Chapter 4-Cell Metabolism

1. Chapter 4-Cell Metabolism Joe Pistack MS/ED

2. Metabolism • Metabolism-series of chemical reactions necessary for the use of raw materials. • The cell is like a factory, must bring in and use raw materials. • Raw materials come from the food we eat: carbohydrates, proteins and fat.

3. Metabolism • Two parts: • Anabolism-includes reactions that build larger, more complex substances from simpler ones. Eg. Building of a large protein from individual amino acids. Anabolic reactions generally require an input of energy in the form of ATP.

4. Metabolism • Catabolism-reactions that break down larger, more complex substances into simpler substances. Eg. Breakdown of a large protein into individual amino acids. Catabolism releases energy that is eventually converted to ATP.

5. Carbohydrates • Sugars and starchy foods: • Bread • Potatoes • Pasta • Candy • Carbohydrates are organic compounds composed of, Carbon (C), hydrogen (H), and oxygen (O).

6. Carbohydrates • Monosaccharides-single sugar compounds. • Single=mono (saccharide) compound • Disaccharides-double sugar • Double=di sugars • Polysaccharides=many sugars

7. Monosaccharides • Sugars that contain three to six carbons. • The six-carbon simple sugars include: glucose fructose galactose • Glucose is the most important, it is used for immediate energy.

8. Polysaccharides • Many glucose molecules linked together. • Glycogen-form in which humans store glucose. • Glycogen is stored primarily in the liver and skeletal muscle. • Glycogen is converted to glucose and released into the blood to restore low blood sugar to normal.

9. Polysaccharides • Cellulose is a polysaccharide found in plants, unable to digest but provides a source of fiber in our diets.

10. Glucose • Glucose is used by the body in three ways: 1. It can be burned immediately as fuel for energy. 2. It can be stored as glycogen and burned as fuel at a later time. 3. It can be stored as fat and burned as fuel at a later time.

11. Glucose • Glucose is broken down under the following conditions: 1. anaerobic catabolism-absence of oxygen. 2. aerobic catabolism-presence of oxygen. • Glycosis- anaerobic process where glucose is broken down by a series of chemical reactions into pyuric acid and lactic acid, occurs in the cytoplasm.

12. Aerobic Catabolism • Three important points: 1. Chemical reactions occurring in the mitochondria require O2. If the cells are deprived of O2, they cannot perform their function. Ex. Need to breathe continuously to ensure a continuous supply of O2.

13. Aerobic Catabolism 2. Glucose is broken down completely to carbon dioxide and water, stored energy is released as ATP or heat. 3. If O2 is not available to the cell, there is a build-up of pyruvic acid lactic acid lack of O2 lactic acidosis.

14. Glucose • Glyconeogenesis-making of glucose from nonglucose sources, especially protein. • Glyconeogenesisis an important mechanism in the regulation of blood sugar. • If blood sugar drops, protein is converted to glucose in the liver and released into the blood, restoring the blood sugar to normal.

15. Glucose • Diabetes-lack of the insulin hormone affects glucose metabolism. • Insulin is needed to transport glucose into the cell, a lack of insulin deprives the cell of glucose and the energy that glucose provides. • Lack of insulin causes body protein to be broken down and converted into glucose.

16. Glucose • Diabetic cells cannot utilize glucose, it accumulates in the blood and causes the person to become hyperglycemic. • Glucose ends up in the blood and not in the cell where it is needed for energy. • Drugs to treat diabetes-increase glucose uptake and supressgluconeogenesis by the liver. (Lower blood sugar)

17. Lipids • Organic compounds. • Commonly called fats and oils. • Solid at room temperature. • Eaten as fatty meats, egg yolks and dairy products.

18. Lipids

19. Lipids • Lipids found in the body: - triglycerides -phospholipids -steroids • Building blocks of lipids-fatty acids and glycerol. • Phospholipids are important components of the cell membrane.

20. Lipids • Steroid-type of lipid. • Cholesterol-most important steroid in the body. • Consumed as meat, eggs and cheese. • Cholesterol is found in all cell membranes, necessary for synthesis of vitamin D and used in the ovaries and testes in synthesis of sex hormones.

21. Lipids • Needed by the body for: 1. source of energy. 2. component of cell membranes and coverings of nerve cells. 3. synthesis of steroids.

22. Metabolism of Lipids • Fatty acids and glycerol can be broken down to release stored energy. • Fatty acids are long structures, need to be chopped into tiny units before they enter the mitochondria. • When chopped into units they enter into the Krebs cycle.

23. Metabolism of Lipids • Krebs Cycle-series of reactions which occur in the mitochondria that results in the formation of ATP.

24. Making Fat Excess calories are consumed Fat enzymes are stimulated Fat is deposited in adipose tissue

25. Fats

26. Proteins • Most abundant organic matter in the body. • Organic material always contains a carbon molecule • Participate in every body function. • Most hormones are proteins.

27. Amino Acids • Building blocks of proteins. • Takes about 20 amino acids to build body protein. • Amino acids come from foods: -lean meat - milk - eggs

28. Amino Acids • Most amino acids are synthesized by the body. • Some amino acids cannot be synthesized and must be obtained from dietary sources. • Dietary intake of amino acids is essential.

29. Amino Acids • Two types: • Essential amino acids-dietary intake of these amino acids is important since the body does NOT make them. • Nonessential amino acids-synthesized by the liver, not necessary to obtain from diet.

30. Proteins • Used in three ways: • Plays a key role in physiological function. • Protein can be broken down and used as fuel as a source of energy for ATP. • Protein can be broken down and converted to glucose.

31. Urea • Nitrogen released by the breakdown of amino acids is converted to urea by the liver. • Urea is a nitrogenous waste. • Blood carries urea from the liver to the kidneys, then eliminates it into the urine.

32. Urea • Under normal conditions the liver extracts ammonia from the blood and converts it to urea. • Liver failure-extraction of ammonia from the blood is diminished, blood levels of ammonia rise. • Hepatic encephalopathy-toxic effects of ammonia on the brain.

33. Urea • BUN : Blood Urea Nitrogen • Laboratory test • Measures the amount of urea in the blood. • Poor kidney function results in an elevated BUN.

34. Protein Synthesis • Genetic Code: • Protein-synthesizing code is stored in the DNA in the nucleus. • When there is a need for protein synthesis, the code is transferred to the ribosome.

35. Aging • As we age: • Number of mitochondria and organelles decrease. • Metabolism slows down, secondary to a decrease in hormonal secretion. • Rate of protein synthesis decreases. • Decrease in metabolism causes, intolerance to cold, tendency to gain weight, decreased efficiency in using glucose.

36. Aging