Microbes

Types of Microbes a) Bacteria b) Fungi c) Protists d) Viruses

Observing Microbes What do we call a scientist who studies microorganisms?

Bacteria

Bacteria Made up of a cell wall, cell membrane and cytoplasm. Made up of a cell wall, cell membrane and cytoplasm. No nucleus No nucleus Rigid cell wall Rigid cell wall Thin, rubbery cell membrane Thin, rubbery cell membrane Contain ribosomes – necessary to reproduce on their own Contain ribosomes – necessary to reproduce on their own Some have flagella. Why? Some have flagella. Why?

Shapes of bacteria NameShape Coccus (sphere) Bacillus (rod) Starting to divide Spirillum (spiral)

Bacterial reproduction Binary fission

Viruses

Viruses Very small (EM to view) Very small (EM to view) Cannot reproduce on own – need host cell Cannot reproduce on own – need host cell Outer protein coat holds DNA or RNA inside (contains instructions to produce new viruses) Outer protein coat holds DNA or RNA inside (contains instructions to produce new viruses) Some may have spiky coat (called envelope) Some may have spiky coat (called envelope) Coat varies in shape Coat varies in shape

Virus reproduction a t-4 bacteriophage infecting e.coli 1.Virus attaches to cell wall and cuts it open 2.Injects genetic material into cell 3.Viral genes tell invaded cell to produce more viruses 4.Eventually there are too many viruses, cell bursts open and dies 5.Released viruses infect new cells

Differences between bacteria and viruses ta/default.aspx ta/default.aspx ta/default.aspx ta/default.aspx

Fungi

Fungi Eg mushroom,mould,yeast Fungi Eg mushroom,mould,yeast Many shapes Many shapes Vary from very small (ringworm) to very large (mushrooms) Vary from very small (ringworm) to very large (mushrooms) Grow into food by secreting digestive enzyme Grow into food by secreting digestive enzyme Some edible and others are poisonous Some edible and others are poisonous Feed on dead and decaying material Feed on dead and decaying material Why are they helpful? Why are they helpful?

Protozoa

Protozoa (protists) Unicellular (one celled organisms) Unicellular (one celled organisms) Have cell membrane, no cell wall Have cell membrane, no cell wall Varied in shape Varied in shape Live in water or moist areas Live in water or moist areas Some are plant like that contain chlorophyll eg euglena Some are plant like that contain chlorophyll eg euglena Others that are animal like eg amoeba, paramecium that catch their own prey Others that are animal like eg amoeba, paramecium that catch their own prey What is the difference between an amoeba and a paramecium What is the difference between an amoeba and a paramecium How does an amoeba move? How does an amoeba move?

Too small to see with the naked eye Can see with the naked eye Always does harm to the host but needs it to live Remain permanently inside host, obtaining food and shelter Visit host briefly to feed Micro-organism Endo- parasite Parasite Macro-organism Ecto-parasite Parasitic organisms which cause disease Pathogen Organism on which a parasite lives Host Outward signs of the presence of a disease Symptoms

How is disease passed on? Droplets in the air from sneezing and coughing Droplets in the air from sneezing and coughing Vectors (carriers) eg. Houseflies and mosquitoes Vectors (carriers) eg. Houseflies and mosquitoes Direct contact with infected areas Direct contact with infected areas

How can we prevent the spread of disease? Taking care of personal hygiene Taking care of personal hygiene Washing hands with soap and hot water Washing hands with soap and hot water Washing clothing regularly Washing clothing regularly Taking care with food preparation Taking care with food preparation Cover food Cover food Cook at high temperature Cook at high temperature Wash raw fruit and vegetables Wash raw fruit and vegetables Proper disposal of sewage and garbage Proper disposal of sewage and garbage Chemical control of vectors Chemical control of vectors Spraying insecticides Spraying insecticides Disinfectants  sterilise clothes, bottles, operating theatres etc Disinfectants  sterilise clothes, bottles, operating theatres etc Antiseptics to clean cuts and grazes Antiseptics to clean cuts and grazes

WAR! First and second line defences

First line of defence Natural barriers to prevent entry of microbes into the organs Natural barriers to prevent entry of microbes into the organs SKIN  protects internal organs from damage from chemicals, water and radiation along with preventing entry of microbes SKIN  protects internal organs from damage from chemicals, water and radiation along with preventing entry of microbes MUCUS & HAIRS  In your nose these act to trap infectious particles. Mucus contains the enzyme lysozome which breaks down the bacteria’s cell wall MUCUS & HAIRS  In your nose these act to trap infectious particles. Mucus contains the enzyme lysozome which breaks down the bacteria’s cell wall SALIVA  also contains chemicals that are antibacterial SALIVA  also contains chemicals that are antibacterial STOMACH ACID  kills most disease causing microbes before they can reach the small intestine STOMACH ACID  kills most disease causing microbes before they can reach the small intestine ACIDIC MUCUS  Provides a chemical environment in the vagina which makes it difficult for microbes to grow and multiply ACIDIC MUCUS  Provides a chemical environment in the vagina which makes it difficult for microbes to grow and multiply

The immune system The immune system protects the body against infections by bacteria, viruses and other parasites. The immune system protects the body against infections by bacteria, viruses and other parasites. It is really a collection of responses that the body makes to infection. So it is sometimes called the 'immune response'. It is really a collection of responses that the body makes to infection. So it is sometimes called the 'immune response'.

Antibodies Produced by white blood cells Produced by white blood cells Y shaped proteins that respond to a specific antigen Y shaped proteins that respond to a specific antigen Each antibody has a special section that is sensitive to a specific antigen and will bind to it in some way Each antibody has a special section that is sensitive to a specific antigen and will bind to it in some way Stops the enemy cell from working in some way Stops the enemy cell from working in some way