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PKM Biochemistry > Special Topics > Flashcards

Special Topics Flashcards

1
Q

Most common method of analyzing plasma proteins

A

Electrophoresis

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2
Q

Plasma Protein Quiz!

  1. Binds heme
  2. Binds extracorpuscular Hg
  3. Binds cortisol
  4. Forms a complex with retinol-binding protein and binds T4
A
  1. Hemopexin
  2. Haptoglobin
  3. Transcortin
  4. Tranthyretin
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3
Q

The following are examples of acute phase reactants.

A
  1. a1-antitrypsin
  2. haptoglobin
  3. a1-acid glycoprotein (orosomucoid)
  4. fibrinogen
  5. C-reactive protein
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4
Q

Transcription factor involved in the stimulation of synthesis of acute phase proteins

A

Nuclear factor kappa B

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5
Q

Released by mononuclear phagocytic cells - the PRINCIPAL - stimular of synthesis of acute phase reactants

A

IL-1

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6
Q

Albumin is the major protein of plasma making up ___ of total protein.

A

60%

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7
Q

This protein prevent loss of free hemoglobin into the kidney; conserving Fe present in Hg

A

Haptoglobin

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8
Q

Haptoglobin is decreased in ___ and increased in ___.

A

Decreased levels in hemolytic anemia. Hemolysis increases free Hg levels (Hg-Hp complex has a short half life of 90 mins vs 5 days for normal halptoglobin.

Increased level seen in chronic inflammatory states (haptoglobin is an acute phase reactant)

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9
Q

Site of absorption of Fe

A

Proximal duodenum

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10
Q

Name the proteins important in Fe metabolism.

  1. Incoming iron in Fe3+ state is reduced to Fe2+.
  2. Carries Fe in serum in the Fe3+ form
  3. Downregulates intestinal absorption and release of iron from macrophages
  4. Transports iron across the apical surface
  5. Transports iron across the basolateral surface
  6. Converts Fe2+ back to Fe3+ at the basolateral surface
  7. Protein which stores Fe in cells
A
  1. Ferrireductase
  2. Transferrin
  3. Hepcidin
  4. Divalent metal transporter 1
  5. Ferroportin
  6. Hephaestin
  7. Ferritin
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11
Q

If Fe levels are sufficient, levels of this protein increase to prevent further absorption of Fe.

A

Hepcidin

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12
Q

Major component of the a1 fraction of human plasma

A

a1-antitrypsin (a1-antiproteinase)

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13
Q

A1-antitrypsin is an example of a ___

A

Serine protease inhibitor

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14
Q

Group of small proteins in the cytosol of liver, kidney, and intestine; with a high content of cysteine and bind Cu, Zn, Cd and Hg

A

Metallothioneins

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15
Q

This plasma protein is synthesized by monocytes, hepatocytes, and astrocytes, inhibits many proteinases and directs many cytokines towards tissues or cells.

A

a2-macroglobulin

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16
Q

Amyloidosis quiz.

  1. Increased in multiple myeloma
  2. Increased in patients on chronic dialysis
  3. Mutant forms exist in familal amyloidotic neuropathies
  4. Alzheimer’s disease
A
  1. Ig light chain
  2. B2-microglobulin
  3. Transthyretin
  4. Amyloid B protein
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17
Q

Cleavage of immunoglobulin with ___ produces two antigen-binding fragments and one crystallizable fragment

A

Papain

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18
Q

Immunoglobulin Quiz!

  1. Lowest concentration in plasma
  2. Exists as dimer and may contain a J chain
  3. The antigen receptor on B cell
  4. Opsonization
  5. Complement fixation
A
  1. IgE
  2. IgM or IgA
  3. IgM
  4. IgG
  5. IgG or IgM
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19
Q

Which two monosaccharides are ACTIVELY transported across the small intestine?

A

Glucose
Galactose

Secondary active transport (via SGLT1)

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20
Q

The major lipids in the diet

A

Triacylglycerol

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21
Q

How does one differentiate lingual/gastric lipases from pancreatic lipases as to its action on TAGs?

A

Lingual/gastric lipases act on the sn-3 ester bond, forming 1,2-DAGs and free fatty acids.

Pancreatic lipase is specific for the ester links in positions 1 and 3 forming 2-MAG.

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22
Q

What is the monoacylglycerol pathway?

