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Nutrition Ch. 7

Metabolism
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Metabolism
The sum total of all the chemcial reactions that go on in living cells. Energy metabolism includes all the reactions by which the body obtains and spends energy from food. Example:...
Energy metabolism
All of the chemical reactions through which the human body acquires and spends energy from food
Anabolism
Small compounds joined together to make largers ones; energy must be used in order to do this Ana = up
Catabolism
Larger compounds BROKEN down into smaller ones; energy is RELEASED kata = down
Coupled reactions
Energy released from the breakdown of a large compounds is used to drive other reactions
ATP
Adenosine triphosphate; energy currency of the body -- produced when large compounds are broken down ATP is used to make large compounds from smaller ones.
Ribosomes
Cellular machinery used to make proteins
Mitochondria
Where energy is derived from fat, CHO, protein via TCA cycle, electron transport chain
Coenzyme
Complex organic molecules that work with enzymes to facilitate the enzymes' activity. Many coenzymes have B vitamins as part of their structures. co = with
Cofactor
The general term for substances that facilitate enzyme action is cofactors; they include both organic coenzymes such as vitamins and inorganic substances such as minerals
Enzymes
Protein catalysts - proteins that facilitate chemical reactions without being changed in the process
Metalloenzyme
Enzymes that contain one or more minerals as part of their structure
BREAKING DOWN NUTRIENTS FOR ENERGY CHO (Carbohydrate)
CHO - glucose (6 carbons)
BREAKING DOWN NUTRIENTS FOR ENERGY Fat
TG's - glycerol (3 carbons) + fatty acid (typically 18 carbons)
BREAKING DOWN NUTRIENTS FOR ENERGY Protein
Protein - amino acids 2C-N, 3C-N, or 5C-N
BREAKING DOWN NUTRIENTS FOR ENERGY New Compounds
Pyruvate (3 carbons) Acetyl CoA (2 carbons)
GLUCOSE BREAKDOWN
CHO - glucose (6 carbons) - pyruvate (3 carbons)
GLUCOSE BREAKDOWN With oxygen present = aerobic
Glucose (6C) - pyruvate (3C) - acetyl CoA (2C) - TCA cycle
GLUCOSE BREAKDOWN With inadequate oxygen present = anaerobid (during strenous exercise)
Glucose (6C) - Pyruvate (3C) - Lactic acid
GETTING RID OF LACTIC ACID Cory Cycle (liver repackages lactic acid as glucose)
Glucose (6C) - Pyruvate (3C) - Lactic acid - liver - glucose - back to blood - muscles (stored as glycogen)
FAT BREAKDOWN Trigycerides
TG's - 3 fatty acids + glycerol
FAT BREAKDOWN TG's - 3 fatty acids + glycerol Glycerol may be convered to
glucose or pyruvate depending on the cells needs; glucose is made if the blood glucose is low; pyruvate is made if energy is needed (will be broken down further in the TCA cycle)
FAT BREAKDOWN TG's - 3 fatty acids + glycerol Fatty acids may be converted to
acetyl CoA and proceeds through TCA cycle; requires oxygen to do this (an aerobic process)
FAT BREAKDOWN TG's - 3 fatty acids + glycerol Can you make glucose from fatty acids?
NO!!!!!
PROTEIN BREAKDOWN Use of protein depends upon
cells needs and availablity of glucose Note: before amino acids maybe used, they must be deaminateed (nitrogen group removed)
PROTEIN BREAKDOWN If glucose is needed....
Protein - amino acid (deaminated) - glucose (Glucose is used by the brain, red blood cells)
PROTEIN BREAKDOWN If energy is needed and glucose level is adequate....
Protein - amino acid (deaminated) - glucose - pyruvate - aceytl CoA - TCA cycle Note: Some amino acids enter pathway and are converted to acetyl CoA, some amino acids enter the TCA...
PROTEIN BREAKDOWN Deamination
amino acic - keto acid (NH3) keto acid - non-essential amino acid (NH3)
PROTEIN BREAKDOWN Transamination
A method for making non-essential amino acids; B6 needed for this process amino acid A + keto acid B = keto acid A = amino acid B
GETTING RID OF AMMONIA PRODUCED FROM DEAMINATION Urea cycle
Ammonia is toxic; must be converted to nontoxic compound immediately; liver packages ammonia as UREA; kidneys excrete UREA High protein intake creates more work for kidneys; if...
