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Biochem 5-19
Biochemistry: Metabolism 1
28
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Undergraduate 3
04/29/2010

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Term
Catabolism
Definition
metabolic processes involved in the degradation of complex bio-molecules to provide energy for other processes (glycolysis)
Term
Anabolism
Definition
energy-requiring metabolic processes involved in the synthesis of complex biomolecules from simpler precursors (gluconeogenesis)
Term
amphibolic pathway
Definition
a metabolic pathway that functions in both catabolism and anabolism
Term
Aerobic respiration
Definition
metabolic process where carbohydrate is oxidized to carbon dioxide and water; giving off energy that is used in the formation of ATP
this is not a single reaction - other processes or reactions must be involved
oxidations and reductions - electrons are precisely moved around; specialized electron carriers must be involved.
Term
The three main stages of cellular respiration and their locations
Definition
1. glycolysis - substrate level phosphorylation in the cytosol
2. krebs cycle - substrate level phosphorylation in the mitochondrion
3. electron transport chain and oxidative phosphorylation - oxidative phosphorylation in the mitochondrion (most adp)
Term
Glycolysis
Definition
- general starting point of respiration
- occurs in the cytoplasm
- anaerobic (does not require oxygen)
Term
Krebs Cycle
Definition
- mid-point of respiration
- occurs in mitochondrial matrix
- indirectly requires oxygen
Term
electron transport
Definition
- final stage of respiration
- occurs in mitochondrial cristae membranes
- requires oxygen
Term
Glycolysis summary reaction
Definition
Glucose + 2 ADP + 2P_i + 2NAD(+) ---> 2 pyruvate + 2 ATP + 2 NADH + 2 H(+) + 2 H_2O
Term
Glycolysis reaction notes
Definition
- glucose is oxidized
- NAD(+) have been reduced
- some ATP produced
- glycolysis is anaerobic
Term
Glycolysis stage 1
Definition
- energy investment or priming stage
- glucose is phosphorylated twice and cleaved in half to form two glyceraldehyde-3p
- 2 ATP are consumed
Term
Glycolysis Stage 2
Definition
- energy payoff stage
- glyceraldehyde-3p oxidized to pyruvate
- 4 ATP & 2 NADH are produced
Term
Hexokinase rxn.
Definition
gate reactions that help trap hexoses within a cell because the large negatively charged phophates prevent it from crossing the membrane
Term
phophofructokinase
Definition
commiting step or reaction that once past this point molecules are committed to pass through glycolysis
- a key point in regulation
Term
aldolase
Definition
can easily cut the c3-c4 bond on hexoses after they have a phosphate group on both ends
Term
energy payoff of glycolysis
Definition
two gald-3p are converted to pyruvate producing 2 NADH and 4 ATP
- note substrate level phosphorylation
Term
Possible pyruvate destinations
Definition
- TCA cycle where they are oxidized to produce more NADH and ATP (Preferred)
- Lactic acid fermentation where they are reduced to form lactic acid and NAD(+)
- alcoholic fermentation where it is reduced to form ethanol and NAD(+)
+ in lack of oxygen more NADH can be created through the citric acid cycle
Term
Lactic acid fermentation
Definition
- allows regeneration of NAD(+) so that glycolysis can continue to produce some ATP
- especially important in over-exercised muscles
- other acids can be produced
Term
alcohol fermentation
Definition
reaction: pyruvate --pyruvate decarboxylase--> CO2 + acetaldehyde --alcohol dehydrogenase--> ethanol
-ethanol in the liver will result in the production of NADH which in turn inhibits glycolysis and fatty acid oxidation resulting in fat accumulation in the liver (cirrhosis) and loss of function
- hangover is ethanol going back tko acetaldehyde
Term
Glycolysis summary
Definition
- present in all organisms
- one of the oldest metabolic processes evolutionarily
- oxygen is not directly required which was important for first organisms where the early atmosphere had no oxygen
- subjected to regulation
Term
Glycolysis regulation
Definition
- normally cells maintain homeostasis - ATP availability must be relatively constant
- cells must respond to changing conditions (ie. produce more/less ATP when required)
- ernergy charge is an important regulatory parameter
Term
glucose-6P regulates...
Definition
inhibits hexokinase
Term
fructose-1,6P_2 regulates...
Definition
promotes pyruvate kinase
Term
AMP, ADP, ATP regulates...
Definition
- AMP stimulates phosphofructokinase and pyruvate kinase
- ADP stimulates phosphofructokinase
- ATP inhibits phosphofructokinase and pyruvate kinase
Term
Citrate regulates...
Definition
inhibits phosphofructokinase
Term
acetyl-CoA regulates...
Definition
inhibits pyruvate kinase
Term
Fructose-6P regulate...
Definition
stimulates phosphofructokinase
Term
Fructose-2,6-Bisphosphate regulation
Definition
high glucose causes Fructose-6P + ATP ---> Fructose-2,6P_2 + ADP
- PFK-2 is the enzyme
- if glucose is low then F-2,6P_2 is the enzyme for the reverse reaction
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