A

In the intestinal cells,

MAGs are hydrolyzes into glycerol and FFA
DAGs are re-acylated to TAGs

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23
Q

How are long-chain FAs different from medium-chain/short-chain FAs different in terms of its absorption?

A

Long chain FAs packaged into chylomicrons which enter lymphatics and thoracic duct.

Medium/short chain FA exist as FFAs and pass into the hepatic portal vein.

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24
Q

How are proteolytic enzymes which are secreted as zymogens activated?

A

Enteropeptidase is secreted by duodenal epithelial cells to activate trypsinogen.
Trypsin activates chymotrypsinogen, proelastase, procarboxypeptidase and aminopeptidase.

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25
Q

How is Vitamin D able to increase Ca absorption

A

It increases synthesis of the intracellular calcium binding protein CALBINDIN.

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26
Q

This compound in cereal and unleavened whole-wheat products chelate Ca and Zn causing deficiency.

A

Phytic acid

Phytase in yeast renders it inactive

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27
Q

How can fat malabsorption cause Ca deficiency?

A

Fat in the intestinal lumen form insoluble Ca salts.

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28
Q

You know that Vitamin C increases absorption of Fe. How?

A

Vitamin C is a reducing agent, reduces Fe3+ to Fe2+, which is the form absorbed by the enterocyte.

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29
Q

What is the effect of the following on Fe absorption?

  1. Alcohol
  2. Ca
  3. Fructose
A
  1. Increase
  2. Decrease
  3. Increase
30
Q

Energy expenditure per L of O2 consumed

A

20 kJ

31
Q

Differentiate cachexia from marasmus.

A

In marasmus, protein synthesis is reduced but catabolism is unaffected.
In cachexia, protein catabolism is increased.

32
Q

Discuss three metabolic changes in cachexia.

A
  1. Tumor releases lactate, which is recycled into glucose (consumes 6ATP/glucose recycled)
  2. Stimulation of uncoupling proteins, leading to thermogenesis and oxidation of fuels
  3. Futile cycling of lipids (hormone sensitive lipase activated; FFAs produced are re-esterified at ATP cost).
33
Q

Very commonly, a ___ precipitates Kwashiorkor.

A

Infection

34
Q

Nutritional studies show that the average daily requirement for N is ___.

A

0.6 g/kg body weight

35
Q

2 amino acids are synthesized in the body but only from essential amino acids.

A

Cysteine (from Methionine)

Tyrosine (from Phenylalanine)

36
Q

Most frequent post-translational modification of proteins

A

Glycosylation (>50% have CHO moieties attached)

37
Q

Mucin contains repeating amino acid sequences rich in:

A

Serine
Threonine
Proline

Mucins exhibit high content of O-glycan chains

38
Q

What is the major class of glycoproteins? It is characterized by ___.

A

N-linked glycoproteins
Asn-GlcNAc linkage

(Other classes are O-linked glycoproteins and GPI-linked)

39
Q

Common pentasaccharide found in N-linked glycoproteins

A

Man3 GlcNAc2

40
Q

The formation of N-linked oligosaccharides is unique because it involves

A

Dolichol-P-P-oligosaccharide

41
Q

Addition of this molecule causes enzymes to be marked for lysosomes. This is synthesized by which enzyme, deficient in which condition.

A

GlcNAc-1-P
GlcNAc phosphotransferase
I-Cell disease

42
Q

Thick transparent, non-cellular envelope surrounding the oocyte

A

Zona pellucida

43
Q

This O-linked glycoprotein functions as a receptor for the sperm

A

ZP3.

Interacts with galactosyl transferase on sperm; when activated, sperm releases proteases and hyaluronidase (acrosomal reaction)

44
Q

What is the test used to diagnose PNH?

A

Ham’s Test.

Red cells much more sensitive to hemolysis in normal serum acidified to pH of 6.2

45
Q

Explain the glycoprotein abnormality in RA.

A

Alteration in glycosylation of circulating Ig; lacking glactose in Fc and terminating in GlcNAc. Mannose-binding protein binds agalactosyl IgG and activates complement system contributing to chronic inflammation in joints.

46
Q

Binds mannose, GlcNAc and other sugars in bacteria, fungi and viruses marking them for opsonization and destruction by complement.

