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DNA Mutations and Repair

MCAT Basics (from MedSchoolCoach)

Release Date: 09/17/2024

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MCAT Basics (from MedSchoolCoach)

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MCAT Basics (from MedSchoolCoach)

One of the most fundamental biochemical processes is the Krebs cycle. This metabolic pathway plays a critical role in both the Chem Phys and Bio/Biochem sections of the MCAT, so understanding it is key. In this episode, our guest host, Alex Starks, walks us through the transformation of pyruvate into acetyl CoA via the Pyruvate Dehydrogenase Complex (PDC). We’ll explore how thioester bonds help transfer energy within the cycle, how acetyl CoA combines with oxaloacetate to form citrate, the difference between enzymes like synthetases and synthases, and how GTP is produced. We’ll also make...

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More Episodes

In this episode, we focus on DNA mutations and repair, a key topic for the Bio/Biochem section of the MCAT. We'll cover the different types of mutations, including point mutations, insertions, and deletions, and explain how they occur due to replication errors or environmental factors like UV radiation.

You'll also learn about the repair mechanisms that fix these genetic changes, such as direct reversal, mismatch repair, and base excision repair. We’ll also discuss how double-strand breaks are addressed through homologous recombination and non-homologous end joining.

By the end of this episode, you'll gain a thorough understanding of how mutations happen and the processes the body uses to repair them, helping you prepare for related MCAT questions.

Visit MedSchoolCoach.com for more help with the MCAT.

Jump into the conversation:

(00:00) Intro

(01:07) Overview of DNA Mutations and Repair

(01:45) What is a Mutation?

(02:30) Mutations During DNA Replication

(03:29) DNA Polymerase Slippage: Causes duplication of repeated sequences in DNA

(06:15) Mutations Before or After Replication: Caused by mutagens like radiation or chemicals

(07:19) Mutagens vs. Carcinogens: Differences between agents that cause mutations and those that cause cancer

(09:56) Types of Mutations: Overview of point mutations, insertions, and deletions

(12:00) Frameshift Mutations: How insertions or deletions shift the reading frame

(29:50) Chromosomal Mutations: Inversions and translocations

(35:35) DNA Repair Mechanisms: Introduction to replication repair, mutation repair, and break repair

(36:51) Proofreading by DNA Polymerase: Repairing replication errors

(39:20) Direct Reversal DNA Repair: Enzymes directly fix damaged DNA

(40:41) Mismatch Repair: Fixing base mismatches and insertion-deletion loops

(43:25) Base Excision Repair: Correcting single-base mutations

(46:03) Nucleotide Excision Repair: Fixing bulky DNA damage like pyrimidine dimers

(47:56) Interstrand Cross-Link Repair: Repairing DNA strands covalently cross-linked together

(50:27) Single-Strand Break Repair: Ligating broken DNA strands back together

(51:16) Double-Strand Break Repair: Homologous recombination and non-homologous end joining

(54:13) Summary of DNA repair mechanisms