Answer:
Okay
Explanation:
Human topoisomerase I plays an important role in removing positive DNA supercoils that accumulate ahead of replication forks. It also is the target for camptothecin-based anticancer drugs that act by increasing levels of topoisomerase I-mediated DNA scission. Evidence suggests that cleavage events most likely to generate permanent genomic damage are those that occur ahead of DNA tracking systems. Therefore, it is important to characterize the ability of topoisomerase I to cleave positively supercoiled DNA. Results confirm that the human enzyme maintains higher levels of cleavage with positively as opposed to negatively supercoiled substrates in the absence or presence of anticancer drugs. Enhanced drug efficacy on positively supercoiled DNA is due primarily to an increase in baseline levels of cleavage. Sites of topoisomerase I-mediated DNA cleavage do not appear to be affected by supercoil geometry. However, rates of ligation are slower with positively supercoiled substrates. Finally, intercalators enhance topoisomerase I-mediated cleavage of negatively supercoiled substrates but not positively supercoiled or linear DNA. We suggest that these compounds act by altering the perceived topological state of the double helix, making underwound DNA appear to be overwound to the enzyme, and propose that these compounds be referred to as ‘topological poisons of topoisomerase I’
Answer:
The processing power of the mammalian brain is derived from the tremendous interconnectivity of its neurons. An individual neuron can have several thousand synaptic connections. While these associations yield computational power, it is the modification of these synapses that gives rise to the brain's capacity to learn, remember and even recover function after injury. Inter-connectivity and plasticity come at the price of increased complexity as small groups of synapses are strengthened and weakened independently of one another (Fig. 1). When one considers that new protein synthesis is required for the long-term maintenance of these changes, the delivery of new proteins to the synapses where they are needed poses an interesting problem (Fig. 1). Traditionally, it has been thought that the new proteins are synthesized in the cell body of the neuron and then shipped to where they are needed. Delivering proteins from the cell body to the modified synapses, but not the unmodified ones, is a difficult task. Recent studies suggest a simpler solution: dendrites themselves are capable of synthesizing proteins. Thus, proteins could be produced locally, at or near the synapses where they are needed. This is an elegant way to achieve the synapse specific delivery of newly synthesized proteins.
Explanation:
Answer:
In interphase cell grow in size, DNA and protein synthesis takes place.
Explanation:
Interphase is the longest phase in the cell cycle and contain three sub phases and one checkpoint at the end of every checkpoint.
G₁ phase: In this phase the size of the cell increases and nearly becomes double, the raw material for DNA synthesis is synthesised e.g: mRNA and proteins(histone).
S phase: In synthesis phase replication of DNA takes place and amount of DNA become double so that it can be evenly distributed between daughter cells.
G₂ phase: In this phase cell continues to grow and synthesize proteins. cell prepare itself to move in mitotic phase so it can divide.
Answer:
Sexual and drug substance use risks should be determined during a routine health history with every new patient and updated regularly during periodic health care.
Risk assessment helps to identify individuals at risk; support recommendations for HIV, STD, and hepatitis screening; and establish risk reduction education topics and strategies.
Risk assessment can help people who are already infected access treatment
and learn how to avoid transmitting HIV to others.
Explanation:
