Genetics: Chromosomes, Meiosis and Mitosis, and Inheritance Patterns

Sep 9, 2025

Dive into the essentials of genetics with a journey through chromosomes, mitosis, and meiosis. Discover Mendel's groundbreaking laws of inheritance and how Darwin's natural selection shapes modern genetics. Explore the structure of X and Y chromosomes, learn about chromosomal mutations, and uncover the significance of alleles in determining phenotypes. Gain insights into genetic diversity through meiosis, as well as concepts like codominance and incomplete dominance. Perfect for MCAT prep, this discussion covers foundational topics with clarity and depth!

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INSIGHT

Mendel’s Foundational Laws

Gregor Mendel established segregation, independent assortment, and dominance as foundational genetic laws despite later exceptions.
These laws explain allele separation, independent sorting, and dominant trait expression for inheritance predictions.

INSIGHT

Natural Selection Focuses On Reproduction

Darwin proposed natural selection as differential reproductive success driven by heritable variation and limited resources.
Selection favors traits that increase offspring number, not merely individual longevity.

INSIGHT

Chromosomal Theory Of Inheritance

Chromosomes carry genetic material and are transmitted in pairs, separating during meiosis to form gametes.
Each parent donates one chromosome set, explaining diploid inheritance.

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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.

Visit MedSchoolCoach.com for more help with the MCAT.

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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