Bacterial Structure

Question 1

Cocci

Answer 1

Cocci – spheres, pairs = diplo, chain = strepto, clump = staph

Question 2

Bacilli

Answer 2

Bacilli – rods, vibrio = curved

Question 3

Spiral

Answer 3

Spiral – spirillum or spirochete

Question 4

Gram Stain

Answer 4

Gram stain: crystal violet → iodine wash → alcohol decolorant → safranin red

Question 5

(+) Gram Stain

Answer 5

Positive – retains blue dye in thick cell wall

Question 6

(-) Gram Stain

Answer 6

Negative – stain in washed away from thin cell wall and red is visible

Question 7

Classification

Answer 7

Classification: >70% same DNA = same species, >97% same rRNA

Question 8

Phenotype

Answer 8

Phenotypic – morphology, Gram stain, markers (fermentation, enzymes, hemolysis), motility

Question 9

Genotypic

Answer 9

Genotypic – variable GC content, 16S rRNA sequence, used to tract outbreaks

Question 10

Nucleoid

Answer 10

Nucleoid – circular haploid chromosome, no nuclear membrane

Question 11

Ribosomes

Answer 11

Ribosomes – 70S

Question 12

Plasmids

Answer 12

Plasmids – small, circular DNA molecules outside the chromosome, transmissible and non-essential

Question 13

Inner membrane

Answer 13

Inner membrane – lipid bilayer w/o sterols, ETC, ATP synthesis, flagella anchors

Question 14

Cell wall

Answer 14

Cell wall – peptidoglycan, thicker in Gram+ and is stained blue

Question 15

Peptidoglycan

Answer 15

Peptidoglycan – alternating NAG and NAM with peptide cross-link, rigid wall

Question 16

Gram (+) Cell Wall Layers

Answer 16

Layers – Gram+ → thick peptidoglycan – Teichoic acid – Lipoteichoic acid

Question 17

Gram (-) Cell Wall Layers

Answer 17

Gram - → thin peptidoglycan – outer membrane

Question 18

Teichoic acid

Answer 18

Teichoic acid – glycerol phosphate polymer w/ Ala or sugar

Question 19

Lipoteichoic acid

Answer 19

Lipoteichoic acid – glycerol phosphate polymer w/ glycolipid terminal anchor

Question 20

Lipopolysaccharide

Answer 20

Lipopolysaccharide – LPS = O-antigen + lipid A + core polysaccharide, outer membrane of Gram – bacteria

Question 21

Mycolic acid

Answer 21

Mycolic acid – waxy lipid outer “membrane”, require acid fast staining, Mycobacteria and Nocardia

Question 22

Mycobacteria

Answer 22

Mycobacteria – acid fast, mycolic acid, least permeable

Question 23

Spirochetes

Answer 23

Spirochetes – have outer membrane but lack LPS

Question 24

Mycoplasmas

Answer 24

Mycoplasmas – no cell walls, most permeable

Question 25

Capsules

Answer 25

Capsules – protection/phagocytosis evasion

Question 26

Flagella

Answer 26

Flagella – locomotion, composed of flagellin

Question 27

Common pili

Answer 27

Common pili - Adhesins – aid in attachment, bind to surface sugars

Question 28

Sex pili

Answer 28

Sex pili – transfer of genetic information

Question 29

Secretion machine

Answer 29

Secretion machine – delivering bacterial proteins directly to eukaryotic cells, like a syringe to modify target cell function

Question 30

Exotoxins

Answer 30

Exotoxins – secreted proteins

Question 31

Cytolytic Exotoxins

Answer 31

Cytolytic – hemolysins, pore formation, phospholipases

Question 32

Cytolytic A-B toxins

Answer 32

A-B toxins – B protein binds and A protein enters cell, cholera, Shiga, botulinum, anthrax

Question 33

Endotoxins

Answer 33

Endotoxins – cell wall component → teichoic acids, PG fragments, LPS

Question 34

Superantigens

Answer 34

Superantigens – toxic shock syndrome

Question 35

Spores: Function

Answer 35

Function – not metabolically active, survive harsh environment and nutrient depletion, not for reproduction

Question 36

Bacterial Spores

Answer 36

Bacteria – produced by bacilli and clostridia, ex: anthrax, botulinum, food poisoning, C. diff

Question 37

Spores in Clinic

Answer 37

Clinical – resistance to treatment and sterilization, requires autoclave