Chr. 25 - Metabolism and Nutrition Flashcards
1
Q
[25.1] What is metabolism?
A
The sum of all the chemical reactions occurring in the body.
2
Q
[25.1] What are the two types of metabolism?
A
Catabolism and anabolism.
3
Q
[25.1] What is catabolism?
A
Chemical reactions breaking down complex organic molecules into simpler molecules. Typically exergonic.
4
Q
[25.1] What is anabolism?
A
Chemical reactions building more complex molecules using simpler ones. Typically energonic.
5
Q
[25.1] What is adenosine triphosphate?
A
A molecule storing energy and most often involved in energy exchanges within living cells.
6
Q
[25.1] Describe the composition of adenosine triphosphate.
A
An adenine molecule with a ribose sugar and three phosphate groups bonded to it.
7
Q
[25.1] How is adenosine triphosphate commonly used in the body?
A
It is formed to store energy through linkage of the third phosphate group. It is broken down to access energy.
8
Q
[25.1] What percentage of energy released in catabolism is used for cellular function?
A
40%. The rest is converted to heat.
9
Q
[25.2] What are oxidation-reduction (redox) reactions?
A
Coupled reactions of oxidation and reduction; one substance must be reduced when another is oxidized.
10
Q
[25.2] What are oxidation reactions?
A
The removal of electrons from an atom or molecule, decreasing the potential energy. Typically exergonic.
11
Q
[25.2] What are dehydrogenation reactions?
A
An oxidation reaction resulting in the loss of a hydrogen atom.
12
Q
[25.2] What are reduction reactions?
A
The addition of electrons to a molecule, increasing the potential energy of the molecule.
13
Q
[25.2] What is phosphorylation?
A
The addition of a phosphate group to a molecule.
14
Q
[25.2] List the mechanisms of ATP generation.
A
- Substrate-level phosphorylation
- Oxidative phosphorylation
- Photophosphorylation
15
Q
[25.2] Describe substrate-level phosphorylation.
A
A process generating ATP by transferring a high-energy phosphate group from a substrate directly to ATP. Occurs in cytosol.
16
Q
[25.2] Describe oxidative phosphorylation.
A
A process generating ATP by removing electrons from organic compounds and passing it through the electron transport chain onto oxygen. Occurs in mitochondrial membrane.
17
Q
[25.2] Describe photophosphorylation.
A
A process generating ATP only occurring in chlorophyll containing plant cells.
18
Q
[25.3] List the uses of glucose by body cells.
A
- ATP production
- Amino acid synthesis
- Glycogen synthesis
- Triglyceride synthesis
19
Q
[25.3] What is glycogenesis?
A
The process of converting glucose monomers into glycogen, a polysaccharide.
20
Q
[25.3] What is lipogenesis?
A
The synthesis of triglycerides.
21
Q
[25.3] Describe glucose movement into cells.
A
Glucose moves into cells using GluT transport molecules. Insulin increases ability of GluT4 into the membranes of cells, increasing facilitated diffusion of glucose into cells.
22
Q
[25.3] What is cellular respiration?
A
The process of oxidating glucose to produce ATP.
23
Q
[25.3] List the steps of cellular respiration.
A
- Glycolysis
- Formation of acetyl coenzyme A
- Krebs Cycle
- Electron transport chain
24
Q
[25.3] What is an anaerobic reaction?
A
A reaction that does not require oxygen in order to occur.
25
[25.3] What is an aerobic reaction?
A reaction that requires oxygen to occur.
26
[25.3] Describe glycolysis and state whether it is aerobic or anaerobic.
A chemical reaction that splits a 6-carbon molecule of glucose into two 3-carbon molecules of pyruvic acid. Can be either aerobic or anaerobic.
27
[25.3] What occurs to pyruvic acid during anaerobic glycolysis?
Pyruvic acid is reduced with two hydrogen atoms to form lactic acid. This produced two NAD+ and allows anaerobic glycolysis to repeat.
28
[25.3] What occurs to pyruvic acid during aerobic glycolysis?
Pyruvic acid is converted to acetyl coenzyme A, linking glycolysis to the Krebs cycle.
29
[25.3] How is pyruvic acid converted to acetyl coenzyme A?
Coenzyme A removes a carbon from pyruvic acid, generating an acetyl group. The acetyl group then binds to the enzyme, forming acetyl coenzyme A.
30
[25.3] What is decarboxylation?
When a substance removed one carbon and two oxygens from a substance, forming carbon dioxide.
31
[25.3] What is another name for the Krebs cycle?
The citric acid cycle.
32
[25.3] What is the Krebs cycle?
A process occurring in the matrix of mitochondria involving the oxidation of pyruvic acid and reducing of coenzymes involved in the process.
