Hole s Essentials of Human Anatomy & Physiology

Transcription

1 Hole s Essentials of Human Anatomy & Physiology David Shier Jackie Butler Ricki Lewis Created by Dr. Melissa Eisenhauer Head Athletic Trainer/Assistant Professor Trevecca Nazarene University Amended by John Crocker Chapter 4 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2 Chapter 4 Cellular Metabolism

3 Introduction A living cell is the site of enzyme-catalyzed metabolic reactions that maintain life. 3

4 Metabolic Processes Metabolic reactions are of two types: A. anabolic reactions 1. larger molecules constructed from smaller ones 2. requires energy B. catabolic reactions 1. larger molecules are broken down 2. releases energy C. Metabolic reactions are often reversible. 4

5 Anabolism 1. via dehydration synthesis,, the removal of a water molecule to join two smaller molecules. 2. provides the substances needed for growth and repair. 5

6 3. Polysaccharides, lipids, and proteins are constructed via dehydration synthesis. A. To form fats, glycerol and fatty acids bond. B. Peptide bond = two amino acids 1) Two bound aminos = dipeptide 2) Three or more = polypeptide 6

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8 Catabolism 1. breaks apart larger molecules into their building blocks. 2. via hydrolysis, the insertion of water molecule into a polymer which splits it into two smaller molecules. 8

9 Control of Metabolic Reactions: Enzymes control the rates of all the metabolic reactions of the cell. 9

10 Enzyme Action 1. Enzymes are complex proteins that function as catalysts 2. Catalysts lower the activation energy of a reaction allowing it to begin and/or to proceed more rapidly. 3. Each enzyme acts on only one kind of substrate. 4. Active sites on the enzyme combine with the substrate and a reaction occurs. Flash 10

11 5. Enzymes work in small quantities and are recycled by the cell. 6. The speed of enzymatic reactions depends on the number of enzyme and substrate molecules. 7. Enzymes can be denatured like other proteins. 11

12 Energy for Metabolic Reactions: A. Energy is the capacity to do work. B. Common forms include: 1. Heat 2. Light 3. Sound 4. Electrical energy 5. Mechanical energy 6. Chemical energy. 12

13 C. Release of Chemical Energy Cellular Respiration 1. Oxidation of glucose is the primary source of chemical energy in the cell. 2. Energy is required to initiate burning of glucose. 3. Enzyme catalyzed reactions occur in the cytosol and mitochondria. 4. End-products = heat + stored energy. 5. Energy is stored as ATP (Adenosine Tri-Phosphate). 13

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15 D. ATP Molecules 1. Up to 38 molecules of ATP are produced for each molecule of glucose oxidized. 2. ATP molecules contain three phosphates in a chain. 15

16 3. Energy is stored in the last phosphate bond when ADP is converted to ATP. 4. When energy is released ATP becomes ADP which can then be regenerated into ATP. 16

17 E. Anaerobic Respiration 1. Glycolysis is the initial step of cellular respiration 2. Glycolysis occurs in the cytosol and is anaerobic (does not use O 2 ) C C glucose is split through a series of enzyme-catalyzed steps resulting in two 3-C C molecules of pyruvate. 4. Energy from ATP is used to start the process but there is a net gain of energy as a result. 17

18 F. Aerobic Respiration 1. Respiration within the mitochondria is aerobic (with O 2 ). 2. Aerobic respiration results in a much greater gain of ATP molecules. 3. Final products of glucose oxidation are carbon dioxide, water, and energy 18

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20 Metabolic Pathways: A. The enzymes controlling either an anabolic or catabolic sequence of reactions must act in a specific order. B. A sequence of enzyme-controlled reactions is called a metabolic pathway. 20

21 C. Regulation of Metabolic Pathways 1. The rate of a metabolic pathway is determined by a regulatory enzyme responsible for one of its steps. 2. A rate-limiting enzyme is the first step in a series. 21

22 Nucleic Acids and Protein Synthesis: A. Deoxyribonucleic acid (DNA) contains the genetic code needed for the synthesis of all cellular proteins. B. A gene is a portion of a DNA molecule that contains the genetic information for making a single protein. 22

23 C. DNA Molecules 1. The nucleotides of DNA form a sugar- phosphate backbone with bases extending into the interior of the DNA molecule. 2. The nucleotides of DNA exhibit complementary base pairing A. adenine pairs with thymine B. cytosine with guanine 23

24 3. The DNA molecule twists to form a double helix and may be millions of base pairs long. 24

25 DNA Replication 1. Each new cell must be provided with an exact replica of the parent cell's DNA. 2. DNA replication occurs during interphase. A. The DNA molecule splits. B. Nucleotides form complementary pairs with the original strands. 3. Each new DNA molecule consists of one parental strand and one newly-synthesized strand of DNA. 25

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27 Genetic Code 1. The sequence of nucleotides in a DNA molecule gives the sequence of amino acids for a given protein. 2. This method of storing information for protein synthesis is the genetic code. 3. RNA molecules copy and transfer this information to the cytoplasm where proteins are manufactured. 27

28 4. Transcription A. RNA molecules 1) Single-stranded 2) Contain ribose rather than deoxyribose 3) Use uracil rather than thymine. B. Messenger RNA (mrna) 1) molecules are synthesized in the nucleus in a process called transcription. 2) sequence is complementary to the DNA template Flash 28

29 5. Translation A. Each amino acid corresponds to a triplet of DNA nucleotides called a codon B. Messenger RNA (mrna) can move out of the nucleus and associate with ribosomes in the cytoplasm where the protein will be constructed via translation. 29

30 C. In the cytoplasm transfer RNA (trna)) has a triplet of nucleotides called the anticodon,, which is complementary to nucleotides of the messenger RNA codon. D. The ribosome holds the messenger RNA in position while the transfer RNA carries in the correct amino acid in sequence, with anticodons matching up to codons. 30

31 E. The ribosome contains enzymes needed to join the amino acids together. F. As the amino acids are joined, the new protein molecule folds into its unique shape. Flash 31

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34 Laboratory Week 2 Chapters 3 & 4 34

35 Chapter 3 Chemistry of Life Colorimetric test for ph Biuret test for protein Benedict s s test for simple sugar Iodine test for starch Sudan IV test for lipids 35

36 Chapter 4 Basic Microscopy Rules for use Elements of a light microscope Slide preparation 36

37 Bring text, lab manual, and supplement Be prepared to stay for the full period Take care with equipment and make sure that everything is cleaned and returned to its proper place 37