Lecture 2 - Bacteriology

Question 1

What types of doman bacteria are there?

Answer 1

Autotrophs - Photosynthetic bacteria (can produce energy from light + CO2), Chemosynthetic bacteria (can produce energy from inorganic chemicals such as hydrogen sulfide, methane, etc

Heterotrophs - 4 common groups (gram+ cocci and bacilli, gram - cocci and bacilli)
3 less common (spirochaetes, rickettsia, mycoplasma

Question 2

how can you describe bacteria?

Answer 2

morphology
size - of individual cell
arrangement
if gram stain available, include if gram pos or neg

Question 3

Describe the cocci morphology

Answer 3

spheres, always give diameter

Question 4

Describe bacilli morphology

Answer 4

rods, can be filamentous (long and thin; almost string-like)

Question 5

describe coccobacilli morphology

Answer 5

short, plump rods; almost ovals in appearance

Question 6

Describe vibrios morphology

Answer 6

comma shapped, curved rod, singular

Question 7

describe spirilla morphology

Answer 7

rigid helix, flagella for motility, singular, less commonly found in short chaings

Question 8

Describe spirochetes morphology

Answer 8

corkscrew (telephone cord), move using flagella to wind by or spring-type creeping, singular

Question 9

What is pleiomorphism

Answer 9

Having more than one shape or form, refers to variability in shape

Question 10

How do you describe size in bacteria?

Answer 10

always measure individual cells in microns
most bacteria are 0.5-3 microns in width
Rods - give diameter
Cocci - give WxL of individual cell
Filamentous, spirilla, spirochetes - give length while curved/folded
slight pleomorphism - describe most commonly represented size

Question 11

How large is 1 micron?

Answer 11

1 mm = 1000 micron

Question 12

Describe each arrangement of cocci and what their names are/what they look like

Answer 12

Coccus – singular
Diplococci – pairs
Streptococci – chains
Staphylococci – grape-like
clusters
Tetrads – 4 cocci in a square
Sarcinae – 8 cocci in cube13

Question 13

Describe each arrangement of bacilli and what their names are/what they look like

Answer 13

Bacillus – singular
Diplobacilli – pairs
Streptobacilli – chains; 3 or
more arranged end-on-end
Palisades – picket-fence;
arranged side-by-side; least
common

Question 14

What is a bacteria colony?

Answer 14

a discrete mound of bateria cells visible to the naked eye
all cells in mound derived from a single bacteria cell
can exist in vitro or in vivo

Question 15

What is an in vitro bacteria colony

Answer 15

diff bacteria produce colonies with distinct shapes and colors when grown in vitro under specific growth conditions

Question 16

What is a colony forming unit?

Answer 16

A SINGLE colony is created frm a SINGLE bacterium that replicates many times until there are enough cells to see with the naked eye

A CFU refers to the single bacterium that started the colony because all cells within the colony are identical

Question 17

Describe the cytoplasmic membrane of a bacteria

Answer 17

aka cell membrane, plasma membrane
phospholipid bilayer
contains diff types of proteins, carbs, cholesterol,
surrounds contents of EVERY living cell
thin, flexible, selectively permeable

Question 18

What are the different types of proteins a cytoplasmic membrane can have? (6)

Answer 18

Channels + transporters
signal receptors
metabolic proteins
attachment proteins
Surface antigens

Question 19

What are channels and transporter proteins in regards to the cytoplasmic membrane?

Answer 19

Move substances ( nutrients, toxins, waste) in/out of cells
Some antibiotics are designed to only target bact cells using these transporters to move into cell

Question 20

What are signal receptors proteins in regards to the cytoplasmic membrane?

Answer 20

proteins that bind to “signals” from outside enviro
tell bact to: start/stop replicating, move from harm, prod enzymes to metab nutes, prod enzyme req to inactive specific antibiotics

Question 21

What are metab proteins in regard to the cytoplasmic membrane?

Answer 21

bact have no mitochondria
energy prod machinery loc along folds/invagination in cytoplasmic membrane (mesosomes)

Question 22

What are attach proteins in regard to the cytoplasmic membrane?

Answer 22

bact use these proteins to attach to specific cells in host animal
certain bact only attach to certain cells
essential for infection

Question 23

What are surface antigens proteins in regard to the cytoplasmic membrane?

Answer 23

any protein or portion of a protein on the surface of a bact cell that can be recognized by the animals immune system
antigens = molecular ID tags found on all cells
diff bact have hiff surface antigens (used as methods of ID diff strains of same species)

Question 24

What are the fuctions of the cytoplasmic membrane

Answer 24

encloses the cytoplasm
barrier prot
regulates movement of molecules in/out of cell
inter. w/ enviro via signal receptors
site for energy prod
attachment - part of infect process

Question 25

What is cytoplasm?

Answer 25

Fluid or gel that fills the cel 60-70% water cytoskeleton - molecular scaffold metabolically active - biochem reactions

Question 26

What are ribosomes?

Answer 26

complex structures consisting of protein and ribosoma RNA sit of protein synthesis where the RNA is read and used to assemble proteins in translation

Question 27

What is chromosomal DNA

Answer 27

A single strand of DNA contains all essential genes fewer genes than in eukaryotic cells Strand of DNA organized by DNA binding proteins and super coiled into tight bundle bundled chromosomal DNA loc in the nucleoid immune system can recog bact DNA

Question 28

What are plasmids?