33
[25.3] List the coenzymes involved in the Krebs cycle and their reduced form.
1. (NAD)+, NADH + (H)+
2. FAD, FAD(H2)
34
[25.3] What is the electron transport chain?
A series of electron carriers within the inner mitochondrial membrane where each carrier is reduced and then oxidized, resulting in a series of exergonic reactions used to generate ATP.
35
[25.3] What is chemiosmosis?
The series of reactions within the electron transport chain, named for the characteristic of pumping hydrogen ions during generation of ATP.
36
[25.3] List the types of molecules involved in the electron transport chain.
1. Flavin mononucleotide
2. Cytochromes
3. Iron-sulfur centers
4. Copper atoms
5. Coenzyme Q
37
[25.3] What is flavin mononucleotide?
A flavoprotein derived from riboflavin.
38
[25.3] What are cytochromes?
Proteins with a heme group that feature an oxidize and reduced form.
39
[25.3] List the cytochromes involved in the electron transport chain.
1. Cyt b
2. Cyt c1
3. Cyt c
4. Cyt a
5. Cyt a3
40
[25.3] What are iron-sulfur centers?
Proteins containing two or four irons bound to sulfur forming an electron transfer center.
41
[25.3] What is coenzyme Q?
A non-protein, low molecular weight carrier mobile in the lipid bilayer.
42
[25.3] How many ATP molecules are produced from glucose in oxidative phosphorylation?
23 - 25, depending if malate shuttles or glycerol phosphate shuttles are utilized.
43
[25.3] What are malate shuttles?
Transfer shuttles transporting electrons across the mitochondrian membrane in place of NADH+(H)+. Found in liver, kidney, and heart cells, produce 2.5 ATP.
44
[25.3] What are glycerol phosphate shuttles?
Transfer shuttles transporting electrons across the mitochondria membrane in place of NADH+(H)+. Found in skeletal muscle fibers and neurons, produce 1.5 ATP.
45
[25.3] How much ATP is produced by substrate-level phosphorylation?
4; two from glycolysis and two from Krebs cycle.
46
[25.3] What are the roles of glucose in anabolism?
Synthesis of glycogen and synthesis of glucose from protein and lipid breakdown.
47
[25.3] What is glycogenesis?
Formation of glycogen from many molecules of glucose when glucose is not being used.
48
[25.3] What is glycogenolysis?
The breakdown of glycogen into glucose.
49
[25.3] Describe the process of glycogenolysis in the liver.
Glucose is split from glycogen via phosphorylation, resulting in glucose-1-phosphate. It is then converted to glucose-6-phosphate, and then glucose. Glucose then leaves hepatocytes into the blood stream.
50
[25.3] Describe the process of glycogenolysis in skeletal muscle.
Glucose is split from glycogen via phosphorylation resulting in glucose-1-phosphate. It then enters glycolysis and the Krebs cycle.
51
[25.3] What is gluconeogensis?
The formation of glucose by the liver cells using glycerol from triglycerides, lactic acid, and amino acids.
52
[25.3] What stimulates gluconeogenesis?
Cortisol, glucagon, T3, and T4.
53
[25.4] What are lipoproteins?
Molecules formed by lipids and proteins. Outer hydrophilic sphere of proteins, phospholipids, and cholesterol and inner hydrophobic sphere of triglycerides.
54
[25.4] What are apoproteins?
Transport proteins forming the outer layer of lipoproteins.
55
[25.4] List the classifications of apoproteins.
1. Chylomicrons
2. Very low density lipoproteins
3. Low density lipoproteins
4. High density lipoproteins
56
[25.4] What are chylomicrons?
Lipoproteins transporting dietary lipids to adipose tissue. Arise in mucosal epithelium of small intestine.
57
[25.4] What are very low density lipoproteins?
Lipoproteins transporting endogenous triglycerides sourced from hepatocytes.
58
[25.4] How do chylomicrons and very low density lipoproteins detach their lipids?
Apoprotein c2 activates endothelial lipoprotein lipase, severing the fatty acid/triglyceride from the lipoprotein.
59
[25.4] What are low-density lipoproteins?
Lipoproteins that transport cholesterol
60
[25.4] How does low density lipoprotein enter cells?
Utilizing apoprotein B100 to enter cells through the plasma membrane.
61
[25.4] How does low density lipoprotein offload cholesterol?
LDL is broken down within cells, releasing cholesterol.
62
[25.4] What are high density lipoproteins?
Lipoproteins removing excess cholesterol from body cells and transporting to the liver for elimination.
63
[25.4] What are the two sources of cholesterol in the body?
Dietary cholesterol and endogenous cholesterol.
64
[25.4] How are lipids utilized in the body?
