Transcript Metabolism What is it?

Chapter 17
Lecture
Slides
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Food Guide Pyramid
• What is it?
- dietary guidelines of what and how much
food should be eaten to remain healthy
- bases on age, gender, activity level
- www.mypyramid.gov
- includes grains, vegetables, fruits, fats, oil,
dairy, meat, beans
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Figure 17.1
Kilocalories
• Calorie (cal):
amount of energy required to raise the temp.
of 1 gram of water 1o C
• Kilocalorie (kcal):
1000 calories
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Types of Nutrients
• Carbohydrates
• Proteins
• Lipids
• All are organic compounds.
• All contain carbon and hydrogen.
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Characteristics of Carbohydrates
• Contain C, H, O
• H:O is a 2:1 ratio
Ex. C6H12O6
• Broken down into monosaccharides.
• Monosaccharide:
- simple sugar (1 sugar)
- Ex. Glucose and fructose
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• Disaccharide:
- 2 sugars
- Ex. Glucose + fructose = sucrose
- Ex. Glucose + galactose=lactose
• Polysaccharide:
- many sugars
- Ex. Starch, grain, vegetables, glycogen, etc.
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Types of Carbohydrates
• Simple:
- no nutritional value
- cause weight gain
- Ex. candy and soft drinks (9 tea. sugar)
- Recommended amount: sparingly
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• Complex:
- fiber helps decrease colon cancer and heart
disease
- Ex. whole grains, pastas, rice, bread
- Recommended amount: at every meal
- Serving 1 piece of bread, ½ cup uncooked pasta
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Functions of Carbohydrates
• Short-term energy storage
• Converted to glucose quickly
• Glucose is used to make ATP (energy)
• Brain cells require glucose
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Characteristics of Proteins
• Contain C, H, O, N
• Broken down into amino acids
• 20 different amino acids
• Amino acids aren’t stored so a daily supply is required
• Recommended amount: 1-2 servings dairy group; 1-3
servings nuts/beans; 0-2 servings fish, poultry, eggs; red
meat sparingly
• Serving 2-3 oz.
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Types of Amino Acids
• Essential Amino Acids:
- 9 of 20 a.a.
- get from diet
- Ex. Tryptophan, valine, leucine, lysine, etc.
• Nonessential Amino Acids:
- 11 of 20 a.a.
- body makes them
- Ex. Glycine, proline, serine, etc.
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Food Sources for Amino Acids
• Complete food sources:
- supply all essential a.a.
- Ex. Red meat, milk, eggs, fish, poultry
• Incomplete food sources:
- supply only a few a.a.
- Ex. Beans, seeds, nuts, grains, leafy green
veg.
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Functions of Proteins
• Used to make skin, hair, nails, muscles
• Hemoglobin
• Act as enzymes
• Immune system functions
• Muscle contractions (actin and myosin)
• Part of cell membrane
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Characteristics of Lipids
• Contain C, H, O
• No 2:1 ratio of H:O
• Insoluble in water
• Ex. Fats, oils, cholesterol, triglycerides,
phospholipids
• Broken down into glycerol and fatty acids
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Types of Lipids
• Unsaturated:
- “better” for us
- liquid at room temp.
- Ex. plant oils
• Saturated:
- “bad” for us
- solid at room temp.
- Ex. meat, fish, and dairy
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• Trans:
- processed fats and oils
- raise LDL and lower HDL
- increase heart disease
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Cholesterol
• What is it?
- steroid
- high conc. in brain, liver, egg yolks, whole milk,
cheese, butter, meats
• LDL cholesterol:
- low density lipoprotein
- “bad” cholesterol
- carries cholesterol from liver to cells
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• HDL cholesterol:
- high density lipoprotein
- “good” cholesterol
- carries cholesterol from cells to liver
(processed)
- increase HDL through exercise
• Normal cholesterol 180 mg/dL
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Lipids and Diet
• Recommended amount:
- sparingly for saturated fats
- cholesterol 300 mg/day (1 egg yolk)
• Why are fats/lipids bad?
- cause weight gain and heart disease
- increase risk of colon and pancreatic cancer
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Reducing Fat and Cholesterol
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Eat poultry, fish, and beans
Eat vegetables and fruits high in fiber
Use herbs and spices for seasonings
Remove skin
Broil, bake, grill
Limit creams and butter
Avoid processed cheese, egg yolks, liver
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Functions of Lipids
• Long term energy storage
• Insulates against heat loss
• Protective cushion for organs
• Cholesterol is part of cell membrane structure
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Table 17.1.1
Vitamins
• Organic molecules in small quantities in food
needed for metabolism
• Balance diet gives body variety of vitamins
• Absence of vitamins results in deficiency
diseases
• Fat or water soluble
Daily Values
• Appear on food labels to help people eat healthy
• Based on 2000 kilocalorie diet
• 60% carbs, 30% total fats, 10% sat. fats, 10%
proteins
• Used to calculate Percent Daily Value
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Figure 17.2
Metabolism
• What is it?
- all chemical reactions in the body
- includes catabolism and anabolism
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Types of Metabolism
• Anabolism (synthesis):
- energy-requiring process
- Ex. ADP + P  ATP
• Catabolism (decomposition):
- energy-releasing process
- Ex. ATP  ADP + P
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Figure 17.3
ATP
• Adenosine Triphosphate
• Energy carrier
• Energy is released when ATP is broken down
• Made in mitochondria
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Background for Aerobic Respiration
• Cytoplasm:
jelly-like fluid inside cell
• Mitochondria:
- produce ATP
- contain inner and outer compartments (cristae)
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Figure
3.18a
• What are some other names for aerobic
respiration?
