lipid synthesis and transport

Question 1

how FA is synthesised

Answer 1

in mitochondria, acetyl coa + oxaloacetate-> citrate
citrate moves out of mito into cytosol
citrate-> acetyl coa + oxaloacetate
acetyl coa + hco3- -> malonyl coa by ACETYL COA CARBOXYLASE; USING ATP
malonyl coa + acetyl coa-> 4C FA + co2 by FATTY ACID SYNTHETASE; USING NADPH
malonyl coa + 4C FA -> 6C FA + co2 USING NADPH

Question 2

How is NADPH produced

Answer 2

hexose monophosphate shunt

Question 3

what are lipoproteins made of? are they polar or non polar

Answer 3

inner core of TAG + cholesterol esters
outer shell of apoproteins + cholesterol + phospholipids
polar on outside, non-polar on inside

Question 4

apoprotein function

Answer 4

structural role in lipoproteins
recognised by receptors
activate enzymes in lipid metabolism

Question 5

types of lipoproteins, from greatest amount of TAG to least, from least dense to most dense. What does each of them do

Answer 5

chylomicron: carries dietary TAG
VLDL: endogenous TAG
LDL: liver-> tissues
IDL
HDL : tissues-> liver

Question 6

chylomicron transport

Answer 6

IN GUT chylomicron + B48 -> IN BS chylomicron+B48+E+C2-> (Lipoprotein lipase activated by C2):
FA-> TAG IN ADIPOCYTES
glycerol-> LIVER
chylomicron+B48+E-> E receptor in LIVER

Question 7

VLDL transport

Answer 7

IN LIVER VLDL-TAG + B100-> IN BS VLDL-TAG+B100+E+C2-> (lipoprotein lipase activated by c2):
FA-> TAG IN ADIPOCYTES
glycerol-> LIVER
IDL-TAG + B100 + C2 + E -> HDL + C2 + E in BS/ LDL-TAG + B100 -> B100 receptor in LIVER OR PERIPHERAL TISSUE

Question 8

HDL transport

Answer 8

IN SMALL INTESTINE HDL+A1 + IN PERIPHERAL TISSUE C-> HDL + A1 + C by LCAT(activated by a1) -> C IN LIVER/ HDL+A1 IN BS

Question 9

cholesterol synthesis regulation

Answer 9

B100 receptor + LDL -> endocytosis-> cholesterol formed-> receptor synthesis + cholesterol synthesis enzymes inhibited

Question 10

cholesterol synthesis steps

Answer 10

acetyl coa + acetoacetyl coa -> HMG coa -> mevalonate by HMG COA REDUCTASE -> cholesterol

Question 11

types of hyperlipoproteinaemias/hyperlipidaemias

Answer 11

hypertriglyceridaemia

hypercholesterolaemia

Question 12

indications of defective LDL receptor

Answer 12

hypercholesterolaemia

high ldl in blood

Question 13

indications of LPL deficiency

Answer 13

high chylomicrons + vldl

Question 14

indications of c2 deficienct

Answer 14

high chylomicrons + vldl

Question 15

indications of deficiency of apoproteins involved in remnant uptake

Answer 15

high chylomicrons + ldl

Question 16

what’s lipoprotein a made of? what is it associated with? how can its levels be increased or decreased? what does it do?

Answer 16

ldl + apoprotein a
CHD
increased by trans fat; decreased by oestrogen
slows down breakdown of blood clots

Question 17

how does oxidised LDL lead to hypercholesterolaemia

Answer 17

oxidised LDL is not recognised by normal receptors and not metabolised by liver/peripheral tissues. instead, it is taken up by scavenger receptors on foam cells. These receptors are not down regulated-> accumulation of cholesterol

Question 18

how does atherosclerosis come about

Answer 18

starts as fatty streak from accumulation of foam cells (macrophages filled with lipid)-> plaque