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