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Molecular Cell Biology Lecture 2, Part B; Chemistry of a cell

Molecular Cell Biology Lecture Series・24 minutes read

Sugars and fats store energy, but ATP powers cell work, mainly produced in mitochondria. ATP's high-energy bond aids in reactions, while NADH drives electron transport, with glycolysis and the citric acid cycle central to cellular metabolism.

Insights

  • ATP is the primary energy source for cellular work, produced mainly in mitochondria through oxidative phosphorylation and storing energy in phosphoanhydride bonds.
  • NADH plays a crucial role in cellular redox reactions, acting as a major electron donor in the electron transport chain, driving ATP synthesis through oxidative phosphorylation, yielding around 30 ATP molecules per glucose molecule.

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Recent questions

  • What is the main energy source for useful work in cells?

    ATP

  • What is the role of NADH in cellular metabolism?

    Major electron donor in the electron transport chain

  • How are molecules like cholesterol built in cells?

    Anabolic processes

  • What is the significance of acetyl coenzyme A in cellular metabolism?

    Vital cellular intermediate

  • How is energy stored in cells for various processes?

    Phosphoanhydride bonds

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Summary

00:00

Cellular Energy Production and Storage Mechanisms

  • Sugars can be stored in glycogen and fats, but ATP is the main energy source for useful work in cells.
  • The majority of ATP is produced in mitochondria through oxidative phosphorylation, with energy stored in phosphoanhydride bonds.
  • Energy in cells is also stored in GTP, NAD, NADH, and FAD, with the phosphate from ATP aiding in catalysis and forming intermediates.
  • ATP's high-energy phosphoanhydride bond can be transferred to substrates as an intermediate in reactions.
  • NAD and NADP, forming NADH and NADPH, are crucial for redox reactions, with NADH being a major electron donor in the electron transport chain.
  • Anabolic processes involve building molecules like cholesterol, while catabolic processes break down molecules, with a shift from anabolic to catabolic as people age.
  • Acetyl coenzyme A is a vital cellular intermediate, with a high-energy bond between the acetyl group and coenzyme A.
  • ATP-driven catalysis uses energy from the gamma phosphate to facilitate reactions, such as converting bicarbonate to oxaloacetate.
  • Condensation joins molecules and releases water, while hydrolysis breaks molecules and consumes water, crucial in various cellular processes.
  • Glycolysis converts glucose to pyruvate, producing ATP and NADH, with lactate formed in the absence of oxygen and ethanol produced by yeast fermentation.

20:21

Alcohol, Glycolysis, and ATP in Cellular Metabolism

  • Alcohol consumption can lead to the production of acetylaldehyde, a carcinogen, contributing to diseases like cancer.
  • Understanding glycolysis involves focusing on steps six and seven, which produce reduced NADH and ATP.
  • In step six of glycolysis, glyceraldehyde 3-phosphate reacts with glyceraldehyde three phosphate dehydrogenase to produce reduced NADH and ATP.
  • Step seven of glycolysis involves the transfer of a high-energy phosphate to ADP to generate ATP, resulting in three phosphoglycerate.
  • Different phosphoester bonds on proteins have varying energies, with pyrophosphate releasing more energy than the gamma phosphate.
  • Sugars can be stored as glycogen in cells, while fatty acids are stored in fat droplets and can be used in the TCA cycle.
  • Glycolysis and the citric acid cycle are central to cellular metabolism, producing ATP mainly through oxidative phosphorylation.
  • The reduced NADH produced in the citric acid cycle drives ATP synthesis through oxidative phosphorylation, resulting in approximately 30 molecules of ATP per glucose molecule.
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