The main processes of the nitrogen cycle are nitrogen fixation, nitrification, denitrification, anammox, and ammonification.
Explanation:
The sequence in which nitrogen passes from the atmosphere to the soil and organisms, and then is eventually released back into the atmosphere, is called nitrogen cycle.
Nitrogen cycle involves the following processes:
•Nitrogen Fixation
It is a process by which atmospheric nitrogen is converted into the form which can be easily absorbed the organisms on earth.
Nitrogen Fixation is carried out by the following ways:
1.By lightning: When lightning occurs, the high temperature and pressure convert nitrogen and water into nitrates and nitrites which get dissolved in water and are readily used by aquatic plants and animals.
2.By bacteria- Molecular nitrogen is converted into nitrates and nitrites by free living bacteria or the bacteria like Rhizobium present in the root nodules of legumes. Some bacteria convert the nitrogen gas (N2) to ammonia (NH3) which plants can use.
• Nitrification: It is the process by which ammonia is converted into nitrites and nitrates.
•Ammonification: It is the process by which soil bacteria decompose dead organic matter and release ammonia into soil.
•Denitrification: It is the process by which nitrates are converted into atmospheric nitrogen back to complete the cycle.
Answer:
a. The directionality of the complementary strand is antiparallel. The double-stranded DNA is antiparallel comprising two strands, which run alongside each other, however, point in reverse directions. In a double-stranded molecule of DNA, the 5 prime ends of one strand align with the 3 prime ends of the other strand, and vice versa.
b. The mediation of base pairing is done by non-covalent hydrogen bonds. It is reversible, that is, the strands can separate and can come combined again without any chemical modification.
The specificity of base pairing is illustrated by hydrogen bonds that is, the first strand produces hydrogen bonds only with a particular base in the second strand, and these two bases produce a base-pair.
c. The interaction or association of non-covalent type, that is, hydrophobic interaction and hydrogen bonding. Collectively, they both are strong. In the process, one base associate with the other base on the complementary strand.
d. The phosphate backbone possesses the tendency to associate with water on the outside of the molecule, and this is favorable chemically as both the strands are held together by hydrogen bond and hydrophobic interaction.
The polar molecules of sugar can produce hydrogen bonds with the surrounding molecules of water. The negatively charged phosphate group associate with the positively charged ions. The nonpolar nitrogen bases are found within the molecule and associate favorably through stacking interactions.
<span>These are enzymes. These molecules allow for the cell to metabolize and break down other molecules within the cell. Enzymes are specialized for the exact substances that they are to work on, and are able to accelerate the reactions by acting as catalysts for these reactions.</span>