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piggy > Biochemistry - Cellular > Flashcards

Biochemistry - Cellular Flashcards

1
Q

A patient presents with blue sclera that results in an inability to form procollagen from pro-α chains. What disease does he have?

A

Osteogensis Imperfecta

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2
Q

List the four main phases of mitosis in order.

A

Prophase, metaphase, anaphase, and telophase

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3
Q

When does mitosis occur in the cell cycle?

A

Mitosis occurs after G2 and before G1 in the cell cycle

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4
Q

When does DNA synthesis occur in the cell cycle?

A

After G1 and before G2 in the cell cycle

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5
Q

What two tumor suppressor genes normally inhibit G1-to-S progression?

A

Rb and p53

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6
Q

During which phase of the cell cycle can a cell enter G0?

A

G1

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7
Q

Which phase of the cell cycle is usually the shortest?

A

Mitosis

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8
Q

Which phase of the cell cycle is shortened in rapidly dividing cells?

A

G1

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9
Q

What is the relationship between cyclin-dependent kinases and cyclins?

A

Cyclins are regulatory proteins that are translated and activate cyclin-dependent kinases at appropriate times in the cell cycle

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10
Q

Permanent and stable cells are typically in which phase of the cell cycle?

A

G0

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11
Q

Rb and p53tumor suppressors prevent which transition in the cell cycle?

A

Transition from G1 to S phase; defective cells are not allowed to undergo DNA synthesis

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12
Q

_____ (Permanent/stable/labile) cells remain in G0 and regenerate from stem cells.

A

Permanent

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13
Q

_____ (Permanent/stable/labile) cells enter G1from G0 when stimulated.

A

Stable

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14
Q

_____ (Permanent/stable/labile) cells never go to G0 and divide rapidly with a short G1.

A

Labile

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15
Q

Neurons, skeletal and cardiac muscle, and red blood cells are examples of _____ (permanent/stable/labile) cells.

A

Permanent

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16
Q

Hepatocytes and lymphocytes are examples of _____ (permanent/stable/labile) cells .

A

Stable

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17
Q

Name four examples of labile cells

A

Labile cells (bone marrow, gut epithelium, skin, and hair follicles)

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18
Q

What happens to cell cycling when there is a mutation in a tumor suppressor such as Rb or p53?

A

There is unrestrained growth in the cell, and thus an increased likelihood to develop a malignancy

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19
Q

List the three components of interphase.

A

G1, S phase, and G2

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20
Q

What are the main functions of the rough endoplasmic reticulum?

A

The synthesis of secretory (exported) proteins and the addition of N-linked oligosaccharides to proteins

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21
Q

Name two types of cells that are rich in rough endoplasmic reticulum.

A

Goblet cells (secrete mucus) and plasma cells (secrete antibodies)

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22
Q

What is the histologic term for rough endoplasmic reticulum in neurons? What substances are synthesized there?

A

Nissl bodies, which are the site of enzyme (such as ChAT) and neuropeptide synthesis

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23
Q

_____ (Free/Attached) ribosomes synthesize cytosolic and organellar proteins, whereas _____ (free/attached) ribosomes synthesize secretory proteins.

A

Free; attached

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24
Q

List two functions of the smooth endoplasmic reticulum.

A

Steroid synthesis and the detoxification of drugs and poisons

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25
Q

Give two examples of cells that are rich in smooth endoplasmic reticulum.

A

Liver hepatocytes and steroid-hormone-producing cells of the adrenal cortex

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26
Q

The Golgi apparatus functions as the distribution center for what?

A

Synthesized proteins and lipids

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27
Q

List three places to which the Golgi apparatus sends proteins and lipids.

A

The plasma membrane, lysosomes, and secretory vesicles

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28
Q

Clathrin is a protein that transports vesicles from the trans face of the Golgi apparatus to where?

A

Clathrin directs from trans-golgi to lysosomes and from plasma membrane to endosome

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29
Q

What type of protein-bound saccharides is modified in the Golgi apparatus?

A

N-oligosaccharides (on asparagine)

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30
Q

In patients with I-cell disease, the failure to add mannose-6-phosphate to proteins in the Golgi apparatus leads to what deficit?

A

There is no signal that targets lysosomal enzymes to the lysosome, resulting in exocytosis of the enzymes

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31
Q

A child presents with coarse facial features, clouded corneas, restricted joint movement, and high plasma levels of lysosomal enzymes. What could this patient have?

