Tools of Recombinant DNA Technology
Restriction enzymes, vectors, host organisms and DNA ligase. (Biology › Biotechnology — Principles and Processes, NEET UG syllabus.)
What is Tools of Recombinant DNA Technology?
An enzyme that cuts DNA at specific recognition sequences, typically palindromic, acting as 'molecular scissors'.
Key points
- Define and classify restriction enzymes based on their cutting patterns.
- Explain the essential features of an ideal cloning vector and their respective functions.
- Describe the mechanism and role of DNA ligase in joining DNA fragments.
- Understand the concept of a competent host and various methods to make cells competent for DNA uptake.
Common exam trap
Confusing exonucleases (remove nucleotides from ends) with endonucleases (cut within DNA).
Definitions
- Term
Restriction Enzyme
- Meaning
An enzyme that cuts DNA at specific recognition sequences, typically palindromic, acting as 'molecular scissors'.
- Term
Cloning Vector
- Meaning
A DNA molecule, such as a plasmid or bacteriophage, used to carry and replicate foreign DNA within a host cell.
- Term
DNA Ligase
- Meaning
An enzyme that catalyzes the formation of phosphodiester bonds to join DNA fragments, acting as 'molecular glue'.
- Term
Competent Host
- Meaning
A cell that has been treated to increase its permeability to DNA, enabling it to take up foreign DNA.
- Term
Palindromic Sequence
- Meaning
A DNA sequence that reads the same forwards and backwards on complementary strands when read in the 5' to 3' direction (e.g., 5'-GAATTC-3' and 3'-CTTAAG-5').
Learning objectives
Define and classify restriction enzymes based on their cutting patterns.
Explain the essential features of an ideal cloning vector and their respective functions.
Describe the mechanism and role of DNA ligase in joining DNA fragments.
Understand the concept of a competent host and various methods to make cells competent for DNA uptake.
Outline the basic steps involved in using these tools to construct recombinant DNA.
Prerequisites
Basic structure and composition of DNA and RNA.
Understanding of the Central Dogma of molecular biology (replication, transcription, translation).
Fundamental knowledge of bacteria and viruses.
Basic concepts of enzymes and their specificity.
Common mistakes
Confusing exonucleases (remove nucleotides from ends) with endonucleases (cut within DNA).
Not understanding the specific functions of *ori* and selectable markers in a vector.
Forgetting the necessity of making host cells competent for DNA uptake.
Misidentifying the role of DNA ligase as cutting DNA instead of joining it.
Incorrectly identifying palindromic sequences or their significance.
Keywords
Restriction enzymes
endonucleases
palindromic sequence
sticky ends
blunt ends
cloning vector
plasmid
bacteriophage
origin of replication
selectable marker
cloning site
DNA ligase
competent host
heat shock
electroporation
transformation
recombinant DNA
Practice preview
Which enzyme is responsible for joining the desired foreign DNA fragment with the vector DNA?…
easy
Restriction enzymes recognize specific sequences on the DNA molecule, which are typically:…
medium
To enable bacterial cells to take up foreign DNA, they are made 'competent'. Which method is commonly used to make E. coli cells competent?…
medium