A

Mannose binding protein

47
Q

Influenza A binds to cell surface receptor molecules containing ___ via ___. Another enzyme allows it to elute newly synthesized progeny from host cells.

A

NeuAc via hemagglutinin

Neuraminidase

48
Q

HIV-1 uses two glycoproteins.

  1. Attach to cell
  2. Fuse with host membrane
A
  1. gp120

2. gp41 (Fourty-one Fuses)

49
Q

Helicobacter pylori attaches to two glycans on the epithelial cells.

A

Adhesin in the tail of H pylori interact with:

Neuraminyl-galactose
Lewis-B substance

50
Q

___ of chilled platelets has been found to prevent clustering thereby prolonging its life.

A

Enzymic galactosylation

51
Q

Major cross-links that form in elastin

A

Desmosine

Condensation of 3 Lys-derived aldehydes with an unmodified lysine

52
Q

This glycoprotein is secreted into the ECM by fibroblasts and incorporated into structures that serve as scaffold for deposition of elastin.

A

Fibrillin

Zonular fiber = ectopia lentis
Periosteum = tall, arachnodactyly
Aorta = aortic aneurysm

53
Q

A major glycoprotein of ECM with domains than binds heparin, fibrin, collagen, DNA and cell surfaces.

A

Fibronectin

54
Q

Fibronectin contains an ___ sequence that binds to the receptor.

A

RGD

Arginine - Glycine - Aspartic acid

55
Q

The basement membrane in the nephron has three protein components and 2 GAGs

A

Proteins

  1. Type 4 collagen
  2. Laminin
  3. Entactin

GAG

  1. Heparin
  2. Heparan sulfate
56
Q

Proteoglycans

  1. Major proteoglycan in cartilage
  2. Bind growth factors (TGF-B
A
  1. Aggrecan

2. Decorin

57
Q

Describe the structure of aggrecan.

A

Bottle-brush-like.

The main stem is hyaluronic acid.
Sticking out of it are core proteins. Attached to core proteins are:
1. Chondroitin sulfate
2. Keratan sulfate

58
Q

All GAGs contain GlcNAc as its aminosugar except these two which has GalN.

Only these two GAGs have iduronic acid as its glucoronic acid. A

A

Remember two TV stars named David.

GalN:
Dermatan sulfate, Chondroitin sulfate
(Goofy, David Caruso!)

Iduronic acid:
Dermatan sulfate, heparin
(Idiot, David Hasselhoff! Dahil kulay dilaw, may hepa rin!)

59
Q

GAG Quiz!

A. Most abundant
B. Intracellular
C. Ubiquitous cell surface GAG
D. Most heterogenous
E. NOT sulfated, NOT attached to protein
F. Also found in bacteria
A 
A. Chondroitin sulfate
(in cartilage, tendon, ligaments, bone)
B. Heparin (mast cells)
C. Heparan sulfate
D. Keratan sulfate
E. Hyaluronic acid
F. Hyaluronic acid
60
Q

GAG Quiz

  1. GalNAc, GlcUA
  2. GalNAc, IdUA
  3. GlcN, GlcUA
A
  1. Chondroitin sulfate
  2. Dermatan sulfate
  3. Heparan sulfate
61
Q

GAG Quiz

  1. GlcNAc, Gal
  2. GlcN, IdUA
  3. GlcNAc, GlcUA
A
  1. Keratan sulfate
  2. Heparin
  3. Hyaluronic acid
62
Q

Compressibility of cartilage is due to high concentrations of these two proteoglycans

A
  1. Chondroitin sulfate

2. Hyaluronic acid

63
Q

GAG found in bone, cartilage and certain neurons

A

Chondroitin sulfate

64
Q

GAG which play a role in corneal transparency

A

Keratin sulfate
Dermatan sulfate

Cornea? Klaro dapat.

65
Q

This GAG bind to lipoprotein lipase and cause its release into the circulation.

A

Heparin

66
Q

This GAG facilitate cell migration

A

Hyaluronic acid

67
Q

Certain cancers induce fibroblasts to synthesize large amounts of this GAG

A

Hyaluronic acid

68
Q

Major GAG synthesized by arterial smooth muscle cells

A

Dermatan sulfate

69
Q

Structure of hydroxyapatite

A

Ca10 (PO4)6 (OH)2

70
Q

Major protein in bone

A

Type I collagen

PKM Biochemistry (8 decks)

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