A

I-Cell Disease

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32
Q

How are serine and threonine residues modified in the golgi?

A

O-oligosaccharides are added

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33
Q

What is the role of coat protein II in vesicular trafficking?

A

Anterograde transport of rough endoplasmic reticulum to the cis-Golgi

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34
Q

True or False: Proteoglycans get assembled from their component core proteins in the Golgi apparatus.

A

True

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35
Q

How are proteoglycans modified in the Golgi?

A

Sulphation

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36
Q

How are tyrosine residues modified in the Golgi?

A

Sulphation

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37
Q

The golgi adds which marker to proteins to target them to lysosomes?

A

Mannose-6-phosphate

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38
Q

What is the role of coat protein I in vesicular trafficking?

A

Retrograde movement from the Golgi apparatus to the endoplasmic reticulum

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39
Q

What is the basic pathophysiologic defect in patients with I-cell disease?

A

The failure of the addition of mannose-6-phosphate to lysosomal proteins and the resulting pathological exocytosis of enzymes

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40
Q

What is the name of the process by which clathrin transports vesicles from outside the cell to inside the cell through fusion of the two lipid-based membranes?

A

Receptor-mediated endocytosis

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41
Q

Microtubules are formed from what two protein building blocks?

A

-Tubulin and -tubulin

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42
Q

What syndrome results from a microtubule polymerization defect that leads to impaired lysosomal emptying and poor phagocytosis?

A

Chediak-Higashi syndrome

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43
Q

Name four cellular structures in which microtubules are found.

A

Cilia, flagella, mitotic spindle, centrioles

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44
Q

True or False? Microtubule filaments grow rapidly but collapse slowly.

A

False; they grow slowly and collapse quickly

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45
Q

Are microtubules involved in fast or slow transport along the neuronal axons?

A

Slow axoplasmic transport

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46
Q

What are the symptoms seen in Chdiak-Higashi syndrome?

A

Pyogenic infections, partial albinism, and peripheral neuropathy

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47
Q

What drug that is used to treat gout acts on microtubules?

A

Vincristine and vinblastine

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48
Q

What anticancer drug used to treat breast cancers stabilizes microtubules?

A

Paclitaxel

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49
Q

What antifungal agent targets microtubules?

A

Griseofulvin

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50
Q

What antihelminthic drugs target microtubules?

A

Mebendazole and thiabendazole

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51
Q

What protein is responsible for retrograde transport on the microtubule?

A

Dynein

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52
Q

What protein is responsible for anterograde transport on the microtubule?

A

Kinesin

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53
Q

How are cilia structurally composed?

A

Nine microtubule doublets around two central microtubules

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54
Q

What syndrome results from a defect in the dynein arm of cilia?

A

Kartagener’s Syndrome

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55
Q

What protein causes the movement of the cilia?

A

Axonemal dynein is an adenosine triphosphatase that causes bending of the cilium

56
Q

Which diagnosis should you consider in a male with infertility, bronchiectasis and recurrent sinusitis?

A

Kartagener’s Syndrome

57
Q

True or False? Kartagener;s syndrome causes only male infertility.

A

False ; Kartagener;s syndrome causes infertility in both sexes

58
Q

A 22-year-old female presents with history of recurrent pneumonia. Subsequent chest x-ray reveals dextrocardia. What is the most likely diagnosis involving these two findings?

A

Kartagener’s Syndrome

59
Q

What is the underlying cellular malfunction that leads to Kartagener;s syndrome?

A

Immotile cilia as a result of a dynein arm defect

60
Q

Microvilli and adhering junctions are composed of which two cytoskeletal elements?

A

Actin and Myosin

61
Q

Which two cytoskeletal elements are necessary for muscle contraction and cytokinesis?

A

Actin and Myosin

62
Q

Cilia, flagella, mitotic spindles, neurons and centrioles are all composed of which cytoskeletal element?

A

Miccrotubule

63
Q

Vimentin, desmin, cytokeratin, glial fibrillary acid proteins, and neurofilaments are all examples of which type of cytoskeletal element?

A

Intermediate filaments

64
Q

Approximately what percent of the plasma membrane is composed of cholesterol?

A

50%

65
Q

Approximately what percent of the plasma membrane is composed of phospholipids?

A

50%

66
Q

What is the effect on melting temperature if the content of cholesterol in the plasma membrane is increased?

A

The melting temperature increases

67
Q

What is the effect of high cholesterol content on the fluidity of a cell membrane?

