Module 3
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metabolism
sum of all chemical & physical processes by which the body breaks down & builds up molecules
Anabolism
-process of making larger molecules from smaller ones - REQUIRES ENERGY
Catabolism
-process of breaking down large molecules to smaller ones -begins with digestion -RELEASES ENERGY
ATP
-adenosine triphosphate -organic compound used by cells as source of energy -mitochondria are the site of energy production (ATP)
dehydration synthesis
-condensation -anabolic process -water is released as a byproduct
hydrolysis
-usually catabolic -molecules are broken down with addition of water
phosphorylation
-addition of phosphate group to compound -high-energy phosphate bonds in ATP are broken -energy is released -phosphate transferred to other molecules *glucose undergoes phos. when it first enters a cell (ATP donates phos. group to glucose) **when glucose is phos. it can be oxidized for energy or stored as glycogen
oxidation
-electron is removed by oxygen
reduction
-molecule gains an electron
what do enzymes do for metabolism?
mediate chemical reactions
coenzymes
-non protein substances (ex: vitamins) -enhance/are necessary for enzyme activity
FAD & FADH2
-coenzymes -FADH2 = riboflavin (vitamin B1)
NADH
-coenzyme -Niacin (vitamin B3)
cofactors
typical minerals required for enzyme activity
after glucose is transported to the liver:
-it’s phosphorylated & metabolized for energy/stored as glycogen -released into circulation for other cells to use as fuel (stored in muscles)
if glucose exceeds energy needs?
-it can be converted to fatty acids & stored as triglycerides in adipose tissue -fructose & galactose are converted to glucose by the liver
glycolysis
-occurs in cytosol -anaerobic -oxidative pathway (glucose is being oxidized) -glucose gives electrons to NAD (becomes NADH) - glucose is broken down to 2 pyruvate molecules - yields ATP and NADH
cori cycle:
-lactate is transported to liver via bloodstream -glucose is transported to muscle via bloodst. -NAD+ regenerated for glycolysis
Acetyl CoA
-occurs in mitochondria -can either enter TCA (Kreb’s) cycle or used for fatty acid synthesis
TCA/Kreb’s cycle
-requires oxygen (aerobic) -occurs in mitochondria -acetyl CoA + oxaloacetate = citrate -formation of citrate is needed to begin cycle -end products = 6NADH + H + 2ATP + 2FADH2
oxidative phosphorylation:
-occurs in the electron transport chain -electrons from NADH and FADH2 transferred to oxygen to produce water (metabolic) -yields ATP
energy from fats:
-lipolysis = triglycerides broken down into 3 free fatty acids -glycerol is converted to pyruvate, then to acetyl CoA (for TCA cycle) -fatty acids are used for energy -112 ATP
fatty acids CANNOT form:
-glucose -there is no metabolic pathway to convert acetyl CoA into pyruvate
energy from protein:
-protein is saved for metabolic functions that cannot be performed by other compounds -excess protein is stored as triglycerides