Prokaryotes and bacterial growth curve

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Prokaryotes and bacterial growth curve
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• This lab
• Bacteria, Archea
• Bacterial morphology, reproduction and growth
  curve
• How to calculate generation time
• How to draw a growth curve
• Exercise on phase contrast microscope
• Inoculating some plates

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Domains of life
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Domains of life
Blue green bacterium
Eukarya
Archaea
chloroxybacteria
Chlo.A
schizomycetes
Intracellular organelles
Chlo. AB
Muramic acid
Nuclear mem.
DNA transcription factors
DNA
RNA
ATP
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Bacteria and Archea

• Bacteria and Archea are unicellular organisms.
• For long time, Archea used to be grouped with
  bacteria
• but it was separated later on. Generally Archea
  can be described as bacteria able to grow and
  multiply in extreme environmental conditions
  (high temperature, high salinity,.)

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Why to study Bacteria and Archea

• Many of them produce diseases (HUS caused by E.
  coli O157).
• Others are beneficial (lactobacillus species is
  used in yogurt, bacteria in association with
  plant roots supply nitrogen).
• Archea is good source for restriction enzymes

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Bacterial morphology

• Bacteria has many shapes
• B.subtilis is bacilli (rod shaped)

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Bacterial reproduction

• Simple binary fission (Asexual)
• The bacterium double its content then divide into
  two
• Bacterial motility
• http//www.bme.jhu.edu/skuo/emph_ListSteps.htmlR
  elevance

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Bacterial growth curve

• Bacteria grow in population called Culture
• Binary fission result in geometric progression
  in number which is termed exponential growth
• 1- 2- 4- 8-16 - 2n.
• Generation time (doubling time)time needed for
  division

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Growth curve
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How to calculate generation timefrom data set

• n 3.3 x log (P/p)
• n number of generations
• P final population number
• p original population number
• Generation time time elapsed to reach P
• minute/generation
  n
• example page 38

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How to calculate generation time

• How to determine the population number?
• By using spectrophotometer (A600)

Detector.reading
light
600nm
Different reading
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How to calculate generation time
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What to do
1- mark your tubes (on the upper part) 25C and
37C 2- using the Blank tube adjust your
machine to zero absorbance (on the lower
scale using right knob). You do not have to
do this step again 3- aseptically (using pasteure
pipette) take 4 ml from each culture into
each tube then take the reading. 4- return
the the 4ml back to the culture and turn on the
shaker 5- repeat step 3 and 4 every 30
minutes P.S make sure that you return it to the
correct culture otherwise it will spoil all the
work
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How to draw a growth curve at the exponential
phase
Plot you A600 or log A600 against your time
point
Log A600
A600
Log A600
A600
Time in minutes
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How to calculate generation timefrom a growth
curve
If you have the growth curve of certain
bacteria (exponential phase), you can calculate
the generation time by this equation generati
on time time elapsed x log2
logA600 example in page 38
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Microscope
Staining of biological specimen enhance
visibility What you should do 1- mount the slid
on the stage 2- chose the low power lens and
start to focus using the coarse focusing the
fine focusing. 3- chose another objective lens
and repeat 4- your goal is to have clear sharp
view of what you are examining
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Lab report on bacteria and bacterial growth curve
c

• Worth 15 point .due next week in class
• Topics to be covered
• 1- title chose suitable title from your
  creation (1)
• 2-abstract summary of the report (3)
• 3-introductionbackground (3)
• 4-experimental procedures (1)
• 5-results include page 3940 from the manual as
  attachments)(3)
• also include tables (A600
  readings)
• 6-discussion (4)
• 7-references cite any references you used in
  you report
• There is a handout on what is expected in lab.
  report.
• There is a handout on group members
  participation.
• I will post an example Lab report (on a different
  topic)
• today.