Transcription factors are necessary for an initiation of transcription at a regulated gene but not sufficient.
Transcription is the first step of gene expression in which DNA molecule is copied (transcribed) into RNA (mRNA) by RNA polymerase. The process of transcription is divided into three phases:
1. Initiation
• RNA polymerase with transcriptional factors bind to gene promoter Transcription factors can enhance the interaction between RNA polymerase and a DNA sequence- promoter, encouraging the expression of the gene. Such transcription factors are called activators. Otherwise, when the gene expression is inhibited, factors are called repressors and they bind to sequence –operator.
• RNA polymerase unwinds DNA double helix (transcription bubble is formed)
2. Elongation
• RNA polymerases adds nucleotides complementary to DNA
3. Termination
• RNA polymerase gets to stop codon (transcribes a sequence of DNA known as a terminator)
• Formed complementary RNA strand is released from DNA-RNA complex
Answer:
Explanation:
The temperature and pressure on the earth's surface is lower than that below the earth's surface. Generally, temperature and pressure increases as you move/dig down the earth's surface. This increase in temperature and pressure causes the earth's sediment (below the earth surface) to form a compact solid rock - this process is known as lithification.
The correct answer is the first statement.
In intraspecies competition, there is a competition for recourses among the individuals from the same species. This is due to the limited availability of the recourses in the habitat. Only the fittest individuals will be able to gather enough recourses and survive.
Blood flows through an artery that is partially blocked. as the blood moves from the wider region into the narrow region, alternately increases and then decreases.
<h3>What is the purpose of blood flow in heart?</h3>
The removal of positive charge by electrochemical gradients causes the membrane potential of the cell to shift more strongly in the direction of the equilibrium potential for potassium.
The membrane would become more negative as potassium permeability through the membrane increased. Given that potassium is a positively-charged ion and that the intracellular environment has a net negative charge, enhancing the membrane's permeability would result in a more negative membrane.
For instance, the amplitude of the potassium concentration gradient across the myocyte decreases as the external potassium level rises, lowering the resting membrane potential.
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