In this episode, we explore enzyme kinetics and inhibition, key concepts for the MCAT Bio/Biochem section. We’ll cover how enzymes accelerate biological reactions by lowering activation energy and introduce two models for enzyme-substrate interaction: the lock-and-key model and the induced fit model.

You'll learn how to apply the Michaelis-Menten equation, focusing on factors like Km and Vmax to understand enzyme efficiency and substrate binding. We’ll also break down the different types of enzyme inhibition—competitive, non-competitive, and uncompetitive—and their effects on enzyme activity. Finally, we discuss the six major types of enzymes and their roles in biological processes, with examples like ligases, isomerases, and hydrolases.

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(00:00) Introduction to enzyme kinetics and inhibition

(01:58) Definition of enzymes and their role

(03:50) Enzyme models: lock and key vs. induced fit

(06:28) Michaelis-Menten Equation

(10:53) Association and dissociation constants

(12:34) Kcat and catalytic efficiency

(14:43) Assumptions of Michaelis-Menten

(18:23) Lineweaver-Burk Plot: linearized Michaelis-Menten Equation

(21:09) Enzyme inhibition: reversible vs. irreversible

(22:14) Competitive inhibition: Km and Vmax

(24:46) Non-competitive inhibition: Effects on Km and Vmax

(27:20) Irreversible inhibition

(29:13) Allosteric inhibition

(31:26) Homotropic and feedback inhibition

(37:40) Common biological enzymes: dehydrogenase, synthetase, and kinase

(43:44) MCAT Advice of the Day

In this episode, we cover the foundational concepts of genetics, focusing on chromosomes, mitosis, meiosis, and inheritance patterns—important topics for the MCAT Bio/Biochem section. We’ll discuss how Gregor Mendel’s laws of segregation, independent assortment, and dominance influence inheritance and how Charles Darwin’s theory of natural selection relates to modern genetics.

The episode includes an overview of chromosome structure, the differences between X and Y chromosomes, and the effects of chromosomal mutations like deletions, duplications, and translocations. Mitosis and meiosis are also explained, with an emphasis on their roles in cell division and genetic diversity. Additionally, we explore genetic concepts such as codominance, incomplete dominance, genetic leakage, and how factors like penetrance and expressivity influence gene expression.

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(00:00) Introduction to Genetics and Chromosomes

(01:41) Background on genetics: Key figures and their contributions (Mendel, Darwin)

(03:37) Mendel’s Laws: Segregation, independent assortment, and dominance

(05:50) Charles Darwin: Evolution and natural selection in genetics

(09:43) Chromosomes and DNA: Discovery and role in inheritance

(11:29) Chromosome Numbers and Structure: Ploidy, chromatids, and human chromosomes

(14:06) X and Y Chromosomes: Sex determination and sex-linked traits

(18:34) Chromosomal Mutations: Duplication, deletion, inversion, translocation

(22:00) Mitosis: Stages and the production of identical daughter cells

(28:16) Meiosis: Gamete formation and genetic diversity

(32:40) Centrosome, Centromere, and Centriole: Roles in cell division

(33:50) Genes and Phenotypes: Alleles, genotypes, and their effect on traits

(38:28) Dominant and Recessive Alleles: How traits are determined

(40:37) Genetic Leakage, Penetrance, and Expressivity: Gene flow, expression likelihood, and variability

(42:47) MCAT Advice of the Day

In this episode, Sam Smith covers the intricacies of metabolism, focusing on glycolysis, the Krebs cycle, and the electron transport chain. 

First, the podcast explores the process of glycolysis, breaking down the key enzymes, intermediates, and regulation points. Next is the citric acid cycle, examining its regulation, energy production, and the roles of specific enzymes and intermediates. Lastly, we look at the electron transport chain and discuss how electrons are transferred through the five complexes, creating a proton gradient that drives ATP synthase to produce ATP. 

