A Level Biology C19 Recap

​ (a)   is the result of inserting a gene(s) of interest into the genome of a different organism.

• Recombinant DNA
• Combinatory DNA
• Spliced DNA
• Complementary DNA

Reorder the following steps when attempting to transfer a gene from one organism to another

• Perform PCR

• Identify and isolate a gene

• Clone transformed vectors

• Treat vector with restriction endonuclease

• Mix vector with gene

Which of the following is NOT part of the genetic engineering "toolkit"?

• Enzymes

• Vectors

• Antibodies

• Markers

Restriction endonucleases (RE) are derived from bacteria. How do bacteria protect their own DNA from being cut by RE (choose all that apply)?

• Chemically altering their DNA

• Genetic material is protected inside a nucleus

• RE are inactive in bacterial cells

• Bacterial genomes do not have target sites for RE

What is the benefit of using reverse transcriptase to generate a gene of interest (DNA) from mRNA compared to extracting the gene from DNA directly?

Which of the following are TRUE regarding complementary DNA (cDNA) (choose all that apply)?

• cDNA is synthesised by reverse transcriptase

• cDNA can be found in nature

• cDNA is shorter than genomic DNA

• cDNA does not contain introns

Which of the following is NOT used as a vector for genetic engineering?

• Plasmids

• Bacteria

• Viruses

• Liposomes

Answer explanation

Although plasmids will eventually be inserted into bacteria, a bacterial cell is not a vector. Vectors transport genes of interest, hence a plasmid is described as a vector, while the bacterial cell is the receiving organism.

Using one restriction endonuclease (RE) on a genome to isolate a gene, and a different RE on a plasmid will not result in transformation of the plasmid. Explain why this happens.

With regards to the insertion of a gene into a plasmid, the restriction endonuclease must be added ​ (a)   the synthesis of complementary DNA (cDNA).

• after
• before
• during

Answer explanation

As the purpose of using a RE is to produce sticky ends (which requires a double-stranded DNA molecule) around our gene of interest, it must be added AFTER the synthesis of cDNA.

What is the role of guide RNA (gRNA) in the Crispr/Cas9 gene editing technique?

• Will be translated to Cas9 enzyme

• Binds to target site and aligns Cas9 enzyme

• Catalyses excision of faulty alleles

• Is reverse transcribed to fix errors in DNA sequences