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Bacteria & Viruses Living or Non-living. Bacteria Prokaryotes = unicellular organisms with no nucleus General characteristics Cell membrane surrounded.

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Presentation on theme: "Bacteria & Viruses Living or Non-living. Bacteria Prokaryotes = unicellular organisms with no nucleus General characteristics Cell membrane surrounded."— Presentation transcript:

1 Bacteria & Viruses Living or Non-living

2 Bacteria Prokaryotes = unicellular organisms with no nucleus General characteristics Cell membrane surrounded by a thick, protective cell wall Genetic material contained on a single strand of circular DNA – plasmid Lack mitochondria, chloroplasts and other membrane bound structures

3 Two New Kingdoms Archaebacteria or “ancient bacteria” Live in extreme environments Cell wall lacks peptidoglycan Cell membrane contains lipids not found in any other organism Many cannot survive in the presence of oxygen Eubacteria or “true bacteria” Thick, rigid cell walls of peptidoglycan Cell wall surrounds a cell membrane Diverse

4 Types of Bacteria Round or spherical = coccus (cocci) Rod shaped = bacillus (bacilli) Spiral or corkscrew shaped = spirillum (spirilla) Named for shape and arrangement of bacteria ex. Staphylococcus or Streptococcus


6 Reproduction in Bacteria Binary fission – splits into two daughter cells Conjugation – part of the genetic information from one cell is transferred to another through a bridge connecting both cells Transformation – pick up bits and pieces of DNA from other bacteria allowing them to pick up new traits

7 Protective behavior Bacteria can make endospores Protective capsules Allow bacteria to remain dormant until appropriate conditions exist Can remain dormant for years

8 Harmful Bacteria Infect other foods and cause illness Infect other organisms Pathogenic Treated with antibiotics Antibiotic resistance

9 Helpful Bacteria Biotechnology Insulin production Gene splicing Recombinant DNA Useful in a variety of products Certain cheeses Yogurt – active cultures Sauerkraut Part of metabolism Example: aids in digestion

10 Viruses Tiny “particle” made of genetic material and protein that can invade and replicate within a living host. General structure Protein coat called a “capsid” Protein coat “tricks” host cells into letting the virus in Nucleic acid core

11 Viruses Viruses are species specific Types of Viruses – classified according to nucleic acid content DNA viruses RNA viruses Retroviruses

12 Viruses TMV – tobacco mosaic virus first discovered by Wendell Stanley. Bacteriophage is a virus that infects bacteria.

13 Viral Reproduction Can only reproduce when they invade or infect a host cell. Lytic cycle Injects its genetic material into a host Immediately takes over the cells metabolic functions Hosts DNA is used to make viral DNA & the host cell makes new viral genes and proteins until it bursts. 5 Step Process

14 Viral Reproduction Retroviruses Contain RNA Make DNA copies of their RNA genes and then insert them into the host cells chromosomes Remain dormant, then become active Direct production of new viruses and kills the host cell Example: HIV which causes AIDS


16 Bacterial Disease in Humans Pathogens = disease causing agents Pasteur – “germ theory of disease” Some bacteria damage cells and tissues by breaking them down to use for food Mycobacterium tuberculosis Some bacteria release toxins that interfere with the normal activities of the host. Diptheria Streptococcus bacterium  Scarlet fever

17 Preventing Bacterial Disease Antibiotics Block growth and reproduction of bacteria Bacterial resistance to antibiotics Vaccines – stimulate the body’s immune system Weakened or killed strain of the disease Stimulates the body to form antibodies

18 Bacterial Disease in Animals Many bacteria can affect both animals and humans Requires special precautions to protect livestock from infection Example: Bacillus anthracis or “anthrax”

19 Diseases Caused by Bacteria Lyme disease Tetanus Tuberculosis Diptheria Bacterial meningitis Strep throat Tooth decay

20 Controlling Bacteria Sterilization by heat Food storage and processing Refrigeration slows down bacterial growth Boiling, frying or steaming foods Preserving foods Disinfectants = chemical solutions that kill pathogenic bacteria Concern with overuse - resistance

21 Viral Diseases in Humans and Animals Viruses produce disease by disrupting the body’s normal equilibrium Attack and destroy specific cells in the body. Poliovirus – attacks the nervous system Some viruses cause infected cells to change their patterns of growth and development. Some cancers

22 Diseases Caused by Viruses Common cold Influenza Small pox Warts AIDS Chickenpox Measles Hepatitis A, B and C West Nile Virus Polio

23 Viroids and Prions – virus-like particles Viroids – cause disease in plant Single stranded RNA molecules with no surrounding capsid Infect cells by making them synthesize new viroids Disrupt plant metabolism and stunt plant growth

24 Viroids and Prions Prions – cause disease in animals First discovered in sheep but also found in other animals including humans Cause disease by forming protein clumps which interfere with normal protein production Particles contain no DNA or RNA, only proteins Prions = “protein infectious particles”

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