- cellular metabolism
- cellular respiration
- aerobic metabolism
• What is aerobic respiration?
breakdown of glucose in the presence of O2
(ATP produced)
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• Where does aerobic respiration occur?
all cells
• What is the equation for aerobic respiration?
C6H12O6 + 6O2 + 38 ADP + 38 P  6CO2 + 6H2O + 38 ATP
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• What is glucose?
C6H12O6 (sugar)
• Where do we get glucose?
food (especially carb.)
• Why do we need glucose?
to make ATP
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• What are the steps in aerobic respiration?
1. Glycolysis
2. Prep Step
3. Citric Acid Cycle
4. Electron Transport Chain
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Glycolysis
• What is glycolysis?
- 1st step
- 10 step enzyme driven reaction
• Where does it occur?
cytoplasm
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• What happens?
C6H12O6 is broken down into 2 pyruvic acid
(C3)
• What are the products?
2 pyruvic acid (C3)
2 ATP
2 NADH
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• What are NAD+ and FAD?
- electron carriers
- from niacin and riboflavin
• Is O2 required?
no
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Prep Step (Acetyl-CoA Formation)
• What is the prep step?
2nd step
• Where does the pyruvic acid formed in
glycolysis go? (Where does it occur?)
into mitochondria
• What happens to the pyruvic acid?
each loses a carbon (C3 – C1= C2)
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• What happens to the carbon that came off
pyruvic acid?
C1 + O2  CO2 (breathe out)
• What is the new C2 molecule?
acetyl
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• What happens to acetyl?
combines with coenzyme A to form acetyl-CoA
• What are the products?
2 acetyl-CoA
2 CO2
2 NADH
0 ATP
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• Is O2 required?
yes
• Is ATP produced?
no
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Citric Acid Cycle
•
What are some other names for the Citric
Acid Cycle?
Kreb’s Cycle
•
What is it?
3rd step
•
Where does it occur?
mitochondria
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• What happens?
acetyl + oxaloacetate  citric acid
C2 + C4
 C6
• What are the products?
4 CO2
2 ATP
6 NADH
2 FADH2
• Is O2 required?
yes
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Electron Transport Chain
• What is the ETC?
4th step
• Where does it occur?
mitochondria’s inner and outer comp. (cristae)
• What are the beginning substrates (things
needed for the reaction)?
NADH and FADH2
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• What happens?
1.NADH and FADH2 carry their electrons/H+ to
inner mit. comp. and “drop” them off.
2.H+ passes through a H+ pump to outer mit. comp.
(more H+ outside than inside)
3.H+ diffuses back into inner mit. comp.
4.As H+ diffuses the reaction of ADP + P  ATP
occurs.
5.H+ combines with O2 to make H2O.
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• What are the products?
34 ATP
6 H2O
• Is O2 required and if so WHY?
Yes, so H+ can diffuse and ATP can be
produced
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Anaerobic Respiration
• What is anaerobic respiration?
breakdown of glucose in the absence of O2
• Where does it occur?
cytoplasm
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• What are the steps?
1. Glycolysis
2. Product formation
• What are the products?
2 lactic acid
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• How many ATP are produced?
2
• Who can perform anaerobic respiration?
animals, bacteria, yeast
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Humans and Anaerobic Respiration
• Occurs in muscles during vigorous exercise:
- if not enough O2 gets to the muscle then
anaerobic resp. occurs
- lactic acid builds up in muscles
- once O2 is available lactic acid is converted
back to pyruvic acid and aerobic resp. takes
place
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Lipid Metabolism
• Triglycerides are body’s main energy storage
molecules
• Between meals triglycerides are broken down
into fatty acids and glycerol
• Metabolism occurs in mitochondria
• Series of reactions where 2 Carbons are
removed for fatty acids to form acetyl-CoA
• Acetyl-CoA combines to form ketones
• Too many ketones leads to acidosis in blood
Protein Metabolism
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Proteins are digested into amino acids
Amino acids are taken up by liver
Amino acids are used to make needed proteins
Amino acids can be converted into pyruvic
acid and acetyl-CoA
• Metabolism results in ammonia which is
converted to urea (liver)
Figure 17.8
Metabolic States
• Absorptive state:
- period immediately after a meal
- nutrients absorbed through intestinal wall
into circ. and lymphatic systems
- 4 hours after meal
- glucose goes to cells and some glycogen and fat
- fats into adipose
- amino acids used in protein synthesis
• Postabsorptive state:
- late in morning, late afternoon, or night after
absorptive state
- blood glucose levels maintained by converting
molecules to glucose
- first source glucose is liver
- triglycerides converted to glucose
- amino acids converted to glucose
Metabolic Rate
• What is it?
- total amount of energy produced and use in
body per unit of time
- basal metabolic rate: energy needed to keep
resting body functional
- used to determine amount of kilocalories
need per day
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Body Temperature Regulation
• Average body temp. is 98.6o F
• Maintained by balancing heat input with heat
loss
• Radiation:
- gain or loss of heat as infrared energy
between 2 objects not in physical contact
- Ex. Sun, hot sand, snow
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• Conduction:
- exchange of heat between objects that in
direct contact
- Ex. Bottom of feet and ground
• Convection:
- transfer of heat between body and air or water
- Ex. cool breeze over body
• Evaporation:
- conversion of water from liquid to gas
- Ex. Water from body surface
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• Amount of heat exchanged between env’t and
body is determined by difference in temps.
• Temp. regulation occurs by dilation and
constriction of blood vessel in skin
• Type of negative feedback system
• Monitored by neurons in hypothalamus
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