Answer:
The preceding section reviewed the major metabolic reactions by which the cell obtains and stores energy in the form of ATP. This metabolic energy is then used to accomplish various tasks, including the synthesis of macromolecules and other cell constituents. Thus, energy derived from the breakdown of organic molecules (catabolism) is used to drive the synthesis of other required components of the cell. Most catabolic pathways involve the oxidation of organic molecules coupled to the generation of both energy (ATP) and reducing power (NADH). In contrast, biosynthetic (anabolic) pathways generally involve the use of both ATP and reducing power (usually in the form of NADPH) for the production of new organic compounds. One major biosynthetic pathway, the synthesis of carbohydrates from CO2 and H2O during the dark reactions of photosynthesis, was discussed in the preceding section. Additional pathways leading to the biosynthesis of major cellular constituents (carbohydrates, lipids, proteins, and nucleic acids) are reviewed in the sections that follow.
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Carbohydrates
In addition to being obtained directly from food or generated by photosynthesis, glucose can be synthesized from other organic molecules. In animal cells, glucose synthesis (gluconeogenesis) usually starts with lactate (produced by anaerobic glycolysis), amino acids (derived from the breakdown of proteins), or glycerol (produced by the breakdown of lipids). Plants (but not animals) are also able to synthesize glucose from fatty acids—a process that is particularly important during the germination of seeds, when energy stored as fats must be converted to carbohydrates to support growth of the plant. In both animal and plant cells, simple sugars are polymerized and stored as polysaccharides.
Gluconeogenesis involves the conversion of pyruvate to glucose—essentially the reverse of glycolysis. However, as discussed earlier, the glycolytic conversion of glucose to pyruvate is an energy-yielding pathway, generating two molecules each of ATP and NADH. Although some reactions of glycolysis are readily reversible, others will proceed only in the direction of glucose breakdown, because they are associated with a large decrease in free energy. These energetically favorable reactions of glycolysis are bypassed during gluconeogenesis by other reactions (catalyzed by different enzymes) that are coupled to the expenditure of ATP and NADH in order to drive them in the direction of glucose synthesis. Overall, the generation of glucose from two molecules of pyruvate requires four molecules of ATP, two of GTP, and two of NADH. This process is considerably more costly than the simple reversal of glycolysis (which would require two molecules of ATP and two of NADH), illustrating the additional energy required to drive the pathway in the direction of biosynthesis.
Answer:mercury, lead, chromium
Explanation:
Answer
D
Glycolysis is the process, which occurs in cytoplasm of cell. This is the process which involves the breakdown of glucose to pyruvate. Citric acid cycle and beta oxidation of fatty acids occurs in the mitochondrial matrix, electron transport chain and oxidative phosphorylation occurs in the oxysomes. So, it is NOT a.
It has to be 2 and 3, which is D.
Explanation:
The land edge that is affected by marine processes is known generally as the coast
- A sea's shore is the area of land there. The coastline is the area of a shoreline where land and water converge.
- Coastlines are shaped in part by currents, tides, and waves. The ground is eroded or worn away when waves crash upon the shore.
- Despite making up only around 8% of the land on Earth, coastlines contain about 26% of all biological diversity.
- This wonderful environment, which is home to many different species of natural communities, is home to seabirds, clams, crabs, starfish, anemones, fish, kelp, and marine mammals, among many other creatures.
- Though it can also be a tough and challenging environment, since it is frequently altered by erosion and tides as well as pounded by waves and sea spray. Typically, there are three types of coasts: rocky, sandy, and muddy.
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Answer: 2
explanation: enzymes are known as proteins used to break down proteins and other macromolecules during digestion