1. To produce ATP
2. Stored in adipose tissue
3. Used as structural molecules
4. Synthesize other essential substances.
65
[25.4] What are two essential fatty acids?
Linoleic acid and linolenic acid.
66
[25.4] What is the major function of adipose tissue?
To remove triglycerides from chylomicrons and VLDLs, storing them.
67
[25.4] Why is triglyceride storage widely used by the body?
Stored more readily than glycogen, triglycerides do not exert osmotic pressure, insulate and protects the body.
68
[25.4] What are lipases?
Enzymes catalyzing lipolysis.
69
[25.4] What is beta oxidation?
A series of reactions in fatty acid catabolism
70
[25.4] What occurs in beta oxidation?
Enzymes remove fragments of a fatty acid forming acetyl. These bind with coenzyme A and initiate the Krebs cycle.
71
[25.4] What is acetoacetic acid?
A molecule formed by two acetyl coenzyme A molecules removing the CoA portion. This allows the molecule to diffuse through plasma membranes.
72
[25.4] What is ketogenesis?
The formation of ketone bodies.
73
[25.4] What are the ketone bodies formed from acetoacetic acid?
1. beta-hydroxybutyric acid
2. Acetone
3. Acetoacetic acid.
74
[25.5] How are proteins utilized in the body?
1. As enzymes
2. Transportation
3. Antibodies
4. Hormones
5. Contractile fibers
6. Structural elements.
75
[25.5] What is demination?
Removal of an amino group from an amino acid allowing for amino groups to be utilized in the Krebs cycle. Produces ammonia which is converted to urea.
76
[25.5] What are essential amino acids?
Amino acids not produced by the body in adequate amounts.
77
[25.5] What are nonessential amino acids?
Amino acids synthesized by body cells in adequate amounts.
78
[25.5] What is transamination?
The transfer of an amino group from amino acid to pyruvic acid
79
[25.6] What are the three key molecules of metabolic crossroads?
1. Glucose-6-phosphate
2. Pyruvic acid
3. Acetyl coenzyme A
80
[25.6] List the main fates of glucose-6-phosphate
1. Synthesis of glycogen
2. Release of glucose into the bloodstream
3. Synthesis of nucleic acids
4. Glycolysis
81
[25.6] List the roles of pyruvic acid.
1. Production of lactic acid
2. Production of alanine
3. Gluconeogenesis.
82
[25.6] List the roles of acetyl coenzyme A.
1. Initiate Krebs cycle and electron transport chain
2. Synthesis of lipids.
83
[25.7] What is the absorptive state?
Duration after a meal where ingested nutrients enter the bloodstream and glucose is available. Requires 4 hours.
84
[25.7] What is the postabsorptive state?
Absorption of nutrients is complete and energy needs are met with body stores.
85
[25.7] What are absorptive state reactions?
Reactions during the absorptive state that satisfy the body's energy needs or synthesize proteins.
86
[25.7] List the reactions of the absorptive state satisfying energy needs or involved in synthesis of proteins.
1. Catabolism of glucose
2. Catabolism of amino acids
3. Protein synthesis
4. Catabolism of dietary lipids
87
[25.7] List reactions of the absorptive state that occur with excess nutrients.
1. Glycogenesis
2. Lipogenesis
3. Transport of triglycerides from the liver to adipose tissue.
88
[25.7] Describe regulation of metabolism during absorptive state.
Eating stimulates release of glucose-dependent insulinotropic peptide, releasing insulin. Insulin increases anabolic enzyme activity and reduces catabolic enzyme activity.
89
[25.7] What is the main function of the postabsorptive state?
To maintain normal blood glucose of 3.9-6.1 mmol/L without a supply of glucose from a meal.
90
[25.7] List the reactions of the postabsorptive state that produce glucose.
1. Glycogenolysis in the liver
2. Glycogenolysis in skeletal muscle
3. Lipolysis
4. Protein catabolism
5. Gluconeogenesis
91
[25.7] What is glucose sparing?
The process where body cells switch to fuels other than glucose as the main source of energy, rationing it for the brain and RBCs.
92
[25.7] List the reaction that produce ATP without glucose.
1. Catabolism of fatty acids
2. Catabolism of lactic acid
3. Catabolism of amino acids
4. Catabolism of ketone bodies.
93
[25.7] How is metabolism regulated during the postabsorptive state?
The hypothalamus monitors blood glucose and releases norepinephrine and the adrenal cortex releases catecholamines, stimulating glycogen breakdown alongside glucagon released by the pancreas. Catecholamines also promote lipolysis.
94
[25.7] What is fasting?
Going without food for many hours or days.
95
[25.7] What is starvation?
Weeks to months with food inadequacy or deprivation.
96
[25.8] What is energy balance?