A

Fluidity is decreased

68
Q

Vimentin stains identify which type of cells?

A

Connective tissue

69
Q

Desmin stains identify which type of cells?

A

Muscle

70
Q

Cytokeratin stains identify which type of cells?

A

Epithelial cells

71
Q

Neurofilament stains identify which type of cells?

A

Neurons

72
Q

Glial fibrillary acid protein stains identify which type of cells?

A

Neuroglia

73
Q

Na+-K+adenosine triphosphatase exchanges how many sodium and potassium ions in each cycle?

A

Three sodium ions out and two potassium ions in per cycle

74
Q

How many adenosine triphosphates are consumed in one cycle of the Na/K pump?

A

One

75
Q

What effect does the inhibition of the Na+-;K+adenosine triphosphatase by digoxin have on cardiac contractility?

A

It increases cardiac contractility by increasing intracellular calcium concentration

76
Q

Where does ouabain bind to the Na+-K+adenosine triphosphatase?

A

At the K+ binding site

77
Q

How does inhibition of Na+-K+exchange result in increased cardiac contractility?

A

There is indirect inhibition of Na+-Ca2+exchange, which results in increased intracellular Ca2+concentration

78
Q

What is the most abundant type of collagen?

A

Type I

79
Q

What type of collagen is found in teeth?

A

Type I, which is found in dentin

80
Q

What type of collagen is found in bone?

A

Type I

81
Q

What type of collagen is found in the connective tissue of the uterus?

A

Type III

82
Q

What type of collagen predominates in fetal tissue?

A

Type III

83
Q

What type of collagen is found in the cornea?

A

Type I

84
Q

What type of collagen is found in the basement membrane?

A

Type IV

85
Q

During wound healing, type ____ collagen is laid down first as part of granulation tissue. Then, type ____ collagen is produced as part of late wound healing.

A

III ; I

86
Q

What type of collagen is found in the skin and fascia?

A

Type I

87
Q

What type of collagen is found in the vitreous body, the clear gel that fills the space between the lens and the retina?

A

Type II

88
Q

What type of collagen is found in the nucleus pulposus, the jelly-like substance in the middle of the spinal disc?

A

Type II

89
Q

What type of collagen is found in hyaline cartilage?

A

Type II

90
Q

What type of collagen is found in blood vessels?

A

Type III

91
Q

What is another name for type III collagen?

A

Reticulin (reticular means net-like)

92
Q

What type of collagen is found on the articular surface of joints?

A

Type II

93
Q

A triple helix composed of three collagen chains that has not yet been cleaved is referred to as what?

A

Procollagen

94
Q

Where does collagen synthesis occur in the cell?

A

In the rough endoplasmic reticulium

95
Q

Which amino acids predominate in collagen?

A

Glycine, proline, hydroxyproline, and hydroxylysine

96
Q

Which vitamin is required for the hydroxylation of proline and lysine in collagen?

A

Vitamin C

97
Q

The conversion of preprocollagen to procollagen requires what process?

A

Glycosylation

98
Q

A single-collagen chain during collagen synthesis is referred to as what?

A

Preprocollagen

99
Q

What form of collagen is exocytosed from the cell into the extracellular space?

A

Procollagen

100
Q

An -OH group is added to _____ and _____ after translation of the collagen chain.

A

Proline ; lysine

101
Q

British sailors in the 17th century come to you due to an inability to hydroxylate proline and lysine residues for collagen synthesis. What disease do they have, and why do you prescribe limes?

A

Scurvy, and the limes will supply them with the vitamin C they are deficient in during their long voyage (and earn them the nickname, limeys)

102
Q

A triple helix that is composed of three collagen chains with the terminal regions cleaved off is referred to as what?

A

Tropocollagen

103
Q

Is tropocollagen formed intracellularly or extracellularly?

A

EC

104
Q

What is the name of the enzyme that covalently cross-links lysine residues to hydroxylysine residues?

A

Lysyl oxidase

105
Q

Many staggered tropocollagen molecules with covalent lysine-hydroxylysine cross-links are referred to as _____ _____

A

Collagen fibrils

106
Q

Does the formation of tropocollagen from the cleavage of procollagen increase or decrease its solubility?

A

Decreases; tropocollagen is insoluble

107
Q

What are the six steps of collagen synthesis in order?

A

Synthesis, hydroxylation, glycosylation, exocytosis, proteolytic processing, cross-linking

108
Q

What disease results in an inability to form procollagen from pro chains?

