Metabolism, Nutrition, and Energetics Flashcards
Subtrates
Substances acted on by an enzyme
Metabolism
Sum of all chemical and physical changes that occur in body tissues
Catabolism
Catabolic reactions
Convert large molecules into smaller ones
Anabolism
Anabolic reactions
Convert small molecules into larger ones
Nutrient pool
All the available nutrient molecules distributed in the blood
Catabolism of fats
Lipolysis
Fats > fatty acids and glycerol
Catabolism of carbohydrates
Glycogenolysis
Carbohydrates > glucose
Catabolism of proteins
Proteins > amino acids
What provides the energy for anabolism?
ATP from mitochondria
4 reasons cells synthesise new organic compounds
- Carry out structural maintenance or repairs
- To support growth
- To produce secretions
- To store nutrient reserves
Energetics
Flow of energy and its transformation from one form to another
Oxidation
Loss of electrons
Decrease in potential energy
Reduction
Gain of electrons
Increase in potential energy
Coenzyme
Acts as an intermediary that accepts electrons from one molecule and transfers them to another molecule e.g. NAD and FAD
Cellular respiration
glucose + 6 oxygen -> 6 carbon dioxide and 6 water
Glycolysis
The cell gains a net 2 molecules of ATP for each glucose molecule broken down anaerobically to 2 molecules of pyruvate. 2 molecules of NADH are also produced. In most cells, electrons are passed from NADH to FAD by an intermediate electron carrier in the intermembrane space, producing FADH2, and then to the electron transport chain
Citric acid cycle
Each of the two revolutions of the citric acid cycle required to break down the 2 pyruvate molecules completely yields 1 molecule of ATP by way of GTP. This cycling provides an additional gain of 2 molecules of ATP. This cycle transfers hydrogen atoms to NADH and FADH2. These coenzymes provide electrons to the electron transport chain
Electron transport chain
For each molecule of glucose broken down, a total of 10 NADH and 2 FADH2 deliver their high-energy electrons to the electron transport chain
Each NADH yields 2.5 ATP and each FADH2 yields 1.5 ATP. The 2 FADH2 molecules from glycolysis yield 3 ATP molecules and 2 water molecules. Each of the 8 molecules of NADH from the citric acid cycle yields 2.5 molecules of ATP and 1 water molecules. Thus, the shuffling from the citric acid cycle to the ETC yields 23 molecules of ATP
Gluconeogenesis
Formation of new glucose
Glycogenesis
Formation of glycogen (storage form of glucose)
Glycogenolysis
Breakdown of glycogen to glucose
Glycolysis
Breakdown of glucose to pyruvate
Beta-oxidation
Fatty acid molecules are broken down in a sequence of reactions into 2-carbon acetic acid fragments, and FAD and NAD+ are reduced
Lipogenesis
Synthesis of lipids
Essential fatty acids
Must be included in diet
How do most lipids circulate the body?
Through the bloodstream as lipoproteins
Why are lipids important energy reserves?
Because their breakdown provides large amounts of ATP
Free fatty acids
Lipids that can diffuse easily across plasma membranes
Generally bound to albumin
Lipoproteins
Lipid-protein complexes that contain large insoluble glycerides and cholesterol
A superficial coating of phospholipids and proteins makes the entire complex soluble
Groups of lipoproteins
Produced in:
Intestines
1. Chylomicrons
Liver
- VLDL
- LDL
- HDL
Good cholesterol
HDL
Returning from peripheral tissues and doesn’t cause circulatory problems
Why does exercise lower cholesterol?
Stimulates enzymes that move LDL from the blood into the liver and exercise increases the size of the protein particles that carry cholesterol in the bloodstream
Transamination
Reversible chemical reaction that transfers the amino group of an amino acid to a keto acid
Keto acids
Resemble amino acids except that the second carbon binds to an oxygen atom rather than to an amino group
Deamination
The amino groups is removed an an ammonium ion is released
Liver cells are the primary site
Amination
An ammonium ion is used to form an amino group that is attached to a molecule, yielding amino acid
Nonessential amino acids
Body can make them on demand
Amination
Adding of an amino group
Absorptive state
Energy storage
Time following a meal
4 hours
Insulin primary hormone
Postabsorptive state
Energy release
When nutrients aren’t being absorbed
Glucagon, epinephrine, glucocorticoids, and GH
Nitrogen balance
Difference between total nitrogen you consume and the amount you excrete
Minerals
Inorganic ions
