Question | Answer |
peptidoglycan | a network of sugar polymers cross-linked by polypeptides |
Gram stain | used to classify bacteria by cell wall composition |
Gram-positive bacteria | have simpler walls with a large amount of peptidoglycan |
Gram-negative bacteria | have less peptidoglycan and an outer membrane that can be toxic |
capsule | a polysaccharide or protein layer covers many prokaryotes |
fimbriae | allow them to stick to their substrate or other individuals in a colony |
Pili | are longer than fimbriae and allow prokaryotes to exchange DNA |
taxis | the ability to move toward or away from a stimulus |
plasmid | a small DNA molecule within a cell that is physically separated from a chromosomal DNA and can replicate independently |
endospores | enable bacteria to lie dormant for extended periods |
transformation | when a prokaryotic cell can take up and incorporate foreign DNA from the surrounding environment |
Transduction | movement of genes between bacteria by bacteriophages (viruses that infect bacteria) |
F factor | piece of DNA required for the production of pili |
R plasmids | carry genes for antibiotic resistance |
Obligate aerobes | require O2 for cellular respiration |
Obligate anaerobes | poisoned by O2 and use fermentation or anaerobic respiration |
anaerobic respiration | form of respiration using electron acceptors other than oxygen |
Facultative anaerobes | can survive with or without O2 |
nitrogen fixation | a process in which nitrogen (N 2) in the atmosphere is converted into ammonia (NH 3) |
heterocysts | photosynthetic cells and nitrogen-fixing cells that exchange metabolic products |
biofilms | surface-coating colonies that enable metabolic cooperation |
extremophiles | archaea that live in extreme environments |
Extreme halophiles | live in highly saline environments |
Extreme thermophiles | thrive in very hot environments |
Methanogens | live in swamps and marshes and produce methane as a waste product; strict anaerobes and are poisoned by O2 |
Mycoplasms | the smallest known cells |