In the 1860’s, an Austrian monk named Gregor Mendel introduced a new theory of inheritance based on his experimental work with pea plants. Prior to Mendel, most people believed inheritance was due to a blending of parental ‘essences’, much like how mixing blue and yellow paint will produce a green color. Mendel instead believed that heredity is the result of discrete units of inheritance, and every single unit (or gene) was independent in its actions in an individual’s genome. According to this Mendelian concept, inheritance of a trait depends on the passing-on of these units. For any given trait, an individual inherits one gene from each parent so that the individual has a pairing of two genes. We now understand the alternate forms of these units as ‘alleles’. If the two alleles that form the pair for a trait are identical, then the individual is said to be homozygous and if the two genes are different, then the individual is heterozygous for the trait.
Based on his pea plant studies, Mendel proposed that traits are always controlled by single genes. However, modern studies have revealed that most traits in humans are controlled by multiple genes as well as environmental influences and do not necessarily exhibit a simple Mendelian pattern of inheritance(see “Mendel’s Experimental Results”).
Mendel’s Experimental Results
Mendel carried out breeding experiments in his monastery’s garden to test inheritance patterns. He selectively cross-bred common pea plants (Pisum sativum) with selected traits over several generations. After crossing two plants which differed in a single trait (tall stems vs. short stems, round peas vs. wrinkled peas, purple flowers vs. white flowers, etc), Mendel discovered that the next generation, the “F1” (first filial generation), was comprised entirely of individuals exhibiting only one of the traits. However, when this generation was interbred, its offspring, the “F2” (second filial generation), showed a 3:1 ratio- three individuals had the same trait as one parent and one individual had the other parent’s trait.
Mendel then theorized that genes can be made up of three possible pairings of heredity units, which he called ‘factors’: AA, Aa, and aa. The big ‘A’ represents the dominant factor and the little ‘a’ represents the recessive factor. In Mendel’s crosses, the starting plants were homozygous AA or aa, the F1 generation were Aa, and the F2 generation were AA, Aa, or aa. The interaction between these two determines the physical trait that is visible to us.
Mendel’s Law of Dominance predicts this interaction; it states that when mating occurs between two organisms of different traits, each offspring exhibits the trait of one parent only. If the dominant factor is present in an individual, the dominant trait will result. The recessive trait will only result if both factors are recessive.
Mendel’s Laws of Inheritance
Mendel’s observations and conclusions are summarized in the following two principles, or laws.
Law of Segregation
The Law of Segregation states that for any trait, each parent’s pairing of genes (alleles) split and one gene passes from each parent to an offspring. Which particular gene in a pair gets passed on is completely up to chance.
Law of Independent Assortment
The Law of Independent Assortment states that different pairs of alleles are passed onto the offspring independently of each other. Therefore, inheritance of genes at one location in a genome does not influence the inheritance of genes at another location.
#MendelianInheritance #BotanyFieldOfStudy #GeneticsFieldOfStudy #DNA #Heterozygous #homozygous #genes #alleles #whatIsAnAllele #whatIsAGene #PTC #PTCTaster #dominant #recessive #trait #dominantTrait #recessiveTrait #heredity #genetics #explanation #biology #chromosomes #Karyotype #chromosome #ptcPaper #dominantVsRecessiveTraits #phenotype #genotype #amoebaSisters #geneticsLab #allelesVsGenes #highSchoolBiology #NikolaysGeneticsLessons
1 view
80
33
4 months ago 00:00:56 1
Adagio from Théolinda, ou, Le lutin de la vallée by Cesare Pugni
4 months ago 00:07:33 1
TCHAIKOVSKY - Hymn of the Cherubim
4 months ago 00:03:31 1
Dirt Nasty & Mickey Avalon - My Dick [MUSIC VIDEO]
4 months ago 00:04:01 1
Kerry King - Toxic (Official Music Video)
4 months ago 00:04:40 2
OTYKEN - CHUKOTKA (Official Music Video)
4 months ago 01:00:29 1
Psychedelic Trance mix III May 2024
4 months ago 00:00:37 3
“Unfair Competition”: Russia’s Putin Slams US Sanctions On Chinese Electronic Vehicles
4 months ago 00:12:28 1
Adelina De Lara - “Clara Schumann and her teaching“ - Reminiscences and Examples
4 months ago 00:34:36 1
ОНИ СВОДИЛИ С УМА МИЛЛИОНЫ женщин! 5 легендарных актеров! Что с ними стало? ЧАСТЬ 2
4 months ago 00:12:20 1
A Beatbox Concerto | Tom Thum & Gordon Hamilton Ft. The Bombay Chamber Orchestra | TEDxGateway
4 months ago 00:31:58 1
How to Crochet the Continuous Join As You Go CJAYG joining granny squares made EASY!
4 months ago 00:00:23 1
Phrasal verbs: at the beach! 🏖️ #englisch #learnenglish #english
4 months ago 00:02:36 1
‘Colossally stupid’: Megyn Kelly blasts Robert De Niro event outside Trump trial
4 months ago 00:07:16 1
Toscanini Says So: How Aida’s father should sing. Giuseppe Valdengo - Ciel! mio padre - 1949 LIVE
4 months ago 00:02:01 1
Noal - With You
4 months ago 01:53:32 1
Robot Design - Spider anatomy design as an example
4 months ago 00:09:56 1
新しいプールに大喜びのカワウソとやっぱりキレるカワウソ Otters’ First Splash in Their Brand New Pool
4 months ago 00:03:13 1
SLY (SKY) NEWS caught Catfishing Nigel Farage
4 months ago 08:00:03 1
Balcony in quiet winter mountains | Birdsong | Fireplace
4 months ago 00:14:23 1
Do This Everyday To Lose Weight | 2 Weeks Shred Challenge
4 months ago 00:04:30 1
A1 Movers Speaking test – Giorgia | Cambridge English
4 months ago 00:01:08 1
A very happy wolf
4 months ago 01:05:02 1
HOW TO CONTROL THOUGHTS & YOUR LIFE with Grandmaster Wolf & Shadow Control
4 months ago 00:00:59 1
Another example of how stunning our Hyunlix are #felix #hyunjin #필릭스 #현진 #hyunlix #shorts