Question

3

 Gene transfer by plasmids

•  are never passed to the offspring

•  are often passed to the zygote cells

•  always cause cancer

•  almost always cause cancer

•  are often found in bacteria

4

 Which of the following regarding translation is correct?

•  Energy is required to move the large and small subunits along the mRNA.

•  When a stop codon is read, an amino-acyl tRNA binds to the A site.

•  The large ribosomal subunit binds to mRNA and then the small subunit is attached.

•  In eukaryotes, the Shine-Dalgarno sequence is where initiation factors assemble.

•  Alanine is always the first amino acid in a newly synthesized protein.

Answer 1

Answer for question number 3: The correct answer is E (are often found in bacteria)

Explanation: Plasmids are double-stranded, covalently closed, autonomously replicating, extrachromosomal DNA molecules present in most of the bacterial genera. They carry genes that provide resistance to naturally occurring antibiotics(passed from one bacterium to another through a process called conjugation) and carry genes which code for proteins which may act as toxins under certain conditions. Plasmids also provide the ability of bacteria to fix elemental nitrogen or to degrade recalcitrant organic compounds.

Answer for question number 4: The correct answer is A (Energy is required to move the large and small subunits along the mRNA)

Explanation: Translocation is the last step in the elongation process. During this step, three events occur such as

1. Ejection of the discharged tRNA from the P site
2. Movement or physical shifting of the tRNA dipeptide from A site to the P site
3. Movement of the mRNA the 5’ to 3’ direction by the length of one codon.

Movement of the entire ribosome relative to the mRNA strand by one codon is called translocation. In prokaryotes, this process requires Elongation factor G or Translocase and also GTP.