Contents

1. Contents Microbes Describe what are microbes? Describe the structure of bacteria and viruses How do bacteria and viruses reproduce? Summary quiz

2. Starter activity • Match the correct keyword to the definition causes damage to the individual’s vital functions or systems. Pathogen the invasion and multiplication of pathogenic microbes in an individual or population. Infection Disease a micro-organism that has the potential to cause disease.

3. Infection and disease • What is a pathogen? • A pathogen is a micro-organism that has the potential to cause disease. • What is an infection? • An infection is the invasion and multiplication of pathogenic microbes in an individual or population. • What is disease? • Disease is when the infection causes damage to the individual’s vital functions or systems. An infection does not always result in disease!

4. Disease • What is communicable? • Communicable - able to be passed from one person to the other • What is non communicable? • Non-Communicable - can’t be passed on from one person to another

5. What causes disease? Why do people become ill? People who lead very unhealthy lifestyles sometimes become ill but it is also clear that people can become ill despite leading a healthy lifestyle. Why? Therefore, rather than something being wrong with that person, perhaps something else changes the normal state of the body and causes disease. These were eventually discovered to be… MICROBES

6. Microbes As the name suggests, they are microscopicorganisms. They can only be seen using a microscope.

7. BACTERIA VIRUSES Microbes The two kinds of microbe that we will be dealing with are: Now it is important at this point to remember what it means to be living organism. A living organism must be able to demonstrate that it can perform the sevenlife processes.

8. The seven signs of life

9. Microbes The reason for looking back to these 7 characteristics is because although bacteria can perform all of these life processes, viruses cannot reproduce on their own. Does this mean that viruses are non-living? This question is still hotly debated!

10. Micro-organisms are made from cell • They are very small – so usually ONE cell • Cells are the smallest unit of life – they can carry out the 7 characteristics of life • Two types of cell: • Prokaryotic • Eukaryotic

11. Prokaryotes • Prokaryotes are the oldest, simplest, and most abundant forms of life on earth. • abundant for over 2 billion years before the appearance of eukaryotes • 5,000 different kinds currently recognized

12. Prokaryotic cells • Single cell organisms • Two main types: bacteria and archaea • Relatively simple structure Figure 1-7a

13. Bacteria • These are tiny single celled organisms that cause a range of illnesses Activity: Name some diseases caused by bacteria

14. Staphylococcus causing skin infections

15. Bacteria • As the bacteria breed successfully they begin to affect the body • Symptoms of infection appear • Symptoms caused by remains of dead bacteria or substances released by the living bacteria (toxins) • Toxins may cause fever • Bacteria may directly damage body cells

16. Fungi - eukaryotes • Can be single-celled organism to a 3.5-mile-wide mushroom.

17. Fungi • These are tiny organisms that can cause a range of infections • They release digestive chemicals onto the surface of the person they grow on. • Activity: Name some diseases caused by fungi

18. Athletes Foot

19. Fungi (yeast that causes thrush)

20. Viruses – living? • Not a cell! • Viruses can’t: • eat, • excrete wastes, • move around on their own, • reproduce (unless they are inside another organism’s cells)

21. Viruses • Viruses are the smallest type of disease causes micro-organism • They reproduce by taking over cells of the body and making these cells produce new viruses. • Viruses do not produce toxins but cause disease by damaging the cells they enter

22. What diseases do these viruses cause? • Rhinovirus attacks cells in nose and throat • HIV attacks cells of immune system • Herpes Simplex • Can you think of any other diseases caused by a virus

23. Protoctista - eukaryotes • Can be single-celled to multi-celled • They’re not plants, animals or fungi • Protoctistas fall into four general subgroups: unicellular algae, protozoa, slime moulds, and water moulds

24. Protozoa • This are single celled animal-like creatures • Cause diseases such as: • Malaria – transmitted through mosquito bites

25. Contents Microbes Describe what are microbes? Describe the structure of bacteria and viruses How do microbes reproduce? Summary quiz

26. cell wall cytoplasm cell membrane loose genetic material present in animal cells absent from animal cells A single bacterium Bacteria can be different shapes but this diagram can represent them.

