Lecture 15

Question 1

How are the nutritional categories named ?

Answer 1

Energy source+ electron source+ carbon source

Question 2

What are the possible energy sources?

Answer 2

Phototrophs

Chemotrophs

Question 3

What are characteristics of chemotrophs?

Answer 3

• Obtain energy from biochemical reactions
• Aerobic1anaerobic respiration, fermentation, methanogenesis
• Biochemical energy can be conserved by formation of energy-storage compounds
• Biochemical energy can be interconverted with membrane potential

Question 4

What are electron sources/categories ?

Answer 4

Organotrophs
- Obtain electrons from oganic compounds

Lithotrophs
- Obtain electron from inorganic compounds

Question 5

What are categories of carbon use?

Answer 5

Heterotrophs

Autotrophs

Question 6

What are characteristics of heterotrophs?

Answer 6

• Assimilate organic compounds as C source for growth
• Take up organic compounds and then use them as source of carbon in their own biosynthetic reactions
• Sugars, organic, amino, nucleic, fatty acids etc
• some CO2 may be re-fixed via enzymes like PEP carboxylase

Question 7

What are characteristics of autotrophs?

Answer 7

• Obtain carbon from inorganic sources (CO2, CH4)