CH 29 Flashcards
What are the two phases of the pentose phosphate pathway?
- The oxidative generation of NADPH
- The nonoxidative interconversion of sugars
net equation for the oxidative reactions of the pentose phosphate pathway
glucose−6−phosphate+2NADP++H2O⟶ribulose−5−phosphate+2NADPH+CO2+2H+
Which molecule controls the rate of the pentose phosphate pathway?
NADP+/NADPH
Which reaction is influenced by the molecule in the first question? Choose the enzyme that catalyzes the reaction.
glucose 6‑phosphate dehydrogenase
MAJOR CONTROLLING STEP
Identify the enzyme that controls the pentose phosphate pathway.
irreversibly converts glucose 6-phosphate to ribulose
6-phosphate
GENERATES NADPH
Reversible rxn
nonoxidative
In what organelle or membrane are triacylglycerols synthesized and fatty acids elongated?
endoplasmic reticulum
Identify the lipids that have phosphatidate as a precursor.
cardiolipin (diphosphatidylglycerol)
glycerophospholipids
triacylglycerols
Determine the balanced equation for the synthesis of triacylglycerol synthesis from glycerol and free fatty acids.
glycerol + 4 ATP + 3 fatty acids + 4 H2O»_space;> triacylglycerol + 1 ADP + 3 AMP + 7 Pi + 6 H+
Place the three stages required for the synthesis of cholesterol from acetyl CoA in order.
ACETYL COA
synthesis of activated isoprene units
condesnation of six isopentyl pyrophosphate molecules to form squalene
cyclization reaction to from lanosterol
Determine the order of the intermediates in the biosynthesis of cholesterol
acetyl CoA→HMG-CoA→mevalonate
isopentenyl pyrophosphate→geranyl pyrophosphate→farnesyl pyrophosphate
squalene→squalene epoxide→lanosterol→cholesterol
Which step is the rate-determining step of cholesterol synthesis?
The conversion of HMG-CoA to mevalonate by HMG-CoA reductase.
Identify the description of statins.
inhibitors of HMG‑CoA reductase
Identify the pharmacological function of statins.
to inhibit cholesterol synthesis
Low‑density lipoproteins (LDL)
known as “bad’ cholesterol
levels increase when overweight
can invade artery walls and trigger inflammatory response
High‑density lipoproteins (HDL)
help to remove cholesterol from arteries
have levels that increase with regular exercise
levels increase with consumption of unsaturated fats
Complete the sentences by selecting the lipoprotein that transports each lipid.
Chylomicrons
transport dietary lipids from the small intestine.
VLDLs
transport triacylglcerols (triglycerides) from the liver to fat storage cells.
LDLs
transport cholesterol from the liver to tissues for membrane synthesis.
HDLs
transport cholesterol from cells to the liver.
What substance, which is produced in the body upon sun exposure, is modified into calcitriol?
vitamin D
