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What is microbiology?
study of microorganisms, including bacteria, viruses, and fungi
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What are bacteria?
prokaryotic organisms; prokaryotes lack a true nucleus and membrane-bound organelles.
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What are viruses?
are not considered living organisms, since they cannot carry out metabolism outside of a host cell.
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What are bacteriophages?
are viruses that infect bacteria
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What are fungi?
lack chlorophyll but are eukaryotic organisms and therefore have membrane-bound organelles.
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what are the two major groups of prokaryotes?
bacteria and archaea
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What does archaea include?
- methanogens (prok. that produce methane), extreme halophiles (prok. that live at very high concentrations of NaCl),
- extreme thermophiles (prok. that live at very high temp.)
- *on test day, the term prok. should make you think of bacteria*
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What are the basic structure/components of prokaryotes?
- -simple single-celled organisms
- - have plasma membrane but lack organelles and cytoskeleton
- -have cell wall, cytoplasm, ribosomes(differ slightly from euk. ribo.)
- -genome, also referred to as bacterial chromosoms, is found in the nucleoid region.
- - lack of organelles means that the interior of prok. is one continuous compartment, the cytosol.
- -may contain plasmids, which are small circular extrachromosomal segments of DNA that replicate independently of the bacterial chromosome
- -sometimes have flagella that used for locomotion.
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what is the purpose of the cell wall on prok.?
serves to maintain the cell's shape and provide protection and rigidity to the cell.
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Bacteria can be divided into two major group based on the structure of their cell wall, what are they?
gram-positive and gram-negative
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What are gram + bacteria cell wall like?
Gram + bact. have a thick cell wall composed of peptidoglycan.
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What are gram - bacteria cell wall like?
thin layer of peptidoglycan sandwiched btwn layers of periplasm and coated w/ a layer of lipopolysaccharide.
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Bacteria may also be classified by their _____. What are they?
- morphology (shape)
- 1) cocci: round or spherical
- 2) bacilli: rod-shaped bacteria
- 3) spirilla: spiral-shaped bacteria
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Another means of classifying bacteria is by their _____ _____. What are they?
- oxygen requirements;
- 1) obligate anerobe: cannot survive in the presence of oxygen
- 2) facultative aerobes: can survive w/ or w/o oxygen
- 3) obligate aerobes: require oxygen to survive.
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Bacterica can also be classified according to their mode of _________. What are they?
- nutrition;
- photoautotrophs
- chemoautotrophs
- photoheterotrophs
- chemoheterotrophs
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What are photoautotrophs?
photosynthetic; use light energy to produce their own nutrient molecules.
Photosynthetic bacteria use the plasma membrane as the site of photosynthesis.
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What are chemoautotrophs?
use energy derived from inorganic molecules such as ammonia (NH3) or hydrogen sulfide (H2S) to drive nutrient production.
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What are photoheterotrophs?
can use light to generate energy but must obtain their carbon in organic form (ex glucose)
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What are chemoheterotrophs?
must consume organic molecules both as an energy source and a source of carbon.
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How do prok. reproduce?
binary fission: cell replicates its DNA and divided in two.
-circular chromosome replicates and a new plasma membrane and cell wall grow inward along the midline of the cell, dividing it into two equal daughter cells, each contain a duplicate of the parental chromosome.
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what is transcription?
The transfer of information from DNA to RNA
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what is translation?
The transfer of information from an RNA molecule into a polypeptide.
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What is polycistronic?
a single mRNA often contains more then one coding region;
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where does transcription and translations occur in prok?
in the cytosol (since there are no separate membrane bound nucleus)
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Where does transcription and translation take place in euk.?
- transcription: nucleus
- post-transcriptional modifications: includes splicing of introns (non-coding sequences in the mRNA) take place before the mature mRNA leaves the nucleus
- translation: takes place outside e of the nucleus in the cytosol.
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Which of the following may be found in a prokaryotic cell?
A) polycistronic mRNA
B) multiple chromosomes
C) centrioles
D) lysosomes
A) polycistronic mRNA (this multiple choice question has been scrambled)
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when does genetic transformation take place and what are the three methods by which prokaryotes transfer genetic material?
takes place when DNA is incorporated (contained) into a recipient cell.
- -transformation
- -transduction
- -conjugation
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what happens in transformation?
DNA is taken up from the environment and integrated into the bacterial genome.
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what happens in transduction?
bacterial genes are transferred from one bacterial cell to another by a virus.
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what happens in conjugation?
genetic information is directly transferred from one bacterial cell to another via a temporary connection known as a conjugation bridge.
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