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

Characteristics of Living Things All living things: –are made of cells –obtain and use energy –grow and develop –reproduce on their own –respond to their environment –adapt to their environment

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.

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

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)

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)

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 Unicellular

Bacterium

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)

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 Strept throat Ear infections Salmonella Cholera E. coli infections Lyme Tetanus Tuberculosis Leprosy

Botulism

Strept throat

Leprosy

HELPFUL BACTERIA In your intestine, E. coli (Escherichia 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

Decomposition over 2 weeks

Legumes with nitrogen fixing bacteria in their roots

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

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. Can be unicellular or multicellular

Animal Cell

Plant Cell

Levels of organization in multicellular organisms Cell – basic unit of structure and function (ex. nerve) Tissue – groups of cells that work together to perform a common function (ex. spinal cord or muscle cell) Organ – groups of tissues that work together to perform a common function (ex. brain or heart) Organ systems – groups of organs that work together to perform a common function (ex. cardiovascular or nervous system) Body – groups of organ systems

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.

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.

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

Bacteriophage (virus) infecting a bacterium

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.

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.

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

Small Pox

Measles

Polio

1918 Flu Epidemic

Herpes

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

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)

Creutzfeld-Jakob Disease

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: