The enzyme produced in the small intestine that converts trypsinogen into trypsin is:
A. Carboxypeptidase
B. Renin
C. Enterokinase
D. Pepsin
Answer: Option C
Solution (By JKExamLibrary)
Enterokinase (enteropeptidase) is secreted by the intestinal mucosa and activates the pancreatic proenzyme trypsinogen to trypsin, which then activates other zymogens. Pepsin is active in the stomach, renin is a milk-curdling enzyme (chymosin), carboxypeptidase is a pancreatic protease. This cascade ensures that protein-digesting enzymes are activated only in the appropriate location to prevent autodigestion.
Explanation:
Chief cells (peptic cells) in the gastric mucosa secrete pepsinogen, which is converted to active pepsin by HCl. Pepsin digests proteins into peptides. Parietal cells secrete HCl and intrinsic factor. Mucous cells produce mucus that protects the stomach lining. G cells secrete gastrin hormone. Pepsin functions optimally at pH 1.8-2.0. The stomach thus initiates protein digestion.
Explanation:
Ribosomes are the molecular machines where mRNA is translated into a polypeptide chain (protein). They consist of two subunits (large and small) and are found free in the cytoplasm or attached to rough ER. The nucleus stores genetic information, Golgi modifies and packages proteins, mitochondria produce ATP. Thus, protein synthesis occurs at ribosomes.
Explanation:
Most bacteria possess a single circular double-stranded DNA molecule located in the nucleoid region. Some bacteria may also have linear chromosomes or multiple chromosomes, but the typical prokaryotic chromosome is circular. Eukaryotes have linear chromosomes. Plasmids are small, circular extra-chromosomal DNA in bacteria.
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