BASE EXCISION REPAIR
Certainly! Imagine your DNA
as a set of instructions that guides everything your body does. Now, sometimes
these instructions get damaged or changed due to things like chemicals or even
natural processes inside your cells. Base Excision Repair (BER) is like a
superhero mechanism that fixes these damaged instructions, making sure your
body's operations run smoothly. Let's break down its steps:
- Recognition and Removal of Damaged Base:
- Think of DNA as a string of beads.
Sometimes, one bead gets damaged. BER uses a special enzyme called DNA
glycosylase to spot and remove this damaged bead, leaving a gap.
- AP Site Incision:
- Now, there's a gap or hole in the string
where the damaged bead used to be. Another enzyme (AP endonuclease) comes
in, recognizes the gap, and cuts the string, creating a space to fix.
- Endonuclease and Lyase Activity:
- A repair enzyme with special abilities
(endonuclease and lyase) cleans up the gap. It removes the leftovers from
the damaged bead, getting the string ready for a replacement.
- Gap Filling and DNA Ligation:
- Now, imagine fixing the gap in the
string by adding a new, undamaged bead. DNA polymerase is like a
bead-maker, filling in the gap with the right beads. Then, DNA ligase
seals the string back up.
- Final Verification:
- Superheroes always double-check their
work! DNA polymerase has a proofreading ability to make sure the new
beads are correct. There are also surveillance mechanisms that keep an
eye on the fixed instructions.
Key Features and
Significance:
- Specificity:
BER is like a specialist for fixing certain types of damage in the DNA.
- Single-Strand Repair:
It deals with problems in just one part of the DNA, which is great for
fixing specific issues.
- Ubiquity:
BER is always on duty, constantly fixing common DNA damages that happen
regularly.
- Preservation of Genetic Information:
By being a DNA fixer, BER helps keep the instructions intact, preventing
mistakes and keeping everything running smoothly.
In simple terms, Base
Excision Repair is like a meticulous repair crew ensuring that the important
instructions in your DNA stay accurate and your body functions as it should!
MIND MAP
Base Excision Repair (BER)
├── Recognition and Removal of Damaged Base
│ ├── DNA Glycosylase
│ └── Cleaves damaged beads from DNA strand
├── AP Site Incision
│ ├── AP Endonuclease
│ └── Cuts DNA strand at AP site, creating a gap
├── Endonuclease and Lyase Activity
│ └── Repair enzyme removes residue and prepares for a new base
├── Gap Filling and DNA Ligation
│ ├── DNA Polymerase
│ │ └── Fills gap with correct nucleotides
│ └── DNA Ligase
│ └── Seals the nick in DNA strand
├── Final Verification
│ └── DNA Polymerase Proofreading
│ └── Ensures accuracy of repaired DNA
├── Key Features and Significance
│ ├── Specificity
│ ├── Single-Strand Repair
│ ├── Ubiquity
│ └── Preservation of Genetic Information
└── BER in Summary
└── Maintains genetic integrity by fixing specific DNA damage