A

Osteogenesis imperfecta

109
Q

Ehlers-Danlos syndrome is a defect of what process?

A

Collagen synthesis

110
Q

Ehlers-Danlos syndrome is associated with what defects of the vasculature of the brain?

A

Berry aneurysms

111
Q

True or False? All types of Ehlers-Danlos syndrome are transmitted through an autosomal recessive inheritance pattern.

A

False; Ehlers-Danlos syndrome shows variable inheritance, depending on the type

112
Q

A patient presents with hyperextensible skin, easy bruising, and hypermobile joints. What is the most likely diagnosis?

A

Ehlers-Danos Syndrome

113
Q

What type of collagen is most frequently affected in Ehlers-Danlos syndrome?

A

Type III collagen (reticulin)

114
Q

Why might patients with Ehlers-Danlos syndrome have an increased risk of organ rupture?

A

Poor type III collagen synthesis results in weak connective tissue

115
Q

What type of inheritance does osteogenesis imperfecta show?

A

Autosomal dominant

116
Q

A baby is born with multiple fractures and hearing loss. What finding is expected during the ophthalmologic examination?

A

Blue sclerae

117
Q

What is the incidence of osteogenesis imperfecta?

A

1 : 10,000

118
Q

Osteogenesis imperfecta is a defect in what process?

A

Type I collagen synthesis

119
Q

What is the common etiology of the blue sclerae and multiple fractures seen in osteogenesis imperfecta?

A

Both symptoms are due to a loss of normal functioning type I collagen; the blue sclerae result from decreased connective tissue over the choroid in the eye, whereas multiple fractures result from decreased collagen in the bone matrix

120
Q

Which type of osteogenesis imperfecta is fatal in utero?

A

Type II

121
Q

A child seen in the emergency room is found to have multiple healing fractures of different ages. What disease should be ruled out before filing abuse charges against the parents?

A

Osteogenesis Imperfecta

122
Q

The dental imperfections seen in osteogenesis imperfecta is due to lack of _____ in the teeth?

A

Dentin

123
Q

A young woman with blue sclerae also has hearing loss. What is the pathophysiology of her hearing loss?

A

Abnormal bones of the middle ear

124
Q

What is the typical inheritance pattern of Alport;s syndrome?

A

X-linked recessive

125
Q

What type of collagen is disrupted in Alport;s syndrome?

A

Type IV collagen

126
Q

You are seeing a man who has progressive deafness and renal failure. The other males in his family show the same symptoms; what is the likely diagnosis?

A

Alport’s syndrome, which is typified by progressive hereditary nephritis and deafness

127
Q

What organ (other than the kidneys and the ears) can be affected in Alport’s syndrome?

A

This disease may result in ocular lesions

128
Q

What is the relationship between Alport;s syndrome and Goodpasture’s syndrome?

A

Both are diseases of type IV collagen (Alport;s is genetic; Goodpasture;s is autoimmune)

129
Q

What enzyme is inhibited by 1-antitrypsin?

A

1-Antitrypsin inhibits elastase, which degrades elastin

130
Q

Marfan;s syndrome is caused by a defect in what protein?

A

Fibrillin

131
Q

What is the function of fibrillin?

A

It acts as a scaffold for tropoelastin

132
Q

What is a stretchy protein found within lungs, large arteries, elastic ligaments, vocal cords and ligamenta flava (which connect the vertebrae)?

A

Elastin

133
Q

Excess elastase activity can result in what lung disorder?

A

Emphysema: 1-antitrypsin inhibits elastase, which degrades elastin; therefore, a lack of 1-antitrypsin can leads to the loss of elastin in the lungs, thereby resulting in emphysema

134
Q

Elastin is rich in which two amino acids? Are they glycosylated or nonglycosylated?

A

Proline and lysine; nonglycosylated

135
Q

In the Na-K-ATPase how many ions are moved?

A

Three sodium ions out and two potassium ions in per cycle

136
Q

A child has bowed legs and low phosphate levels. His family pedigree shows fathers passing the disease to daughters, who pass it on to sons. What is the mode of inheritance of this disease?

A

X-linked dominant ; the disease is hypophosphatemic rickets

137
Q

Muscle biopsy of your patient reveals ragged red fibers. His family pedigree shows all children from an affected female inheriting the disease. What is the mode of inheritance of this disease?

A

Mitochondrial inheritance

piggy (83 decks)

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