Chapter 25 Metabolism Lecture Notes

Chapter 25 Metabolism Lecture Notes - Metabolism Chapter 25...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Metabolism Chapter 25 METABOLIC REACTIONS • All the chemical reactions of the body. Metabolism = catabolism + anabolism Catabolism: – Decomposition reactions, break down complex organic molecules into simpler ones – Release the chemical energy stored in organic molecules (glycolysis, Krebs cycle) – Exergonic: they produce more energy than they consume Anabolism – Synthesis reactions combine simple molecules to form complex structures ( protein synthesis) – Endergonic: they consume more energy than they produce • ATP: participates most often in energy exchanges; catabolism reactions to anabolism reactions
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Coupling of Catabolism and Anabolism by ATP • ATP – Typical cell has about a billion molecules of ATP that lasts for less than a minute before being used. – ATP is not a long-term-storage form of energy – Consist of: adenine molecule, a ribose molecule, 3 phosphate group • 40% of the energy released in catabolism is used for cellular functions, the rest is converted to heat – Some is used to maintain normal body temperature – The excess is lost to the environment Adenosine Triphosphate, ATP The energy currency of living systems Stores and transfers energy Consist of: Ribose Adenine 3 Phosphate group attached to an adenosine unite Energy is liberated when the third phosphate group is hydrolyzed (ATPase) by the addition of water molecule. The energy is used by the cell to power its activities ATP + H2O b ADP + E (energy) + P (phosphate group). To replenish ATP, ATP synthase catalyze the reaction ADP + P + E b ATP + H2O
Background image of page 2
3 Oxidation-Reduction (dehydrogenation) Reaction Oxidation – the removal of electron from an atom or molecule b decrease in the potential energy of the atom or molecule – Usually exergonic – Example: the conversion of lactic acid into pyruvic acid ( 2H are removed ) • CH3-H2CO-COOH b CH3-CO-COOH + 2H Reduction – addition of electrons to a molecule b increase in the potential energy of the molecule – Compounds that have many H atoms are highly reduced b contain more chemical potential energy – example: conversion of pyruvic acid into lactic acid • CH3-CO-COOH + 2H b CH3-H2CO-COOH Two coenzyme transfer hydrogen atoms immediately to another compound – nicotinamide adenine dinucleotide ( NAD) a derivative of vit B (niacin) – Falvin adenine dinucleotide (FAD) • Derivative of vitamin B2 (riboflavin), Oxidation- reduction always coupled b redox reactions – Example: lactic acid oxidized b form pyruvic acid b hydrogen atoms used to reduce NAD Mechanism of ATP Generation Phosphorylation: the addition of Phosphate group Energy released during oxidation is captured to make ATP High energy phosphate bond that attaches the third phosphate group contains the energy stored in the reaction three mechanisms for phosphorylation: 1. Substrate-level phosphorylation generates ATP by transferring a high-energy phosphate group from an
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 36

Chapter 25 Metabolism Lecture Notes - Metabolism Chapter 25...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online