Card Set Information
The sum of chemical reactions in cells
Energy (ATP) yielding.
Conversion of fuels to end products.
Energy (ATP) requiring
forming ATP by direct phosphorylation of ADP.
Transfer of phsphoryl group from "high energy" to ADP.
Does not require O2
important for ATP in tissues short of 02, for example,
For synthesis of ATP
Oxidation of 2 nucleotides by electron transport chain
: flavin adenine dinucleotide
"Emergency" energy-producing pathway when oxygen is the limiting factor
important in RBC
: they lack mitochondria, so they only use glycolysis.
: When oxidative metabolism can't keep up with increased demand.
: Glucose is it's main fuel (120g/day)
Pyruvate is the end product in mitochondria cells and from oxygen supply
occurs in the cytosol
Common step in BOTH Respiration and Fermentation
uses 2ATP in energy investment phase & produces 4ATP in payoff phase.
pyruvic is last step, if too much then turns acidic
regulated by phosphofructokinase
The oxidation of glucose to pyruvate
oxygen is required to reoxidize NADH that formed during glyceraldehyde
oxidative decarboxylation of pyruvate to acetyl CoA, a fuel of TCA(citric acid) cycle
Glucose+2ADP+2NAD+ -> 2Pyruvate+2ATP+2NADH+2H
: 4atp + 5atp by oxidation of 2nadh) - Energy Invested: 2atp = 7ATP
Electrons from NADH are transferred to electron transport chain(ETC) via 2 shuttle systems & NAD is returned to cytosol
Net gain of 2atp & 2nadh/glucose
Glycerol phosphate shuttle
: 2nadh to 4 atp
Malate asparate shuttle
: 2nadh to 6ATP
oxidation of glucose to lactate
Pyrvate reduced to lactate as NADH is oxidized to NAD+
Occurs without oxygen
Allow ATP production in tissue lacking mitochondria ex; in RBC's and cells deprived of O2
Glucose+2ATP --> 2Lactate -> 2ATP
requires initial input of ATP
Occurs in Cytoplasm
provides substrate with 1st step in respiration
: 2ATP - energy generated: 4ATP = 2ATP total
reduction of pyruvate to lactate by lactate dehydrogenase NAD
Net gain of 2atp & no NADH/glucose
Lactate converts back to pyruvate in liver & excreted in the urine.
RBC has no mitochondria so only anaerobic resp.
G Protein coupled receptor (GPCR)
Binding site for ligand (a hormone or neurotransmitter)
G Protein coupled receptor (GPCR)
Interacts with G-proteins
Slide 12: GTP-dependent regulatory proteins
The G proteins (A,B,Y) sub-units bind to GTP and GDP to form a link between Receptor and Adenylyl Cyclase
: A is bound to to GDP
: A is bound to GTP and dissociates from B and Y sub-units.
active state is short-lived because A has inherent GTPase activity, resulting in hydrolysis
: 2nd messenger system
CyclicAMP activates protein kinase A by binding to 2 regulatory subunits, causing release of active catalytic subunits
Active subunits transfer phosphate from ATP to protein substrates
Phphorylated proteins act directly on cell's ion channels, and in enzymes they become activated or inhibited
Protein Kinase A can also phosporylate proteins that bind to DNA, causing changes in gene expression
Dephosphorylation of proteins
phosphate added to proteins by protein kinases are removed by protein phosphatases
Hydrolysis of cAMP
cAMP -> 5AMP by
5amp is not intracellular signaling molecule
: Inhibited by methylxanthine derivatives such as theophylline in caffein
2 transport mechanisms for glucose to go into cells
1. NA+ independent, facilitated diffusion
2. Na+ Monosaccharide COtransporter system
glucose transports from extracellular fluid
In tissues such as muscle and fat, the hormone Insulin is required to transport
Ch.8 slide14, Control of Glucose: high glucose
Pancreas B cells are in effect,
takes glucose into target tissue.
Ch.8 slide14, Control of Glucose:Low glucose
Pancreas A cells are in effect,
is used in the target tissue.
COtransports 1 glucose or galactose, and 2 sodium ions
Transports glucose and galactose, not fructose.
Transports glucose, glactose, and fructose.
transports glucose and galactose, not fructose.
Transports fructose, but not glucose or galactose.
Nicotinamide Adenine Dinucleotide
accepts 2 H to reduce to NADH+H+
One H is in medium as proton H+.
The other as hydride ion, H- attaches to the top of nico. ring.
1st step of glycolysis
Phosphorylation of Glucose to Glucose-6-phosphate
Irreversible & traps glucose inside cell
2 enzymes involved
: Hexokinase, Glucokinase.
active in low (Km) glucose conc.
; High affinity for glucose. high substrate affinity.
; doesn't phosphorylate more sugars (large amount of glucose) than the cell can use
active in low glucose concentrations
Can't phosphorylate large amount of glucose
Inhibited by G-6-P
induced by insulin
Glucose, fructose, galactose.
: provides cells with Glu. 6 Phos. needed for energy
liver and pancreatic B cells
: Active in high glucose concentrations. low substrate affinity.
