ALELOS LETAIS: O QUE SÃO, EXEMPLOS NA ESPÉCIE HUMANA (GENÉTICA) | Resumo de Biologia para o Enem

🎓 Free ENEM Course: https://goo.gl/2rebsa 📑 Introduction to Genetics: https://bit.ly/3yu20VY 📑 Mendel's First Law: https://bit.ly/2T18NYa Subscribe to the channel to receive everything about the ENEM 100% FREE https://bit.ly/37WGBZi /// ABOUT THE VIDEO Alleles are versions of a gene. They arise in populations through mutations. In genetics, we use the word allele to refer to the variant of a gene when we are studying a cross. Mendel called alleles "factors". According to Mendel's first law, a characteristic is usually caused by a pair of factors. Today we know that these factors are allelic genes, located at the same locus (region) of a pair of homologous chromosomes. It's also worth remembering that in crosses, genes are represented by letters (usually the initials of some phenotype produced). Homozygosity: Homozygosity occurs when, in a given pair of genes (located at the same locus on two homologous chromosomes), we have two identical alleles. An individual who is homozygous for a trait is called homozygous. Example: Albinism is produced by the gene called "a", which produces the characteristic when it is homozygous: aa (two "a" alleles, one on each homologous chromosome). Heterozygosity: Heterozygosity occurs when, in a given pair of genes, we have two different alleles. We call heterozygous the individual who is heterozygous for some studied trait. Example: The typical production of melanin is conditioned by the gene "A". This trait can be produced in both homozygosity (AA) and heterozygosity (Aa – gene "A" on one of the chromosomes of the homologous pair and "a" on the other). In some cases, including in humans, there are alleles that can be lethal. In this lesson, Professor Juliana explains what lethal alleles are and gives examples of lethal alleles in humans. Questions? Leave them in the comments. ;) ⏱ TIMESTAMPS / TOPICS 00:40 - Inheritance pattern of lethal alleles X inheritance pattern of complete dominance (Mendel's First Law) 05:18 - Discovery of lethal alleles 07:02 - Lethal alleles in the human species: example 🔴 ALSO WATCH Introduction to Genetics https://bit.ly/2DEd6jR Mendel's First Law https://bit.ly/3e0vbbh ❤️ SOCIAL MEDIA INSTA @cursoenemgratuito TWITTER @enemgratuito FACE /cursoenemgratuito/ /// SO, WHAT IS THE FREE ENEM COURSE? We are a channel of completely free classes on the topics that most frequently appear on the ENEM and university entrance exams. We're here to democratically share content and information about the ENEM exam, helping you get into your dream college ♥ We also have a website with written lessons, practice questions, and a study plan to help you get organized! Ready to study with us? 🎓 ACCESS OUR 100% FREE ENEM COURSE https://goo.gl/2rebsa