Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

15 Cards in this Set

  • Front
  • Back
What is the relationship between bacteria and O2?
How bacteria deal with O2 is a major factor regarding their classification.
What is the effect of O2 on bacteria?
Molecular O2 is very reactive, and when it snatches up electrons, it can form, H2O2/superoxide radicals (O2-) /and a hydroxyl radical(OH-).
What is the effect of these substances?
All are toxic, unless they are broken down. Infact, the bodys macrophages produce these O2 radicals to pour over bacteria.
Can bacteria possess enzymes to break down these O2 products?
Yes. 1. Catalase breaks down H2O2.(2H2O2--2H2O+ O2)
2. Peroxidase- also breaks down H2O2.
3. Superoxide dismutase, breaks down the superoxide radical.(O2+O2- +2H+--H2O2 + O2)
How are bacteria classified regarding oxygen requiremets?
At one end, are those that love O2, and have all the protective enzymes, and cannot live without O2. There are as well bacteria which have no enzymes, and will not survive in its presence.
What are the 4 classifications of bacteria based on thier O2 utilization.
1. Obligate aerobes
2.Facultative anerobes
3. Aerotolerant aerobes
4. Obligate anerobes
What is an obligate aerobe?
They use glycolysis, the Krebs TCA cycle, and the electron transport chain with O2 as the final electron acceptor. They possess all of the above mentioned enzymes.
1. Catalase breaks down H2O2.(2H2O2--2H2O+ O2)
2. Peroxidase- also breaks down H2O2.
3. Superoxide dismutase, breaks down the superoxide radical.(O2+O2- +2H+--H2O2 + O2)
What is a facoltative anerobe?
These bacteria may be aerobic as well, they use O2 as an electron acceptor in their electron transfer chain and have catalase and superoxide dismutase. However, they can occasionally grow without O2 by using fermentation for energy, yet they prefer aerobic environments. This process is similar to the switch to anerobic glycolysis that human muscle cells undergo during sprinting.
What are aerotolerant anerobes?
These bacteria use fermentation and do not possess an electron transport. They can tolerate low amounts of O2.
What are obligate anerobes?
These bacteria cannot survive in an O2 environment. They have no enzymes to defend themselves against.
How are bacteria classified by their carbon and energy source?
Some use light as an energy source(phototrophs), and some use chemical compounds as a source(chemotrophs)Of those that employ chemical sources, those that use inorganic sources, such as ammonium and sulfide are called autotrophs. Others that use organic carbon are called heterotrophs. Nearly all the medically relevant bacteria are chemoheterotrophs, b/c they use chemical and organic compounds, such as glucose(C6H12O6), for energy.
Why do some bacteria use fermentation?
Fermentation(glycolysis) is used by many bacteria for O2 metabolism. Glucose is broken down to pyruvic acid, yielding ATP directly. The most common pathway, for this process is the Embden Meyerhof pathway. The pyruvate must be broken down and the diverse end products formed in this process can be used for bacterial classification.
When the pyruvate is broken down, what are some of the products formed?
Lactic acid
Proprionic acid
Butyric acid
Acetone, as well as other mixed acids.
How is respiration used with some bacteria?
It is used with aerobic and facultative anerobic organisms. Respiration includes glycolysis, Krebs tricarboxylic-acid cycle, and the electron transport chain coupled with oxidative phosphorylation. these pathways combine to produce ATP.
Regarding the previously mentioned pathways, how do obligate intracellular organisms relate to these processes?
They are not capable of the metabolic pathways for ATP synthesis, and thus must steal ATP from their host. These bacteria live in their hosts cell and cannot survive without the host.