Viral diseases

• in the leaves of plants, causing them to produce abnormal patterns.
• Pathogens are disease-causing viruses, bacteria, fungi or protists, which can infect animals and plants.
• Humans have an immune system, which can defend them from pathogens.
• Viruses are ultramicroscopic infectious non-cellular organisms that can replicate inside the cells of living hosts, with negative consequences.
• Viruses are not alive because they do not complete all of the seven life processes: Movement, Respiration, Sensitivity, Nutrition, Excretion, Reproduction and Growth.
• Viruses are referred to as 'strains' of virus and not species.
• Viruses are made of a relatively short length of genetic material DNA Deoxyribonucleic acid The material inside the nucleus of cells, carrying the genetic information of a living being which is surrounded by a protein coat.
• The life cycle of a virus is the same as other pathogens Microorganism that causes disease.
• Viruses can often survive outside a host The organism lived on or in by a parasite for long periods of time.
• When viruses have infected a suitable host cell or cells, they replicate themselves within the cell thousands of times.
• Viruses do not divide and reproduce, but replicate their DNA and protein coats.
• The DNA and protein coats of viruses are then assembled into new virus particles.
• The host cell or cells then burst and other nearby cells can be infected with the virus.
• The process of a virus infecting a host cell or cells and replicating itself can be as quick as twelve hours in the case of the Norovirus A common 'upset tummy' infection caused by a virus which is highly contagious or several days for Ebola Often fatal disease caused by a virus which originated in Africa.
• Viral infections cannot be treated by antibiotics Substances that control the spread of bacteria in the body by killing them or stopping them reproducing.
• Measles is transmitted through the air in tiny droplets after an infected person sneezes.
• AIDS stands for acquired immune deficiency syndrome, a disease of the human immune system caused by infection with Human Immunodeficiency Virus (HIV).
• Immediately after infection, people often suffer mild flu-like symptoms.
• Currently, infected people are given antiviral drugs, which can slow the development of AIDS.
• Many children in developed countries are given vaccines against measles, but sadly this is not the case throughout the world.
• These pass and for a period of time infected people might not know they are infected.
• The virus infection can cause leaves to grow properly, which reduces the crop yield.
• The virus infection can make leaves crinkle or curl up.
• The virus infection reduces the plant's ability to photosynthesise.
• Plant leaves change their colour from green to yellow or white in a mosaic pattern due to a virus infection.
• HIV at this point has become AIDS.
• HIV stands for human immunodeficiency virus, a disease which damages cells in the immune system.
• Tobacco mosaic virus infects chloroplasts in the leaves of plants The tobacco mosaic virus infects tobacco and lots of other closely related species, such as tomatoes and peppers.
• There is no cure for HIV /AIDS although many scientists are trying to find one.
• Measles causes a fever and skin rash.
• Infection with measles can cause more serious effects like infertility in adults who did not catch the disease as children.
• HIV is transmitted by body fluids, often during unprotected sex, but also through cuts and injecting drugs using shared needles.
• There is no cure for the virus infection, therefore farmers must try to reduce the infection to their crops or attempt to reduce the spread of the virus.
• Measles is a very infectious viral disease that is often caught by young children.
• Algae subsumed within plants and some bacteria are also photosynthetic.
• The tobacco mosaic virus is transmitted by contact between plants, either naturally or through the hands of farmers.
• The tobacco mosaic virus infects the chloroplasts Contains the green pigment chlorophyll; the site of photosynthesis.
• Infected chloroplasts produce abnormal patterns.