Name: forked line method for trihybrid crosses
Uploaded: 2021-04-07T12:11:58.000Z
Duration: 2 min 27 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

North Carolina K-12 Science Standard Course of Study

9-12

Biology

heredity-inheritance-and-variation-of-traits

Heredity- Inheritance and Variation of Traits

LS.Bio.7.1

Trihybrid Crosses

멘델은 완두콩 식물에 대한 연구를 트라이하이브리드 교배종으로 더욱 확장했는데, 이 교배종에서는 유기체가 세 가지 다른 형질로 다양한데, 예를 들어 식물 높이(여기서는 대문자 또는 소문자 T-로 표시됨), 여기에서 대립유전자 R로 표시된 종자 모양, 그리고 문자 Y로 표시된 종자 색상.
이 십자가에서 동형 접합 우성 식물은 둥글고 노란색 씨앗과 유전자형 대문자 TTRRYY를 가진 키가 큰 식물입니다. 동형 접합 열성 식물은 주름진 녹색 씨앗과 유전자형 소문자 ttrryy가있는 짧은 식물입니다.
이 식물이 교배될 때, 모든 F1 세대 식물은 트라이하이브리드이며, 이는 여기에 표시된 유전자형을 가진 세 가지 형질 모두에 대해 이형접합적임을 의미합니다.
F1 세대 식물은 모든 식물이 키가 큰 지배적 인 표현형을 나타냅니다 ... 둥근..., 노란색 씨앗.
세 쌍의 대조되는 특성이 있을 때 F2 세대에는 64개의 잠재적인 유전자형이 있기 때문에 Punnet 사각형은 빠르게 실용적이지 않게 됩니다.
이러한 경우 갈래 선 방법이 대신 사용되는 경우가 많습니다. 여기서, 3쌍의 형질을 가진 F1 이형접합체는 3개의 행으로 배열되어 있으며, 각 유전자는 한 줄을 차지합니다.
식물 높이에 대한 대립유전자는 첫 번째 줄에 배치되며 3개의 식물이 크고 1개의 식물이 짧은 단일잡종 교배에서 예상되는 비율로 분리됩니다.
종자 모양의 대립유전자는 두 번째 줄에 배치되고 3:1 비율로 유사한 방식으로 갈래 선에서 분리됩니다. 이 과정은 종자 색상에 대한 대립유전자와 함께 세 번째 행에서 다시 반복됩니다.
이제 각 분기된 경로를 따라 8개의 서로 다른 결과 각각에 대해 값을 곱합니다.
예를 들어, 가장 왼쪽에 있는 포크를 따라 3 곱하기 3 곱하기 3은 27입니다. 따라서 이 세대의 64가지 잠재적 유전자형 중에는 둥글고 노란색 씨앗을 가진 27개의 키 큰 식물이 있습니다. 
각 path는 전체 F2 generation에 대한 표현형 비율을 찾기 위해 이후에 곱할 수 있습니다.

<ol>
	<li>스누스타드, D. 피터, 마이클 J. 시몬스. 유전학의 원리. 존 와일리 앤 선즈(John Wiley & Sons), 2015. 페이지 46 - 47.</li>
	<li>"상속의 법칙", 2021년 5월 10일 액세스 <a href="https://www.oercommons.org/courseware/module/14996/student/?task=5">https://www.oercommons.org/courseware/module/14996/student/?task=5</a></li>
</ol>

삼중 잡종 교배

삼중 잡종 교배

멘델의 교배 중 일부는 세 쌍의 대조되는 특성을 조사했습니다. 이러한 교배를 삼교배(trihybrid cross)라고 한다. 삼중 잡종 교배는 세 개의 개별 단일 잡종 교배의 조합입니다. 예를 들어 식물 높이(길다 vs. 짧다), 종자 모양(둥근 vs. 주름진), 종자 색깔(노란색 vs. 녹색) 등이 있습니다.

삼중잡종 교배의 F1 세대 식물은 세 가지 특성 모두에 대해 이형접합체이며 8개의 배우자를 생산합니다. 자가 수정 시 이러한 배우자는 F2 세대에서 64가지 서로 다른 유전자형 조합을 생성할 수 있는 동일한 기회를 갖습니다. 이와 같은 경우 연구할 대조 특성이 두 쌍 이상인 경우 퍼넷 정사각형은 다루기 힘들고 비실용적입니다. 퍼넷 정사각형 대신 갈래선 방법을 사용하여 유전자형 및 표현형 비율 예측을 단순화할 수 있습니다.

F2 세대의 유전자형당 실제 개체수를 예측하는 것은 불가능하지만, 이 방법을 사용하면 표현형 비율인 27:9:9:9:3:3:3:1을 예측할 수 있습니다. 둥근 노란색 씨앗이 있는 키가 큰 식물과 주름진 녹색 씨앗이 있는 왜성 식물이 교배되면 둥글고 노란색 씨앗이 있는 키가 큰 식물 27개, 노란색 둥근 씨앗이 있는 짧은 식물 9개, 주름진 노란색의 키가 큰 식물 9개를 찾을 수 있습니다. 이는 녹색 둥근 씨앗이 있는 키 큰 식물 9개, 노란색 주름진 씨앗이 있는 짧은 식물 3개, 녹색 둥근 씨앗이 있는 짧은 식물 3개, 주름진 녹색 씨앗이 있는 키가 큰 식물 3개, 주름진 녹색 씨앗이 있는 짧은 식물 1개입니다.

