BIOL 226 Lecture Notes - Lecture 27: Horizontal Gene Transfer, Gram Staining, Crystal Violet
Document Summary
Function: adheres to substrates or other individuals in a colony, protects against dehydration, defends against pathogens: fimbriae: hair-like appendages -another way for cells to stick to their substrate, to attach to surfaces or other cells. Peptidoglycan: polymer composed of modified sugar-cross linked by short polypeptides, mesh-like layer outside plasma membrane, anchors other molecules extending from its surface. Rank 3 types of prokaryotes in terms of the amount of peptidoglycan in their cell wall: gram stain used to classify bacterium into 2 groups (based on cell wall composition) Samples are stained with iodine and crystal violet dye, rinsed in alcohol then stained with red dy. Gram + = high amount of peptidoglycan, bacteria with simple walls. Gram - = little amount of peptidoglycan, bacteria with complex outer membranes (made of lipopolysaccharides = carbohydrates bonded to lipids) Motility- taxis = directed movement toward/away from stimulus. Plasmid-independent rings of replicating dna- carry only a few genes: lack nucleus.
