Bacteria

Question 1

bacterial cell envelope

Answer 1

• bacterial cell sheath
• cytoplasmic membrane
• cell wall
• slime layer (capsule)

Question 2

bacterial cell sheath: inner layer

Answer 2

cytoplasmic membrane

Question 3

b.c.s.: middle layer

Answer 3

cell wall

Question 4

b.c.s.: outer layer

Answer 4

slime layer capsule

Question 5

cytoplasmic membrane is

Answer 5

a lipid bilayer with proteins but without sterols like cholesterol

Question 6

functions of cytoplasmic membrane

Answer 6

• active transport of metabolites from outside to inside against the gradient
• synthesis of cell wall components
• sensory function → information from ext. to internal by proteins
• electron transport and energy production → enzymes of respiratory chains and for energy production in the cytoplasmic membranes
• secretory function → release of biologically active substances

Question 7

cell wall is

Answer 7

• a porous middle layer of sheath -> characteristic cell shape

Question 8

functions of cell wall

Answer 8

• maintains cell shape
• diffusion of metabolites via pores
• protects cell from excess of water and its lysis because of osmotic pressure

Question 9

cell wall structure of gram+ bacs

Answer 9

• thick layer of peptidoglycan → polymer of N-acetyl-glucosamine and N-acetylmuramic acids connected by ß-1,4-glycosidic bonds
• teichoic acid and lipoteichoic acid → glycerol, phosphate and ribitol

Question 10

cell wall structure of gram - bacteria

Answer 10

• thin layer of peptidoglycan

- LPS (O polysaccharide, core polysaccharide and lipid A)

Question 11

slime layer (capsule)

Answer 11

• outer layer of bacterial sheath
• polysaccharides → very thin layer slime → less than 0,2 um
• water
• if they have slime layer they can attach to certain surfaces

Question 12

functions of slime layer

Answer 12

• provides adhesion to various surfaces → natural and artificial (protestes, valves)
• inhibits phagocytosis
• accumulates water

Question 13

internal components of bacterial cell

Answer 13

• cytoplasm
• chromosome
• plasmids
• ribosomes
• inclusion bodies

Question 14

cytoplasm of bacterial cell

Answer 14

• analogous to eukaryotic cells

- more dense and vicous

Question 15

chromosome of bacterial cells

Answer 15

• bac. chromosome → single, double stranded circular DNA in nucleoid

Question 16

plasmids of bac. cells

Answer 16

• plasmids → circular extrachromosmal DNA → one bacterium to another → encode certain virulence

Question 17

ribosomes of bac. cells

Answer 17

ribosomes → 50s and 30s subunits forming 70s ribs→ protein synthesis

Question 18

inclusion bodies of bacteria. cells

Answer 18

• inclusion granules → accumulation of nutrients

Question 19

external components of bacteria. cell

Answer 19

• flagella

- pili

Question 20

flagella of bacs

Answer 20

• for movement

- long filament of twisted fibrils

Question 21

flagella in gram - bacteria

Answer 21

• long filament

- gets thicker when it approaches the cell wall and forms hook

Question 22

flagella in gram + bacteria

Answer 22

• only 2 inter moldings

Question 23

monotrichous

Answer 23

• single flagellum at one pole

Question 24

amphitrichous

Answer 24

• 2 flagella at opposite poles

Question 25

peritrichous

Answer 25

• evenly distributed flagella over the entire surface of the cell

Question 26

lophotrichous

Answer 26

multiple flagella at the same point

Question 27

pili

Answer 27

• hair like appendages of fibrous proteins
• adhere bacteria to natural surface and transmit genes
• conjugation
• highly selective process
• have a canal to transfer genes

Question 28

bacterial spores layers

Answer 28

from outer to inner:

• exosporium
• keratin protein coat
• outer membrane
• cortex
• spore wall
• inner membrane
• core

Question 29

structure of bacterial spores

Answer 29

• dehydrated and multi shelled
• allows bacteria to survive in extreme conditions
• exists in dormant state
• complete copy of chromosome
• high calcium bound

Question 30

spore formers are

Answer 30

some gram positive bacteria like clostridium and bacillus

Question 31

characteristic location of spores

Answer 31

e.g. at the terminal end of bacteria

Question 32

decontamination of spores

Answer 32

• very difficult with desinfection due to mulitshelled layer which protects bacterial spore from environmental factors
• spores are for preservation of bacteria
• spores for reproduction for fungal cells

Question 33

sporogenesis

Answer 33

• depletion of specific nutrients → production of a spore

Question 34

steps of sporogenesis 1-3

Answer 34

• mRNA of spore are transcribed and other turned off
• dipicolinic acid is produced and antibiotics and toxins are often excreted
• duplication of chromosome
• → one copy of DNA and cytoplasmic contects are surrounded by cytoplasmic membrane, peptidoglycan and membrane of septum

Question 35

steps of sporogenesis 4-7

Answer 35

• → wraps DNA in two layers of membrane
• → 2 layers surrounded by cortex made of thin inner layer of peptidoglycan and loose outer peptidoglycan layer
• cortex surrounded by tough keratin like protein coat
• requires 6-8 hours

Question 36

germination of bacterial spores

Answer 36

• stimulated by disruption of outer coat by mechanical stress
• requires water and triggering nutrient
• takes approx. 90min
• spore will take up water, swell, shed its coats and produce one new vegetative cell → complete entire cycle

Question 37

function of spores

Answer 37

• spores are for preservation of bacteria

- spores for reproduction for fungal cells