Lecture 9 - The Cellular Basis of Human Metabolism. Part 1 - Digestion Begins in the Mouth

Lecture 9 - The Cellular Basis of Human Metabolism. Part 1 - Digestion Begins in the Mouth

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1 The Cellular Basis of Human Metabolism. Part 1: Digestion Begins in the Mouth Biology 1F25 for Biology Non-Majors Lecture 9 Background Reading Textbook, Chapter 8 The People Who Prepared This Lecture Harry Peery Jeff Stuart Today’s lecture (1) Understand the cellular basis of human metabolism (2) Begin to understand human metabolism and energy homeostasis at the whole body level
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2 Inside the cell Energy transduction Definition: to convert one form of energy to another In human cells: energy in food ATP ATP is the cell’s ‘energy currency’ Spend ATP and for change get ADP (worthless) Must re-convert ADP to ATP ADP ATP ADP ATP mitochondrion Cytosol of cell Mitochondria re-convert ADP to ATP using the energy in food
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3 Re-conversion of ADP to ATP using energy from oxidizing food is called ‘Oxidative Phosphorylation’ The last two steps in oxidative phosphorylation : - Conversion of oxygen to water - Conversion of ADP to ATP Mitochondria convert ADP to ATP What converts ATP to ADP? All cellular processes that require energy to drive them ATP consuming cellular processes Common to all cells : DNA transcription Protein synthesis (translation) Rebuilding membranes and other cellular structures Moving things around within the cell Expelling sodium and taking up potassium Endocytosis and Exocytosis Specific to certain cell types : Muscle contraction – skeletal muscle, heart muscle Nervous conduction – brain, spinal cord, sensory nerves everywhere Filtering blood to make urine – kidneys Digestion of food – stomach & intestines
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4 Heart rate reflects metabolic rate which in turn reflects the sum of cellular ATP usage Heart rate at rest? Heart rate during exercise? Summary –metabolism in all human cells - All ingested food converted to a form that can be ‘burnt’ by mitochondria - These molecules of broken down food enter Kreb’s (=citric acid) cycle - Kreb’s cycle produces NADH - Oxidation of NADH (oxygen consumed) drives the creation of an electrical gradient between mitochondria and cytosol - Electrical current flows back into mitochondria driving the ATP synthase motor; ATP is produced - How fast this works depends on how rapidly cells are using up ATP **your metabolism is the sum of the metabolism of all 100 trillion cells in your body! Getting Food into Your Body
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Lecture 9 - The Cellular Basis of Human Metabolism. Part 1 - Digestion Begins in the Mouth

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