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The color of a star is primarily determined by its surface temperature.
For example, the really hot stars, called White Dwarf stars, have a white surface temperature, while a cooler star would have a more red color.
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Living organisms adapt to their moves and positions in response to the environmental changes for their protection or to their advantage. When an entity reacts to the changes in its surroundings, it is referred to as stimulus while the reaction to the stimulus is referred to as a response. Common stimuli are sound, light, air, heat, smell, taste, water and gravity.
Think of burning your finger of fracturing your bone without any pain sensation. It may certainly sound like a superpower or an ideal situation, however, when it comes to the standpoint of survival, it can be disastrous.
It is a characteristic behaviour of living entities to respond to stimuli with the intervention of the Nervous System. It is an organ system ascribed to send signals from the spinal cord and the brain throughout the body and then back from all the body parts to the brain. Neuron acts as the mediator and is the basic signalling unit of the Nervous system.
Pain is the body’s way of letting us know that something is not right. It can prevent further injuries or push us to seek medical attention. Moreover, all of this is possible because humans can respond and react to stimuli due to control and coordination among the various organs and organ systems.
Control and Coordination in simple multicellular organisms take place through only the Nervous system which coordinates activities of our body. It is the control system for all our actions, thinking, and behaviour.
- "This energy is usually in the form of low-level thermal energy. It is only possible to extract work when there is a temperature difference, so low-level thermal velocity; this means that the force of friction and the applied force are equal in magnitude."
- "An energy transformation is the change of energy from one form to another. Energy transformations occur everywhere every second of the day. There are many different forms of energy such as electrical, thermal, nuclear, mechanical, electromagnetic, sound, and chemical."
The DNA polymerases are enzymes that create DNA molecules by assembling nucleotides, the building blocks of DNA. These enzymes are essential to DNA replication and usually work in pairs to create two identical DNA strands from one original DNA molecule. During this process, DNA polymerase “reads” the existing DNA strands to create two new strands that match the existing ones.
Every time a cell divides, DNA polymerase is required to help duplicate the cell’s DNA, so that a copy of the original DNA molecule can be passed to each of the daughter cells. In this way, genetic information is transmitted from generation to generation.
Before replication can take place, an enzyme called helicase unwinds the DNA molecule from its tightly woven form. This opens up or “unzips” the double stranded DNA to give two single strands of DNA that can be used as templates for replication.
DNA polymerase adds new free nucleotides to the 3’ end of the newly-forming strand, elongating it in a 5’ to 3’ direction. However, DNA polymerase cannot begin the formation of this new chain on its own and can only add nucleotides to a pre-existing 3'-OH group. A primer is therefore needed, at which nucleotides can be added. Primers are usually composed of RNA and DNA bases and the first two bases are always RNA. These primers are made by another enzyme called primase.
Although the function of DNA polymerase is highly accurate, a mistake is made for about one in every billion base pairs copied. The DNA is therefore “proofread” by DNA polymerase after it has been copied so that misplaced base pairs can be corrected. This preserves the integrity of the original DNA strand that is passed onto the daughter cells.

A surface representation of human DNA polymerase β (Pol β), a central enzyme in the base excision repair (BER) pathway. Image Credit: niehs.nih.gov
Structure of DNA polymerase
The structure of DNA polymerase is highly conserved, meaning their catalytic subunits vary very little from one species to another, irrespective of how their domains are structured. This highly conserved structure usually indicates that the cellular functions they perform are crucial and irreplaceable and therefore require rigid maintenance to ensure their evolutionary advantage.