ELECTRON TRANSPORT CHAIN (an aerobic process, requires oxygen) Process?
1. Once acetyl CoA (2 carbon) enters the TCA cycle it quickly combines with a 4 carbon compound to create a 6 carbon compound 2. 2 carbons are lost during one turn of the cycle --...
FEASTING What happens to excess CHO's?
1. CHO's used first to replenish glycogen stores 2. Extra is converted to fat CHO - glucose - pyruvate - acetyl CoA - fatty acids OR CHO - glucose - gylcerol + (see notes)
FEASTING What happens to excess Fat?
Triglycerides stored directly into fat tissues, no breakdown required (except for chylomicron formation in GI)
FEASTING What happens to excess protein?
1. Dispose of Nitrogen group first via deamination 2. keto acid (amino acid minus nitrogen group) may enter metabolic pathway at pyruvate, acetyl CoA stage - acetyl CoA - fatty acids...
FASTING What happens if you fast less than 24 hours?
Will use up glycogen stores in liver and muscle tissue
FASTING What happens if you fast LONGER than 24 hours, but less than 3-4 days?
Will begin gluconeogenesis using muscle tissue protein to generate new glucose (about 90% of glucose supplied by breaking down muscle tissue; fat (via glycerol) contributes only 10%)
FASTING What happens if you fast LONGER THAN 3-4 DAYS?
Body shifts to KETOSIS to preserve muscle tissue; ketone bodies are 2 acetyl CoA' stuck together; some brain tissue is able to use ketone bodies for energy instead of glucose, which...
FAD DIETS Fad diets which promote eating only protein and fat will result in...
KETOSIS after 24 hours of diet
ALCOHOL AND NUTRITION Historical findings show humans have used alcohol for over...
5000 years
ALCOHOL AND NUTRITION; Biochemisty ethanol
alcohol in fermented beverages
Fuel
Compounds that cells can use for energy. The major fuels include glucose, fatty acids, and amino acids; other fuels include ketone bodies, lactic acid, glycerol and alcohol.
Photosynthesis
The process by which green plants use the sun's energy to make carbohydrates from carbon dioxide and water. photo = light synthesis = put together (making)
Name one of the body's high-energy molecules, and describe how it is used.
ATP (adenosine triphosphate) is a common high-energy compound composed of a purine (adenine), a sugar (ribose) and three phosphate groups. During digestion the energy-yielding...
What are the coenzymes, and what service do they provide in metabolism?
MEtabolic reactions almost always require enzymes to facilitate their action. In many cases, the enzymes need assistants to help them. Enzyme helpers are called coenzymes. Coenzymes...
Name the four basic units, derived from foods, that are used by the body in metabolic transformations. How many carbons are in the "backbones" of each?
Glucose - 6 carbons Glycerol - 3 carbons Fatty acid - even number of carbons (commonly 16 or 18) Amino acid - 2, 3 or more carbons with a Nitrogen attached
Define aerobic and nonaerobic metabolism. How does insufficient oxygen influence metabolism?
aerobic - requiring oxygen anaerobic - not requiring oxygen an = not Anaerobic pathway yield energy quickly, but cannon be sustaned for long - a couple of minutes at most....
How does the body dispose of excess nitrogen?
The liver continuously produces small amounts of ammonia in deamination reactions (removing nitrogen from amino acids). Some of this ammonia provides the nitrogen needed for the synthesis...
Summarize the main steps in the metabolism of glucose, glycerol, fatty acids and amino acids.
The digestion of carbohydrates yields glucose (and other momosaccharides): some is stored as glycogen, and some is broken down to pyruvate and acetal CoA to provide energy. The acetyl...
Describe how a surplus of the three energy nutrients contributes to body fat stores.
ALL EXCESS NUTRIENTS STORED AS FAT!!! Carbohydrate - broken down to glucose - used for liver and muscle glycogen stores - excess stored as FAT Fat - broken down to fatty acids...
What adaptations does the body make during a fast?
*Increasing the breakdown of fat to provide energy for most of the cells *Using glycerol and amino acids to make glucose for the red blood cells and central nervous system *Producing...
What are ketone bodies?
Ketone bodies are compounds produced during the imcomplete breakdown of fat when glucose is not available. Ketosis is a sign that the body's chemisty is going awry; Ketosis is the...
Define ketosis
An undesirably high concentration of ketone bodies in the blood and urine. Ketosis is the body's way to use its fats stores to fuel the brain by using ketones as an alternature...
