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.
Go to:
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:
If the sun was farther away from Earth
Explanation:
Answer:
D. Aa
Explanation:
Given:
Jill (mother) is heterozygous for gene A --------- i.e Jill = Aa
Jack (father) who is homozygous recessive for gene A-------- i.e Jack = aa
Now if both cross and fertilization occurs, we have:
A a
a Aa aa
a Aa aa
The offsprings are (Aa, Aa, aa, aa)
Nondsijunction is the inability of homologous chromosomes to seperate properly during cell division. Now, we were told that this fertilization undergone nondisjunction in meiosis 1. Hence, both homologous chromosome move into the same daughter cells instead of different daughter cells because separation of homologous chromosome does not occur properly.
Therefore the result of these fertilization of a normal haploid sperm with an egg that had undergone nondisjunction in meiosis yields offspring with genotype Aa of their Mother (Jill).
Answer:
Option B, It increases the probability that some offspring will survive long enough to reproduce.
Explanation:
The larger the number of eggs, the larger will be the available opportunities for at least few of the youngsters to develop into adult being and survive till the age of fertility. This shall enhance the chances of producing new offspring before the older one dies thereby replacing them without changing the population number and further producing offspring that can survive to replace them and continue this chain.
Hence, option B is correct
Hey there! Here is your answer: Horseshoe crab is considered living fossils because they have existed unchanged for about 445 million years. They are usually not crab; they are not closely related to lobsters or crab. ... Horseshoe crab looks is almost the same with their ancient relatives despite the fact that they have been around for so long. I hope this helped! Your fellow Brainly user, GalaxyGamingKitty. (THE FOLLOWING INFORMATION HAS BEEN USED FROM GOOGLE)