: Phosphorylates large amount of glucose
Not inhibited by Glucose-6-Phos
. but promotes clearance of glucose by liver in FED (Feeding) state
: allows for intracellular glucose to convert to glycogen or triacylglycerols.
indirectly inhibited by fruct6phos
indirectly stimulated by glucose
functions as a glucose sensor in maintenance of blood glucose homeostasis.
Diabetes type 2 (maturity onset) decrease the activity of glucokinase
Isomerization of glucose 6 phosphate
Isomerization of glu6phos to Fructose 6-phosphate
catalyzed by phosphoglucose isomerase
Not rate-limiting or regulated step
important control point
committed step of glycolysis.
regulation of energy in PFK-1
Inhibited allosterically by high levels of ATP, and high levels of citrate (indicates cell is making ATP).
Activated allosterically by high conc. of of AMP, with which energy stores are depleted, and fruc. 2,6 Biphosphate formed by PFK2.
1 ATP is utilized
Most potent activator of PFK-1
Activates enzyme even when ATP levels are high.
Formed by phosphofructokinase-2 (PFK-1)
: produces fructose 2,6biphosphate
: dephosphorylates fructose 2,6 bisphosphate to to fructose 6-phosphate.
In liver-kinase domain is active if dephosphorylated, inactive if phosphorylated.
Phosphorylation of glucose to glucose-6-phosphate
1st regulated step in glycolysis
: traps glucose inside the cell
1. ATP utilized
2. enzymes involved (hexokinase & glucokinase)
induction of insu
and lack of inhibition of G6P promote clearance of glucose by liver.
Decreased levels of glucagon
and elevated levels of of insulin following a carb-rich meal.
Increase fructose 2,6-bisphosphate
intracellular signal, glucose is abundant.
Starvation (fasting state)
elevated levels of glucagon
low levels of insulin
occur during fasting.
decrease in intracellular conc. of fruc 2,6 bisphos.
decrease in glycolysis
inrease in gluconeogenesis
Glycerol 3-P is converted to DHAP(used in gluconeogenesis)
pg.100 High Insulin/glucagon ratio causes *
reduced active protein kinase A
decreased protein kinase A favors *
Dephosphorylation of pfk-2/FBP-2
Dephosphorylated pfk2 is active when *
FBP-2 is inactive; favors fructose 2,6-bisphosphate.
Elevated fructose 2,6-bisphosphate activates *
PFK-1; which leads to increased glycolysis.
Reversible reaction ?
conversion of G6P to Fructose-6-phosphate
Irreversible reaction ?
conversion of F-6-P to 1,6 bisphosphate by PFK1
Rate limiting step of glycolysis
Fructose 2,6 biophosphate controlled by
Reversible conversion of F-1,6 bisphosphate to ?
3 Carbon by aldolase A. triophosphate isomerase
slide 31: triophosphate isomerase reversibly converts ?
glyceraldehyde 3 phosphate to dihydroacetone phosphate (DHAP)
DHAP reversibly converts ?
glycerol 3 phosphate by glycerol 3 phatsphate dehydrogenase (needs NADH as cofactor)
Slide 33: Reversible glyceraldehyde 3P to 1,3BPG by glyc. 3P dehydrogenase using
NAD(must be replenished for glycolysis to continue)
Regulation & irreversible rxn involves
conversion of PEP to pyruvate by kinase
Anaerobic Respiration/metabolic acidosis/anaerobic glycolysis
reversible conversion of pyruvate to lactate by lactate dehydrogenase using NADH cofactor
in shock, extreme exercise cyanide poison, CO poisoning
In alcoholics do to inc. NADH
over production or under utilization of lactic acid leads to lactic acidosis
Genetic defects/toxins that inhibit glycolysis
Recessive inherited pyruvate kinase defeciency
: have up to 25% normal PK
Fluoride ions inhibit enolase
arsenate works as an uncoupling agent to substrate by binding to P-glycerate kinase & glyc-hyde3P Dehydrnase.
pathway proceeding without ATP synthesis. Resulting in 0 ATP yield.
regulated rxns are also irreversible rxns
8.2 rxn catalyzed by PFK1
is the rate limiting rxn of glycolytic pathway
8.3 contracting skeletal muscle shows
incr. conversion pyruvate to lactate.
8.4. pt has weakness, fatigue, sob, vertigo. hemoglobin <7(normal 13.5), isolated RBC's, low lactate production. what anemia is this?
(this is defect in glycolysis)
ethanol synthesis ?
in yeast and bacteria (inestinal flora)
thiamine pyrophosphate dependent pathway
Pyruvate dehydrogenase complex ?
inhibited by acetyl CoA
source of Acetyl coA for TCA and faty acid synthesis
Pyruvate carboxylase ?
activated by Acetyl CoA
replenishes intermediates of TCA
provide substrate for gluconeogen.
nutrients like Carbs, fats, proteins through catabolism gives you
energy poor productus CO2, H20, NH3
Precursor molecules like AA's sugars, fatty acids, nitrogenous bases through Anabolism give you
complex molecules like proteins, polysaccarieds, lipids, nucleic acids.