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Biology 11: Prokaryotes
Purpose: Analyze Bacteria as a life form at the prokaryotic level of organization
Evaluate the effectiveness of various antibiotics, disinfectants or antiseptics on bacterial cultures.
Text Pages: 319 to 329 *This is required reading!
What are Prokaryotes and why do We Care?
-In the table below list some major differences between Prokaryotic and Eukaryotic Cells:
Characteristics Prokaryotes Eukaryotes
Size
Cell Wall
Organelles
Nucleus
Genetic Material
-Prokaryotes represent the earliest forms of life that existed on Earth, with the Geologic Record indicating that they were present almost 4 bya!
-Today, most people associate Prokaryotes with Bacterial Pathogens but it is important to remember that there are many times more beneficial or benign prokaryotes than there are harmful ones.
-Here are some important roles of Prokaryotes in our world:
a) Ancient photosynthetic prokaryotes are responsible for the creation of our atmospheric oxygen, allowing aerobic life to develop.
b) The hundreds of bacteria species living on/in our bodies perform functions necessary for humans to live! e.g. The bacteria in our intestines release nutrients from food molecules that we can’t digest and also supply us with essential vitamins!
c) Act as decomposers by breaking down dead animal and plants remains, releasing their nutrients back into the environment so that they can be used again.
*In short, Prokaryotes made it possible for all other forms of life to exist on Earth and continue to do so today!
Why are Prokaryotes so Successful?
-The collective biomass of Prokaryotes is at least 10 times as much as that of all Eukaryotes and they are also able to survive in habitats that are too cold, hot, salty, acidic or alkaline for any Eukaryote.
-What characteristics make them so successful?
External Features
a) Cell Shape:
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b) Cell Wall
-The cell wall functions as:
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-There are two different types of Prokaryote cell walls:
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-Many Prokaryotes have cell walls that are covered by
capsules, a _____________________________________
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c) Projections
-Flagella ______________________________________
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-Fimbriae/pili _________________________________________________________________________
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d) Rapid Adaptation to Changes in Environment
-Prokaryotes can reproduce quickly in ideal environmental conditions: Some species of can create a new generation in under 20 minutes by
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-Through binary fission
-Is the binary fission method of reproduction sexual or asexual? If this is true, how is genetic variation created in Prokaryotic cells?
i) ____________________________________________________________________________
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ii) ____________________________________________________________________________
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-http://www.hhmi.org/biointeractive/animations/conjugation/conj_frames.htm
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Why is genetic variation important? _______________________________________________________
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-If the environment becomes too extreme, an endospore can form:
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-Some endospores can remain dormant for centuries. Not even boiling water kills most of these resistant cells. To sterilize laboratory equipment, microbiologists use an autoclave, a pressure cooker that kills endospores by heating to a temperature of 121°C (250°F) with high-pressure steam. The food-canning industry uses similar methods to kill endospores of dangerous bacteria such as Clostridium botulinum, the source of the potentially fatal disease ___________________.
e) High Nutritional Diversity
-Energy Source:
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-Carbon Source:
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-Mode of nutrition:
i) Photoautotroph ______________________________________________________________________
ii) Photoheterotroph ____________________________________________________________________
iii) Chemoautotroph ____________________________________________________________________
iv) Chemoheterotroph __________________________________________________________________
-Diversity of nutritional modes means that prokaryotes can obtain energy and carbon in almost any habitat!
-In which of the categories above would you be classified? _____________________________________
Prokaryotic Domains
Domain Archaea
-Some archaea possess unusual proteins and other molecular adaptations to living in extreme environments and, as such, are called extremophiles:
a) Halophiles
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b) Thermophiles
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c) Methanogens
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-Many archaea also live in non-extreme environments.
-Little is known about Archaea as bacteria have thus far been the subject of most prokaryotic research.
Domain Bacteria
-Genetic analysis (molecular biology) has resulted in bacteria being divided into five groups. Take your own brief notes on these groups.
a) Proteobacteria (Gram Negative)
b) Gram Positive Bacteria _______________________________________________________________
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c) Cyanobacteria ______________________________________________________________________
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d) Chlamydias ________________________________________________________________________
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e) Spirochetes _________________________________________________________________________
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Disease Causing Bacteria
-Bacteria cause diseases by producing either:
a) Exotoxins __________________________________________________________________________
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b) Endotoxins_________________________________________________________________________
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-Below are some bacterial disease outbreaks and methods of infection:
Helpful Bacteria
-Conduct your own research to discover some beneficial and important bacteria that benefit humans.
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Bacteria and Antibiotic Resistance (text 272)
-What is an antibiotic and where have they been harvested from?
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-How does a population of bacteria adapt to become resistant to antibiotics?
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-http://www.scq.ubc.ca/attack-of-the-superbugs-antibiotic-resistance/ is an article worth reading if you want to learn more about antibiotic resistance in bacteria.