Answer 28

"extra", sm, circular pieces of DNA containing 1 or 2 genes NOT part of chromosomal DNA loc outside of nucleoid Genes on plasmid not essential to life, but beneficial to survival by evolutionary advantage -proteins that provide antibiotic resist (ex beta-lactamase enzyme) -genes for specific toxins or attachment proteins genes that enable the bact to prod capsules can have none, one or more than one diff plasmid

Question 29

How do plasmids replicate?

Answer 29

replicate independently of the chromosomal dna once a bact aquires a plasmid, it will duplicate itself inside the cell until there are 100s-100000s of copies per cell very resist to degration - may remain stable in the enviro after bact cell has died

Question 30

What are the three ways plasmids are transferred btw cells?

Answer 30

during replication transformation bacterial conjugation

Question 31

Describe plasmids replicating through replication

Answer 31

any time the bact cell divides, plasmids also duplicate and an equal # of plasmids are transferred to the daughter cell

Question 32

Describe plasmids being transferred through transformation

Answer 32

Process where the cell membrane opens up and allows the bact cell to take up a plasmid from the enviro

Question 33

describe plasmids being transferrred thru bacterial conjugation

Answer 33

process where there is direct contact btw 2 bact cells thru creation of a temp cytoplasmic membrane bridge to allow plasmid transfer

Question 34

What are the external structures of bact?

Answer 34

cell wall, periplasmic space, flagella, fimbriae and pilli, capsules, slime layers

Question 35

Describe the cell wall

Answer 35

All bact (except mycoplasma) have a cell wall rigid -surrounds cytoplasmic memb categories - Gram +/-, acid fast necessary for survival

Question 36

What is the func of the cell wall in bact?

Answer 36

maintain bact shape protect cell from lysis due to osmotic pressure helps protect from toxi materials (inc. antibiotics, sm molecules (<2nm) can diffuse btw peptidoglycan chains; lg molecules excluded) helps w/ attachment prevents phagocytosis by WBC in immune system

Question 37

How can you break down the bact cell wall?

Answer 37

lysozymes - enzyme found in tears/saliva beta-lactams - class of antibiotics (inc penicillins + cephalosporins) prevents proper synthesis of the cell wal

Question 38

What are the two components of the bact cell wall?

Answer 38

Peptidoglycan layer peptide cross-links

Question 39

What is gram staining? What use does it server?

Answer 39

A method of staining bact separates most bact genera into 2 groups based on diff in cell walls structure whether bact are gram +/- is important for certain growth req, pathology + tx during infection

Question 40

Gram pos cell wall

Answer 40

thicc - 40-90% of total cell mass 20-80 layers of peptidoglycan, layers joined by peptide cross-links enzyme called transpeptidase is req to make the cross links Teichoic acid may have additional teichoic acids on surface of cell wall that help bact to attach to other bact and/or animal cells

Question 41

What is teichoic acid?

Answer 41

long molecules that help embed the cell wall to the cytoplasmic membrane

Question 42

What is the relationship between gram + cell wall and beta-lactam antibiotics

Answer 42

gram + bact are suspectible to the beta-lactam class of antibiotics beta-lact antibiot binds to and block funct of the transpeptidase enzyme to prevent formation of peptide cross links btw peptidoglycan strands w/o cross-links, cell wall cannot withstand osmotic pressure and cell lyses

Question 43

Describe the gram - cell wall

Answer 43

Thin, roughly 10% of total cell mas multiple layers peptidoglycan layer - closest to the cytoplasmic membrane (1-2 layers) outermembrane - complex, composed of 2 layers. 1 - inner layer is single sheet of phospholipids. 2 - outer layer is single sheet of lipopolysaccharide (LPS) periplasmic space - space bwn the cytoplasmic plasma membrane and outer membrane

Question 44

What is LPS?

Answer 44

Lipopolysaccharide molecule that makes up the outmost layer of gram - cell walls, outer membrane layer important to bact for establish infection: important to host while fighting off an infection 3 parts - O antigen, core polysacc, lipid a (endotoxin)

Question 45

What is the O antigen of LPS?

Answer 45

repeats of polysacc units "smooth" bact with long O chains "rough" bact with very short or lacking O chains hydrophilic certain species or strains are distinguished by the specific sugar molecule in their O chain

Question 46

What are O antigen's of LPS important for? How can they help the cel:

Answer 46

Imp for back to estab infection WBC are unable to grab smooth bac; WBC can easily phagocytose rough cells o-anti take part in attach to epithel cells some bact can alter sugars to make up o-anti, variation over time allows bact to evade the immune system immune system uses o antigen when trying to fight off infection sometimes, immune system can recog sugars in chain and target these cells for destruction presence of o chain will trigger non=specific inflam

Question 47

what is the lipid a portion of LPS?

Answer 47

endotoxin "tail" made up of lipid chains same in all gram neg bact hydrophobic fuct to hold the lps molecule in place normally hidden from enviro- if gram neg bact dies, sm amount is released into enviro one of the strongest activators of inflam

Question 48

What is endotoxic shock?

Answer 48

Condition in body where overwhelming inflam causes vasodilation- drops BP -systemic shock caused by sudden release of lg amounts of lipid a during gram ned infect lipid a enters circulation and turns on systemic inflam can be fatal if not treated immediately

Question 49

What are some bacteria that do not gram stain?

Answer 49

acid-fast bacteria + mycoplasma They do not have the cell wall structures like gram +/-

Question 50

What is acid-fast bact?

Answer 50

cell wall structure is vry sim to gram + but contain lg numbers of mycolic acid (waxy molecules) in the cell wall. ex mycobacterium