Chapter 14; Glycolysis and Gluconeogenesis

What are the 2 Phases of Glycolysis?

1) Preparatory Phase (first 5 steps of glycolysis) 2) Payoff phase (last five steps of glycolysis)

What are the most noteworthy chemical reactions in glycolysis? (3)

1) degradation of glucose(6C) to produce 2x pyruvate (3C) 2) Phosphorylation of ADP to ATP 3) Hydride ion transfer to NAD+ = NADH

What happens to the pyruvate molecules produced during glycolysis?

1)Aerobic conditions lead to complete oxidation of glucose 2) lactic Acid Fermentation (pyruvate reduced to lactate 3) Alcohol Fermentation (catabolism of pyruvate produces ethanol)

Isozymes

2 enzymes that catalyze the same reactions but are encoded in different genes

What is needed to form of molecule of glucose from pyruvate?

4 ATP, 2 GTP, and 2 NADH = expensive

Glycolysis

A process by which a molecule of glucose is aerobically broken down, via enzyme-catalyzed reactions, to produce 2 molecules of pyruvate (3C sugar) = glucose catabolism - largest flux of carbon in most cells

Preparatory Phase of Glycolysis

ATP is invested

Fermentation

Anaerobic degradation of glucose or other organic nutrients to obtain energy in the form of ATP - living organisms first arose from an atmosphere without oxygen, fermentation is the most ancient mechanism for obtaining energy from organic molecules

What is the Ninth step of glycolysis?

Enolase removes water from 2-phosphoglycerate = phosphoenolpyruvate (PEP)

After the production of Pyruvate, what is its fate?

It can: A) go through aerobic catabolism B) go through anaerobic catabolism = lactic acid fermentation or alcohol fermentation

What happens to NAD+ during glycolysis?

It is REDUCED to become NADH = electron acceptor - remember the lingo

Hypoxia

Low oxygen conditions

What happens when animals tissues cannot be supplied with sufficient oxygen to support aerobic respiration of pyruvate and NADH?

NAD+ is regenerated from the NADH by the reduction of pyruvate to lactate catalyzed by lactate dehydrogenase

During Glycolysis is all the energy from the glucose molecule converted to ATP?

No not all of the energy from the glucose molecule is converted to ATP, most of it remains in the product; pyruvate = releases a fraction of the potential energy within glucose

Can animals covert acetyl coA from fatty acids into glucose?

No they can't but plants and microorganisms can

What is the third step of Glycolysis?

Phosphofructokinase-1 (PFK-1) catalyzes the transfer of a phosphoryl group from ATP to Fructose 6-phosphate = Fructose 1, 6-bisphosphate

What is the seventh step of glycolysis?

Phosphoglycerat kinase catalyzes the transfer of a phosphorylation group from 1,3-bisphosphoglycerate to ADP = ATP and 3-phosphoglycerate

What is the 8th step of Glycolysis?

Phosphoglycerate mutase catalyzes the transfer of the phosphoryl group from the C-3 position to the C-2 Position on 3-phosphoglycerate = 2-phosphoglycerate

What is the tenth step of glycolysis?

Pyruvate Kinases catalyze the transfer of a phosphoryl group from phosphoenolpyruvate to ADP = pyruvate + ATP

Alcohol/Ethanol Fermentation

Pyruvate lose a carboxyl group via pyruvate decarboxylase to acetaldehyde which is then REDUCED by NADH to produce ethanol while also oxidizing NADH = NAD+ so that it can be used again in Glycolysis = major energy source

What are the polymeric storage forms of glucose?

Starch and glycogen

What is the second step of Glycolysis ?

The enzyme Phosphohexose isomerase catalyzes the isomerization of glucose 6-phosphate to fructose 6-phosphate

Lactic acid fermentation

The use of pyruvate to oxizide NADH to become NAD+ so that glycolysis can continue since there is no available oxygen to act as an electron acceptor - Organisms that use fermentation rely on glycolysis as their main energy source, aka they don't get a lot of energy recovered from one glucose molecule - pyruvate becomes pyruvic acid = byproduct

What is the purpose of Gluconeogenic Enzymes

These enzymes allow the bypass of irreversible steps in the glycolytic pathway

What happens to the intermediate products that are produced during glycolysis?

They are phosphorylated but since the PM lacks transporters for phosphorylated transporters they generally do not leave the cell. 1) High-energy phosphate compounds can also donate their phosphate groups to ADP = ATP 2) Binding energy released from the addition of a phosphate group to the active site of an enzyme lowers the activation energy and increases their specificity

What is the enzyme that hydrolyzes starch?

alpha-amylase

Hexokinase

enzyme that catalyze the transfer of a phosphorylation group from ATP to an acceptor - used in first step of glycolysis - present int all cells of all organisms

What is the fourth step of Glycolysis?

fructose 1, 6-bisphosphate aldolase (aldolase) catalyzes the condensation of fructose 1, 6-bisphophate to two Trios phosphates ( glyceraldehyde 3-phosphate) and dihydroxyacetone phosphate)

Fermentation

general term for processes that extract energy in the form of ATP but that do not consume oxygen or alter the concentrations of NAD+ or NADH

What occurs in the first step of glycolysis?

glucose is phosphorylated = glucose 6-phosphate and is catalyzed hexokinase

Whats the sixth step of glycolysis (the firs step of the payoff phase)?

glyceraldehyde 3-phosphate dehydrogenase catalyzes the reaction of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate

What is the fifth step of Glycolysis?

glyceraldehyde 3-phosphate, can be directly degraded in the subsequent steps of glycolysis. The other product, dihy- droxyacetone phosphate, is rapidly and reversibly converted to glyceraldehyde 3-phosphate by the fifth enzyme of the sequence, triose phosphate isomerase

Substrate-level Phosphorylation

the formation of ATP from ADP with the transfer of a phosphoryl group from a chemical intermediate with the aid of an enzyme - e.g. 7th step of glycolysis (a Pi is transferred from 1,3-bisphosphoglycerate to ADP)

Gluconeogenesis

the process in which pyruvate (or related 3 carbon sugar) is converted to glucose in seven steps, these seven steps use the same enzymes as glycolysis

Respiration-linked Phosphorylation

the use of membrane bound enzymes and transmembrane proton gradient to induce the addition of a phosphoryl group to ADP