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Jump into the conversation:

(00:00) Intro

(03:15) Ten steps of glycolysis: Intermediate names and enzymes

(08:01) Simplified glycolysis process: Breaking down key steps

(12:30) Glycolysis regulation: Allosteric regulation of enzymes

(21:13) Mnemonics for Krebs cycle intermediates

(25:52) Regulation of the Krebs cycle: ATP, calcium, and more

(30:26) Electron transport chain: Overview and key steps

(34:35) ATP synthase

(33:00) Reduction potentials in the electron transport chain

(37:31) Synopsis of metabolism

(40:34) MCAT Advice of the Day

 

Acids and bases are foundational topics in chemistry, crucial for understanding various biological and chemical systems you'll encounter in the MCAT.

In this episode, host Sam Smith discusses the selection and use of indicators in titrations to the pH at the equivalence point and the importance of buffers in maintaining physiological pH levels. You'll learn about the Henderson-Hasselbalch equation, the blood buffer system, and how to tackle common problems involving acids and bases. Plus, we'll break down strong and weak acids and the significance of their dissociation constants. This episode also shares tips on calculating pH, using ICE tables for weak acid problems, and converting between pH, pOH, and ion concentrations.

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Jump into the conversation:

(00:00) Intro
(02:16) Basic definitions of acids and bases
(11:33) Calculating pH
(24:55) Titrations
(35:26) Buffers
(41:16) Blood buffer system
(45:25) MCAT advice of the day

A foundational topic for the MCAT is the nervous system, appearing in several exam sections and impacting everything from neurotransmission to brain structure.

In this episode, Sam Smith walks us through the nervous system, covering its major components and functions. From the organization of the central and peripheral nervous systems to neurotransmitters and brain structures, Sam provides clear explanations to help you understand key topics like the autonomic nervous system's fight-or-flight response, brain imaging techniques, and more. 

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Jump into the conversation:

(00:00) Intro

(01:03) How the central and peripheral nervous systems are organized

(02:33) Autonomic and somatic systems

(03:22) Sympathetic and parasympathetic branches

(04:12) How the brain is structured: forebrain, midbrain, and hindbrain

(11:44) How brain imaging techniques (CT, MRI, EEG, fMRI, PET) are used

(14:06) How neurons are structured and how they transmit signals

(16:00) How action potentials work and how ion channels play a role

(20:30) How myelin sheaths speed up signals

(25:00) How language processing happens in Broca's and Wernicke's areas

(28:00) Neurological disorders

(43:45) The structures of the limbic system

(47:25) The structures of the brain related to addiction

 

 

Amino acids are the building blocks of life and an essential topic for the MCAT.

In this episode, host Sam Smith takes us through the key concepts of amino acids, including their structures, naming conventions, and roles in protein formation. We’ll cover the differences between hydrophobic and hydrophilic amino acids, how to memorize single-letter abbreviations, and the importance of charged amino acids in physiological conditions. Additionally, Sam touches on mutations and how they can affect protein folding and enzyme function.

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Jump into the conversation:

(00:00) Intro

(01:47) Amino acids naming conventions and abbreviations

(04:49) Hydrophobic vs. hydrophilic amino acids

(05:39) Charged and uncharged amino acids

(10:14) Explanation of mutation notation

(11:53) Mutations affecting the substrate pocket of enzymes

(13:15) Mutations impacting enzyme functionality

(15:58) Role of amino acids in protein tertiary structure

(17:15) Salt bridges and protein stability

(20:47) Quiz

This MCAT BAsics episode covers the muscular system. It begins with the differences and similarities between the three types of muscle (smooth, cardiac, and skeletal). Then, the podcast explores the basic structure of a skeletal muscle cell and the various organelles unique to this cell type, including the sarcolemma, sarcoplasm, myofibrils, sarcomeres, and more. Next, it discusses three main differences between Type 1 and Type 2 muscle fibers. Finally, it delves into muscle contraction, starting at the neuromuscular junction and ending with the shortening of sarcomeres, which causes muscle flexion.

 

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[00:00] Introduction

[02:09] Types of muscle - smooth, cardiac, skeletal

[04:49] The structure of a muscle cell in skeletal muscle

[15:11] The difference between Type 1 and Type 2 muscle fibers

[23:08] Understanding how a muscle contracts

[27:53] The Cross-Bridge cycle

This MCAT Basics episode covers fluid statics (fluids standing still). It begins with different fluid properties, including surface tension, vapor pressure, adsorption and absorption, adhesion and cohesion, and Henry's law. Next, it discusses several important fluid statics concepts: static fluid pressure, Pascal's law, gauge pressure vs absolute pressure, osmotic pressure, and buoyancy.

