Bacteria

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Bacteria
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Modes of Reproduction

• 1. Asexual
• a) Binary fission
• bacterium divides w/o exchanging genetic material
• each daughter cell receives single circular,
  double stranded DNA
• 2 genetically identical cells

b) Budding or fragmentation
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Modes of Reproduction2. Genetic Recombination

• c) Conjugation
• Structure called a pili joins 2 cells and
  transfer DNA between the two cells.
• Exchange can be between different species of
  bacteria
• exchange small circular pieces of DNA carrying a
  few genes (plasmids)
• These new genetic combinations create variation
  in the population

? How does this type of reproduction relate to
the increase in antibiotic-resistant bacteria?
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Genetic Recombination possible

• Endospore
• a tiny structure that contains a bacteriums DNA
  and a small amount of its cytoplasm, encased by a
  tough outer covering that resists drying out,
  temperature extremes, and harsh chemicals
• Some germinated after 1000s of years of dormancy
• can survive a temperature of 100C
• To kill endospores, items must be
  sterilizedheated under high pressure in
• a pressure cooker or
• an autoclave

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Ex. Diseases caused by endospore-forming bacteria
Botulism

• Canned food must be sterilized and acidified.
• This is because the endospores of the bacterium
  called Clostridium botulinum easily get into
  foods being canned.
• Bacteria grow in the anaerobic environment of the
  can and produce a powerful deadly poison, called
  a toxin, as they grow
• When eaten causes food poisoning called botulism.

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Anthrax
Ex. Diseases caused by endospore-forming bacteria

• Bacillus anthracis, lives in the soil, causes
  anthrax
• commonly infects cattle and sheep
• Usually harmless on human skin
• However, bacterial spores can become airborne and
  when inhaled in large amounts, it germinates in a
  persons lungs, causing a deadly infection

monkey with inhalational anthrax rod-shaped
bacilli (yellow) and a red blood cell (red).
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What are some ways that we can control bacterial
growth?

• Bacteria require a certain environment to
  maintain homeostasis.
• By manipulating their environment we can control
  their growth
• High Temperature
• Boiling
• Autoclaving (like a pressure cooker)
• Low Temperature
• Refrigeration
• Freezing
• Canning
• Salting
• Pickling

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? QUIZ
Answer B

• What process is shown in the illustration?
• A Cellular ingestion
• B Binary fission
• C Protein synthesis
• D Meiosis

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How are Bacteria Harmful?
Bacteria Can Cause Disease

• disease - causing bacteria are called PATHOGENS
• bacteria can attack the tissues directly or
  produce deadly TOXINS

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What are some symptoms associated with a
bacterial infection?

1. Elevated body temperature
2. Sweating
3. Swelling of tissue
4. Skin rashes or lesions
5. Increased pulse rate
6. Fast breathing
7. Increased white blood cell count

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Disease Pathogen Transmission
Tooth decay Streptococcus mutans Bacteria grow between teeth and leave plaque
Skin Infection Staphylococcus aureus Contact with infected person or contaminated surfaces
Lyme disease Borrelia burgdorferi Deer ticks
Bubonic plague Versinia pestis Flea infected rats
Tetanus Clostridium tetani Open wound
Tuberculosis (TB) Mycobacterium tuberculosis Airborne
Pneumonia Streptococcus pneumoniae Airborne
Anthrax Bacillus anthracis Airborne and skin contact
Food poisoning Salmonella enteritidis E.coli O157H7 Clostridium botulinum Tainted countertops, rags, cooking utensils, undercooked food
Cholera Vibrio cholerae Contaminated water
Syphilis Treponema pallidum Sexual contact
Gonorrhea Neisseria gonorrhoea Sexual contact
Leading cause of death prior to 1900s Leading cause of death prior to 1900s Leading cause of death prior to 1900s
http//www.cdc.gov/
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What are some ways that you can be exposed to
disease-causing bacteria?
Modes of Disease Transmission

