Answer:
transcription initiation
Explanation:
Transcription is a process by which genetic information from DNA is used to synthesize an RNA molecule, usually, a messenger RNA (mRNA), which is subsequently utilized to synthesize a protein by a process called translation. Transcription in prokaryotes has three steps:
1-Initiation: the RNA polymerase is a multisubunit enzyme (holoenzyme) composed of two α, one β, one β’ and one ω and σ subunits (α2ββ’ωσ). This holoenzyme binds to the promoter region of the template DNA strand.
2-Elongation. The sigma σ factor of the holoenzyme is released and the complex and the core enzyme (α2 ββω) moves along the template strand, thereby producing an mRNA sequence
3-Termination. This step can be Rho-dependent, where a protein named "Rho" recognizes the termination site and stop transcription, and Rho-independent (transcription continues until the termination sequence is reached).
In consequence, Rifamycin is likely to block the initiation of transcription because the core RNA enzyme needs to bind the sigma factor (σ) for initiation of transcription in bacteria.
Environmental manipulation of a crop can not only have unexpected consequences, but also have a negative impact on the atmosphere as well. The crops produced might be of inferior quality than expected. The amount of crop that grows can also be less. More water might be needed for the crops to grow.
Stem cells are what allow planaria to grow and regenerate as the stem cells can change into any of the cells that make up the planaria.
Answer:
Positive natural selection.
Explanation:
The positive natural selection is a type of natural selection that increases the frequency of an allele or trait when it is advantageous for the population. What happened in the example is that the mouth with the slight change in morphology (trait) was more advantageous for the population in the south in relation to the ancestral morphology (still preserved in the population in the north), and therefore its frequency increased. This, in turn, is due to the fact that the food (prey) is not the same in the two habitats (north and south). The specific prey in the south, caused the new morphology to be selected, (increasing the frequency of individuals with the new mouth), becasue probably that trait allows the trouts in the south to hunt more effectively.
