L5: Acellular Infectious Agents and Microbial Nutrition

Question 1

What are viroids

Answer 1

they are smaller than a virus, they are RNA only, they can cause plant disease

Question 2

How do viroids work?

Answer 2

they may pair with plant RNA and cause RNA silencing, which prevents RNA from being translated into protein, leading to cell death

Question 3

What are prions?

Answer 3

infectious proteins that are often associated with neurodegenerative diseases

Question 4

What process leads prions to cause disease symptoms?

Answer 4

initial misfolding of normal form into prion form, promoting conversion of other proteins into prion form, then the prion forms aggregate

Question 5

What are nutrients?

Answer 5

substances used in biosynthesis and energy release; required for growth

Question 6

What do microbes need raw materials and nutrients for?

Answer 6

to obtain energy and construct new cellular components

Question 7

What are the macronutrients?

Answer 7

C, O, H, N, S, P, Fe

Question 8

What are the micronutrients?

Answer 8

Co, Cu, Zn, Mn

Question 9

What is often a source of micronutrients?

Answer 9

water

Question 10

What forms of nitrogen can most microbes use?

Answer 10

Ammonia (NH3) or Nitrate (NO3)

Question 11

What is nitrogen fixation?

Answer 11

N2 reduced to ammonia

Question 12

What are two species that can use nitrogen gas (N2)

Answer 12

Rhizobium and Azotobacter

Question 13

What are some challenges microbes face when acquiring nutrients

Answer 13

need at high rates
enters across membranes
must enter in a selective fashion (to avoid toxins)
often need to move against concentration gradient

Question 14

What does passive transport require?

Answer 14

gradient of [higher] to [lower]

Question 15

What are the 2 subcategories of passive transport

Answer 15

passive diffusion

facilitated diffusion

Question 16

What is passive diffusion

Answer 16

movement of small molecules and some gases down a gradient

Question 17

What is facilitated diffusion

Answer 17

movement of molecules across a membrane using membrane carrier proteins

Question 18

What membrane carrier protein forms water channels?

Answer 18

Aquaporins

Question 19

What does active transport require?

Answer 19

energy

Question 20

What are the 2 types of active transport?

Answer 20

primary and secondary

Question 21

What is used for energy in active transport?

Answer 21

ATP or proton motive force

Question 22

What is the purpose of active transport

Answer 22

to move nutrients against gradients

Question 23

What does ABC stand for in ABC transporters

Answer 23

ATP Binding Cassette

Question 24

What do uptake ABCs do

Answer 24

move nutrients in

Question 25

What do export ABCs do

Answer 25

move substances out

Question 26

What role do ABC transporters play in antibiotic resistance?

Answer 26

they move antibiotics out of a cells before it can reach its target

Question 27

What is used in primary active transport?

Answer 27

ABC transporters

Question 28

What is used in secondary active transport?

Answer 28

potential energy of ion gradients

Question 29

What membrane protein moves lactose in by using the potential energy of proton also moving into cell?

Answer 29

Lac Permease

Question 30

What do bacteria use to power flagella?

Answer 30

potential energy

Question 31

What is group translocation

Answer 31

a form of active transport that chemically alters the nutrients

Question 32

How does the phosphotransferase system in bacteria work?

Answer 32

energy from phosphoenolpyruvate attaches P to sugars

it’s a metabolic pathway that converts glucose to pyruvate

Question 33

What is a key intermediate in glycolysis?

Answer 33

phosphoenolpyruvate

Question 34

What is the problem with iron uptake?

Answer 34

all microbes require iron, but there is little free Fe available, and it is often insoluble form (Fe3+)

Question 35

How do microbes solve the iron uptake problem?

Answer 35

release siderophores to acquire Fe

Question 36

What is a type of E. coli siderophore?

Answer 36

enterobactin

Question 37

What are the steps to siderophore-iron complexes being transported into a gram-negative bacterial cell?

Answer 37

1. E. coli synthesize and secretes enterobactin that binds Fe3+
2. complex is transported to the periplasm through a membrane protein
3. complex is transported into cell by an ABC transporter
4. Iron is released inside the cell and reduced to Fe2+