Question

11. A gene is best defined as a. A segment of DNA b. Three nucleotides that code for an amino acid. C. A sequence of nucleotides in DNA that codes for a functional product. d. A sequence of nucleotides in RNA that codes for a functional product. e. A transcribed unit of DNA. 12. Which of the following statements is false? a. DNA polymerase joins nucleotides in one direction only. b. The leading strand of DNA is made continuously c. The lagging strand of DNA is started by an RNA primer. d. DNA replication proceeds in one direction around the bacterial chromosome. e. Multiple replication forks are possible on a bacterial chromosome. 13. The enzyme responsible for synthesis of mRNA is: a. DNA polymerase b. RNA polymerase C. Ligase d. Reverse transcriptase 14. During the replication DNA polymerase makes mistakes with frequency 10° bases (mutation) True/ False 15. Transcription begins when RNA polymerase binds to the specific DNA sequence of the gene called a. AUG codon b. Operator C Promotor d. None of the above 16. In eukaryotic cells mRNA is synthesize as a precursor (exons + introns) and undergo splicing (processing, introns are deleted and exons are connected) True False 17. Alternative splicing of introns in eukaryotic mRNA produce multiple variant proteins from a single gene True / False

Answer 1

1) gene is the DNA sequence which codes for functional RNA or protein.

in human all cells has the same genome, but all genes are not transcribed in all cells,.

Three nucleotides that codes for an amino acid is codon.

so the answer is c) A sequence of DNA that codes for a functional product.

2) DNA polymerase can add nucleotides to the 3`-OH of the nucleic acid, eading strand is synthesized continously and lagging strand is synthesized as small fragments called Okazaki fragments synthesis of both Okazaki fragments and leading strand starts with RNA primer.

In the prokaryotes the circular DNA has only one origin of replication and the replication is bidirectional so it has 2 replication fork, so the answers are

d) DNA replication proceeds in one direction around the bacterial chromosome.

e) multiple replication forks are possible on a bacterial chromosome.

3) mRNA is synthesised by RNA polymerase it uses DNA as the template for the synthesis of RNA.

DNA polymerase synthesizes DNA using DNA as the template.

ligase links nucleic acids by making phosphodiester bond.

Reverse transcriptase make DNA using RNA template.

so the aswer is b) RNA polymerase.