27. Structure of a bacteria Cytoplasm • circular chromosome of DNA • few organelles • food storage granules Cell Wall – multi-layered structure - 2 distinct types - slimy capsule surrounds cell wall Flagella • one or more projection from cell wall • Allow the bacterium to move in liquids Cell Membrane – bilayer with proteins floating in it • controls what goes in and out of bacteria

28. So, the bacterium shares some structural characteristics with an animal cell but shows important differences. The most obvious differences are: the absence of a distinct nucleus the presence of a cell wall Bacteria cells are 10-1000 times smaller than animal cells. Bacterium The other major difference is the size of the cell. To get an idea of how small these cells are, remember that the human body consists of approximately 100 million animal cells.

29. 1 1 mm to mm 1000 20 Bacterium If we wanted to measure a single bacterium, its length would range from: If a full stop is 1mm wide how many bacteria could you line up along it? Between 1000 and 20 bacteria would fit on a full stop!

30. Virus Now let’s consider the structure of the virus. protein coat injection tube loose genetic material tail plate Absent in animal cells

31. Viruses - how small? Viruses are very different to bacteria because they do not have a cellular structure and are much smaller. Bacteria are 100 times smaller than a human cell. Viruses are 1000 times smaller than a bacteria. So how small are viruses compared to a human cell? 100 000 times smaller!

32. Viruses and tennis balls! If a common cold virus was the size of a tennis ball, how big would a nose be? Here’s another way to think about the size of viruses... A. the size of a supermarket B. the size of Birmingham C. the size of Wales

33. If viruses are such tiny microbes, how do they cause so much havoc? Viruses need to hijack a host cell, like a human body cell, in which to live and make more viruses. Viruses cannot function if they are outside of a host cell. Viruses – living or not? Some scientists say that viruses are not ‘alive’ because of how they reproduce. Would you say a virus was living or not?

34. Virus and bacterium properties

35. Contents Microbes Describe what are microbes? Describe the structure of bacteria and viruses How do bacteria and viruses reproduce? Summary quiz

36. Contents Microbes Describe what are microbes? Describe the structure of bacteria and viruses How do bacteria and viruses reproduce? Summary quiz

37. Bacteria can reproduce quickly and independently . One bacteriumcan divide into two new bacteria every 20 minutes! Bacteria reproduction

38. This means that if 1bacterium enters your body at 8.00am, 4 hours later, you would have 4096bacteria within your body! Bacteria reproduction Do viruses reproduce in the same way as bacteria? No!

39. virus Virus reproduction Viruses need ahostcell to reproduce within. This is a body cell, which will provide the machinery, and chemicals the virus requires to make copies of it. host cell e.g. a human body cell

40. Virus replication Virus Replication

41. 2. Attachment 1. Approach The virus secures itself to the surface of the host cell. The virus approaches the host cell The process of host cell infection Therefore the virus not only infects the body; it also infects the body cells.

42. 3. Insertion The virus injects its genetic material through the injection tube and into the host cell. 4. Replication The genetic material makes multiple copies of itself. The process of host cell infection

43. 5. Assembly New viruses are assembled using chemicals from the host cell. The original virus dies and breaks down. The process of host cell infection It is at this stage that the viruses within the host cell can remain dormant. In other words, they sit within the cell without killing it or breaking out. With some viruses such as HIV, this period can last a number of years. This is why people can remain infected with HIV without realizing they are infected.

44. Virus reproduction CELL LYSIS

45. Student task • USE BIOVIEWERS AND OBSERVE SOME SLIDES. • DRAW 2 BACTERIAL, VIRUS, PROTOZOA AND FUNGI CELLS AND WRITE ABOUT THEM USING THE BOOKLETS

46. VIRUSES BACTERIA Influenza (flu) Food poisoning Mumps Sore throats Chickenpox Tuberculosis (TB) Smallpox Tetanus Polio Cholera Rabies Typhoid German measles Whooping cough Common illnesses Most people have suffered from at least one of these illnesses: So, how do these microscopic organisms actually cause illness in such a complex and relatively enormous organism like a human being? 

47. Virus reproduction - what’s the order?

48. Virus reproduction - explain it!

49. Microbes quiz