In a DNA strand, two nucleotides are linked through a ___________ linkage to form a dinucleotide.
1. 3’ – 5’ phosphodiester bond
2. 5’ – 3’ phosphodiester bond
3. 1’ N-glycosidic bond
4. Two or three hydrogen bonds
Replication in prokaryotes differs from replication in eukaryotes for which of the following reasons?
1. | Prokaryotic chromosomes have histones, whereas eukaryotic chromosomes do not. |
2. | Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many. |
3. | The rate of elongation during DNA replication is slower in prokaryotes than in eukaryotes. |
4. | Prokaryotes produce Okazaki fragments during DNA replication, but eukaryotes do not. |
Consider the following two statements:
I: | During transcription, the template strand is read in a 3'-to-5' direction. |
II: | During transcription, an RNA is transcribed in the 5'-to-3' direction. |
The correct statements is/are:
1. | I only | 2. | II. Only |
3. | I and II | 4. | None |
Identify the correct statements from the given statements and choose the correct option:
I: | Both prokaryotic and eukaryotic mRNAs have a 5' cap. |
II: | Only prokaryotic mRNAs are polyadenylated at the 3' end. |
III: | In prokaryotes, transcription is coupled to translation. |
IV: | In eukaryotes, RNA splicing occurs after the mRNA is transported into the cytoplasm. |
V: | RNA splicing requires the formation of a spliceosome. |
VI: | Both prokaryotic and eukaryotic mRNAs are synthesized by RNA polymerase. |
1. | III, V, and VI only |
2. | II, III, V, and VI only |
3. | I, III, V, and VI only |
4. | I, III, IV, V, and VI only |
What radioactive isotope was used in Meselson and Stahl experiment to prove the semi-conservative mode of DNA replication?
1. | 35S | 2. | 32P |
3. | 15N | 4. | None |
Under conditions where methionine must be the first amino acid, what protein would be coded for by the following mRNA?
5'-CCUCAUAUGCGCCAUUAUAAGUGACACACA-3'
1. | pro his met arg his tyrlyscys his thr |
2. | met arg his tyrlyscys his thr |
3. | met arg his tyrlys |
4. | met pro his met arg his tyrlyscys his thr |
Which of the following is likely if there is a mutation in the lacY gene of the lac operon in E.coli?
1. | The lac genes would be expressed efficiently only in the absence of lactose. |
2. | The lac genes would be expressed efficiently until the lactose supply in the cell is exhausted. |
3. | The lac genes would be expressed continuously. |
4. | Expression of the lac genes would cease immediately. |
The difference between ATP and the nucleoside triphosphates used during DNA synthesis is that:
1. | The nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose. |
2. | The nucleoside triphosphates have two phosphate groups; ATP has three phosphate groups. |
3. | ATP contains three high-energy bonds; the nucleoside triphosphates have two. |
4. | ATP is found only in human cells; the nucleoside triphosphates are found in all animal and plant cells. |
Which of the following pairs of codons encode the same amino acid?
1. | AUG and AUC | 2. | UAA and UAC |
3. | GUA and GUG | 4. | UAG and UAC |
Griffith wanted to make a vaccine to prevent pneumonia. He injected heat-killed S-strain bacteria into the mice for this purpose. How can a killed bacteria help in making a vaccine?
1. | The heat-killed bacteria is a more potent toxin than the live one. |
2. | Protein denaturation due to heat changes the proteins of the bacterium. |
3. | Molecules from the cell surface are still intact and can provoke an immune response. |
4. | DNA molecules can transform other strains of bacteria. |