Question

21. Double helix 22. Repressor protein 23. Adenine 24. Ribosome. 25. Promoter 26. Replication 27. RNA Polymerase. 28. Codon

A. Enzyme that synthesizes RNA B. Organelle where proteins are assembled C. Complementary to either Thymine or Uracil D. mRNA sequence that codes for one amino acid E. Shape of double stranded DNA F. Sequence of DNA that controls gene expression G. binds an operator and stops gene expression in LAC operon by preventing RNA polymerase from binding gene and transcribing. H. Duplication of DNA in 5 phase of Interphase

Answer 1

Double helix	Shape of double stranded DNA (DNA molecule has two polynucleotide strands held together by hydrogen bonds and has a helical structure, hence called double helix)
Repressor protein	binds an operator and stops gene expression in LAC operon by preventing RNA polymerase from binding gene and transcribing. (Repressor is a protein encoded by regulator gene which prevents the transcription by binding the operon at the operator site and thus regulates the operon).
Adenine	Complementary to either Thymine or Uracil (In DNA A forms base pair with T and in RNA, Adenine forms base pair with U)
Ribosome	Orgaelles where proteins are assembled (Protein synthesis occurs at the ribosome with the help of mRNA and tRNAs)
Promoter	Sequence of DNA that controls gene expression (Promoter is the site where RNA polymerase binds and promotes the trascription)
Replication	Duplication of DNA in S phase of interphase (Synthesis of DNA from DNA is called replication and it occurs during S phase of cell cycle.
RNA polymerase	enzyme that synthesizes RNA (RNA polymerase is the enzyme involved in transcription for synthesis of RNA from DNA)
Codon	mRNA sequence that codes for one aminoacid (a codon consists of three nitrogenous bases which code for one aminoacid)

Thank you