Distinguish between a loss of fat and a loss of weight, and describe how each might happen.
Weight loss can be caused by shrinkage in the mass of organ tissues and wasting of muscles (due to starvation, fasting, etc.) Because of slowed metabolism during these conditions FAT...
Hydrolysis is an example of: a) coupled reaction b) anabolic reaction c) catabolic reaction d) synthesis reaction
b) catabolic (breaking)
During metabolism, released energy is captured and transferred by: a) enzymes b) pyruvate c) acetal CoA d) adenosine triphosphate
d) adenosine triphosphate (ATP)
Glycolysis: a) requires oxygen b) generates abundant energy c) converts glucose to pyruvate d) produces ammonia as a by-product
c) converts glucose to pyruvate
The pathway from pyruvate to acetyl CoA: a) produces lactic acid b) is known as gluconeogenesis c) is metabolically irreversible d) requires more energy that it produces
c) is metabolically irreversible
For complete oxidation, acetyl CoA enters: a) glycolysis b) the TCA cycle c) the Cori cycle d) the electron transport chain
b) the TCA cycle
Deamination of an amino acid produces: a) vitamin B and energy b) pyruvate and acetyl CoA c) ammonia and a keto acid d) carbon dioxide and water
c) ammonia and a keto acid
Before entering the TCA cycle, each of the energy-yielding nutrients is broken down to: a) ammonina b) pyruvate c) electrons d) acetyl CoA
d) acetyl CoA
The body stores energy for future use in: a) proteins b) acetl CoA c) triglycerides d) ketone bodies
c) triglycerides
During a fast, when glycogen stores have been depleted, the body begins to synthesize glucose from: a) acetyl CoA b) amino acids c) fatty acids d) ketone bodies
b) amino acids
metabolism **
all of the chemical reactions which take place in the body
energy metabolism **
all of the chemical reactions through which the human body acquires and spends energy from food
anabolism **
small compounds joined together to make larger ones; energy must be USED in order to do this
catabolism **
larger compounds broken down into smaller ones; energy is RELEASED
coupled reaction **
energy released from the breakdown of large compounds used to drive other reactions
ATP **
adenosine triphosphate - the body's energy currency; produced when large compounds are broken down; ATP is USED when smaller compounds are made into larger ones
ribosomes **
cellular machinery used to make proteins
mitochondria **
where energy is derived from fat, CHO, protein via TCA cycle, electron transport chain
Breaking down nutrients for energy CHO's Fats Protein What do they break down to and how many carbons do they each have?
CHO - glucose (6c) TG's - glycerol (3c) + fatty acid (typically 18c) Protein - amino acids (2C-N, 3C-N, or 5C-N)
Breaking down nutrients for energy New compounds; number of carbons
Pyruvate (3c) acetyl CoA (2c)
Glucose Breakdown CHO (glucose 6c) - pyruvate (3c) With oxygen present.....
aerobic glucose (6c) - pyruvate (2c) - Acetyl CoA (2c) - TCA cycle
Glucose Breakdown CHO (glucose 6c) - pyruvate (3c) Without oxygen present.....
withinadequate oxygen = anaerobic (during strenuous exercize for 1-3 minutes) glucose (6c) - pyruvate (3c) - LACTIC ACID
Getting rid of Lactic Acid: Cori Cycle (liver repackages lactic acid as glucose)
glucose (6c) - pyruvate (3c) - lactic acid - liver - glucose - back to blood - muscles (stored as glycogen)
Fat breakdown: TG's 3 fatty acids + glycerol
A) GLYCEROL may be converted to glucose OR pyruvate depending upon cells needs, glucose is made if blood glucose is low -- pyruvate is made if enertgy is needed (will be broken down...
Can you make glucose from fatty acids?
NOOOOOO!!!!! Only the glycerol portion of TG's can be coverted to glucose.
Protein breakdown: Use of protein depends on cells needs, availability of glucose. Note: Before amino acids can be used, they must be deaminated - take off Nitrogen group 1)...
1) protein - amino acid (deaminated - glucose; glucose used by brain, red blood cells 2) protein - amino acid (deaminated) - glucose - pyruvate -acetal CoA - TCA cycle Note: some...
Getting rid of ammonia produced from deamination
A) urea cycle (ammonia is toxic; must be converted to nontoxic compound immediately; liver packages ammonia as UREA; kidneys excrete urea B) high protein intake creates more work...


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