Lecture 6: Microbial Physiology

Question 1

What do bacteria have instead of membrane bound organelles?

Answer 1

they have internal organization

Question 2

What gives bacterial cytoplasm/cytosol a gelatinous consistency?

Answer 2

very high concentration of protein, nucleic acid, carbohydrates, and ions

Question 3

What shape is bacterial genome?

Answer 3

Circular with a few exceptions

Question 4

What is genome?

Answer 4

chromosomes plus plasmids

Question 5

What are plasmids?

Answer 5

small circular self replicating DNA strands

Question 6

What is a chromosome?

Answer 6

one long DNA chain

Question 7

What does bacteria do instead of having a cell nucleus?

Answer 7

may partition genetic material to different parts of the cell

Question 8

Where does DNA partition when bacterial cells divide?

Answer 8

partitions to plasma membrane on either side of the division plane

Question 9

What are ribosomes?

Answer 9

the structures
responsible for translation of mRNA

Question 10

What do ribosomes do?

Answer 10

converts gene sequence to polypeptide

Question 11

What are ribosomes made of?

Answer 11

RNA (called rRNA or ribosomal RNA) and protein

Question 12

What are the subunits of ribosomes?

Answer 12

• 50S (bacterial)
• 30S (bacterial)

(40, 60, and 80 are for eukaryotes)

Question 13

What is the final ribosome?

Answer 13

70S

Question 14

What does S mean?

Answer 14

• Svedberg Unit
• sedimentation rate
• how long it takes for a particular piece to end up where it belongs

Question 15

What does the kind of ribosome tell you?

Answer 15

the target of a number of antibiotics

Question 16

Are ribosomes present in every cell?

Answer 16

Yes, they are in every cell of every kind. Cells cannot function without them

Question 17

carboxysomes

Answer 17

contain ribulose 1,5
diphosphate carboxylase enzyme for CO2 fixation by photosynthetic bacteria

Question 18

What do metachromatic granules do?

Answer 18

store inorganic phosphate (volutin) in Corynebacterium diphtheriae

Question 19

Forms of nutrient storage

Answer 19

• carboxysomes
• metachromatic granules
• polysaccharide granules
• sulfur granules in thiobacillus
• lipid inclusions (PHB)

Question 20

PHB

Answer 20

polyhydroxy butyric acid

Question 21

Functional inclusions

Answer 21

• ex: take energy from iron and use it for themselves?
• magnetosomes from magnetospirillum magneticum
• cyanobacterial gas vacuole

Question 22

How do some bacteria respond to stress/heat/fryness/freezing/radiation?

Answer 22

by forming hardy endospores that are resistant to the stresses

Question 23

why sterilize things with an autoclave?

Answer 23

because the heat can kill the bacteria

Question 24

What kind of bacteria produces endospores?

Answer 24

gram positive
- clostridium and bacillus primarily

Question 25

what do vegetative cells do in response to stress?

Answer 25

start sporulation (takes several hours)

Question 26

What is sporulation?

Answer 26

spores form inside vegetative cell and then the cell body breaks apart, leaving the spore intact

Question 27

How to get rid of spores?

Answer 27

special sterilization techniques are needed

Question 28

what components of bacteria are good targets for antibiotics? What properties of a bacterial cell component make it a good antibiotic target?

Answer 28

- peptidoglycan, cell, ribosomes (different), DNA/RNA replication, transcription, gyrase (unwind DNA in bacteria) - essential to cell viability and replication - is common in many/all bacteria - not present in human cells

Question 29

Biofilm physiology

Answer 29

- Heightened resistance to antibiotics -- Catheter infections - Very strongly adherent to surface - Plaque on teeth - Highly differentiated substructure - Anaerobic regions - Nutrient micropores

Question 30

Bacteria that is harmless on your skin, but dangerous if it gets on your heart? (for example)

Answer 30

Staphylococcus Epidermis

Question 31

How does biofilm cause cavities?

Answer 31

Bacteria at the bottom of the biofilm are not exposed to oxygen, so when they are exposed to sugars, they ferment and produce acids that degrade the teeth

Question 32

What are some significant morphological changes that species of bacteria go through?

Answer 32

Biofilm formation - fruiting body formation (myxobacteria) - caulobacter crescentus (stalked/swarmer transition)

Question 33

Most bacteria in the world are in... (about 90%)

Answer 33

biofilms (mostly mixed species biofilms)

Question 34

What are myxobacteria?

Answer 34

predatory bacteria - fruiting body formation that is controlled by cell-cell contact, response to starvation - individual cells also undergo morphogenesis into spores

Question 35

Caulobacter crescentus

Answer 35

great model for programs of cell differentiation

Question 36

cell cycle in bacteria

Answer 36

- stalked cell attaches to a surface - elongates (pre-divisional cell) - asymmetrically divides -produces a cell without a stalk, but a single polar flagellum (swarmer cell) - swarmer uses flagellum to move on and attach somewhere else - turns into a stalked cell to continue the cycle (swarmer never makes swarmer and stalked never makes stalked)

Question 37

What is quorum sensing?

Answer 37

coordinated behavior

Question 38

What bacteria have virulence quorum sensing?

Answer 38

S. aureus

Question 39

What bacteria have symbioses quorum sensing?

Answer 39

- vibrio fischeri (that squid "Tom Kleindinst") - euprymna scolopes

Question 40

What bacteria have horizontal gene transfer quorum sensing?

Answer 40

- agrobacterium (crown gall - a cancer in plants) - enterococcus

Question 41

quorum sensing - autoinducer

Answer 41

Gram negative: - lux I: makes the signal - Lux R: site of binding to make a dimer? - amphipathic ring with a fatty acid tail Gram positive: - peptides cant go across membranes so ComQ/X gives a way to send the signal across the surface? - ComP auto-phosphorylates comA, activating transcription

Question 42

What things does the bacterium need to do before and during division?

Answer 42

- Divide cytoplasm in two - Replicate DNA - Partition critical cellular proteins, cofactors, substrates - Invaginate membrane(s), divide into two separate cells

Question 43

DNA replication in bacteria

Answer 43

- circular genome - has an origin of replication - bidirectional replication - DNA pol III (dominant) - DNA pol I – okazaki fragments (dominant) - Topoisomerase - unwind DNA (gyrase for bacteria, also good for antibiotic target cause all bacteria have it)

Question 44

Binary fission

Answer 44

- DNA replicates - partitioning of daughter strands - septum formation --FtsZ: related to eukaryotic tubulin -- ring structure at nascent division site - membrane invagination

Question 45

fts

Answer 45

filamentous temperature sensitive

Question 46

What does mutagenesis result in?

Answer 46

FTS mutants