The virus needs to speak the molecular language of cells. This is how he manages to dominate and enslave them so that they become factories for new viruses, producing the proteins that the infectious agent requires to assemble its descendants. If this conversation is not fine-tuned, even if the virus has the key and enters, it is doomed to failure.
<h3>Why does a virus lethal to us not infect animals?</h3>
For a virus to be able to enter a cell, it must have the right key. And this key, which are the proteins on the surface of viruses, has to enter the correct lock, the receptors that are on the cell membrane. Cells are actually houses with many different doors and locks. Some viruses have keys that open the lock of any cell and any kind of host, and others do not, so the infection caused by viruses is specific.
With this information, we can conclude that some viruses have keys that open the lock of any cell and any kind of host, and others do not, so the infection caused by viruses is specific.
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The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder).[1] In this system, the process of digestion has many stages, the first of which starts in the mouth. Digestion involves the breakdown of food into smaller and smaller components, until they can be absorbed and assimilated into the body.
Chewing, in which food is mixed with saliva begins the process of digestion. This produces a bolus which can be swallowed down the esophagus and into the stomach. Here it is mixed with gastric juice until it passes into the duodenum, where it is mixed with a number of enzymes produced by the pancreas. Saliva also contains a catalyticenzyme called amylase which starts to act on food in the mouth. Another digestive enzyme called lingual lipase is secreted by some of the lingual papillae on the tongue and also from serous glands in the main salivary glands. Digestion is helped by the mastication of food by the teeth and also by the muscular actions of peristalsis and segmentation contractions. Gastric juice in the stomach is essential for the continuation of digestion as is the production of mucus in the stomach.
Peristalsis is the rhythmic contraction of muscles that begins in the esophagus and continues along the wall of the stomach and the rest of the gastrointestinal tract. This initially results in the production of chyme which when fully broken down in the small intestine is absorbed as chyle into the lymphatic system. Most of the digestion of food takes place in the small intestine. Water and some minerals are reabsorbed back into the blood in the colon of the large intestine. The waste products of digestion (faeces) are defecated from the anus via the <span>rectum</span>
Answer:
Addition of a(n) methyl group to certain lysine residues of a histone protein makes the region of chromatin transcriptionally silent; addition of a(n) acetyl group to certain lysine residues makes the region of chromatin transcriptionally active.
Explanation:
The changes suffered in the expression and activity of the genes are studied by the Epigenetics.
Answer:
Radiogenic isotopes.
Explanation:
Dating is a process by which archaeologists get to know the absolute or relative age of a past objects. Absolute dating deals with the process of determining the absolute age of the element. During dating of objects, or during the radiometric dating if we know the half-life of the element, it will be easy to know the age of that object by determining the decay rate of the isotopes.
Answer:A. Solar energy, which enables plants to photosynthesize and helps humans produce electricity
Explanation:
