Table of contents

1. Introduction to Biology2h 42m
2. Chemistry3h 37m
3. Water1h 26m
4. Biomolecules2h 23m
5. Cell Components2h 26m
6. The Membrane2h 31m
7. Energy and Metabolism2h 0m
8. Respiration2h 40m
9. Photosynthesis2h 49m
10. Cell Signaling59m
11. Cell Division2h 47m
12. Meiosis2h 0m
13. Mendelian Genetics4h 44m
14. DNA Synthesis2h 27m
15. Gene Expression3h 6m
16. Regulation of Expression3h 31m
17. Viruses37m
- Viruses
  37m
18. Biotechnology2h 58m
19. Genomics17m
- Genomes
  17m
20. Development1h 5m
21. Evolution3h 1m
22. Evolution of Populations3h 53m
23. Speciation1h 37m
24. History of Life on Earth2h 6m
25. Phylogeny2h 31m
26. Prokaryotes4h 59m
27. Protists1h 12m
28. Plants1h 22m
29. Fungi36m
- Fungi
  19m
- Fungi Reproduction
  17m
30. Overview of Animals34m
- Overview of Animals
  34m
31. Invertebrates1h 2m
32. Vertebrates50m
33. Plant Anatomy1h 3m
34. Vascular Plant Transport1h 2m
- Water Potential
  1h 2m
35. Soil37m
- Soil and Nutrients
  20m
- Nitrogen Fixation
  16m
36. Plant Reproduction47m
- Flowers
  33m
- Seeds
  14m
37. Plant Sensation and Response1h 9m
38. Animal Form and Function1h 19m
39. Digestive System1h 10m
- Digestion
  1h 3m
- Blood Sugar Homeostasis
  7m
40. Circulatory System1h 49m
41. Immune System1h 12m
42. Osmoregulation and Excretion50m
- Osmoregulation and Excretion
  50m
43. Endocrine System1h 4m
- Endocrine System
  1h 4m
44. Animal Reproduction1h 2m
- Animal Reproduction
  1h 2m
45. Nervous System1h 55m
- Neurons and Action Potentials
  1h 8m
- Central and Peripheral Nervous System
  46m
46. Sensory Systems46m
- Sensory System
  46m
47. Muscle Systems23m
- Musculoskeletal System
  23m
48. Ecology3h 11m
49. Animal Behavior28m
- Animal Behavior
  28m
50. Population Ecology3h 41m
51. Community Ecology2h 46m
52. Ecosystems2h 36m
53. Conservation Biology24m
- Conservation Biology
  24m

8. Respiration

Glycolysis

General Biology

8. Respiration

Glycolysis

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3:26 minutes

Problem 8

Textbook Question

Step 3 in Figure 9.8 is a major point of regulation of glycolysis. The enzyme phosphofructokinase is allosterically regulated by ATP and related molecules (see Concept 8.5). Considering the overall result of glycolysis, would you expect ATP to inhibit or stimulate activity of this enzyme? Explain.
(Hint: Make sure you consider the role of ATP as an allosteric regulator, not as a substrate of the enzyme.)

Verified step by step guidance

Identify the role of phosphofructokinase in glycolysis: It catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate, a key regulatory step in glycolysis.

Understand the concept of allosteric regulation: Allosteric regulators bind to an enzyme at a site other than the active site, causing a change in its activity.

Consider the role of ATP as an allosteric regulator: ATP can bind to phosphofructokinase and affect its activity, not just serve as a substrate.

Analyze the effect of ATP levels on glycolysis: High levels of ATP indicate that the cell has sufficient energy, which may lead to the inhibition of phosphofructokinase to slow down glycolysis.

Conclude the expected effect of ATP on phosphofructokinase: Given that ATP is an allosteric inhibitor, it is likely to inhibit the enzyme's activity, reducing the rate of glycolysis when energy is abundant.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Glycolysis

Glycolysis is a metabolic pathway that converts glucose into pyruvate, generating ATP and NADH in the process. It consists of ten enzymatic steps, with phosphofructokinase playing a crucial role in the third step. This pathway is essential for cellular respiration, providing energy and metabolic intermediates for cells.

Phosphofructokinase Regulation

Phosphofructokinase (PFK) is a key regulatory enzyme in glycolysis, controlling the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate. It is allosterically regulated by ATP, which can inhibit its activity when ATP levels are high, thus slowing down glycolysis. This regulation ensures that energy production is balanced with the cell's energy needs.

Allosteric Regulation

Allosteric regulation involves the binding of molecules at a site other than the enzyme's active site, causing a conformational change that affects enzyme activity. In the case of phosphofructokinase, ATP acts as an allosteric inhibitor, reducing the enzyme's activity when energy levels are sufficient, thereby preventing unnecessary ATP production.

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