Viruses Flashcards
What are viruses made of?
Viruses are composed of a core of nucleic acid surrounded by a proton donor
Where do viruses grow?
Because they are not made of cells, they do not have the cell machinery for their own metabolism, so they only grow in living tissue.
What can viruses be considered outside of living cells?
Where they exist outside of living cells, they may be considered non-living chemicals, since they do not display any of the characteristics of life.
What can viruses do once inside a living cell?
Once they are inside a living cell they can replicate with the help of the host cell and so are clearly alive.
Do viruses have features of living or non-living material?
So, viruses have features of both living and non-living material.
What are viruses called because since they can only multiply inside living cells?
Since they can only multiply inside living cells, they are called obligate parasites
What can viruses do as parasites?
As parasites they cause many diseases in humans, domestic animals and crop plants.
What are viruses called because since they can only multiply inside living cells?
Since they can only multiply inside living cells, they are called obligate parasites
What does being obligate parasites mean in terms of agar?
This means that they cannot be grown on agar like bacteria or fungi
What does being obligate parasites mean to do with antibiotics?
It is also the reason why antibiotics do not work against them, as there is no cell machinery for the antibiotic to damage.
What is one way of recognising and classifying different viruses?
Different kinds of viruses have different shapes and this is one way of recognising and classifying them.
How can we only see viruses because they are so small?
Because viruses are so small, we can only see them with an electron microscope.
How many viruses could fit side by side on the tip of your pen?
10,000 viruses could fit side by side on the tip of your pen.
Draw virus replication.
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What are the disadvantages of viruses?
Diseases of humans, plants and animals
What are common human diseases?
Measles, Mumps, Rubella, Cold, Warts
How do plant diseases gain entry to a plant?
.
What are examples of plant diseases?
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What are examples of animal diseases?
Foot and mouth, SARS (Sudden Acute Respiratory Syndrome) and Rabies
What are the advantages of viruses?
Genetic engineering, where they are used inject a gene into target cells.
Mosaic patterns give new variety to garden plants.
What is immunity?
Immunity is the ability of an organism to resist infection.
What are pathogens?
Pathogens are micro-organisms [microbes] that cause disease.
What is the human body designed to do in terms of foreign cells or invaders?
The human body is designed to protect itself from foreign cells or invaders, and we have two lines of defence - general and specific.
What does our general defence system consist of?
Our general defence system consists of skin, mucous membranes, platelets and white blood cells.
What is the barrier to entry?
Barrier to entry: the skin and mucous membrane lining of the respiratory, digestive and reproductive tract.
How does the skin act as a barrier to entry?
The skin, acting as a structural barrier, secretes chemicals from the sebaceous glands that harm or kill bacteria.
How does the respiratory and digestive tracts act as barriers to entry?
The respiratory and digestive tracts as well as other organs of the body secrete mucus and/or further chemicals that may remove foreign particles.
What does our specific defence system involve?
An antigen-antibody response, involving specialised white blood cells, called lymphocytes and monocytes [macrophages].
What is the function of lymphocytes?
Lymphocytes - stored in lymphatic system (spleen, lymph nodes, tonsils, adenoids and thymus gland), have large nucleus and make antibodies. (25% of white cells)
What is the function of monocytes?
Monocytes - digest bacteria, have kidney shaped nucleus and lilve for 6-9 days (5% of white cells)
What are monocytes?
Phagocytic white blood cells - also called macrophages. These engulf bacteria and viruses upon contact.
What do other types of monocytes do?
Others secrete chemicals that stimulate general defence and cause fever to destroy microbes at high temperatures
What makes up the specific defence system?
Organs specific to the immune system: the spleen, thymus and lymph nodes.
What do lymph and blood vessels contain?
Lymph and blood vessels contain cells called lymphocytes and monocytes - both are produced in the bone marrow and they respond to antigens