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Microbiology It’s a small world… Chapters 7 and 19.

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1 Microbiology It’s a small world… Chapters 7 and 19

2 LIFE IS CELLULAR Cell Theory –All living things are made up of cells. –Cells are the basic units of both structure and function in living things. –New cells are made only from existing cells.

3 BASIC CELL STRUCTURE All cells have: –Cell membrane – thin layer that surrounds cells –Cytoplasm – gel like material inside cells (the “juice”) –Genetic material (DNA and/or RNA) –Ribosomes – make proteins

4 Some cells have: –Cell wall – more rigid structure on outside of some cell membranes –Nucleus – contains genetic material (brain of the cell) –Mitochondria – make energy (powerhouse) –Chloroplasts – make sugar (photosynthesis)

5 DIVERSITY OF LIFE All cells fall into two categories of cells: 1.Prokaryotes Includes bacteria 2.Eukaryotes Includes animals, plants, fungi, and protists (like amoebas and paramecium)



8 CHARACTERISTIC OF PROKARYOTES No membrane-bound organelles (“little organs” in cells) No nucleus, mitochondria, or chloroplasts Have DNA, ribosomes, cytoplasm, cell membrane, and cell wall

9 Bacterium

10 Fossil evidence shows that bacteria have been on the earth for over 3.5 billion years Three major shapes –Cocci (round) –Bacilli (rod-like) –Spirilla (spiral)


12 HARMFUL BACTERIA Some bacteria are pathogens (disease causing) Some bacteria can make endospores, which allow bacteria to survive long periods of time (even in bad conditions) Diseases caused by bacteria: Pneumonia Strep throat Ear infections Salmonella Cholera E. coli infections Lyme Tetanus Tuberculosis Leprosy

13 Botulism

14 Strep throat

15 Leprosy

16 HELPFUL BACTERIA In your intestine, E. coli help to digest food Used to make yogurt Can be used to degrade oil and toxic waste spills Used to make certain medicines Used as “gene” factories Help plants fix nitrogen Major decomposers

17 Decomposition over 2 weeks

18 Legumes with nitrogen fixing bacteria in their roots

19 KILLING BACTERIA Antibiotics- drugs that kill bacteria by blocking growth or reproduction –Antibiotics do NOT kill any viruses so they do not cure the common cold or flu –Some bacteria are now resistant to antibiotics (ex. MRSA) –We must always take antibiotics as prescribed! Sterilization – destroying bacteria by heating or with chemicals



22 Archaea Extremophiles activity. List seven different types of extremophiles from the archaea domain and explain their habitat requirements.

23 CHARACTERISTICS OF EUKARYOTES Cell membrane Cytoplasm Cytoskeleton Ribosomes Organelles that are membrane bound (ex. mitochondria and chloroplasts) Fossil evidence shows that eukaryotic cells have been on the earth for approximately 1 billion years.

24 Animal Cell

25 Plant Cell

26 VIRUSES Viruses are particles made up of nucleic acid (DNA and/or RNA), protein, and sometimes lipids. Viruses are NOT living because they cannot reproduce by themselves. All viruses enter (infect) living cells and once inside of a cell, they make more viruses. All viruses are pathogens. Viruses are thought to have evolved from pieces or fragments of cells.

27 VIRUS STRUCTURE Viruses have a core of genetic material surrounded by a capsid (protein coat) They are much smaller than bacteria and animal cells. They come in many shapes.



30 VIRAL INFECTIONS All cells can be infected by viruses including bacteria, animals, and plants. Bacteriophage – a virus that infects a bacterial cell There are two main methods of infection: 1.Lysogenic 2.Lytic

31 Bacteriophage (virus) infecting a bacterium


33 LYTIC CYCLE Viruses inject their genetic material (DNA or RNA) into the host cell. This genetic material gives instructions to make viruses. The viruses are released by causing the cell to burst (lyse), which kills the cell.

34 LYSOGENIC CYCLE A virus injects its genetic material (DNA or RNA) into the host cell. The virus’s genetic material is mixed in with the host DNA. Viral DNA can stay embedded in the host DNA for long periods of time. Sometimes, the viral DNA will instruct new viruses to be made and the lytic cycle begins.

35 VIRAL DISEASES Polio AIDS Influenza (the flu) Yellow fever Rabies Common cold Some cancers like cervical cancer Measles Small pox

36 Small Pox

37 Measles

38 Polio

39 1918 Flu Pandemic

40 Herpes

41 VACCINES Vaccines – made from weakened or “killed” viruses Vaccines stimulate the immune system to fight a specific disease Vaccines help prevent viral and bacterial diseases from developing, but cannot help someone already infected Examples include: HPV, MMR, Hep A


43 PRIONS Prions - possibly infectious proteins that can change brain proteins causing brain damage Diseases caused by prions progress rapidly and are almost always fatal Diseases caused by prions include: –Mad Cow DiseaseMad Cow Disease –Creutzfeldt-Jakob Disease (CJD)

44 Creutzfeld-Jakob Disease

45 Spread the word, not the germs! 1) WASH your hands when they are dirty and BEFORE eating. 2) DO NOT cough into your hands. 3) DO NOT sneeze into your hands. 4) DO NOT put your fingers into your eyes, nose, or mouth. Regular soap and water are best. Antibacterial soaps are not necessary if you have spent enough time (at least 20 seconds) cleaning your hands with regular soap and water. (Source:

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