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Humans rely heavily on pollinator bees to sustain food production globally. But for decades, the insects’ population has declined, in part because of pesticide use. If the die-off continues, it will have huge economic and public health consequences for people. William Brangham reports on groups that are working on innovative ways to save the world’s jeopardized bee population — or supplement it.
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Yes capital letters are generally the dominant alleles while lowercase are recessive alleles. RR would be homozygous dominant, rr would be homozygous recessive and Rr would be heterozygous taking on the phenotype of the dominant
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Answer: Upwelling brings nutrient-rich deep waters to the surface, where algae can thrive in the sunlight, feeding the fish. ... The strong dependency of upwelling processes on the strength of trade winds contains one hint. Remember that trade winds are zonal winds, which feed off the latitudinal temperature gradient.
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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.
For an ecosystem that covers 70 percent of the planet, oceans get no respect.
All they’ve done is feed us, provide most of the oxygen we breathe, and protect us from ourselves: Were it not for the oceans, climate change would have already made Earth uninhabitable.
How?
The oceans have gamely absorbed more than 90 percent of the warming created by humans since the 1970s, a 2016 report found. Had that heat gone into the atmosphere, global average temperatures would have jumped by almost 56 degrees Celsius (100 degrees Fahrenheit).
But as vast as the seas are, there is a limit to how much they can absorb, and they are beginning to show it. Today, on World Oceans Day, Human Nature examines some of the ways that climate change affects life in the oceans — and what that means for humanity.
