Answer: Infection occurs when the host is exposed to pathogens. virus uses the cell's metabolism, and replicates itself while destroying the cell or changing the cell's genetic makeup.
Explanation:
- A virus is a miniscule pocket of protein that contains genetic material.
- Viruses pose a considerable challenge to the body’s immune system because they hide inside cells.
- This makes it difficult for antibodies to reach them. Some special immune system cells, called T-lymphocytes, can recognise and kill cells containing viruses, since the surface of infected cells is changed when the virus begins to multiply.
- Many viruses, when released from infected cells, will be effectively knocked out by antibodies that have been produced in response to infection or previous immunisation.
- Antibiotics are useless against viral infections. So antiviral drugs work differently to antibiotics, by interfering with the viral enzymes instead.
Hence virus are the pathogen that use the cell's metabolism. And replicate itself while destroying the cell or changing the cell's genetic makeup. viruses are so simple that they use their host cells to perform their activities for them
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Answer: The DNA on the paternal copy of the chromosome will be methylated at the imprinting center, while the DNA on the maternal copy of the chromosome will not be methylated in this region.
Explanation:
Chromosomes are DNA structures associated with proteins such as histones. They are found in the nucleus of cells and contain genetic information for the development and functioning of an organism. Human beings are diploid, meaning that they possess two copies of each of the 23 chromosomes (a total of 46).
Gametes, which are sex cells such as the sperm (produced by the male) and the egg (produced by the female) that are haploid. This means that they possess only one chromosome of each pair. During fertilization, a male gamete fuses with a female gamete to generate a zygote, which will give rise to a new human being. <u>This new individual will possess half of the genetic material from its father and half from its mother. Thus having a total of 46 chromosomes, 23 from each parent</u>.
Genetic imprinting modulates gene expression by chemical modification of DNA and/or modification of chromatin structure. Often, genetic imprinting causes a gene to be expressed only on the chromosome inherited from one of the parents. One example of imprinting is DNA methylation, which is a process by which methyl groups are added to DNA. <u>Methylation modifies DNA function when found in the promoter gene, repressing gene transcription. This means that a methylated gene will not be expressed</u>, that is, it will not produce a protein encoded by that gene. So, if a region of DNA is imprinted in the sperm cell, the paternal chromosome inherited from this sperm will be methylated in the genes of the offspring. And the offspring will only express the maternal copy inherited, which will not be methylated.
Solar energy or fuel does little to pollute the earth's atmosphere.
Answer:
1.) Compounds that contain a fused ring systerm are called _steroids_. These have three 6-membered rings and one 5-membered ring. some of these compounds are found in biological membranes.
2.) _Fatty acids__ are the building blocks for many lipids, and they generally contain an even number of carbon atoms and an unbranched hydrocarbon chain
3.) _Glycolipid__ are formed when a carbohydrate is glycosidically linked to a hydroxyl group of a lipid. examples include gangliosides and cerebrosides. these are also found in biological membranes.
4.) _Triacylglycerols_are the storage form of lipids, accumulating in adipose tissue, and they can be used as metabloic fuel. these compounds have a polar part, made of three ester groups, and a nonpolar fatty acid tail.
5.) _Sphingolipids__ are made up of a long-chain amino alcohol joined, either by a glycosidic linkage or a phosphodiester linkage, to a fatty acid. these do not contain _glycerol__. they are abundant in the nervous system.
6.) When glycerol esterified to two fatty acids and a phophoric acid molecule a _glycerophospholipid_ is formed. These are found in biological membranes.
