Q: What is the role of NADPH in the biosynthesis of fatty acids, and which reaction demonstrates its use?

NADPH provides reducing power; $$\text{Acetoacetyl-ACP} + 2\text{NADPH} \rightarrow \text{Acyl-ACP} + 2\text{NADP}^+$$

Q: Which of the following reactions is an example of transamination in amino acid biosynthesis?

$$\text{Glutamate} + \text{Oxaloacetate} \rightarrow \alpha\text{-Ketoglutarate} + \text{Aspartate}$$

Question 1

Which process allows certain bacteria to convert atmospheric nitrogen gas ($$N_2) $$into a biologically usable form, and what is the main product of this reaction?

Accepted Answer

Nitrogen fixation; main product is ammonia ($$NH_3)$$

Question 2

During the Calvin Cycle, which molecule is the initial acceptor of $$CO_2$$ and what is the immediate product formed?

Accepted Answer

Ribulose 1,5-bisphosphate; immediate product is 3-phosphoglycerate

Question 3

Which pathway is primarily responsible for the synthesis of ribose-5-phosphate, a precursor for nucleotide biosynthesis?

Accepted Answer

Pentose phosphate pathway

Question 4

In gluconeogenesis, which reaction requires the input of energy from GTP or ATP to convert pyruvate to phosphoenolpyruvate ($$PEP$$)?

Accepted Answer

Pyruvate carboxylase and PEP carboxykinase

Question 5

Which enzyme complex is responsible for mediating nitrogen fixation, and how many ATP molecules are consumed per $$N_2$$ molecule fixed?

Accepted Answer

Nitrogenase; 16 ATP per $$N_2$$

Question 6

Which metabolic pathway allows nonphotosynthetic autotrophs to synthesize glucose from noncarbohydrate precursors, and what is the key intermediate produced from the Calvin Cycle?

Accepted Answer

Gluconeogenesis; key intermediate is 3-phosphoglycerate ($$3$$-$$PG)$$

Question 7

Which of the following is a major outcome of the pentose phosphate pathway in prokaryotes?

Accepted Answer

Production of NADPH and ribose-5-phosphate

Question 8

What is the role of NADPH in the biosynthesis of fatty acids, and which reaction demonstrates its use?

Accepted Answer

NADPH provides reducing power; $$	ext{Acetoacetyl-ACP} + 2	ext{NADPH} ightarrow 	ext{Acyl-ACP} + 2	ext{NADP}^+$$

Question 9

Which process describes the incorporation of free ammonia ($$NH_3) $$into glutamate, and what enzyme catalyzes this reaction?

Accepted Answer

Reductive amination; catalyzed by glutamate dehydrogenase

Question 10

Which of the following statements best describes lithotrophy in bacteria?

Accepted Answer

Lithotrophs use inorganic compounds as electron donors and are generally autotrophic

Question 11

Which of the following is NOT a product of the pentose phosphate pathway?

Accepted Answer

Glucose-6-phosphate

Question 12

In the biosynthesis of amino acids, what is the primary source of the amino group incorporated into most amino acids?

Accepted Answer

Free ammonia ($$NH_3)$$

Question 13

Which metabolic process is essential for bacteria growing on noncarbohydrate sources to synthesize cell wall components such as N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)?

Accepted Answer

Gluconeogenesis

Question 14

Which of the following reactions is an example of transamination in amino acid biosynthesis?

Accepted Answer

$$	ext{Glutamate} + 	ext{Oxaloacetate} ightarrow \alpha	ext{-Ketoglutarate} + 	ext{Aspartate}$$

Question 15

Which of the following statements about chemolithotrophy is TRUE?

Accepted Answer

Chemolithotrophs use inorganic compounds as electron donors and typically do not use fermentation

Question 16

Which of the following is a key difference between chemoorganotrophy and chemolithotrophy?

Accepted Answer

Chemoorganotrophs can use fermentation, while chemolithotrophs typically do not

Question 17

Which of the following is a major outcome of the Calvin Cycle in autotrophic bacteria?

Accepted Answer

Fixation of $$CO_2$$ into cellular biomass as 3-phosphoglycerate

Question 18

Which of the following statements best describes the biosynthesis of fatty acids in bacteria?

Accepted Answer

Fatty acids are synthesized two carbons at a time with the help of acyl carrier proteins

Question 19

Which of the following is TRUE regarding the electron donors in lithotrophic metabolism?

Accepted Answer

Electron donors are inorganic compounds such as $$H_2S or$$ $$NH_3$$

Microbial Biosynthesis: Autotrophy, Nitrogen Fixation, and Macromolecule Formation

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