What do you think this is?What do you think this is?

VirusesViruses

What do you Think These Objects What do you Think These Objects are? Are They Living?are? Are They Living?

Plant Virus Tobacco MosiacPlant Virus Tobacco Mosiac

Bacteria Vs Virus

VIRUSES

Virus: infectious particle that contains DNA or RNA surrounded by a protein coat that can only reproduce in a host cell.

Latin for “poison”.

Bacteriophage attacking a bacteria!Bacteriophage attacking a bacteria!

At the boundary of life, between the macromolecules At the boundary of life, between the macromolecules (which are not alive) and the prokaryotic cells (which (which are not alive) and the prokaryotic cells (which are), lie the viruses and bacteriophages (phages). are), lie the viruses and bacteriophages (phages).

These twilight creatures are These twilight creatures are parasitesparasites responsible for responsible for causing many diseases in living things (herpes and causing many diseases in living things (herpes and HIV in humans, for example).HIV in humans, for example).

Viruses are found everywhere.Viruses are found everywhere.

Are viruses alive? Scientists are still arguing!!!

In isolation, viruses and In isolation, viruses and bacteriophages show bacteriophages show none of the expected none of the expected signs of life. They do not signs of life. They do not respond to stimuli, they respond to stimuli, they do not grow, they do not do not grow, they do not do any of the things we do any of the things we normally associate with normally associate with life. life.

Characteristics of Living ThingsRespond to stimulus: virus respond when a cell is near and attaches.Cells: Not cells as we know themAdapt: The viruses do mutate to become stronger but only in a host cell.Reproduces: only in a host cellEnergy: Uses energy of the hostDNA: Yes they do have their ownGrow and develops: Only in host

Viruses are parasites that can only perform certain characteristics in host cells.Host: The cell that the virus attaches and uses their DNA and resources.

How do They Name VirusesHow do They Name Viruses

1.1. After the disease they cause.After the disease they cause.

2.2. After the organ or tissue they attackAfter the organ or tissue they attack

3.3. Today, they are given a genus name Today, they are given a genus name ending in the word virus. Code numbers ending in the word virus. Code numbers are given to similar virusesare given to similar viruses

Viruses consist of aViruses consist of a core of nucleic acid, core of nucleic acid, either DNA or RNA, and a protective coat of either DNA or RNA, and a protective coat of protein molecules and sometimes protein molecules and sometimes lipids(capsid). lipids(capsid).

PARTS OF A VIRUS

CAPSID: Protein coatSurrounding the DNA.

Why is Capsid Important?Why is Capsid Important?It is the protein coat around the virus that It is the protein coat around the virus that protests its DNA or RNA. protests its DNA or RNA.

IT IS WAY THEY ARE SO HARD TO KILL!!!!!!IT IS WAY THEY ARE SO HARD TO KILL!!!!!!

How Do Viruses Attack Their How Do Viruses Attack Their HostHost

Host - Cell the virus attacks. Host - Cell the virus attacks. Attaches to the host cell and interlocks Attaches to the host cell and interlocks

with the protein of the host cell. with the protein of the host cell. Viruses are very specific to the cells Viruses are very specific to the cells they attack. This helps in the spread they attack. This helps in the spread of the disease.of the disease.

The outside envelope matches the cell The outside envelope matches the cell that it attacks. Viruses are specific!that it attacks. Viruses are specific!

Attacking Host

The virus will attach itself to the host cell. It will then shoot its DNA into the host cell. The virus is a parasite that uses the host cell for its energy and reproduction. It is a little different if it is a bacteria cell or eukaryotic cell.

Attacking the host

The size and shape of a virus determines which cells or host they can attack.

Virus Attached to HostVirus Attached to Host

Size and Shape of Viruses

Viruses come in all shapes sizes. You can only see them with a microscope.

3 shapes of viruses1.Enveloped – round with spikes( flu viruses)2.Helical – Long narrow coiled shape( rabies)3.Polyhedral- many sides(foot and mouth disease)

                                            

The different proteins that make up the capsid determines the shape of the virus.

BacteriophagesBacteriophages attack bacteria (prokaryotes) attack bacteria (prokaryotes) virusesviruses attack eukaryotic cells(have a nucleus). attack eukaryotic cells(have a nucleus).

Viruses and bacteriophages invade cells and use the Viruses and bacteriophages invade cells and use the host cell's machinery to synthesize more of their own host cell's machinery to synthesize more of their own macromolecules.macromolecules.

Difference between a bacteriophage and a virus

How Do Vaccines WorkHow Do Vaccines WorkA vaccine contains a killed or weakened part of a A vaccine contains a killed or weakened part of a germ that is responsible for infection. Because the germ that is responsible for infection. Because the germ has been killed or weakened before it is used germ has been killed or weakened before it is used to make the vaccine, it can not make the person to make the vaccine, it can not make the person sick. When a person receives a vaccine, the body sick. When a person receives a vaccine, the body reacts by making protective substances called reacts by making protective substances called "antibodies". The antibodies are the body's "antibodies". The antibodies are the body's defenders because they help to kill off the germs defenders because they help to kill off the germs that enter the body. In other words, vaccines that enter the body. In other words, vaccines expose people safely to germs, so that they can expose people safely to germs, so that they can become protected from a disease but not come become protected from a disease but not come

downdown with the disease.with the disease.

Jenner was operating on the now widely accepted principle that once a person catches a certain disease, he or she is immune to it for the rest of their life. For example, once you've had the chickenpox, it's extremely unlikely that you'll ever catch it again. This is because your body, when exposed again, will recognize the disease and fight it off. The beauty of vaccines is that they help the body develop disease-fighting abilities without making you sick. Vaccines accomplish this amazing feat by tricking the body into believing it already has the full-blown disease. Here are the steps in this process, known as the "immune response":

Videos

http://virus.stanford.edu/uda/

https://www.youtube.com/watch?v=a34izRvmuIo

https://www.youtube.com/watch?v=jJwGNPRmyTI&list=TLd9hZ4eK7hl9XlSUOM9Tw7otujWPTj8Ce

https://www.youtube.com/watch?v=UEKS4w9bfJg

https://www.youtube.com/watch?v=UhtKoH-oO1M

Vaccine-preventable Diseases

Anthrax

Cervical Cancer

Diphtheria

Hepatitis A

Hepatitis B

Haemophilus influenzae type b

Human Papillomavirus

Influenza

Japanese encephalitis

Lyme disease

Measles

Meningococcal

Monkey pox

Mumps

Pneumococcal

Polio

Rabies

Rotavirus Bird Flu

Rubella

Shingles

Smallpox

Tetanus

Typhoid

Tuberculosis

Varicella

Yellow Fever

Common Cold

Swine Flu

BacteriaBacteria VirusVirus

1.1.OrganellesOrganelles DNADNA

2.2.Kill with antibioticKill with antibiotic ReproducesReproduces

3.3.Reproduces on ownReproduces on own Energy from Energy from

4.4.Needs energyNeeds energy hosthost

5.5. CellCell MutatesMutates

6.6.RespondsResponds hard to killhard to kill

7.7.AdaptsAdapts CapsidCapsid

8.8.GrowsGrows