Bacteria introduction Flashcards
what colour are gram positive bacteria?
purple
what colour are gram negative bacteria?
red/pink
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?
provides motility
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?
asymmetrical
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?
1
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)
how are bacteria named?
name is based on their genus and species
