Bacterial Growth and Metabolism

Question 1

Auxotrophs and Prototrophs

Answer 1

Auxotrophs - mutant bacteria which have an additional growth requirement, Prototrophs - the wild type relatives of auxotrophs

Question 2

Do fastidious bacteria have a lot of growth requirements or few growth requirements?

Answer 2

A lot of growth requirements

Question 3

Which end of the protein are signal sequences typically located at?

Answer 3

The N terminal end

Question 4

What are the typical signal sequences for folded and unfolded proteins respectively?

Answer 4

Folded - Tat, Unfolded - Sec

Question 5

Exoenzymes

Answer 5

Enzymes secreted by bacteria to create nutrients from materials around them

Question 6

What is the most common nutrient-limiting strategy the human body uses to fight bacteria and what is the implication of this in a particular patient group?

Answer 6

Iron limitation. Pts with liver dysfunction have high free iron levels and are very susceptible to bacterial infection

Question 7

Sideophores

Answer 7

Iron-chelating compounds secrete by bacteria to suck up all the iron they can (they need iron and we try to keep it away from them)

Question 8

List the major nutrients that bacteria need to grow

Answer 8

Carbon, Nitrogen, Energy source, Water, Ions, Phosphorus, Sulfur, Metals (esp iron)

Question 9

Facultative anaerobe

Answer 9

A bacterium that can grow in presence or absence of oxygen

Question 10

Microaerophilic

Answer 10

Term for bacteria that ferment for energy but can grow at O2 levels less than atmospheric pressure

Question 11

Superoxide dismutase eliminates superoxide. What enzyme eliminates hydrogen peroxide?

Answer 11

Catalase (or energy expensive peroxidase in certain aerotolerant and facultative anaerobes)

Question 12

How does the two-component system of sensing the environment work?

Answer 12

Sensor kinase (HPK) senses change, autophosphorylates (using ATP), phosphorylates response regulator (RR), which binds DNA or protein to change cell behavior

Question 13

How are sugars typically transported into bacterial cells?

Answer 13

By phosphorylation-linked transport

Question 14

What pathway do most bacteria use for fermentation, what are the starting and end products, what must be done after?

Answer 14

Embden-Meyerhof pathway. From carbohydrates to pyruvic acid. Pyruvic acid must be reduced at the end

Question 15

Generally bacterial anabolism is similar to human anabolism, and thus provides few drug targets. What is an important exception to this?

Answer 15

Synthesis of folic acid. Bacteria have their own enzymes and can not use exogenous folic acid

Question 16

What are two methods of targeting bacterial folic acid synthesis that are used as targets?

Answer 16

Sulfonamides are structural analogs and compete with para-amino benzoic acid (intermediate in synthesis) and Trimethoprim targeting Dihydrofolate reductase

Question 17

What are two drugs that interrupt bacterial folic acid synthesis and what does each target?

Answer 17

Sulfonamides (target an intermediate called para-amino benzoic acid) and trimethoprim (targets an enzyme called dihydrofolate reductase)