Answer:
The correct answer is option 4.
Explanation:
Viruses cannot be considered alive as they cannot carry out metabolic reactions on their own. Metabolism signifies the tendency to gather and use energy. The chemical reactions in the cells spontaneously change the molecules into the forms of energy, which can be utilized by the organism.
However, in the case of viruses, they are too small and simple to collect and utilize their own energy. They are completely dependent upon the host cells for energy. The viruses only require energy when they need to make duplicates of themselves, however, they do not require any energy when they are present outside of the cell. Thus, as they cannot carry out metabolic reactions, they are not considered as living.
Answer:
Prokaryotic cells are surrounded by a plasma membrane and have DNA, cytoplasm, and ribosomes, like eukaryotic cells. They also have cell walls and may have a cell capsule. Prokaryotes have a single large chromosome that is not surrounded by a nuclear membrane.
Explanation:
Hydrogen bonds.
The nucleotides in a base pair are complementary which means their shape allows them to bond together with hydrogen bonds. The A-T pair forms two hydrogen bonds. The C-G pair forms three. The hydrogen bonding between complementary bases holds the two strands of DNA together
Answer:
knowledge of the sequence product
Explanation:
A gene knockout is a technique used in molecular genetics to deactivate target genes in an organism in order to study their functions by reverse genetics (i.e., gene loss). Knockouts are generated by different methods including, for example, homologous recombination or site-specific nucleases (zinc-fingers, TALENS, CRISPR/Cas9). These techniques require to know a priori the sequence of each gene to be knocked out in order to target desired mutations. In the last years, the CRISPR/Cas9 tool has gained attention to knockout genes of interest because it is a genome editing system that can be easily used for deletion or insertion of bases.
