Gaucher’s disease? What accumulates?

A

Glucocerebrosidease

Glucocerebrosides accumulate

110
Q

What is the defective enzyme in Hurler disease? What accumulates?

A

alpha-L-iduronidase

Dematan sulfat, heparan sulfate

111
Q

You are looking at a cell that has intense acidophilia of the cytoplasm, as well as an empty area outside the cell. What type of cell is this?

A

Osteoclast. (lysosomes are acidophillic)

112
Q

You are looking at a muscle cell at note that there are large white areas where the contractile filaments should be. Using PAS, a sample from the same tissue demonstrates a deep magenta coloration. What is your diagnosis?

A

Pompe’s disease (glycogen accumulating in muscle cells leaves no room for contractile filaments)

113
Q

A low alk phos / bili is indicative of what disease?

A

Wilson’s

Cell and tissue (45 decks)

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