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BCH210H1 Lecture Notes - Hi-Nrg, Acetyl-Coa, Glycogen

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Michael Baker

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BCH210H © Lisa Zhao 2012 | Page 1
L E C T U R E 2 6 : M E T A B O L I S M A N D B I O E N E R G E T I C S
metabolism: the entire network of enzyme rxns in cells
anabolism: rxns that synthesize molecules or make more complex molecules
building up of proteins from the 20 AAs (thousands of diff proteins depending on seq)
makes things that are more complex
divergent20 AAs to thousands of proteins
NRG input required
ex. pyruvate (3C) to glucose, glucose to branched glycogen, pyruvate to acetyl coA, acetyl coA to
fatty acids
catabolism: rxns that degrade larger molecules to smaller molecules
convergentfrom thousands of proteins broken down to 20 AAs (smaller # of diff types)
NRG released
ex. glycogen to glucose phosphate
ex. proteins to AA
ex. nucleic acids to nucleotides
ex. fats to FFA
ex. glycolysisglucose to 2C and 3C parts through
ex. β-oxidationfatty acids to acetyl coA with release of NRG
ex. glycogenolysisbreakdown of glycogen to glucose-1-phosphate
roles of metabolism:
produce NRG by the breakdown of fuelsglucose, FFA
make moleculesDNA, RNA, lipids, proteins, AAs, glucose
make fuel storage moleculestriglycerides, glycogen
convert one molecule into anotherex. glucose FFA
generally NRG released during catabolism is used in anabolic pathways or in cellular work ex.
muscle contraction
catabolic paths fuel anabolic paths
usually requires many enzymes that work in sequence
complete change is a result of steps of changes with each step with an enzyme
pathways: the synthesis or breakdown of a molecule usu relies on a number of sequential enzyme
product of one enzyme serves as substrate of next enzyme
linear pathway: a number of enzyme steps in seq to achieve a final product ex. glycolysis
potential problems: if there is a block in the pathway, you can’t get past it
pathway can be made more efficient if there is an enzyme with multiple active sites built-in
or diff subunits
mammals have large multifunctional enzymes that have more than one active site
thus, 1 large complex can carry out a seq of rxns
complex enzyme: separate enzymes held together covalently
enzyme cycle: a circle of rxns where the last step generates the first substrate
imp components are the inputs and products put into and going out of the cycle
ex. Kreb’s Cycle
bioenergetics: production of NRG and use of NRG
ATP is the principal carrier of NRG in cells
NRG is stored as ATP
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