Lecture 1 (Exam 2) Flashcards
Substrate
Carbs, Fats, and Protein
- fuel sources from which we make energy (ATP)
- moderate to severe muscle effort relies on carbs
- protein provides little energy for cellular activity, but serves as a building block for body’s tissues
- Resting: ~50% carbs, ~50% fats
Bioenergetics
- process of converting substrates into energy
- Allows for metabolic reactions to occur
Anabolism
-involves the covalent bonding of electrons, protons, and small molecules to produce larger molecules
Catabolism
-breakdown of larger molecules and compounds into smaller molecules and compounds
Metabolism
- chemical reactions in the body
- catabolism + anabolism = metabolism
Anaerobic Metabolism
production of energy (ATP) in the absence of oxygen
-involves cytoplasm (sarcoplasm)
Aerobic Metabolism
process occurring in the mitochondria that uses oxygen to produce energy (ATP)
-aka cellular respiration
Adenosine Triphosphate (ATP)
- high-energy intermediate compound for for storing and conserving energy
- has all the potential energy to power all of the cell’s energy requiring processes
- cells extract energy from food and store it as ATP
Glycolysis
- breakdown of glucose through a pathway that involves a sequence of glycolytic enzymes
- allows carbs to be readily available and easily metabolized by muscles
Glycogenesis
the break down of glycogen by the muscles and liver into glucose-1-phosphate
Glycogenolysis
the conversion of glycogen into glucose
Glycogen
- stored in the sarcoplasm of muscles cells until those cells use it to form ATP
- can be stored in the liver and can be converted back to glucose as needed and then transported by the blood to active tissues where it is metabolized
- aka complex polysaccharide
Glucose
6-carbon sugar that is the primary form of carbohydrate used for metabolism
Lipolysis
- the process of breaking down triglycerides to its basic units (glycerol and FFA’s) to be used for energy
- controlled by enzymes called lipases
Lipogenesis
- the process of converting protein into fatty acids
- FFA’s convert protein into fats in times of starvation
Gluconeogenesis
the conversion of protein or fat into glucose
Rate Limiting Enzymes
- enzyme found early in a metabolic pathway that determines the rate of the pathway
- activity is determined by the accumulation of substances farther down the pathway that decrease enzyme activity through negative feedback
Mass Action Effect
substrate availability influences metabolic rate
- more available substrate = higher pathway activity
- excess of given substrate = cells rely on that energy substrate more than others
Endergonic Reactions
- require energy to be added
- endothermic (if heat is gained)
Exergonic Reactions
- release energy
- exothermic (if heat is released)
Coupled Reactions
release of energy in an exergonic reaction drives an endergonic reaction (exergonic and endergoinc are coupled reactions)
-ex. You eat a cracker (primarily with CHO energy). The body will release the energy gained from the consumed cracker and cause an exergonic reaction (release of energy) which will drive endergonic reactions
Laws of Thermodynamics (2)
1) Conservation of energy: energy can neither be created nor destroyed
2) Directionality: the direction of a reaction occurs in the direction of increased entropy (randomness and disorder) and release of free energy
How do the Laws of Thermodynamics relate to metabolism?
reactions in the body occur in the direction of energy release, thus, metabolism depends on the direction of reaction
What substrates are utilized during rest?
50% carbs and 50% fat
Energy Value for Fats
9.4 kcal/g; +70,000 kcal stored in body
Energy Value for Protein
4.1 kcal/g
Energy Value for Carbs
4.1 kcal/g; ~2,500 kcal stored in body
Monosaccharides
- any of the class of sugars (e.g., glucose and fructose) that cannot be hydrolyzed (broken down) to make a simpler sugar
- transported through blood to all body tissue
Disaccharides
any of a class of sugars whose molecules contain two monosaccharide residues (e.g. sucrose, lactose, maltose)
- provide energy to muscles
- fuel the central nervous system
- metabolize fat
- keep tissues from consuming protein for energy.
Polysaccharides
a carbohydrate (e.g., glycogen) whose molecules consist of a multiple sugar molecules bonded together -stored in muscles and liver until ready to be used to form ATP
How is the rate of energy production controlled by mass action effect?
aka: the availability of of primary substrates
-Substrate availability affects metabolic rate
More available substrates = higher pathway activity
Excess of given substrate (fuel; e.g. carbs) causes cells to rely on that energy substrate more than others
How is the rate of energy production controlled by enzyme activity?
Enzymes speed up the breakdown (catabolism) of chemical compounds
- each step of biochemical pathway requires specific enzyme(s)
- More enzyme activity (temperature & pH) = more product
