4.2.1 Glycolysis: The Initial Steps: Energy Input Flashcards Preview

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Flashcards in 4.2.1 Glycolysis: The Initial Steps: Energy Input Deck (9)
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1
Q

glycolysis

A
  • glucose, a six-carbon molecule, is split into two pyruvates (three-carbon molecules).
  • The first stage of glycolysis involves an energy investment of two ATP
  • When studying metabolic pathways, pay attention to the name of the enzyme and what the enzyme did.
2
Q

Glycolysis: The Energy Investment

A
  • Step 1: Glucose is phosphorylated by the enzyme hexokinase to form glucose-6-phosphate. Glucose gains energy by being phosphorylated at the expense of one ATP.
  • Step 2: Glucose-6-phosphate is converted into its isomer, fructose-6-phosphate, by an isomerase enzyme. By converting into its isomer, the molecule is further energized.
  • Step 3: Fructose 6-phosphate is phosphorylated by the enzyme phosphofructokinase to form fructose-1, 6-bisphosphate. This step adds even more energy to the molecule at the expense of one ATP.
  • Step 4: Fructose-1,6-bisphosphate is split into two molecules, dihydroxyacetone phosphate and glyceraldehyde phosphate.
  • Step 5: Dihydroxyacetone phosphate is converted into glyceraldehydes-3-phosphate. This reaction runs in both directions, but because the glyceraldehydes-3-phosphate is converted further in glycolysis, the equilibrium favors the formation of glyceraldehydes-3-phosphate.
  • Glyceraldehyde-3-phosphate goes on to the next phase of glycolysis, the energy-payoff phase.
3
Q

The role of hexokinase in the first part of glycolysis is:

A
  • The phosphorylation of glucose
4
Q

During two steps in glycolysis, ATP is hydrolyzed in order to form phosphorylated intermediates. Which two enzymes mediate these respective reactions?

A
  • Hexokinase; Phosphofructokinase
5
Q

In the energy investment phase of glycolysis

A
  • two molecules of ATP are invested making glucose and its derivatives more reactive
6
Q

Glycolysis begins in the __________ and ends in the _____________.

A
  • cytoplasm; cytoplasm
7
Q

The pathway in which glucose is broken down to form pyruvate is called

A
  • glycolysis
8
Q

An important goal of the energy investment phase of glycolysis is the

A
  • phosphorylation of a 6-carbon molecule.
9
Q

Which statement regarding the isomerase enzyme in the first half of glycolysis is true?

A
  • Isomerase interconverts glyceraldehyde-3-phosphate to dihydroxyacetone phosphate, and vice versa

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