Microbiolgy Lecture 3
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Explain these ways to measure growth ?
spread plate method,
pour plate method–
How do you use this formula ?
The doubling time is 20 minutes at 37o
C. The bacteria have been incubating for 8 hours, which means there will be doubling taking place 3 times an hour. So there will be (8 hrs x 3) = 24 doubling moments taking place.There will be 24 generations of bacteria after 8 hours.
- 5000 x 224 = Nt
- Nt = 83,886,080,000
- or 8.388 x1010
Utilizing the equation Nt
- Nt=population size at specified time
- No= initial population size
- n= # of generations
What is an
Aerobe: organism that grows in the presence of oxygen
Obligate aerobe: requires atmospheric oxygen (20% O2) for growth and metabolism
Microaerophile :requires O2 for metabolism, but at very low concentrations
What is an
Anaerobe: organism that grows in the absence of oxygen
Obligate anaerobe:cannot grow in the presence of oxygen
Facultative anaerobe: able to use both pathways; therefore, does not require O2 , but grows better in its presence–
Aerotolerant: does not require O2 but can withstand the presence of O2; grows just as well in and out of the presence of O2
Where do each of these grow in a test tube culture ?
Obligate aerobe : Top growth
Facultative anaerobe: Full column
Obligate anaerobe: bottom growth
Microaerophile : Middle growth
Aerotolerant : Full column
What are the important enzymes that destroy free radicals ?
- Superoxide Dismutase:
- Superoxide dismutase & catalase:
- Superoxide reductase:
What are Cytochromes and Siderophores ?
–Cytochromes: proteins involved in electron transport and redox reactions
-Siderophores: organic molecules that bind to Fe3+ making it possible for the cell to take up iron
What is the purpose Hydroxamic acid and Enterbactins in the function of bacteria ?
Hydroxamic acid: strongly chelates iron–
Enterobactins: produced by enteric bacteria like E. coli and Salmonella
How do the two different photosynthesis differ ?
Differ in the wavelengths at which light is absorbed
Cyclic photophosphorylation–the electrons return to the chlorophyll after passing through the electron transport chain
Non-cyclic photophosphorylation–the electrons are used to reduce NADP and electrons are returned to chlorophyll from H2O and H2S
In terms of Oxygenic vs. Anoxygenic photosynthesis ,Which is for (Chlorophyll or bacteriochlorophyll) ?
Which one has water as the electron donor ?Which one produces oxygen?
Which one is frequently and aerobic process?
- Oxygenic = Chlorophyll
- Oxygenic = water as electron donor
- Oxyegnic= produces oxygen
- Oxygenic = frequently aerobic
What does a porphyrin do in chlorophyll ?
What colors does it absorb and transmit?
- It binds to Mg2+
- Absorbs light red and blue light; transmits green light
What are the absorption spectrums for Chlorophyl a and Chlorophyl b?
Which is the most common ?
Which one does alage use ?
680nm and 660nm
680nm is the most common
Where are thykaloid cells located in Eukaryotes and Prokaryotes ?
Eucaroytes: Occurs in thykaloid membranes within the chloroplast•Procaryotes: Occurs in thykaloid membranes within the cell
Eucaroytes: Occurs in thykaloid membranes within the chloroplast
Procaryotes: Occurs in thykaloid membranes within the cell
what is the final electron acceptor in a bacteriochlorophyll ?
What type of bacteria use bacteriochlorophyll ?
Blue and Green bacteria
Where is the bacteriochlorophyll located in the following bacteria.
Purple bacteria: invagination of the cytoplasmic membrane–
Heliobacteria: cytoplasmic membrane (unique)–
Green bacteria: both cytoplasmic membrane and membrane-enclosed structures called chlorosomes
what are carotenoids ?
- -Most widespread; associated with chlorophyll or bacteriochlorophyll
- –Hydrophobic pigments firmly embedded in the membrane
- –Oxygenic photosynthesis: Typically yellow, green, red, brown
–Anoxygenic photosynthesis: Typically red, purple, pink, green, yellow, brown
–Do not function in ATP synthesis
–Transfer light to the reaction centers•Reaction centers are a complex of pigments used to harvest light and generate ATP
–Act as photoprotective agents from toxic oxygen species (e.g. singlet oxygen)
What are Phycolbilins / Phycobiliproteins ?
What bacteria usually has them ?
Phycobilins/Phycobiliproteins–Present in cyanobacteria and red algal chloroplast
–Red (phycoerythrin) or blue (phycocyanin) pigments
–Allophycocyanin (red pigment)•Occur in aggregates called phycobilisomes, attached to the photosynthetic membranes
Usually seen in serratia
What are osmotolerant microbes ?
What are Halophiles?
•Osmotolerant: to grow over a wide range of water activity or osmotic concentration.
•Halophile:require high levels of NaCl to grow; usually above 0.2M
What are Acidophiles , Neutrophiles , and Alkalophile ?
what type are usually found in our bodies ?
Where would the bacteria Helicobacter pylori be?
- Acidophile: pH 0 and pH 5.5
- Neutrophile: pH 5.5 and pH 8.0
- Alkalophile: pH 8.5 and pH 11.5
Neutrophiles are usually in our bodies
Helicobacter pylori would be an acidophile
What is a
Which tend to live in the human body ?
- Psychrophile– 0-15oC
- Psychrotroph– 20-30oC; minimum range:
- 0-7oC; maximum: 35oC.
- Hyperthermophile (extreme thermophile):80-113oC
What is the difference between Barotolerant and Barophile ?
Barotolerant–able to grow at different ranges of hydrostatic pressures
Barophile–Grows more rapidly at high hydrostatic pressures
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