glycolysis

what is reduction?

reduction is when electrons are gained, oxygens are lost, & hydrogens are gained

what’s oxidation?

oxidation is when electrons are lost, oxygen is gained, and hydrogen is lost

what’s the most common hydrogen (or electron?) carrier in cell respiration & what’s its function?

NAD - Nicotinamide adenine dinucleotide

it acts as a coenzyme, so it’s a non-protein molecule that helps enzymes carry out their function

it can be reduced (meaning it gains electrons) & oxidized (meaning it loses electrons). this allows it to perform its critical role as a hydrogen carrier

what are reduction-oxidation (redox) reactions?

chemical reactions that involve the exchange of electrons between 2 molecules


when electrons are lost from a molecule, ion, or atom, its oxidised. the molecule, ion, or atom that “accepts” the electrons is reduced

  • so, whenever smthg is oxidised, another substance is reduced


what’s an oxidiser?

a molecule that will cause other molecules to lose electrons, or be oxidised, and accepts the electrons, thus becoming reduced

what’s an example of an oxidiser?

NAD!!

  • it will cause other substances to be oxidised (will oxidise other substances?) & then will accept the electrons, and become reduced

  • in cell respiration, this involves the transfer of hydrogen, which contains electrons


what does it mean if a molecule or substance in dehydrogenated?

it occurs when a molecule or substance is oxidised, so they are also dehydrogenated

  • is when a molecule or atom or ion or substance loses an atom of hydrogen


what causes NAD to be reduced?

NAD will become reduced when it accepts the hydrogen (which contains electrons) & will become reduced NAD, otherwise known as

NADH

what’s another less frequently used hydrogen carrier?

FAD - Flavin Adenine Dinucleotide. this is a coenzyme that carries electrons from one reaction to another in the electron transport chain

what is glycolysis & where does it occur?

glycolysis basically involves the splitting of a single hexose sugar (like glucose, or a 6-carbon compound) into 2 molecules of pyruvate (3-carbon compounds)


it occurs in the cytoplasm of a cell, and is the first step in cell respiration.

it occurs in both anaerobic & aerobic cell respiration

is each step in glycolysis catalysed by the same enzyme?

no, each step in the pathway is catalysed by a different enzyme

glycolysis begins with a hexose sugar (like glucose). what is the first main stage?

note: the following descriptions of glycolysis occur for one cycle

PHOSPHORYLATION

  • 2 phosphate groups are added to the hexose sugar

    • this is caused by 2 ATP molecules converting to 2 ADP molecules

      • cuz the conversion means a loss of 2 phosphate groups

  • hexose sugar is less stable & can react more easily in the metabolic pathway


what’s the 2nd stage?

LYSIS

  • lysis is a chemical reaction where a molecule is split by breaking one or more bonds

  • the hexose phosphate (or the phosphorylated glucose molecule) is split into 2 triose phosphates (or 2 glyceraldehyde 3-phosphate (G3P) molecules)


whats the 3rd stage?

DEHYDROGENATION/OXIDATION

  • each G3P molecules is hydrogenated & oxidised

    • so they “lose” electrons & a hydrogen

  • the released hydrogen is “accepted” by the coenzyme NAD

    • it is then reduced to become NADH

  • i think the energy released by the reduction of NAD is used for the next stage


whats the 4th stage?

ATP FORMATION

  • substrate level phosphorylation - a phosphate group is transferred from a substrate molecule to ADP

  • this transfer of phosphate group to ADP forms ATP



what are the yields from ONE cycle of glycolysis?

2 ATP molecules, 2 NADH molecules, and 2 pyruvates.

glycolysis uses an investment of 2 ATP to produce 4 ATP, with a net gain of 2 ATP - true or false

true

under aerobic conditions, what happens to pyruvate when its further oxidized?

when pyruvate is further oxidized, it yields more ATP

under anaerobic conditions, what happens to pyruvate?

pyruvate is converted to lactic.

  • the pyruvate can be utilized in alcoholic & lactic fermentation

  • alcoholic fermentation produces carbon dioxide & alcohol

    • in yeasts, alcoholic fermentation is used in brewing & breaking

  • lactic fermentation in humans produces lactate


what is needed in humans to allow glycolysis to continue into aerobic respiration?

the production of pyruvate & regeneration of NAD in humans allows glycolysis to continue into aerobic respiration

how many times does glycolysis hv to occur in order to produce one glucose molecule?

i’m pretty sure it’s 2 times