What happens when your DNA is damaged? - Monica Menesini

Summary

The video explains how DNA in our cells experiences constant damage, with up to a quintillion errors occurring daily across the body. DNA repair mechanisms, involving specialized enzymes, correct these errors through processes like mismatch repair, base excision repair, and nucleotide excision repair. While most damage is fixed, severe issues like double-strand breaks can lead to serious conditions, including cancer. These repair pathways are vital for maintaining genetic stability, preventing premature aging, and protecting against diseases. Although mutations can sometimes be beneficial for evolution, the body's goal is to preserve DNA integrity.

Takeaways

• 🧬 The DNA in a single cell can be damaged tens of thousands of times per day, and when multiplied by the body's trillions of cells, this amounts to a quintillion DNA errors daily.
• ⚠️ DNA damage can cause serious issues, including cancer, as it disrupts the blueprint for the proteins cells need to function properly.
• 🧱 Errors in DNA can take various forms, such as damaged nucleotides, incorrect base pairing (mutations), and nicks in DNA strands that can affect replication.
• 🔧 Cells have multiple repair pathways to address different types of DNA damage, using specialized enzymes for each repair process.
• 🔍 One common error, base mismatches during replication, is corrected by DNA polymerase and additional proteins in a process called mismatch repair, reducing errors to about one in a billion.
• 🛡️ DNA can also be damaged after replication due to environmental factors like tobacco smoke or natural cellular molecules like hydrogen peroxide.
• ✂️ Base excision repair is used to fix single damaged bases, while nucleotide excision repair addresses more complex damage, such as UV-induced DNA distortions.
• 🌟 High-frequency radiation, like gamma and x-rays, can cause dangerous double-strand breaks in DNA, which are repaired by homologous recombination or non-homologous end joining.
• 🔄 Homologous recombination uses an undamaged DNA template for accurate repair, while non-homologous end joining directly fuses broken DNA ends but with less precision.
• ⏳ Defects in DNA repair are linked to premature aging and cancer, making efficient DNA repair systems crucial for maintaining cellular health and stability.

Q & A

What causes DNA damage in cells?

DNA damage can be caused by environmental factors like UV light and chemicals in tobacco smoke, as well as natural cellular processes involving molecules such as hydrogen peroxide.

How often does DNA polymerase make a mistake during replication?

DNA polymerase makes a mistake about once every 100,000 nucleotide additions.

What is mismatch repair, and why is it important?

Mismatch repair is a system where proteins correct base pairing errors after DNA replication. It reduces base mismatch errors to about one in one billion, ensuring the integrity of the genetic code.

What is the difference between base excision repair and nucleotide excision repair?

Base excision repair fixes single damaged bases, while nucleotide excision repair handles more complex damage, like UV-induced distortions where adjacent nucleotides stick together.

How do homologous recombination and non-homologous end joining differ in repairing double-strand breaks?

Homologous recombination uses an undamaged DNA template to repair the break, while non-homologous end joining trims the ends and fuses them without a template, which can lead to gene mix-ups.

What are the dangers of double-strand DNA breaks?

Double-strand breaks are the most dangerous type of DNA damage, and even one break can cause cell death if not properly repaired.

Why are DNA repair mechanisms so crucial to health?

DNA repair mechanisms prevent mutations that can lead to serious problems like cancer and premature aging, ensuring the stability of the genome.

What type of DNA damage does UV light cause?

UV light can cause adjacent nucleotides to stick together, distorting the DNA double helix, which requires repair by the nucleotide excision repair process.

What are beneficial mutations, and how do they relate to DNA damage?

Beneficial mutations are changes in DNA that can improve an organism's ability to survive, driving evolution. While most DNA changes are harmful, some are advantageous.

How are DNA repair defects linked to aging and cancer?

Defects in DNA repair mechanisms are associated with accelerated aging and various forms of cancer, as damaged DNA accumulates in cells and disrupts normal functioning.