biochem- glycolysis and gluconeogenesis

it is a 10 step pathway for producing ATP by the oxidation of glucose

define glycolysis

no

does glycolysis require oxygen?

the synthesis of lipids and nucleotides in the pentose phosphate pathway

the NADH that is generated during glycolysis is used for what other pathway?

fat

when there is no glucose available, what is the second option to produce energy?

glycogen; liver and muscles

the stored form of glucose is called ______. it is stored where in the body?

aerobic glycolysis

which is a more exergonic reaction- aerobic or anaerobic glycolysis?

2

the oxidation of 1 glucose molecule ultimately provides us with ____ molecule(s) of pyruvate

ribose 5-phosphate

if glucose is oxidized in the pentose phosphate pathway, what is the product?

2

to perform glycolysis, we must first invest ____ molecules of ATP

the cytosol
(it is the only catabolic pathway that occurs in the cytosol)

where does glycolysis occur in the cell?

1. preparatory phase- conversion of glucose into 2 mol of glyceraldehyde 3-phosphate (uses 2 ATP)

2. payoff phase- conversion of glyceraldehyde 3-phosphate into pyruvate (gains 4 ATP and 2 NADH)

there are 2 phases of glycolysis. what are they called and what is the purpose of each?

glyceraldehyde 3-phosphate

in the preparatory phase of glycolysis, glucose goes through a series of reactions that converts it into _______.

hexokinase

what is the first enzyme of glycolysis that phosphorylates glucose into glucose 6 phosphate?

it converts glucose to glucose 6-phosphate in the first step of glycolysis

what does hexokinase do in carbohydrate metabolism?

glucose 6-phosphate

in glycolysis, hexokinase converts glucose into ________

conversion by phosphohexose isomerase into fructose 6-phosphate

in glycolysis, after hexokinase converts glucose into glucose 6-phosphate, what is the next step?

2; 4; 2

to perform the preparatory phase of glycolysis, it is necessary to invest ______ molecules of ATP, but in the payoff phase we gain _______. so our net ATP is ______

fructose 1.6 bisphosphate

in glycolysis, fructose 6-phosphate is phosphorylated into _________ by phosphofructokinase 1.

1. glucose to glucose 6-phosphate
2. fructose 6-phosphate to fructose 1.6 biphosphate

what 2 reactions in glycolysis require ATP?

the cleavage of fructose 1.6-biphosphate into glyceraldehyde 3-phosphate (+dihydroxyacetone phosphate) by the enzyme aldolase

in glycolysis, after phosphofructokinase phosphorylates fructose 6-phosphate into fructose 1.6-biphosphate, what is the next step?

glycolysis

in what carbohydrate metabolic pathway is glucose phosphorylated?

this phosphorylation causes glucose to be trapped inside of the cell

what is the purpose of the phosphorylation of glucose into glucose 6-phosphate by the enzyme hexokinase?

the phosphorylation of fructose 6-phosphate to fructose 1.6-biphosphate by the enzyme phosphofructokinase 1.

at this point, fructose 1.6 biphosphate is committed to becoming pyruvate and producing energy

which reaction of glycolysis is the first "committed reaction"?

it is the second and final phase of glycolysis, where glyceraldehyde 3-phosphate is oxidatively converted to pyruvate and ATP and NADH are formed.

what is the payoff phase of glycolysis?

the oxidation of glyceraldehyde 3-phosphate to 1.3 biphosphoglycerate

what reaction of glycolysis produces NADH?

1.3-biphophoglycerate to 3-phosphoglycerate (by the enzyme phosphoglycerate kinase)

phosphoenolpyruvate to pyruvate (by the enzyme pyruvate kinase)

which 2 reactions of glycolysis produce ATP?

the transfer of a phosphoryl group from phosphoenolpyruvate to ADP, creating pyruvate and ATP. catalzed by the enzyme pyruvate kinase

what is the final step of glycolysis?

1, 2, 2;
2, 4, 2

in glycolysis, we use ____ glucose, _____ NAD+, and _____ATP to produce _____ pyruvate, ______ATP, and _____ NADH

2 NADH
4 ATP (net yield of 2)
2 pyruvate

what are the products of glycolysis?

