1. Chapter 17 Metabolism & Energetics

2. 17-1: Metabolism
Chemical reactions within mitochondria provide cells with energy
Supports growth, cell division, etc.
Metabolism—all the chemical reactions that occur in the body
Relies on amino acids, lipids, & simple sugars

3. Catabolism—breakdown of organic molecules
Releases energy for use in making ATP
Anabolism—formation of new organic molecules
Forms new chemical bonds
Requires energy formed from catabolic reactions

4. Reasons for making new compounds:
Performing body repairs
Support growth
Produce secretions
Build nutrient reserves (store nutrients)

5. 17-1 Checkpoint Define metabolism. Compare catabolism and anabolism.
Explain why cells need to make new compounds.

6. 17-2: Carbohydrate Metabolism
Most ATP is generated by breaking down carbohydrates, inside mitochondria
Anaerobic reactions don’t require oxygen; aerobic reactions require oxygen
Cellular respiration—responsible for ATP production
Glycolysis, citric acid cycle, electron transport chain

7. Glycolysis
Glycolysis—breakdown of 6-carbon glucose to two 3-carbon pyruvate molecules
Occurs in the cell cytosol
Uses 2 ATP to start process; produces 4 ATP (net gain of 2)

8. Glycolysis steps: Final products: Glucose enters cell
2 ATP break down to 2 ADP, release 2 P
Glucose molecule split to two 3-carbon chains
Final products:
2 pyruvate
2 ATP

10. The Citric Acid Cycle
Citric acid cycle—pyruvate combines with a substrate to form ATP
Occurs in the outer mitochondria
Pyruvate combines with coenzyme A (CoA) to form 2-carbon acetyl-CoA

11. Citric acid cycle steps:
Acetyl-CoA combines with 4-carbon oxaloacetic acid to form 6-carbon citric acid
Rearrangement of molecules produces 2 CO2 & ATP
Cycle turns twice (once per pyruvate molecule)
Final product: 2 ATP

13. The Electron Transport System
Electron transport system (ETS)—series of proteins that generates 95% of ATP
Occurs in the inner mitochondria
Electrons passed through ETS generate ATP
Requires oxygen
Final product: 32 ATP

14. Energy Yields of Glycolysis & Cellular Respiration
From one molecule of glucose:
Glycolysis: 2 ATP, 2 pyruvate
Citric acid cycle: 2 ATP
Electron transport chain: 32 ATP
36 ATP total made from 1 glucose molecule

16. 17-2 Checkpoint
What molecule is needed for glycolysis, and what is formed upon completion of glycolysis?
What is the primary role of the citric acid cycle in the production of ATP?

17. 17-3: Lipid Metabolism Lipolysis—breaking down lipids
1 lipid molecule can provide 144 ATP
Glucose metabolized quicker than lipids
Lipogenesis—formation of lipids
Lipids circulate in bloodstream as lipoproteins (lipid-protein complexes)

18. Cholesterol Cholesterol composes cell membranes, hormones
Low-density lipoproteins (LDLs)—deliver cholesterol to peripheral tissues
“Bad cholesterol”
High-density lipoproteins (HDLs)—transport excess cholesterol from tissues
“Good cholesterol”

19. High cholesterol linked to atherosclerosis, heart disease
Genetics, lifestyle choices affect cholesterol levels
Below 200 = OK
200 – 239 = modify diet
Above 240 = lifestyle changes

20. 17-3 Checkpoint Define lipolysis.
Why are high-density lipoproteins (HDLs) considered beneficial?
What are some benefits with cholesterol? What are some problems with cholesterol?

21. 17-4: Protein Metabolism Proteins broken down into amino acids
More difficult to break down than carbs/lipids
Amino acids combine to form proteins
Phenylketonuria (PKU)—disorder in which phenylalanine can’t be converted to another amino acid
Can damage CNS & brain
Tests performed after birth

22. 17-4 Checkpoint How are proteins formed?
Why is phenylketonuria (PKU) a dangerous disorder if undetected?

23. 17-6: Nutrition Nutrition—absorption of essential nutrients from food
Balanced diet—contains all the nutrients needed to maintain homeostasis
Prevents malnutrition—inadequate or excessive intake of nutrients

24. Food Groups Food pyramid updated to “MyPlate”
Color-coded food groups indicate proportions of food needed from five basic food groups
Grains, vegetables, fruits, protein, dairy

26. Nutrients must be obtained in sufficient quantity & quality
Complete proteins—contain essential amino acids (beef, fish, poultry, eggs, milk)
Incomplete proteins—missing essential amino acids (plants)

27. Minerals & Vitamins Minerals—ions important for body processes
Vitamins—organic nutrients
Fat-soluble—dissolve in lipids (A, D, E, K)
Water-soluble vitamins—easily move throughout body (B, C)

28. 17-6 Checkpoint Identify the two types of vitamins.
What is the difference between foods described as containing complete proteins and those described as containing incomplete proteins?

29. 17-7: Metabolic Rate Energy Content of Food
Calorimeter—device used to measure Calorie content of food
Lipids = 9.46 Calories/g
Carbohydrates = 4.18 Calories/g
Proteins = 4.32 Calories/g

30. Metabolic Rate Metabolic rate—sum of all processes occurring in body
Increases with exercise/activity
Basal metabolic rate (BMR)—represents the minimum energy needed by an awake, resting person
Influenced by age, gender, fitness, genetics

31. Thermoregulation
Thermoregulation—processes that keep body temp within normal ranges
Mechanisms of heat transfer:
Radiation—heat lost as infrared radiation
Conduction—heat lost through contact
Convection—heat lost as warm air rises
Evaporation—sweat on skin evaporates & cools body

33. Heat-loss centers & heat-gain centers in brain adjust body temp
Promoting heat loss:
Blood vessels dilate, sweat glands stimulated
Promoting heat gain:
Blood vessels constricted, sweat glands inhibited, shivering begins

34. 17-7 Checkpoint
Compare a pregnant woman’s BMR to her BMR when she is not pregnant.
What effect would vasoconstriction of blood vessels have on a hot day?
Why does shivering promote heat gain in the body?