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.
Answer and Explanation:
Ribosomes are the primary structure for protein synthesis. They can be found in the rough endoplasmic reticulum or floating in the cytosol.
Free ribosomes are not attached to any cytoplasmic structure or organelle. They synthesize proteins only for internal cell use. Other ribosomes are attached to the membrane of the endoplasmic reticulum and they are in charge of synthesizing membrane proteins or exportation proteins. Free and attached ribosomes are identical and they can alternate their location. This means that although free ribosomes are floating in the cytosol, eventually, they can get attached to the endoplasmic reticulum membrane.
Synthesis of proteins that are destined to membrane or exportation starts in the cytoplasm with the production of a molecule portion known as a <u>signal aminoacidic sequence</u>. This signal sequence varies between 13 and 36 amino acids, is located in the <u>amino extreme</u> of the synthesizing protein, and when it reaches a certain length, it meets the <u>signal recognizing particle</u>. This particle joins the signal sequence of the protein and leads the synthesizing protein and associated ribosome to a specific region in the Rough endoplasmic reticulum where it continues the protein building. When they reach the membrane of the endoplasmic reticulum, the signal recognizing particle links to a receptor associated with a pore. Meanwhile, the ribosome keeps synthesizing the protein, and the enlarged polypeptidic chain goes forward the reticulum lumen through the pore. While this is happening, another enzyme cuts the signal sequence, an action that requires energy from the ATP hydrolysis. When the new protein synthesis is complete, the polypeptide is released into the reticulum lumen. Here it also happens the protein folding (which is possible by the formation of disulfide bridges of proteins are formed) and the initial stages of glycosylation (the oligosaccharide addition).
Once membrane proteins are folded in the interior of the endoplasmic reticulum, they are packaged into vesicles and sent to the Golgi complex, where it occurs the final association of carbohydrates with proteins. The Golgi complex sends proteins to their different destinies. Proteins destined to a certain place are packaged all together in the same vesicle and sent to the target organelle. In the case of membrane proteins, they are packaged in vesicles and sent to the cell membrane where they get incrusted.
There are certain signal sequences in the <u>carboxy-terminal extreme</u> of the protein that plays an important role during the transport of membrane proteins. A signal as simple as one amino acid in the c-terminal extreme is responsible for the correct transport of the molecule through the whole traject until it reaches the membrane.
Answer:
The mutation for sickle cells will start to disappear because there's no benefit to carrying the disease if malaria is cured.
Explanation:
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Answer:
The nervous system takes in information through our senses, processes the information and triggers reactions, such as making your muscles move or causing you to feel pain. For example, if you touch a hot plate, you reflexively pull back your hand and your nerves simultaneously send pain signals to your brain
