The enzyme that seals nicks in the sugar-phosphate backbone of DNA is:
A. Primase
B. DNA polymerase
C. Ligase
D. Helicase
Answer: Option C
Solution (By JKSSB Mock Tests)
DNA ligase catalyzes the formation of phosphodiester bonds between adjacent nucleotides, sealing breaks in the DNA backbone. It is essential for joining Okazaki fragments on the lagging strand during replication and in DNA repair. Polymerase adds nucleotides, helicase unwinds, primase synthesizes RNA primer.
Explanation:
The loop of Henle creates a countercurrent multiplier system in the medulla, establishing an osmotic gradient that allows the collecting duct to reabsorb water and produce concentrated urine. The other parts handle filtration, reabsorption, and secretion.
Explanation:
Translation is the ribosome-mediated synthesis of a polypeptide chain according to the mRNA template. tRNA molecules bring amino acids, and peptide bonds form. Replication duplicates DNA, transcription synthesizes RNA from DNA, transformation is genetic uptake by bacteria.
Explanation:
The bacterial cell wall is a rigid structure that provides shape and protection. It is primarily composed of peptidoglycan (also known as murein), a polymer consisting of sugars and amino acids. Gram-positive bacteria have a thick peptidoglycan layer, while Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane. Cellulose is in plant walls, and chitin is in fungal walls.
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