bacterial cell structure

Question 1

morphology of bacteria

Answer 1

shape

Question 2

morphology:
coccus
coccobacilllus
bacillus
vibrio
spirillum
spirochete
pleomorphic

Answer 2

coccus- spherical
coccobacilllus
bacillus- rod shaped
vibrio- curved rod
spirillum- stiff sinusoid
spirochete- flexible sinusoid
pleomorphic- abnormal

Question 3

binary fission steps in bacteria

Answer 3

1. chromosome replication begins
2. replication continues
3. replication finishes
4. two daughter cells results

2 copies of origin in chromosome get separate to either side then membrane pinches so that daughter both have organ of replication (the DNA sequence that makes copies of DNA)

Question 4

bacterial reproduction via snapping division

Answer 4

cell wall outer portion remains in tact

inner portion snaps and splits into two cells

Question 5

bacterial reproduction vis spores of actinomycetes

Answer 5

spores on filaments break off and create new filaments

Question 6

bacterial reproduction via budding

Answer 6

DNA is replicated –> one daughter DNA molecules is moved into bud –> young bud forms –> pinches off into daughter cell

Question 7

arrangement of bacteria in cocci

1. plane of cell division
2. do cells stick together after dividing?

Answer 7

diplococci- pairs
streptococci- line
–> both 1 plane of division

tetrads- split into flat 4; 2 planes

sarcinae; 3 planes creates 8 cell cube

staphylococci; many random planes creates big clump

Question 8

arrangement of bacteria in bacilli

Answer 8

only can divide in one plane along short axis (rod shape)

single bacillus

diplobacilli

streptobacilli

palisade and v shape are weird snapping division

Question 9

glycocalyces (external structure of bacterial cell)

Answer 9

glyocalyx could be tightly packed capsule or slime layer

made of polysaccharide sugar and protein

Question 10

flagella (bacterial cell external structure)

Answer 10

protein rings allow for it to whip around

tail that is made of flagellin protein

peritrichous: flagella everywhere
single polar flagellum: 1 at 1 end
tuft of polar flagella: clump at 1 end

Question 11

how do flagellated bacteria move: biased random walk

Answer 11

1. tumble
2. run

eventually move toward chemotaxis, phototaxis (attractants)

Question 12

fimbriae (bacterial cell external structure)

Answer 12

adhere to other substances (short little projections)

Question 13

pili (bacteria cell external structures)

Answer 13

conjugation pilus –> specialized fimbria

let bacterial cells connect and have “sex” and exhcngae nucleic acid genetic material;
= conjugation -transfer genes

Question 14

roles of bacterial cell wall

Answer 14

-protection (many antimicrobial drugs target cell walls)
-attachment to other bacteria or cells
-resistance to osmotic forces
-give shape to the cell

Question 15

what are cells walls made of?

Answer 15

peptidoglycan: polysaccharide comprised of repeating N-acetylglucoasmine (NAG) and N-acetylmuramic acid (NAM)

these sugar backbones are connected by a chain of amino acids and a tetra peptide amino acid cross bridge

Question 16

gram negative vs gram positive cell wall

Answer 16

gram negative has a cytoplasmic membrane then the peptidoglycan layer of the cell wall then the outer membrane of the cell wall

in the gram negative cell wall there is lipopolysaccharide (LPS) which has lipid A which is very toxic

in a gram positive cell wall there is only the inner membrane and then a thick cell wall (no outer membrane)

Question 17

gram stain

Answer 17

Hans Christian Gram-

1. primary stain; crystal violet to stain all cells
2. mordant (iodine) to make crystal violet less soluble and make it stick better to all cells
3. decolorize: flood with ethanol and acetone
   –> Et and Ac destroy cell wall- gram + have a thicker cell wall so they will remain purples
   gram negative are now colourless
4. counter-stain: safranin to stain everything
   -gram positive remain purple
   -gram negative become pink

Question 18

what does gram stain fail to identify?

Answer 18

mycobacterium and nocardia bacteria
–>gram positive; they have very waxy cell walls that reject crystal violet

so use Ziehl-Neelsen acid-fast staining technique
-turn acid fast bacteria pink and the others will be blue

Question 19

cytosol of bacteria

Answer 19

cytosol has ions, carbs, proteins (enzymes), lipids, waste products

and nucleoid region (DNA compartmentalizes even though there’s no nucleus)

Question 20

cytosol

1. inclusion

Answer 20

1. inclusions; deposits of lipids, starch, nitrogen, sulphur, phosphorus, contained by protein membrane (polyhydroxybutyrate PHB in inclusion bodies)

Question 21

endospores

Answer 21

hibernate from harsh environment and are able to survive

-after binary fission
1. membrane grows and enfolds foreshore within a second membrane
2. cortex of calcium and dipicollnic acid is deposited between memrbanes
3. form spore coat
4. maturation and get outer spore coat
4. endospore is released from original cell
… many membrane layers