Microbiology

study of microorganisms, including bacteria, viruses, and fungi

prokaryotic organisms; prokaryotes lack a true nucleus and membrane-bound organelles.

are not considered living organisms, since they cannot carry out metabolism outside of a host cell.

are viruses that infect bacteria

lack chlorophyll but are eukaryotic organisms and therefore have membrane-bound organelles.

bacteria and archaea

• 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*

• -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.

serves to maintain the cell's shape and provide protection and rigidity to the cell.

gram-positive and gram-negative

Gram + bact. have a thick cell wall composed of peptidoglycan.

thin layer of peptidoglycan sandwiched btwn layers of periplasm and coated w/ a layer of lipopolysaccharide.

• morphology (shape)
• 1) cocci: round or spherical 
• 2) bacilli: rod-shaped bacteria
• 3) spirilla: spiral-shaped bacteria

• 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.

• nutrition; 
• photoautotrophs
• chemoautotrophs
• photoheterotrophs
• chemoheterotrophs

photosynthetic; use light energy to produce their own nutrient molecules. 

Photosynthetic bacteria use the plasma membrane as the site of photosynthesis.

use energy derived from inorganic molecules such as ammonia (NH3) or hydrogen sulfide (H2S) to drive nutrient production.

can use light to generate energy but must obtain their carbon in organic form (ex glucose)

must consume organic molecules both as an energy source and a source of carbon.

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.

The transfer of information from DNA to RNA

The transfer of information from an RNA molecule into a polypeptide.

a single mRNA often contains more then one coding region;

in the cytosol (since there are no separate membrane bound nucleus)

• 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.

A) polycistronic mRNA

takes place when DNA is incorporated (contained) into a recipient cell. 

• -transformation
• -transduction
• -conjugation

DNA is taken up from the environment and integrated into the bacterial genome.

bacterial genes are transferred from one bacterial cell to another by a virus.

genetic information is directly transferred from one bacterial cell to another via a temporary connection known as a conjugation bridge.