Flashcards in Bacteria introduction Deck (21)
what colour are gram positive bacteria?
what colour are gram negative bacteria?
what do cocci and bacilli mean respectively?
cocci - spherical
bacilli - rod shaped
what is the structure of peptidoglycan?
carbohydrate polymers, linked by beta 1,4 glycosidic bonds, provide strength and shape
what is the structure of a lipopolysaccharide?
lipid and O antigen, illicits strong immune response.
what are the differences in cell wall structure between gram positive and gram negative bacteria?
gram positive - thick peptidoglycan layer, lack of lipopolysaccharides
gram negative - thin peptidoglycan layer, presence of many more lipopolysaccharides.
what is the function of the bacteria capsule?
mostly present in gram negative bacteria - helps with prevention of phagocytosis of bacterial cells via macrophages etc
what is the function of a flagellum?
what are the 4 different classifications of flagellum attachment?
A monotrichous - one flagellum
B lophotrichous - attachment at only one point
C amphitrichous - attachment on both sides
D peritrichous - attached all over
what is the function of fimbriae?
adherence to epithelial cells
when would spore formation occur and why is it advantageous to the bacteria?
under unfavourable/stressful environmental conditions.
spores are resistant to environmental conditions and will start dividing as bacterial cells when conditions are favourable again.
does formation of spores occur as a result of symmetrical or asymmetrical cell division?
what is a bacteriophage?
virus that infects bacteria
what is a lysogenic cycle?
when DNA from the bacteriophage is integrated into the bacterial cell
what is a plasmid?
small DNA molecule within a cell that is physically separated from a chromosomal DNA and can replicate independently.
what are some of the functions of plasmids?
can transfer resistance from one bacteria to another via the formation of a PILUS; a bridge between two bacterial cells that is used for communication (conjugation)
what are the two classifications of bacteria with regards to plasmids?
F+ - bacteria that contains the plasmid
F - - bacteria that doesnt contain the plasmid
how many strands of DNA are donated during conjugation?
how do bacteria replicate?
binary fission - produces identical progeny
how do bacterial cells display genetic variation?
spontaneous mutation and the transfer of DNA (transductions and transformations)