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BACTERIA. Biology Chapter 24. Bacteria are very small. This is a pore in human skin and the yellow spheres are bacteria. Bacteria are very small compar-ed to cells with nuclei. Bacteria compared to a white blood cell that is going to eat it. Bacteria.

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Biology Chapter 24

evolution classification
  • Most numerous on Earth
  • Most Ancient
  • Microscopic Prokaryotes
  • Evolution has yielded many species adapted to survive where no other organisms can.
  • Grouped based on:
    • Structure, physiology, molec. Compositionreaction to specific types of stain.
    • Eubacteria= Germs/bacteria
    • Archaebacteria
kingdom archaebacteria
Kingdom Archaebacteria
  • First discovered in extreme environments
  • Methanogens: Harvest energy by converting H2 and CO2 into methane gas
    • Anaerobic, live in intestinal tracts
  • Extreme halophiles: Salt loving, live in Great Salt Lake, and Dead sea.
  • Thermoacidophiles: Live in acid environments and high temps.
    • Hot Springs, volcanic vents
kingdom eubacteria
Kingdom Eubacteria
  • Can have one of three basic shapes
  • Bacilli – rod-shaped
  • Spirilla – spiral-shaped
  • Cocci – sphere-shaped
  • Staphylococci – grape-like clusters

Streptococci – in chains



Staphylo - bacteria occur in clumps, such as this staphylococcus bacteria that causes common infections of cuts


Strepto- bacteria occur in chains of bacteria, such as this streptococcus bacteria that causes some types of sore throats


The tip of a needle

The red and yellow dots are bacteria

gram stain
Gram Stain
  • Gram-positive retain stain and appear purple
    • Have thicker layer in cell wall.
  • Gram-negative do not retain stain and take second pink stain instead.
nutrition and growth
Nutrition and Growth
  • Heterotrophic or Autotrophic
  • Some are Photoautotrophs – Use sunlight for Energy
  • Some are Chemoautotrophs.
  • Many are Obligate Anaerobes.
    • Oxygen = Death
      • Ex. Clostridium tetani – Tetanus
  • Some are Faculatative Anaerobes
    • With or without Oxygen
      • Ex. Escherichia Coli
  • Some are Obligate Aerobes
    • Ex.) Mycobacterium tuberculosis
  • Temperature requirements
    • Some are Thermophilic, Some prefer acidic envmt.

These heterotrophic bacteria digest oil -- remember oil is partially decayed plant and animal cells



(please add to notes)



First the chromosomal DNA makes a copy

The DNA replicates



The two resulting cells are exactly the same

genetic recombination
Genetic Recombination
  • Nonreproductive Methods bacteria can acquire new genetic material.

This plasmid of DNA is new to the bacteria – added by transformation! Produces the glowing protein


Leprosy is a bacterial infection that decreases blood flow to the extremities resulting in the deterioration of toes, ears, the nose and the fingers.

some final information
Some Final Information
  • Because antibiotics have been overused, many diseases that were once easy to treat are becoming more difficult to treat.
  • Some Bacteria are Useful
    • Ex.) Producing and Processing food
    • Breaking down dead organic material
    • Make unripened cheese like ricotta and cottage by breaking down the protein in milk.


Non-living but depends on the living!

  • Nonliving
  • Composed of Nucleic acid and protein
  • Cause many diseases
  • Virology – Study of Viruses
  • Comparison of Viruses and Cells below
characteristics of viruses
Characteristics of Viruses
  • 2 essential features
  • 1. Nucleic Acid
    • May be DNA or RNA
    • Helical, closed loop, or long strand
  • 2. Protein Coat – called CAPSID
  • Some have ENVELOPE
    • Ex. Influenza, chickepox, herpes simplex, HIV
    • Icosahedron – 20 triangular faces
      • Ex.) herpes, chickenpox, polio
    • Helix – Coiled spring
      • EX.)Rabies, measles, tobacco mosaic

All viruses have two main parts:

  • DNA or RNA – genetic info
  • Capsid – a protein encasement
grouping viruses
Grouping Viruses
  • Grouped according to:
    • Presence of Capsid and envelope – shape
    • RNA or DNA, single or double stranded – struct.
grouping viruses62
Grouping Viruses
  • Viroids- The smallest known particle that can replicate.
    • Disrupt plant cell metabolism
    • Can destroy entire crops
  • Prions – Abnormal forms of proteins that clump together inside cells.
    • Clumping eventually kills the cell
    • Examples
      • Scrapie – in sheep
      • Mad Cow Disease
viral replication
Viral Replication
  • Can replicate only by invading host cell and using its enzyme and organelles.
  • Bacteriophage – viruses that infect bacteria
    • Used to study viruses
  • Lytic Cycle
    • Viral genome is released into the host cell
    • Replication follows immediately
    • Cellular components used to make new viruses
    • Viral enzyme kills cell.
viral replication picture
Viral Replication Picture

Click Movie to Play

replication cont
Replication cont’
  • Lysogenic Cycle
    • Nucleic acid of virus becomes part of the host cell’s chromosome
    • Nucleic acid remains in the cell in this form for many generations
    • HIV follows this pattern
    • HIV infects WBC and remains as proviruses
    • As immune system fails, opportunistic infections occur = AIDS

Here is a classic picture of HIV viral progeny being released from the surface of a T- cell. Notice the membrane coating they receive.

viruses and human disease
Viruses and Human Disease
  • Control and Prevention of spread.
    • Vaccination & Antiviral drugs
      • Ex.) chickenpox vaccine, AZT, Acyclovir, protease inhibitors.
  • Emerging Viruses – exist in isolated habitats
    • Do not usually infect humans unless environmental conditions favor contact.
  • Several viruses are now linked to cancers such as leukemia, liver cancer, Burkitt’s lymphoma, cervical cancer.

After polio infections, the killer T-cell have destroyed the motor neurons that are producing the virus. The result is a loss of muscle control including the diaphragm. The iron lung changes the pressure to pump air in and out of the lungs.




What does bacteria have to do with DNA technology?
  • Bacteria are simple
  • Bacteria have DNA that is made of nucleotides (A,T,G,C)
  • Bacteria can be grown quickly and easily
    • Give them food, warmth and dark (like inside you shoe) and they will multiply like mad (binary fission)
Plasmids are DNA – made out of A,T,C,G nucleotides
  • The same nucleotides found in human DNA, plant DNA, dog DNA, fish DNA, fungus DNA
  • Get it – it’s all the same molecule
Then put it back in the bacteria and grow more bacteria with that new plasmid that we have created! Hmmm?

How could rDNA and transformation be useful?
  • To be answered in DNA technology presentations
Transduction – viruses attack cells
  • Bacteriophages: like tiny little syringes that inject DNA into the cell
Look at how the virus infects

How could scientists use viruses for DNA technology
  • To be answered in DNA technology presentations
time to take ownership
Time to take ownership
  • Here’s what you should have down by the end of the class Wednesday:
    • Bacteria and virus structures
    • Types of bacteria
    • Types of viruses
    • How bacteria and viruses cause infection
    • How bacteria and viruses can be useful DNA technology tools
    • Overview of various DNA technologies – refer to chapter 13