• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Viruses. Viruses are not like cells or bacteria as they do not contain Chemical Machinery enzymes but only have one or sometimes two enzymes which simply decode their genetic instructions. This means the virus particle must have a HOST CELL which

Extracts from this document...


Viruses What is a virus? If you could see a virus you would be able to tell that it is a tiny particle. In fact they are about a thousandth of the size of a bacteria cell, and a bacteria cell is a lot smaller than a human cell. Viruses are that small they can only be seen through an electron microscope as they are a mere 17 to 300 nanometres in length (about a millionth of an inch). A virus particle is called a VIRION and is made up of:- > Nucleic acid- This is a set of genetic instructions, either DNA or RNA ( double stranded or single stranded ) > A coat of protein- This surrounds the DNA or RNA to protect it. > Lipid membrane- This is only found in some viruses such as influenza. It surrounds the coat of protein. These types of viruses are called "ENVOLOPE" viruses where if there isn't a lipid membrane it is called a "NAKED" virus. Viruses vary widely in there shape. ...read more.


This diagram shows what scientists call the LYTIC cycle. Regardless to the type of host cell, all viruses follow the lytic cycle. What the virus is doing is using the host cells chemical machinery enzymes to reproduce. The red spiral represents the virus genetic instructions and the orange part represents the protein coat around it. The lytic cycle is the process in which viruses use the host cell. 1) A virus attaches to the host cell 2) The particle releases its genetic instructions into the host cell. 3) The injected genetic material recruits the host cell's enzymes. 4) The enzymes make parts for more new virus particles. 5) The new particles assemble the parts into new viruses. 6) The new particles break free from the host cell. The protein on the out side of the virus particle " feels " or "recognises" the proper host cell. This protein attaches its self to the membrane of the host cell. Some envelope viruses dissolve straight through the membrane of the host cell. This happens because both the virus envelope and the cell membrane are made of lipids. ...read more.


When your body's immune system responds to the infection, and whole fighting the infection, it produces" PYROGENS ". These are chemicals that cause your body temperature to increase. This slows down the rate in which the virus spreads as your body's reactions work at their optimal at 37oC and when it rises above that, the rate starts to slow down. Example viruses This is what the HIV AIDS virus looks like. It stands for human immunodeficiency virus. It is a very complex virus, but nowhere as near as complicating as some viruses can get. It is an envelope virus and reproduces in the lysogenic cycle. This is an image of hepatitis B. It is a naked virus as its outer coat is the protein (HBc) These are all pictures of Ebola. As you can see it is a very weird shape compared to the other viruses. It is longs and skinny rather than circular. It is one of many hemorrhagic fevers and is often fatal. It gets it name from the democratic republic of Congo in Africa where it was first recognised. It is one of two RNA viruses in the Filovirdae virus family. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Molecules & Cells section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Molecules & Cells essays

  1. Aids and HIV.

    These are called "opportunistic infections" (OIs) because they take advantage of the body's weakened defences. You have heard it said that someone "died of AIDS." This is not entirely accurate, since it is the opportunistic infections that cause death. AIDS is the condition that lets them take hold.

  2. The Application of Enzymes in Industry and Medicine.

    Some proteases are used as anti-inflammatory reagents. The enzyme named superperoxide dismutase is also available as an anti inflammatory agent, but how successful it has been as a commercial product is unclear. Within drug manufacturing the chemical synthesis of complex drugs is often difficult and companies use enzymes to perform chemical conversions.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work