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Genetic Engineering — Questions and Answers

Genetic engineering questions follow the recombinant DNA workflow end to end: cut the DNA with restriction enzymes, join it to a vector with ligase, transform a host, screen the recombinants, then amplify or express the product. Knowing which enzyme or tool belongs to each step answers the large majority of exam questions on the topic.

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Genetic Engineering— Concepts, Formulas & Shortcuts

  • Restriction endonucleases cut DNA at specific palindromic recognition sequences, often leaving sticky ends.
  • DNA ligase seals the phosphodiester backbone, joining insert to vector.
  • Common vectors: plasmids, bacteriophages, cosmids, BACs and YACs, chosen by insert size.
  • PCR amplifies DNA using primers, dNTPs and the thermostable Taq polymerase through denaturation, annealing and extension.
  • Gel electrophoresis separates DNA fragments by size, with smaller fragments migrating faster towards the anode.
  • The Ti plasmid of Agrobacterium tumefaciens is the standard vector for plant transformation; human insulin was the first commercial recombinant protein.

Genetic Engineering Practice Questions with Answers

Attempt each question first, then open the explanation. All 8 questions below are free to read and require no signup.

  1. Q1.Restriction endonucleases cut DNA:

    Easy
    • AAt random positions
    • BAt specific recognition sequences
    • COnly at the ends
    • DOnly single-stranded DNA
    +Show Answer & Explanation

    Answer: B. At specific recognition sequences

    Explanation: They recognise specific, usually palindromic, sequences — the property that makes precise cloning possible.

    Genetic Engineering question 1 of 8

  2. Q2.Which enzyme joins two DNA fragments together?

    Easy
    • ADNA polymerase
    • BDNA ligase
    • CHelicase
    • DPrimase
    +Show Answer & Explanation

    Answer: B. DNA ligase

    Explanation: DNA ligase forms the phosphodiester bond that seals the nick between insert and vector.

    Genetic Engineering question 2 of 8

  3. Q3.The most commonly used vector in recombinant DNA technology is:

    Easy
    • APlasmid
    • BRibosome
    • CLysosome
    • DCentriole
    +Show Answer & Explanation

    Answer: A. Plasmid

    Explanation: Plasmids are small, self-replicating circular DNA molecules carrying selectable markers, ideal for small inserts.

    Genetic Engineering question 3 of 8

  4. Q4.The first human protein produced commercially by recombinant DNA technology was:

    Moderate
    • AGrowth hormone
    • BInsulin
    • CInterferon
    • DErythropoietin
    +Show Answer & Explanation

    Answer: B. Insulin

    Explanation: Recombinant human insulin (Humulin) was approved in 1982, the first such therapeutic protein on the market.

    Genetic Engineering question 4 of 8

  5. Q5.Which enzyme is essential for PCR?

    Moderate
    • ADNA ligase
    • BTaq polymerase
    • CReverse transcriptase
    • DRestriction enzyme
    +Show Answer & Explanation

    Answer: B. Taq polymerase

    Explanation: Taq polymerase is thermostable, so it survives repeated denaturation at ~95 °C.

    Genetic Engineering question 5 of 8

  6. Q6.The Ti plasmid used for plant transformation is obtained from:

    Moderate
    • AEscherichia coli
    • BAgrobacterium tumefaciens
    • CBacillus thuringiensis
    • DSaccharomyces cerevisiae
    +Show Answer & Explanation

    Answer: B. Agrobacterium tumefaciens

    Explanation: Agrobacterium tumefaciens naturally transfers T-DNA into plant cells, which is exploited for genetic transformation.

    Genetic Engineering question 6 of 8

  7. Q7.Gel electrophoresis separates DNA fragments on the basis of:

    Moderate
    • ACharge only
    • BSize
    • CSequence
    • DBase composition
    +Show Answer & Explanation

    Answer: B. Size

    Explanation: DNA has a uniform negative charge per unit length, so migration through the gel matrix depends on fragment size.

    Genetic Engineering question 7 of 8

  8. Q8.The restriction enzyme EcoRI is isolated from:

    Difficult
    • AEscherichia coli
    • BEnterobacter cloacae
    • CErwinia carotovora
    • DEubacterium rectale
    +Show Answer & Explanation

    Answer: A. Escherichia coli

    Explanation: The naming convention encodes the source: E. coli, strain R, first enzyme identified — EcoRI.

    Genetic Engineering question 8 of 8

Genetic Engineering — Frequently Asked Questions

What are sticky ends and why do they matter?+

Many restriction enzymes cut the two DNA strands at staggered positions, leaving short single-stranded overhangs. Because these overhangs base-pair with complementary ends cut by the same enzyme, they let an insert and a vector join precisely before ligase seals them.

Why is Taq polymerase used in PCR?+

It comes from the thermophile Thermus aquaticus and survives the 94–95 °C denaturation step, so fresh enzyme does not have to be added each cycle — the discovery that made PCR automatable.

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