biochemistry 9

Question 1

what are the components of phospholipids

Answer 1

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

Question 2

what is sphingosine

Answer 2

• 18 carbon amino alcohol
• unsaturated hydrocarbon tail
• example in sphingomyelin

Question 3

where does the phosphate in phospholipids come from

Answer 3

ATP

Question 4

what is the two methods of forming fatty acids for phospholipids

Answer 4

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

Question 5

how is the alcohol added to a phospholipid

Answer 5

• 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

Question 6

what does phosphatidic acid phosphatase catalyse

Answer 6

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

Question 7

what are the 4 stages of phospholipid synthesis

Answer 7

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

Question 8

what os diacylglycerol acylated by

Answer 8

diglyceride acyltransferase
- forms triacylglcerol

Question 9

how is sphingosine produced

Answer 9

• from ceramide formed from parmitoyl CoA and serine
• occurs in ER

Question 10

where does ceramide processing occur

Answer 10

plasma membrane
via ceramidase and spingosine kinase

Question 11

what are glycolipids made form

Answer 11

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

Question 12

what are glycolipids used for

Answer 12

• cell-cell recognition and adhesion
• electrical potential across the membrane

Question 13

what are cerebrosides

Answer 13

containing only one sugar

Question 14

what are globosides

Answer 14

contain a branched sugar chain

Question 15

what are gangliosides

Answer 15

contain a branched chain

Question 16

what are the features of plasmalogens

Answer 16

• one fatty alcohol is attached through an ester linkage

Question 17

what are the examples of plasmalogens

Answer 17

• Phosphatidylcholine Plasmalogen
• Phosphatidylethanolamine Plasmalogen

Question 18

how is spingomyelin formed

Answer 18

• phosphorycholine bound to the terminal hydroxyl group

Question 19

how is cerebroside formed

Answer 19

• single glucose or galactose bound to terminal hydroxyl group

Question 20

how is gangliosides produced

Answer 20

• additional sugars added

Question 21

what is myelin

Answer 21

• insulating cover around axons
• stacked bilayers with specific phospholipids

Question 22

what are the causes and symptoms of tay-sachs disease

Answer 22

• 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

Question 23

what are eicosanoid hormones

Answer 23

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

Question 24

what do phospholipase A2 do

Answer 24

• release arachidonate from phospholipids

Question 25

what do diacylglycerol lipase do

Answer 25

- release arachidonate from diacylglycerols

Question 26

what is the process that causes inflammation

Answer 26

- inflammation in macrophage or endothelial cells - inflammatory signal from TLR or puringeric receptor - increase phospholipase A2 - release arachidonate

Question 27

how are prostanoids produced

Answer 27

produced from arachidonate by cyclooxyrgenase

Question 28

what do prostanoids do

Answer 28

- mediate inflammation and pain - induce sleep - regulate blood coagulation and blood pressure - relief of asthma and nasal congestion

Question 29

what is prostaglandin H2 be used for

Answer 29

- induction of labour at term - prevention of conception - termination of pregnancy

Question 30

what are the 3 types of prostanoids

Answer 30

1) Thromboxanes 2) Prostacyclins 3) Prostaglandins

Question 31

where are thromboxane produced and what do they do

Answer 31

- produced from PGH2 by thromboxane synthase - TXA2 synthesised in platelets - facilitate platelet aggregation

Question 32

where is prostacyclin produced and what does it do

Answer 32

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

Question 33

how is prostaglandins produced and what does it do

Answer 33

- produced from PGH2 by prostaglandins synthase - decreases hair length

Question 34

what do nonsteroidal anti-inflammatory drugs do

Answer 34

- inhibits COX-1 and COX-2

Question 35

what do COX-2 selective inhibitors do

Answer 35

- reduce side effects in stomach - major side effects eg. heart attacks and strokes

Question 36

how are leukotrienes produced and what do they cause

Answer 36

- produced from arachidonates by lipoxygenases - found in immunocompetent cells - cause allergic reactions, inflammation, muscle contraction and asthma

Question 37

how are lipoxins produced

Answer 37

Produced from Arachidonate by Lipoxygenases

Question 38

what is the dual action of lipoxins

Answer 38

Pro-inflammatory - Attract monocytes to apoptotic cells Anti-inflammatory - Role at the end of inflammation - Decrease neutrophil infiltration

Question 39

what are the causes, symptoms and treatments of gout

Answer 39

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

Question 40

what are the causes, symptoms and treatments of IBS

Answer 40

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