Glycolysis Flashcards
What type of bond links monosaccharides together?
Glycosidic bonds
Is glycolysis aerobic or anaerobic?
Anaerobic
Where does glycolysis occur?
Cytosol
What are the two stages of glycolysis?
Energy investment and energy payoff
What is the net ATP yield of glycolysis?
2 ATP/glucose
Why does energy need to be invested in the first stage of glycolysis?
Glucose is too stable, it needs to be destabilized so it can react
a) What is step 1 of glycolysis? b)What is the enzyme that catalyzes it?
c) Is it reversible or irreversible?
d) coupled or uncoupled?
a) phosphorylation of glucose through a phosphate transfer reaction
b) Hexokinase
c) Irreversible
d) coupled
What two reactions are coupled in glycolysis step 1? Which one is favourable and which one is unfavourable?
Phosphorylation of glucose and ATP hydrolysis. ATP hydrolysis is favourable and the released energy powers the unfavourable phosphorylation of glucose
What are the two reasons why step 1 of glycolysis is necessary?
Glucose-6-phosphate is more reactive than glucose, and there is no transporter for G6P so it is trapped in the cell
How does hexokinase prevents wasteful ATP hydrolysis when glucose isn’t there?
Induced fit. Glucose binds and causes a conformational change, which then allows ATP to bind. ATP won’t bind if there’s no glucose there
a) What is step 2 of glycolysis? b) What is the enzyme that catalyzes it?
c) Is it reversible or irreversible?
d) coupled or uncoupled?
a) Isomerization of G6P.
b) phosphoglucose isomerase.
c) Reversible
d) uncoupled
What is the key different between the reactant and the product of glycolysis step 2?
G6P is an aldose and F6P is a ketose. When circular, goes from a 6-membered ring to a 5 membered ring
a) What is step 3 of glycolysis?
b) What is the enzyme that catalyzes it?
c) Is it reversible or irreversible?
d) coupled or uncoupled?
a) A second phosphorylation
b) phosphofructokinase (PFK-1)
c) Irreversible
d) Coupled
What is the rate-limiting step of glycolysis?
Step 3, PFK-1
a) What is step 4 of glycolysis?
b) What is the enzyme that catalyzes it?
c) Is it reversible or irreversible?
d) coupled or uncoupled?
a) Lysis
b) Aldolase
c) Reversible
d) uncoupled
What is the coupled reaction in glycolysis step 3?
ATP hydrolysis and phosphorylation
a) What is step 5 of glycolysis?
b) What is the enzyme that catalyzes it?
c) Is it reversible or irreversible?
d) coupled or uncoupled?
a) isomerization of DHAP into GAP
b) Triose phosphate isomerase
c) reversible
d) uncoupled
Why does step 5 of glycolysis need to occur?
GAP can continue on in glycolysis, but DHAP needs to be converted first. DHAP is a ketose and needs to be an aldose
Which step is the end of the energy investment stage?
Step 5 with the formation of GAP
a) What is step 6 of glycolysis?
b) What is the enzyme that catalyzes it?
c) Is it reversible or irreversible?
d) coupled or uncoupled?
a) Oxidation
b) GAPDH
c) Reversible
d) Uncoupled
Which position in GAP gets oxidized in step 6 of glycolysis?
Position 1, the aldehyde
Where does the phosphate added to GAP in glycolysis step 6 come from?
Free phosphate, not from ATP
What type of reactions do dehydrogenase enzymes catalyze?
Redox
How is the energy released from glycolysis step 6 captured?
NAD+ gets reduced to NADH
