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medical science xy1110 > biochemistry 9 > Flashcards

biochemistry 9 Flashcards

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Biology 101 flashcards USMLE® Step 1 flashcards
1
Q

what are the components of phospholipids

A
  • platform - usually glycerol or sphingosine
  • phosphate
  • fatty acid - usually 1 or more
  • alcohol
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2
Q

what is sphingosine

A
  • 18 carbon amino alcohol
  • unsaturated hydrocarbon tail
  • example in sphingomyelin
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3
Q

where does the phosphate in phospholipids come from

A

ATP

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4
Q

what is the two methods of forming fatty acids for phospholipids

A

1) phosphaidate formed in the ER or the outer mitochondrial membrane
- two fatty acids added to glycerol-3-phosphate catalysed by glycerol phosphate acyltransferase
2) phopshatidate formed from diacylglycerol catalysed by diacylglycerol kinase using ATP

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5
Q

how is the alcohol added to a phospholipid

A
  • phosphoglycerides - derived from phosphatidate
  • via ester bond formed between the phosphate and alcohol
  • requires nucleotide activation of phoshatidate or alcohol - PI and CL
  • in many glycerophospholipids a nucleotide-phosphate alcohol is added directly to diacylglycerol
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6
Q

what does phosphatidic acid phosphatase catalyse

A
  • conversion of phosphatidate to diacylglycerol
  • different lipids synthesised depending on activity
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7
Q

what are the 4 stages of phospholipid synthesis

A

1) gluconeogenesis
2) triacylglycerol breakdown
3) triacylglycerol synthesis
4) phospholipid synthesis

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8
Q

what os diacylglycerol acylated by

A

diglyceride acyltransferase
- forms triacylglcerol

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9
Q

how is sphingosine produced

A
  • from ceramide formed from parmitoyl CoA and serine
  • occurs in ER
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10
Q

where does ceramide processing occur

A

plasma membrane
via ceramidase and spingosine kinase

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11
Q

what are glycolipids made form

A
  • carbohydrate containing lipids derived from sphingosine
  • carbohydrate linked to the primary alcohol of sphingosine
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12
Q

what are glycolipids used for

A
  • cell-cell recognition and adhesion
  • electrical potential across the membrane
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13
Q

what are cerebrosides

A

containing only one sugar

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14
Q

what are globosides

A

contain a branched sugar chain

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15
Q

what are gangliosides

A

contain a branched chain

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16
Q

what are the features of plasmalogens

A
  • one fatty alcohol is attached through an ester linkage
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17
Q

what are the examples of plasmalogens

A
  • Phosphatidylcholine Plasmalogen
  • Phosphatidylethanolamine Plasmalogen
18
Q

how is spingomyelin formed

A
  • phosphorycholine bound to the terminal hydroxyl group
19
Q

how is cerebroside formed

A
  • single glucose or galactose bound to terminal hydroxyl group
20
Q

how is gangliosides produced

A
  • additional sugars added
21
Q

what is myelin

A
  • insulating cover around axons
  • stacked bilayers with specific phospholipids
22
Q

what are the causes and symptoms of tay-sachs disease

A
  • beta-N-acetylhexosaminidase (HEXA) deficiency
  • lysosomal enzyme, autosomal recessive mutation
  • decrease in ganglioside break down to Gm3
  • Gm2 accumulates and toxic levels accumulate in neurons, brain and spinal cord
  • muscle weakness, exaggerated reaction of loud noises, hearing and vision loss
23
Q

what are eicosanoid hormones

A
  • short lived hormones that affect nearby cells - paracrine and autocrine
  • 20 carbon polyunsaturated fatty acid
  • derived from arachidonate (four double bonds)
24
Q

what do phospholipase A2 do

A
  • release arachidonate from phospholipids
25
Q

what do diacylglycerol lipase do

A
  • release arachidonate from diacylglycerols
26
Q

what is the process that causes inflammation

A
  • inflammation in macrophage or endothelial cells
  • inflammatory signal from TLR or puringeric receptor
  • increase phospholipase A2
  • release arachidonate
27
Q

how are prostanoids produced

A

produced from arachidonate by cyclooxyrgenase

28
Q

what do prostanoids do

A
  • mediate inflammation and pain
  • induce sleep
  • regulate blood coagulation and blood pressure
  • relief of asthma and nasal congestion
29
Q

what is prostaglandin H2 be used for

A
  • induction of labour at term
  • prevention of conception
  • termination of pregnancy
30
Q

what are the 3 types of prostanoids

A

1) Thromboxanes
2) Prostacyclins
3) Prostaglandins

31
Q

where are thromboxane produced and what do they do

A
  • produced from PGH2 by thromboxane synthase
  • TXA2 synthesised in platelets - facilitate platelet aggregation
32
Q

where is prostacyclin produced and what does it do

A
  • produced from PGH2 by prostacyclin synthase
  • PGI2 produced by epithelial cells
  • counters the effect of thromboxane - inhibits platelet activation
33
Q

how is prostaglandins produced and what does it do

A
  • produced from PGH2 by prostaglandins synthase
  • decreases hair length
34
Q

what do nonsteroidal anti-inflammatory drugs do

A
  • inhibits COX-1 and COX-2
35
Q

what do COX-2 selective inhibitors do

A
  • reduce side effects in stomach
  • major side effects eg. heart attacks and strokes
36
Q

how are leukotrienes produced and what do they cause

A
  • produced from arachidonates by lipoxygenases
  • found in immunocompetent cells
  • cause allergic reactions, inflammation, muscle contraction and asthma
37
Q

how are lipoxins produced

A

Produced from Arachidonate by Lipoxygenases

38
Q

what is the dual action of lipoxins

A

Pro-inflammatory
- Attract monocytes to apoptotic cells

Anti-inflammatory
- Role at the end of inflammation
- Decrease neutrophil infiltration

39
Q

what are the causes, symptoms and treatments of gout

A

causes - excess uric acid

symptoms - severe pain, swelling, redness and warmth of joints

urate crystals - damage cellular membranes, release lysosomal enzymes in joints

treatment - anti inflammatory agents and dietary changes

40
Q

what are the causes, symptoms and treatments of IBS

A

causes - unknown, increases change with long term NSAIDs use
symptoms - abdominal pain, diarrhoea
treatment - corticosteroids

medical science xy1110 (33 decks)

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