The precise matching of energy intake to energy expenditure over time.
97
[25.8] What is a calorie?
The amount of energy in the form of heat required to raise the temperature of 1g of water 1 degree Celsius.
98
[25.8] What is a kilocalorie?
A measurement of calories used to express energy content of food, equivalent to 1000 calories.
99
[25.8] What is the metabolic rate?
The overall rate at which metabolic reactions use energy.
100
[25.8] List the factors affecting metabolic rate.
1. Hormones
2. Exercise
3. Nervous system
4. Body temperature
5. Ingestion of food
6. Age
7. Other factors incl. gender, sleep, malnutrition, climate, etc
101
[25.8] What is the basal state?
The state of the body in a quiet, resting, fasting condition.
102
[25.8] What is the basal metabolic rate?
The measurement of metabolism obtained under the basal state.
103
[25.8] What is the total metabolic rate?
The total expenditure of the body per unit of time.
104
[25.8] List the component contributing the the total metabolic rate.
1. Basal metabolic rate
2. Physical activity
3. Food-induced thermogenesis
105
[25.8] What is non-exercise activity thermogenesis?
The energy cost for maintaining muscle tone, posture, and involuntary fidget movements
106
[25.8] Describe food-induced thermogenesis.
The heat produced while digesting, absorbing, and storing food.
107
[25.8] What is satiety?
The feeling of fullness accompanied by lack of desire to eat.
108
[25.8] What is leptin?
A hormone helping to decrease adiposity, total body-fat mass.
109
[25.8] What is neuropeptide Y?
A neurotransmitter released when leptin and insulin is low, stimulates food intake.
110
[25.8] What is ghrelin?
A hormone that increases appetite, produced by endocrine cells of the stomach.
111
[25.9] What is heat?
A form of energy measured as temperature.
112
[25.8] What is core temperature?
The temperature in body structures deep to the skin.
113
[25.8] What is shell temperature?
Temperature near the body surface.
114
[25.8] List the mechanisms of heat transfer.
1. Conduction
2. Convection
3. Radiation
4. Evaporation
115
[25.8] Describe conduction as a mechanism of heat transfer.
Heat exchange that occurs between two materials in contact with each other. Approximately 3% of body heat is lost this way. Greater exchange with water than air.
116
[25.8] Describe convection as a mechanism of heat transfer
The transfer of heat by movement of air or water between areas of different temperature.
117
[25.8] Describe radiation as a mechanism of heat transfer.
The transfer of heat in the form of infrared rays between a warmer object and a cooler object, lacking physical contact.
118
[25.8] Describe evaporation as a mechanism of heat transfer.
The conversion of a liquid to a vapor, taking heat with it as it evaporates.
119
[25.8] What is insensible water loss?
The loss of water through evaporation through the skin, as well as through the mucous membranes of the mouth and respiratory system.
120
[25.8] Which control center of the CNS regulates temperature?
The hypothalamus, specifically the preoptic area, heat-losing center, and the heat-promoting center.
121
[25.8] What is thermoregulation?
The ability of the body to monitor core temperature and the mechanisms to produce or reduce heat.
122
[25.8] List the mechanisms of the body that participate in thermoregulation.
1. Vasoconstriction
2. Release of epinephrine and norepinephrine
3. Shivering
4. Release of thyroid hormones.
123
[25.10] What are nutrients?
Chemical substances in food that body cells use for growth, maintenance, and repair.
124
[25.10] List the main nutrients.
1. Carbohydrates
2. Water
3. Lipids
4. Proteins
5. Minerals
6. Vitamins
125
[25.10] What are essential nutrients?
Nutrients that the body cannot make in sufficient quantity to meet its needs.
126
[25.10] What are the recommended distribution of calorie consumption?
- 50-60% carbohydrates, less than 15% from sugars
- 30% from fat, less than 10% from saturated fats
- 12-15% from protein
127
[25.10] What are minerals?
Inorganic elements occurring naturally in the earth's crust.
128
[25.10] What are vitamins?
Organic nutrients required in small amounts to maintain growth and metabolism. Do not provide energy or serve as building material.
129
[25.10] What are provitamins?
Raw material of vitamins than can be used by the body to assemble full vitamins.
130
[25.10] What are the main groups of vitamins?
Fat soluble and water soluble.
131
[25.10] List the fat soluble vitamins.
1. A
2. D
3. E
4. K
132
[25.10] List the water soluble vitamins.
1. B
2. C
133
[25.10] What are antioxidant vitamins?
Vitamins that inactivate oxygen free radicals - highly reactive ions carrying an unpaired electron.
134
[25.10] List the antioxidant vitamins.
1. Vitamin C
2. Vitamin E
3. Beta-carotene
