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What is microbiology?
study of microorganisms, including bacteria, viruses, and fungi
What are bacteria?
prokaryotic organisms; prokaryotes lack a true nucleus and membrane-bound organelles.
What are viruses?
are not considered living organisms, since they cannot carry out metabolism outside of a host cell.
What are bacteriophages?
are viruses that infect bacteria
What are fungi?
lack chlorophyll but are eukaryotic organisms and therefore have membrane-bound organelles.
what are the two major groups of prokaryotes?
bacteria and archaea
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*
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.
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.
Bacteria can be divided into two major group based on the structure of their cell wall, what are they?
gram-positive and gram-negative
What are gram + bacteria cell wall like?
Gram + bact. have a thick cell wall composed of peptidoglycan.
What are gram - bacteria cell wall like?
thin layer of peptidoglycan sandwiched btwn layers of periplasm and coated w/ a layer of lipopolysaccharide.
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
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.
Bacterica can also be classified according to their mode of _________. What are they?
What are photoautotrophs?
photosynthetic; use light energy to produce their own nutrient molecules.
Photosynthetic bacteria use the plasma membrane as the site of photosynthesis.
What are chemoautotrophs?
use energy derived from inorganic molecules such as ammonia (NH3) or hydrogen sulfide (H2S) to drive nutrient production.
What are photoheterotrophs?
can use light to generate energy but must obtain their carbon in organic form (ex glucose)
What are chemoheterotrophs?
must consume organic molecules both as an energy source and a source of carbon.
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.
what is transcription?
The transfer of information from DNA to RNA
what is translation?
The transfer of information from an RNA molecule into a polypeptide.
What is polycistronic?
a single mRNA often contains more then one coding region;
where does transcription and translations occur in prok?
in the cytosol (since there are no separate membrane bound nucleus)
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.
Which of the following may be found in a prokaryotic cell?
A) polycistronic mRNA
B) multiple chromosomes
A) polycistronic mRNA
(this multiple choice question has been scrambled)
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.
what happens in transformation?
DNA is taken up from the environment and integrated into the bacterial genome.
what happens in transduction?
bacterial genes are transferred from one bacterial cell to another by a virus.
what happens in conjugation?
genetic information is directly transferred from one bacterial cell to another via a temporary connection known as a conjugation bridge.