What is energy? Distinguish between various types of stored (potential) chemical
ID: 177506 • Letter: W
Question
What is energy? Distinguish between various types of stored (potential) chemical energy. What are the structural and functional consequences of storing energy as carbohydrate (glucose) versus ATP? What are some other kinds of stored (potential) energy found in a cell?What is energy? Distinguish between various types of stored (potential) chemical energy. What are the structural and functional consequences of storing energy as carbohydrate (glucose) versus ATP? What are some other kinds of stored (potential) energy found in a cell?
What is energy? Distinguish between various types of stored (potential) chemical energy. What are the structural and functional consequences of storing energy as carbohydrate (glucose) versus ATP? What are some other kinds of stored (potential) energy found in a cell?
Explanation / Answer
Answer:
Energy is the chemical form of ATP (adenosine triphospahte) produced from the metabolic activity and useful for cellular respiration and muscular activity to perform physiological functions.
Various types of stored (potential) energy:
Energy is stored in the form of carbohydrates, proteins and fats. At the time of fasting or low levels of glucose, or energy-deprived levels in the body, these stored molecules are going to undergo oxidation to produce glucose finally to generate ATP
Fats have higher stored energy compared to other macromolecules such as carbohydrates (glycogen in liver) & proteins (in liver & muscles). Therefore, oxidation of fat generate higher amount of energy as described below
1 gram of fat ---> 9 calories
1 gram of carbohydrate contain ------> 4 calories
1 gram of protein contain ------> 4 calories
The hunger is going to trigger glucose homeostasis through feedback mechanism to promote, transition from absorptive phase to post-absorptive phase to trigger glucose release from glycogenolysis (glucose from store glycogen), gluconeogenesis (glucose generation from non-carbohydrate sources such as fatty acid, proteins etc). This transition is leading o generation of energy from these sources to produce active energy for metabolic needs during cellular respiration.
Structural & functional consequences of storing energy as "carbohydrates" versus ATP:
Simple digestion of glucose rich carbohydrates by salivary amylase, pancreatic amylase and intestinal "maltase, sucrase and lactase" into simple monomers of glucose units
Glucose uptake into the liver cells, muscle cells and brain cells
Glucose monomers undergoes oxidation to generate energy
1. Glycolysis
2. Citric acid cycle
3. Electron transport-Oxidative phosphorylation
Excess glucose is going to convert into branched glycogen & stored inside the liver.
When body is under fasting, glycogen is going to convert into active glucose to generate energy.
The major break down of food molecules such as proteins, glycosides, lipids into simple soluble absorbable molecules in three stages to generate energy in various organelles. Stage-1 is the digestion of macromolecules by enzymatic action into the micromoleucles and monomers of glucose, amino acids and triglycerols, faaty acids respectively & occurs within the lysosomes followed by oxidation of monomers into energy carriers such as ATP, FADH2, NADH (3 types of energy carriers). Stage-II is the process of major energy -converting stage occurs in the cytosol as described below from monomer units by glycolysis generate 2 moles of ATP & 1 NADH energy carrier. Stage III is the process of generation of energy from these energy carrier activated molecules such as NADH, FADH2 that occurs inside the mitochondria.
The primary function of cellular respiration is to generate ATP, which traps some of the chemical energy of food molecules in its high- energy bonds (adenosine triphosphate). The process of generation of ATP is via glycolysis and Krebs’s cycle finally through oxidative phosphorylation.
The overall balanced reaction of cellular respiration is:
CHO + 6O 6CO + 6HO + ATP
Glucose + oxygen carbon dioxide + water + energy
In this reaction, glucose oxidized and oxygen reduced.
Glucose ----> 686 kcal/mol of free energy
One ATP ----> produce 7.3 kcal/mol
Now 7.3 x 36 (ATP produced from one mole of glucose via glycolysis, Kreb's cycle, oxidative posphorylation) = 262.8 kcal/mol for all ATP's produced
262.8 / 686 = 38.3% energy efficiency & it is recovered from aerobic respiration of one mole of glucose
The remaining 423.2 kcal/mole is the energy used for the other cellular miscellaneous activities such as some of the phosphorylation processes are mediated by ATP in both glycolysis, Krebs’s cycle as well as during electron transport. Therefore, remaining 61.6% energy utilized during enzymatic reaction mediated by substrate level phosphorylation reactions of cellular respiration.
Adenosine triphosphate is the energy molecule used during various metabolic, oxidation -reduction reactions starting from a series of energy transformations, starting with the energy stored in highly reduced carbons of acetyl coenzyme A, pyruvate etc. The glycolysis and citric acid cycle produce various forms of energy deriving molecules such as GTP (guanosine monophosphate), NADH (3 ATP), FADH2 (2ATP, flavin nucleotides). These molecules are going to undergo oxidative phosphorylation to generation ATP in the mitochondria finally each ATP produce G°= -7.3 kcal/mol for every anabolic & catabolic reaction to proceed during any metabolic process. The transformation of these molecules such as NADH, FADH2 into the ATP are in the presence of cytochrome complexes (complex I to complex IV) of mitochondria through electron transfer, proton motive force, ATP synthase (Fernadez -moran particles).
ATP undergoes hydrolysis into AMP plus pyrophosphate (PPi), a high- energy form of phosphate. This reaction is going to produce similar amount of energy as teh exact amount of free energy delivered during the hydrolysis of ATP to ADP.
Other kinds of stored (potential) energy found in a cell:
Energy is stored in the form of fatty acids, protens (non-carbohydrate sources) and glycogen (carbohydrate sources)
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