30-32

what is the total yield of ATP per glucose molecule if oxygen is involved?(everything)

2

what is the total yield of ATP per glucose molecule if oxygen is not present?

in aerobic conditions- oxidized into acetyl coa
in anaerobic conditions- reduced to lactate

what is the next step for the pyruvate molecules produced in glycolysis?

it is reduced to lactate and then fermented, which produces NAD+ that can allow glycolysis to continue

in anaerobic conditions, what happens to the pyruvate that was produced in glycolysis?

it will be oxidized into acetyl coa

if there is oxygen present, what will happen to the pyruvate that was produced in glycolysis?

lactate dehydrogenase

in anaerobic conditions, what enzyme converts pyruvate into lactate?

NAD+

what needs to be replenished for glycolysis to continue?

the metabolic pathway that occurs between the liver and muscles to regulate the metabolism of lactate and glucose during periods of high energy demand or low oxygen availability. pyruvate is the final product of glycolysis, which in anaerobic conditions is converted into lactate (producing NAD+), and is carried to the liver, where it is converted back to glucose (via gluconeogenesis)

what is the cori cycle?

usually, the pyruvate obtained from glycolysis would be oxidized into acetyl coa and enter the CAC and ETC. however, when there is low oxygen (so oxidation cannot happen), it is instead converted into lactate, because this causes NAD+ to be replenished, which is necessary to continue glycolysis

why is pyruvate converted to lactate in anaerobic conditions?

glucose, other hexoses and hexose phosphates from stores polysaccharides and dietary carbohydrates

on what molecules can we perform glycolysis?

it is another metabolic pathway that involves the oxidation of glucose and yields pentoses for nucleotide synthesis and reduced cofactors for fatty acid and sterol synthesis.

the main important products are ribose 5-phosphate and NADPH

what is the pentose phosphate pathway?

the pentose phosphate pathway

ribose 5-phosphate is a precursor of nucleotides, used for synthesis of RNA/DNA

what pathway will ultimately lead to the production of ribose 5-phosphate, and what is the importance of this compound?

pentose phosphate pathway

(it produces ribose 5-phosphate, which is a precursor of nucleotides that are used for RNA/DNA synthesis)

which metabolic pathway is involved in the synthesis of RNA/DNA?

pentose phosphate pathway

it is important because it is an electron donor, and is used in the synthesis of fatty acids and steroids. it can also repair oxidative damage

what metabolic pathway will produce NADPH? why is NADPH important?

gluconeogenesis

what is the name for the metabolic pathway that synthesizes glucose?

pyruvate and lactate

(there are others, including oxaloacetate, but these are the main precursors)

what are the molecules that can be used to synthesize glucose (gluconeogenesis)?

in the cytosol

where in the cell does gluconeogenesis occur?

in the liver (gluconeogenesis)

where in the body can new glucose molecules be formed?

-thermodynamically favorable
-use reversible and irreversible reactions
-occur in the cytosol

what do glycolysis and gluconeogenesis have in common?

gluconeogenesis

what metabolic process performs the opposite process of glycolysis?

pyruvate/lactate; glucose; glucose; pyruvate/lactate

gluconeogenesis converts _____ into ______, while glycolysis converts _______ into ________

fatty acids

there are many options for precursors of glucose, like sugars (pyruvate, lactate, oxaloacetate), CAC intermedates, and proteins, but what molecule can absolutely NOT become glucose?

NO, fatty acids cannot become glucose.
the product of fatty acid degradation is Acetyl CoA, which cannot be converted into oxaloacetate

can fatty acids enter the gluconeogenesis pathway?

Acetyl-CoA

what is the product if fatty acids are degraded?

pyruvate carboxylase
gluconeogenesis

what enzyme uses ATP to add 1 carbon to pyruvate, making it oxaloacetate?
what metabolic pathway is this reaction belonging to?

pyruvate carboxylase uses ATP to add a carbon, making it oxaloacetate. then, phosphoenolpyruvate carboxykinase (PEPCK) phosphorlates and decarboxylates it using GTP, making it phosphoenolpyruvate

if we have a molecule of pyruvate and need to create a new glucose molecule, what is the first step?

it helps the conversion of pyruvate/oxaloacetate into phosphoenolpyruvate

gluconeogenesis

what is the role of PEPCK (phophoenolpyruvate carboxykinase), and what metabolic pathway does it belong to?

gluconeogenesis

which metabolic pathway uses fructose 1.6 biphosphatase-1 to convert fructose 1.6 biphosphate into fructose 6-phosphate?

glycolysis

to which pathway does the enzyme phosphofructokinase 1 belong?

removes a phosphate from fructose 1.6 biphosphate, releasing a free Pi, and converting it into fructose 6 phosphate

what does fructose 1.6 biphosphatase do?

glycolysis

which pathway involves phosphorylation reactions- glycolysis or gluconeogenesis?

gluconeogenesis

which pathway, involves dephosphorylation reactions- glycolysis or gluconeogenesis?

glucose 6 phosphatase

what enzyme in gluconeogenesis dephosphorylates glucose 6 phosphate into glucose?

gluconeogenesis

to what metabolic pathway does the enzyme glucose 6 phosphatase belong?

only in the liver

where in the body can gluconeogenesis occur?

