Communicable diseases

Chapter 12

What are communicable doeases caused by?

pathogens - bacteria, viruses, fungi and protoctista

How do communicable diseases spread amongst animals and plants?

animals - most commonly from one individual of a species to another

Plants - directly from plant to plant

What are vectors

Vectors carry pathogens from one organism to another and this means they spread animal and plant diseases.

Common vectors. Water and insects

Are there more deaths caused by communicable or non communicable diseases

non communicable - 68%

Bacteria structure

prokaryotes - do not have membrane bound nucleus or organelles

What are the two main ways bacteria are classified?

• by their basic shape - can be rod shaped, spherical, comma shaped etc

• By their cell walls - the two main types of bacterial cell walls react differently with a gram staining

  gram positive - purple blue

  Gram negative - red

How is the different type of bacteria ell wall useful

The type of cell walls react differently affects how bacteria react to different antibiotics

Viruses

• non living

• 0.02 - 0.3 micrometers

• Basic structure - some genetic material surrounded by a protein

• Pathogenic - cause disease in every other type of organism

how are viruses successful pathogens

they invade living cells where the genetic material of the virus takes over the biochemistry of the host cells to make more viruses

Viruses reproduce rapidly and evolve by developing adaptations to their host

Name of viruses that attack bacteria

Bacteriophages - they take over bacterial cels and cause them to replicate, destroying bacteria at same time.

Protista

• eukaryotic

• Include single celled organisms and cells grouped into colonies

• Arasiti

• Protists may need a vector to transfer them to hosts

Fungi

• affect plants more than animals

• Eukaryotic

• Often multicellular

• Some are saprophytes - feed on dead and decaying matter

• Can stop plant leaves from photosynthesising

How do viruses damage the host

take over cell metabolism.

Viral genetic material gets into host cell and inserted into host DNA virus then uses host cell to make new viruses which then burst out the cell, destroying it and then spread to other cells

How do protoctista damage the host

Take over cells and break them open as the new generation emerge

Do not take over genetic material of cell

Digest and use cell contents as they reproduce

how do fungi damage host tissues

Fungi digest living cells and destroy them

What are toxins and what produces them

Most bacteria produce toxins that poison the host cells causing disease

Some bacteria toxins damage the host cells by breaking down the cell membranes, some damage or inactivate the enzymes or interfere with the hoss genetic materials

Some fungi also produce toxins

Ring rot and effect on plants

• bacterial disease

• Affects tomatoes, potatoes and aubergines

• Caused by gram positive bacteria

• Damages leaves, tubers and fruit

Tobacco mosaic virus

Infects tobacco plants and others

Damages leaves flowers and fruits

Stunning growth, reducing yield, can lead to an almost total crop loss

Potato blight

• caused by fungus-like protoctist

• Destroys leaves, tubers and fruit

• Causing millions of pounds worth of crop damage a year

Black sigatoka

• banana disease cased by fungus

• Attacks and destroys the leaves

• Leaves turn black

Tuberculosis

• bacterial disease

• Humans cows pigs badgers and deer

• Damages an destroys nuts and suppresses the immune system

Be