Bacteria Morphology

Question 1

virus replication cycle

Answer 1

Attachment
Penetration
Uncoating
Transcription
Translation
Genome replication
Assembly
Release

Question 2

characteristics of bacteria

Answer 2

no membrane-delimited nuclei
cytoplasm is gel-like
not homogenous
DNA replicates semi-conservatively
genome attached to cell membrane
one or two circular chromosomes

Question 3

translation in bacteria

Answer 3

large and small ribosomal subunit
IF1, IF2 initiation factors
initiation: mRNA binds small ribosomal subunit with Shine Dalgarno sequence (AGGAGG)
requires energy
occurs in cytoplasm

Question 4

what does no nuclear membrane allow for

Answer 4

simultaneous transcription and translation

Question 5

what kind of cell membrane do bacteria have

Answer 5

lipid bilayer

Question 6

plasma membrane

Answer 6

a selective barrier
limit the free-diffusion of ions
most polar compounds must be specifically transported across the membrane by proteins

Question 7

transport against a concentration gradient requires

Answer 7

energy

Question 8

why is membrane potential essential to generate energy

Answer 8

proton motive force
electrical potential does work:
generate ATP, turn flagella, move solutes

Question 9

what does the cell wall do

Answer 9

maintains structure
surrounds cell protoplast
prevents osmotic lysis of cell protoplast

Question 10

types of solutions

Answer 10

isotonic: same solute concentration, no net movement of water particles
hypertonic: has a higher solute concentration than another solution, particles move out of cell (crenation)
hypotonic: solution has a lower solute concentration than another solution, particles move into cell (lyse)

Question 11

peptidoglycan
gram + structure VS gram - structure

Answer 11

made of peptides and glycans
gram+ structure contains pentapeptide and tetrapeptide between NAG and NAM
gram- structure has a direct link between NAG and NAM

Question 12

gram staining

Answer 12

if there is a thick peptidoglycan layer (gram+) the colour stays in (purple)

Question 13

porins

Answer 13

create pores in outer membrane
mainly in gram- bacteria
homotrimers
small channels allow for passage of small solutes
antibiotics can pass through

Question 14

lipopolysaccaharide (LPS)

Answer 14

an endotoxin
only in gram-
very stable
reduces blood pressure
septic shock

Question 15

lipoteichoic acid

Answer 15

gram+ only
covalently link to peptidoglycan
negative charge and hydrophobic site
antigenic

Question 16

mycobacteria have

Answer 16

an additional mycolic acid and arabinogalactan layer

Question 17

mycoplasma

Answer 17

has no cell wall
requires a isotonic environment
can cause respiratory disease

Question 18

capsules

Answer 18

a glycocalyx around the cell wall
sugar coat (polysaccharides)
promotes adhesion
limit permeability (negative staining with dyes)
inhibit phagocytosis
nutrient reserve
enhance pathogenicity

Question 19

endospores

Answer 19

nutrient limited conditions
very stable
keratin-like coat
resistant to UV, heat, dessication, antibiotics, disinfection

Question 20

sporulation

Answer 20

DNA replicates
membranes around DNA
forespore
protective cortex
protein coat
spore is released
germinate (enzymatic digestion of coat, growth)

Question 21

how are endospores associated with disease

Answer 21

harmless themselves until they germinate, involved in many human diseases; tetanus, botulism, gas gangrene

Question 22

flagella

Answer 22

motility
require membrane potential (proton motive force)
60 cell-lengths/sec
antigenic and a PAMP

Question 23

flagella arrangements

Answer 23

monotrichous
amphitrichous
lophotrichous
peritrichous

Question 24

flagella rotation

Answer 24

running: bundled flagella (counter-clockwise rotation)
tumble: flagella separated (clockwise rotation)
attractant: chemical gradient (tumbling or running)

Question 25

taxis

Answer 25

movement in response to stimulus
positive (towards stimulus)
negative (away from stimulus)

Question 26

examples of taxis

Answer 26

chemotaxis: towards a chemical
phototaxis: towards light
aerotaxis: towards or away from oxygen
magnetotaxis: orientation within a magnetic field

Question 27

fimbriae and pili

Answer 27

rigid, antigenic, mostly on Gram-

somatic pili: adhesion, stabilize biofilms, aid motility
sex pili: fimbriae used for conjugation, tend to be longer

Question 28

biofilms development

Answer 28

1. reversible attachment of planktonic cells
2. becomes irreversibly attached
3. growth and division
4. EPS and water channels
5. secondary colonizers and microbes dispersed to new sites

Question 29

quorum

Answer 29

sensed by autoinducers
support survival
controls virulence factors
inter- and intraspecies communication

Question 30

Gram+ and Gram- difference in Quorum

Answer 30

Gram+ = short peptide
Gram- = N-acetylated homoserine lactone