BISC 120 MidTerm 3
Prokaryote - Answer- A unicellular organism that lacks a nucleus and membrane bound organelles
Archaea - Answer- Domain of unicellular prokaryotes that have cell walls that do not contain peptidoglycan
Archaea and Bacteria - Answer- two domains of prokaryotes (= a type o...
BISC 120 MidTerm 3
Prokaryote - Answer- A unicellular organism that lacks a nucleus and membrane
bound organelles
Archaea - Answer- Domain of unicellular prokaryotes that have cell walls that do not
contain peptidoglycan
Archaea and Bacteria - Answer- two domains of prokaryotes (= a type of cell lacking
a membrane-enclosed nucleus and membrane-enclosed organelles; Uncellular and
SMALL); They are NOT sister taxa (Archaea and Bacteria are); They are
Paraphyletic
Prokaryotic Cell Wall - Answer- Maintains shape, protects the cell, prevents it from
bursting in a hypotonic environment.
- Bacterial cell walls: Peptidoglycan
- Archaea: diff components, contain polysaccharides and proteins but not
peptidoglycan.
[Eukaryotic Cell Walls are made of cellulose or chitin]
Peptidoglycan - Answer- Cell wall of prokaryotes, but NOT ARCHAEA. Made of a
sugar polymer and polypeptide.
Gram Staining - Answer- Used to classify bacteria by cell wall compostition
- Positive = simpler walls w/ large amount of peptidoglycan (traps crystal violet --
stains PURPLE)
- Negative = less Peptidoglycan and an outer membrane that can be toxic (crystal
violet easily rinsed away -- stain RED/PINK)
--*B/c many antibiotics target Peptidoglycan and damage cell walls, gram neg
bacteria are more likely to be resistant to them*
gram positive vs gram negative bacteria - Answer- there is an extra outer membrane
in gram-negative that stains red
Prokaryotes and Internal DNA - Answer- - Prok genome has LESS DNA than most
Euk genomes
- Many bacterial genomes consist of a circular chromosome
- Chromosome not surrounded by a membrane; its in the nucleoid region (where its
tightly coiled and compressed)
- Some species of bacteria have smaller pieces of DNA called plasmids
Plasmids - Answer- small circular DNA molecules that replicate separately from the
bacterial chromosome
• Extra-chromosomal DNA circles that can exist in up to 600 copies/cell
• Encode as few as 3 genes; up to 100's
• Very important in conferring antibiotic resistance in bacteria
•Used extensively in molecular biology
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