 

For information on fluid dynamics (moving fluids), skip to the 43:00 mark in the cardiovascular system + fluids podcast.

 

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[00:00] Introduction

[02:18] Properties of fluids

[07:10] Surface Tension

[11:54] Difference between adsorption and absorption

[14:09] Vapor Pressure

[19:07] Henry’s Law

[20:35] Static Fluid Pressure

[25:10] Pascal’s Law

[29:23] The difference between gauge pressure and absolute pressure.

[31:24] Osmotic Pressure

[44:35] Buoyancy

 

The electron transport chain is a fundamental pathway in biochemistry, critical for understanding the energy production that powers cellular function.

In this episode, guest host Alex Starks breaks down the intricate process of the electron transport chain (ETC). Building on previous discussions of glucose metabolism, Alex walks through the components that play key roles in the movement of electrons through complexes within the inner mitochondrial membrane. We also cover the functions of coenzyme Q and cytochrome c, as well as oxygen’s critical role in completing the process. 

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Jump into the conversation:

(00:00) Intro

(02:11) Recap of glycolysis, pyruvate, and the Krebs cycle

(03:02) Location of the TCA cycle and ETC in the mitochondria

(04:22) Overview of NADH and FADH2 production

(05:38) Complex I: NADH dehydrogenase and coenzyme Q

(08:00) Complex II: Succinate dehydrogenase and FADH2

(11:15) Complex III: Cytochrome c reductase and the role of proton pumping

(14:32) Complex IV: Cytochrome c oxidase and oxygen

(18:14) The role of ATP synthase

(21:47) Total ATP yield from aerobic respiration

(26:00) How the electron chain is disrupted

(30:20) Uncouplers and their metabolic effects

(35:16) Quiz

 

One of the body's key survival mechanisms is gluconeogenesis, a vital metabolic process, and the body's clever way of making glucose when supplies are low.

On this episode of the MCAT Basics podcast, guest host Alex Starks walks through the process of gluconeogenesis. He explains how the body generates glucose when levels drop. Highlighting the liver's role, Alex explains how amino acids, lactate, and glycerol are converted into glucose. The episode also touches on the energy demands of the process and why muscle cells aren't involved in gluconeogenesis. 

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Jump into the conversation:

(00:00) Intro

(02:15) Overview of glucose metabolism and glycogen storage

(03:37) The liver’s role in maintaining blood glucose levels

(05:11) Glucogenic amino acids and their role in glucose production

(06:06) Conversion of alanine and glutamine to pyruvate

(06:53) Lactate and the Cori cycle

(07:34) Glycerol from triglycerides entering gluconeogenesis

(08:27) The first bypass reaction: Pyruvate to oxaloacetate

(09:55) The role of mitochondria and the malate-aspartate shuttle

(11:00) Phosphoenolpyruvate formation and energy requirements

(12:16) Steps of gluconeogenesis and ATP consumption

(13:38) The second bypass reaction: Fructose 1,6-bisphosphate to fructose 6-phosphate

(14:16) The third bypass reaction: Glucose 6-phosphate to glucose

(15:31) Gluconeogenesis regulation and the role of glucagon

(17:10) Quiz

 

In this episode, we delve into three common types of isomers that you are likely to encounter on the MCAT: structural isomers, geometric isomers, and stereoisomers.  We start by defining each type of isomer, providing clear and concise explanations to ensure a solid understanding. Next, we present common examples of each isomer type to illustrate their unique characteristics. Finally, we discuss real-world applications and scenarios where these isomers are relevant, particularly in the context of the MCAT. This material will appear in the Physical Chemistry section of the MCAT and may also be found in the Biochemistry section.

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Jump Into the Conversation:

[00:00] Introduction

[02:06] Structural isomers

[06:03] Geometric isomers

[15:50] Three different kinds of stereoisomers

[16:30] Enantiomers

[17:44] Diastereomers

[18:46] Conformational isomers

[22:06] Key terms regarding stereoisomers

[26:54] Difference between absolute and relative configurations of stereoisomers

[28:22] Interesting example of stereoisomers in different sugars