bacteria - lqc 3a Flashcards
ribosomes in bacteria
site of translation, smaller than eukaryotic ones
pilus in bacteria
allow bacteria to attach to surfaces and are involved conjugation
plasmid in bacteria
small loop of dna
capsule in bacteria
protective outer layer which prevents dehydration
flagellum in bacteria
used for cell movement
mesosome in bacteria
infolding of the cell surface membrane
cell wall in bacteria
made of peptidoglycan. it’s composition makes bacteria either gram negative or gram positive
how do bacteria reproduce
asexually by binary fission
what do bacteria not make during asexual reproduction that animals cells do
spindle fibres
singular of bacteria
bacterium
plural of bacteria
bacteria
diseases caused by pathogens are called
infectious diseases
bacteria facts:
- prokaryotes
- size between 0.5 and 5 um
- they don’t have a nucleus or other membrane bound organelles
- do not produce a spindle during cell division
- produce 2 identical daughter cells
2 classes of bacteria based on their cell walls:
gram positive, gram negative
gram positive bacteria take up stain:
purple
gram negative bacteria reject the stain:
pink
label gram positive bacteria
label gram negative bacteria
how are gram negative bacteria different?
- cell wall is a thinner layer of peptidoglycan
- is a ‘periplasmic space’ between the cell wall and the cell membrane
- outer membrane contains lipopolysaccharides (LPS), porin channels and murein lipoprotein
- LPS is an endotoxin, it blocks antibiotics, dyes and detergents- so it protects the thin inner membrane and cell wall, this makes gram negative bacteria resistant to penicillin and lysozyme
gram staining procedure:
1) begin with heat fixed cells
2) flood slide with crystal violet dye for 1 min
3) add iodine solution for 1 minute
4) wash slide with alcohol for 20 seconds
5) counter stain with safranin
gram positive cell wall affects of staining procedure
1) cell wall remains clear
2) peptidoglycan cell wall is flooded with crystal violet and appears purple
3) a crystal violet- iodine complex is formed within the peptidoglycan cell wall trapping the purple stain
4) the crystal violet- iodine complex is trapped with the peptidoglycan cell wall and doesn’t wash out
5) as the peptidoglycan cell wall remains stained purple the red safranin has no effect
gram negative cell wall affects of staining procedure
1) cell wall remains clear
2) cell wall is stained purple from the crystal violet dye
3) a crystal violet- iodine complex is formed but does not adhere to the cell wall due to the thin layer of peptidoglycan
4) the crystal violet- iodine structure is washed out of the thin peptidoglycan layer
5) the red safranin stains the washed gram negative cells
