Small, smaller, smallest

1
Small, smaller, smallest

• Science uses the metric system
• Each unit differs by 1000x (103)
• Length meter, millimeter, micrometer, nanometer
• Molecules are too small to talk about length
• Units are molecular weight grams/mol
• i.e. how much do 6.023 x 1023 molecules weigh?
• What sizes are we talking about?
• We can see things about 0.1 mm (100 µm)
• Bacteria are generally 1 5 µm (0.0001 mm)
• We need special microscopes to see smaller than
  that.

2
Something cant be smaller than the parts it is
made of!
Sand is used to make bricks, and bricks are
assembled to make a house. A house cant be
smaller than a brick a brick cant be smaller
than grains of sand. Likewise, small molecules
are combined to make polymers and polymers are
used to make cells.
www.littleitalymd.com/images/BrickLayer.gif
cic.nist.gov/lipman/sciviz/scan/jun24_ptC1a.jpg
www.kevscartoons.com/images/illustration/chil...
3
In the world of small, whats big?

• Cells of eukaryotic organisms are big
• Nerve cells can be quite long
• White blood cells are about 10 µm in diameter
• An amoeba may be around 20 µm
• Prokaryotes and cell organelles are smaller
• E. coli is about 1 µm long
• A mitochondrion is about the same size
• Particles are smaller
• Viruses range from 20 to 200 nm (0.02 0.2 µm)
• Ribosomes, found inside cells, are about 20 nm

4
In the world of small, whats smaller?

• Ribosomes, viruses, cell walls are made of
  polymers
• Ribosomes and viruses are combinations of
  proteins and nucleic acids
• Cell walls are made of large molecules like
  peptidoglycan and lipopolysaccharide
• Polymers are larger than the monomers they are
  made of
• Proteins range from 10,000 to 500,000 MW
• Bacterial DNA is over 1 mm long! (but very
  skinny)
• Polysaccharides can be gt 100,000 MW (grams/mol)

5
In the world of small, whats smallest?

• These are all small molecules ranging from 18
  g/mol to 1,000 g/mol
• Water, oxygen gas, nitrogen gas
• Sugars (glucose, sucrose, etc.)
• Amino acids
• Nucleotides
• Fatty acids, cholesterol, (even phospholipids
  arent big)
• Organic acids found in metabolism
• Vitamins
• Antibiotics and most other drugs

6
History of microbiology

• Ancient times
• People understood contagion
• Exposure to sick people resulted in disease
• Something was being spread (didnt know what)
• Lepers had to wear a bell and live away from
  town
• People understood immunity
• Chinese exposed themselves to mild smallpox virus
  to build up protection against the often fatal
  major smallpox virus.

7
Cant have a science of microbiology if you dont
know the microbes are there

• Microbiology as a biological science
• Robert Hooke, 1665, discovery of cells
• Antony van Leeuwenhoek, father of microbiology
• Dutch amateur lens grinder
• First person to see microbes, late 1600s
• Mid 1800s, microbes taken more seriously and
  studied using the scientific method

micro.magnet.fsu.edu/.../ introduction.html
8
History the Golden Age

• From about 1850 to start of 20th century
• Pasteur lays to rest the idea of spontaneous
  generation
• Pasteur shows fermentation associated with life
• Prevents unwanted fermentation by Pasteurization
• Saves the French wine industry
• Saves the French silkworm industry
• Germ theory of disease sicknesses caused by
  microbes
• Robert Koch Germany
• lab techniques like agar, staining
• Kochs postulates how to link a microbe w/ a
  disease.

9
More history

• Semmelweis and handwashing (1848)
• Medical students vs. midwives students working
  on cadavers killed 20x more new mothers than
  midwives.
• Handwashing in chlorinated water greatly reduced
  incidence of fatal infection.
• Lister and aseptic surgery (late 1800s)
• Spraying phenol on, over patients, greatly
  reduced rate of infections following surgery
• Ehrlich and antimicrobials
• Differential staining of bacteria instilled idea
  of chemicals that would attack bacteria, not
  host.
• Minor success, but beginning of antimicrobial
  therapy.

10
20th Century Microbiology

• Molecular biology
• Use of microbes as model systems for study
• Study of DNA, proteins synthesis
• Tools and processes for recombinant DNA
• Applied microbiology
• Food industry
• Water and sewage treatment
• Bioremediation
• Medicine
• Emerging diseases antibiotic resistance