1. energy demand inside of the cell
2. metabolic state (substrate availability and product accumulation)
3. hormone regulation

what 3 factors regulate glucose metabolism?

glucose 6-phosphate

because hexokinase phosphorylates glucose into glucose 6-phosphate, so if there is already a high concentration of glucose 6-phosphate, it is signalled to not perform this conversion

the accumulation of ______ inhibits hexokinase 1

glucokinase (hexokinase IV)

hexokinase in the liver is called?

the form of hexokinase that is in the liver

what is glucokinase?

NO, it can function at higher blood glucose levels than hexokinase I

is hexokinase IV/glucokinase inhibited by glucose 6-phosphate?

nuclear sequestration and transcription

what regulates hexokinase IV/glucokinase?

clears blood glucose at high blood glucose concentrations (hyperglycemia) for storage

what is the function of hexokinase IV/glucokinase?

hexokinase IV/glucokinase

which, hexokinase 1 or hexokinase IV/glucokinase can function at higher glucose levels?

it inhibits glycolysis by inhibiting phosphofructokinase 1, because it signals that we already have a lot of energy

what does the accumulation of citrate do to glucose metabolism?

glycolysis
(high AMP activates phosphofructokinase)

if there is high AMP and low ATP, which- glycoylsis or gluconeogenesis is activated?

gluconeogenesis
(high ATP activates fructose 1.6 biphosphatase)

if there is low AMP and high ATP, which- glycoylsis or gluconeogenesis is activated?

it is a regulator produced specifically to regulate glycolysis and gluconeogenesis

it activates glycolysis by activating phosphofructokinase 1

what is fructose 2.6 biphosphate?

activation of glycolysis (by activating phosphofructokinase 1)

what is the effect of fructose 2.6 biphosphate on glucose metabolism?

it activates phosphofructokinase 1, which is the enzyme that catalyzes the conversion of fructose 6 phosphate to fructose 1.6 biphosphate (glycolysis)

where in the glycolysis/gluconeogenesis pathway does fructose 2.6 biphosphate act?

catalyzes the transformation of phosphoenolpyruvate to pyruvate in glycolysis

what does pyruvate kinase do?

glucagon

in the liver, what hormone inactivates pyruvate kinase?

high energy levels (ATP, acetyl coa, alanine)

in all tissues, what inactivates pyruvate kinase?

accumulation of fructose 1,6 biphosphate

in all tissues, what activates pyruvate kinase?

fructose 1.6 biphosphate

accumulation of _________ activates pyruvate kinase

hyperglycemia

insulin is produced in response to ______

increases glucose uptake into cells
increases glycogenesis and decreases glycogenolysis
increases glycolysis and acetyl coa production

what does insulin do?

prepares for action by:
decreasing glycogenesis and increasing glycogenolysis
increasing glycolysis in muscle
increasing gluconeogenesis in liver

what does epinephrine do?

hypoglycemia

what triggers glucagon?

increases glycolysis

how does insulin impact gluconeogenesis/glycolysis?

increases glycogenesis
decreases glycogenolysis

how does insulin impact glycogenolysis/glycogenesis?

prepare for action by increasing blood glucose levels

what is the ultimate goal of epinephrine?

increases glycolysis in the muscle
increases gluconeogenesis in the liver

how does epinephrine impact glycolysis/gluconeogenesis?

increases glycogenolysis
decreases glycogenesis

how does epinephrine impact glycogenesis/glycogenolysis?

the liver

glucagon only affects what organ?

increased gluconeogenesis/ decreased glycolysis
increased glycogenolysis/ decreased glycogenesis

what are the effects of glucagon?

hypoglycemia and stress

cortisol responds to what triggers?

mobilizes glucose precursors in adipose and muscle
acts in the long term
induces expression of PEPCK in the liver, increasing gluconeogenesis
decreases expression of PEPCK in adipose, decreasing glycerol synthesis

what is the function of cortisol in glucose metabolism?

cortisol

this increases gluconeogenesis in the liver and decreases glycerol synthesis in adipose

which hormone increases the expression of PEP CK in the liver and decreases it in adipose? why?