In genetic engineering, the enzyme used to cut DNA at specific sequences is:
A. Helicase
B. Restriction endonuclease
C. DNA polymerase
D. Ligase
Answer: Option B
Solution (By JKExamLibrary)
Restriction endonucleases (restriction enzymes) recognize specific palindromic DNA sequences and cleave the phosphodiester bonds, producing sticky or blunt ends. They are essential tools for recombinant DNA technology. DNA polymerase synthesizes DNA, ligase joins fragments, helicase unwinds. Examples: EcoRI, HindIII. These enzymes are naturally present in bacteria as a defense against viruses.
Explanation:
Genotype is the set of alleles an individual possesses for a particular gene or trait (e.g., TT, Tt, tt). Phenotype is the observable characteristic. Karyotype is the chromosome complement.
Explanation:
Veins have thinner walls and larger lumens; arteries are thick and elastic; capillaries are thin for exchange; venules are larger than capillaries. Valves are in veins.
Explanation:
The endocrine islets of Langerhans in the pancreas contain alpha cells that secrete glucagon and beta cells that secrete insulin, which regulate blood glucose. The liver stores and releases glucose, the spleen filters blood, the kidneys excrete waste. The pancreas also has exocrine functions secreting digestive enzymes.
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