1. Airborne Contact with contaminated air through
   cough or sneeze
2. Foodborne Consuming contaminated food
3. Waterborne Consuming contaminated water
4. Direct contact with contaminated surfaces or
   utensils
5. Puncture wounds in the skin
6. Bites from infected animals (i.e. mosquitoes,
   fleas, small mammals)
7. Sexually transmitted

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What are some ways to protect yourself and
others from disease-causing bacteria?
Prevention of Disease Transmission

• Handwashing
• ? RULE?
• 20 sec
• warm water
• Soap lather, lather, lather
• Scrub, scrub, scrub
• Cook foods thoroughly and at high enough
  temperatures
• Cover mouth when coughing or sneezing
• Clean contaminated surfaces with disinfectants
• Avoid contaminated water
• Antibiotics kill bacteria

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Fighting Back

1. Natural defense provided by antibodies
2. injection of antitoxin or of serum containing
   antibodies against specific bacterial antigens
   can prevent infection (e.g. tetanus)
3. immunity can be induced (for viruses) by
   vaccination
4. Bacteria are killed by antibiotics.

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Antibiotics

1. In 1928, Sir Alexander Fleming accidentally
   discovered penicillin, the 1st antibiotic
2. disrupts cell wall production, causing holes,
   water enters by osmosis ? cell bursts

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Side effects of antibiotics

• Due to bacterial death
• Upset stomach
• Diarrhea
• Vomiting
• Vaginal yeast infections
• more severe may disrupt the function of the
  kidneys, liver, bone marrow, or other organs.

The result of the overuse of antibiotics in
treating minor illnesses is antibiotic
resistant bacteria like MRSA (methicillin-
resistant Staphylococcus aureus)
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Antibiotic-Resistant Bacteria

• Due to overuse of antibiotics
• prescriptions for minor illness
• growth enhancers in livestock and fruits and
  vegetables
• Examples
• MRSA (methicillin-resistant Staphylococcus
  aureus)
• TB (tuberculosis)

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? QUIZ

• The graph shows data for botulism, a form of food
  poisoning. The conclusion in the box is based on
  these data. Which of the following is the best
  reason this conclusion may be unreliable?
• A The greatest number of reported botulism cases
  was 50.
• B The number of reported botulism cases remained
• relatively constant from 1988 to 1995.
• C More botulism cases were reported in the 1980s
  than in
• the 1990s.
• D The number of reported botulism cases decreased
  after
• 1994.

Answer B
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? QUIZ
Answer D

• Mycobacterium tuberculosis causes tuberculosis in
  humans.
• When treated with antibiotics, most M.
  tuberculosis bacteria are killed, but some have
  genes that allow them to survive.
• M. tuberculosis bacteria that survive the
  antibiotic treatment may reproduce.

• Which of the following conclusions is supported
  by the information above?
• A Antibiotics have intensified the symptoms of M
  tuberculosis
• infections.
• B M. tuberculosis is becoming extinct because of
  antibiotics.
• C Antibiotics have cased M. tuberculosis to
  reproduce at a
• faster rate.
• D M. tuberculosis has developed resistance to
  antibiotics.

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Interactive sites

• Dividing Bacteria Video http//encarta.msn.com/m
  edia_461536639_761574409_-1_1/Dividing_Bacteria.ht
  ml
• Interactive Crossword - http//www.glencoe.com/sec
  /science/activities/bdol/bdolxwords/BDOLXWCH18.HTM
  L
• PowerPoint Quiz Bacterial shapes -
  https//www.msu.edu/kommkris/072008StAIRKK.ppt30
  3,1,Bacterial Shape Configuration
• Interactive QUIZ
• Glencoe - http//www.glencoe.com/qe/science.php?qi
  2508
• Bitezise - http//www.bbc.co.uk/schools/gcsebitesi
  ze/biology/humansasorganisms/maintaininghealthrev1
  .shtml