다중 잡종 수정의 규칙

F1 세대와 F2 세대 자손의 생식 세포와 유전자형을 각각 식별하는 규칙이 있습니다. 이러한 규칙은 독립 분류의 법칙을 따르고 우성-열성 패턴을 따르는 모든 다중 잡종 교배에 적용됩니다. F1 세대에 형성된 배우자 수는 2n 공식을 사용하여 식별할 수 있습니다. 여기서 n은 이형접합성 유전자 쌍의 수입니다. 예를 들어, XxYy와 XxYy 이형접합체 사이의 번식은 n이 2입니다. 따라서 F1 이형접합체에 의해 형성된 배우자 수는 22개, 즉 4개가 됩니다.

마찬가지로, XXYy와 XXyY 이형접합체 사이의 번식은 X가 이형접합성이 아니기 때문에 n이 1입니다. 따라서 F1 이형접합체에 의해 형성된 배우자의 수는 21개, 즉 2개가 됩니다. 마찬가지로 F2 세대의 유전자형은 3n 공식을 사용하여 식별할 수 있습니다.

트라이하이브리드 십자가
멘델의 십자가 중 일부는 세 쌍의 대조적인 특성을 조사했습니다. 이러한 십자가를 트라이 하이브리드 십자가라고합니다. A ...

Education

교육

JoVE Core

Molecular Biology

분자생물학

Unit 2

제2단원

Mendelian Genetics

멘델의 유전학

KEY TERMS AND CONCEPTS

주요 용어 및 개념

forked line method for trihybrid crosses

Forked line method for trihybrid crosses helps predict the outcome of three-trait Mendelian crosses. A trihybrid cross studies three pairs of contrasting characteristics. It combines three separate monohybrid crosses. Common examples include plant height, seed shape, and seed color.

In a typical trihybrid cross, the F1 plants are heterozygous for all three traits. They can produce eight different gametes. After self-fertilization, these gametes can lead to 64 genotype combinations in the F2 generation. When more than two contrasting traits are studied, a Punnett square becomes hard to use. The forked line method gives a simpler way to predict genotype and phenotype ratios.

This method does not predict the exact number of offspring in the F2 generation. It can predict the phenotypic ratio instead. For a cross between tall plants with round, yellow seeds and dwarf plants with wrinkled, green seeds, the expected ratio is 27:9:9:9:3:3:3:1. That means 27 tall plants with round, yellow seeds, 9 short plants with yellow, round seeds, 9 tall plants with yellow, wrinkled seeds, 9 tall plants with green, round seeds, 3 short plants with yellow, wrinkled seeds, 3 short plants with green, round seeds, 3 tall plants with green, wrinkled seeds, and 1 short plant with green, wrinkled seeds.

Rules for multi hybrid fertilization also help identify gametes and F2 genotypes. These rules apply to crosses that follow independent assortment and a dominant-recessive pattern. The number of gametes in the F1 generation can be found with the 2n formula, where n is the number of heterozygous gene pairs. For example, XxYy × XxYy gives four gametes because n equals 2. If one gene is not heterozygous, as in XXYy × XXyY, n equals 1 and the F1 plants form two gametes. The genotype of the F2 generation can then be found with the 3n formula.

Forked Line Method for Trihybrid Crosses

punnett squares

Predicting Traits with Punnett Squares

Punnett squares help students predict how traits may be passed from parents to offspring. They are a simple grid used in genetics to organize possible allele combinations. An allele is a version of a gene. The square compares the alleles each parent can give. By filling in the boxes, students can see possible genotypes, which are the genetic makeup of offspring. The results can also help connect those genotypes to traits that may appear in the next generation.

monohybrid crosses

Tracking One Trait in Monohybrid Crosses

Monohybrid crosses track how one trait is passed from parents to offspring. They are used to study inheritance when only a single characteristic is followed at a time. A monohybrid cross can compare the possible outcomes for a monogenic trait, which is a trait controlled by one gene. This approach helps show how one gene can shape different inherited forms of the same characteristic. The method also connects with Mendel's work on genetics. It is a useful way to predict patterns of inheritance...

dihybrid crosses

Predicting Two-Trait Genetic Crosses

Dihybrid crosses are used to predict how two traits can be passed from parents to offspring. A dihybrid cross tracks two genes at the same time, so it helps students see how different alleles can combine in a genetic pattern. This topic is closely tied to Mendelian genetics and independent assortment. Independent assortment means that allele pairs for different traits can separate into gametes independently of one another. When students work through a dihybrid cross, they can compare the...

trihybrid crosses

Forked line method for trihybrid crosses helps predict the outcome of three-trait Mendelian crosses. A trihybrid cross studies three pairs of contrasting characteristics. It combines three separate monohybrid crosses. Common examples include plant height, seed shape, and seed color. In a typical trihybrid cross, the F1 plants are heterozygous for all three traits. They can produce eight different gametes. After self-fertilization, these gametes can lead to 64 genotype combinations in the F2...

law of independent assortment

Independent Chromosome Assortment in Meiosis

Independent chromosome assortment in meiosis explains how different gene pairs can be inherited independently. This idea is one of Mendel’s laws of inheritance and is often called the law of independent assortment. The pattern depends on how homologous chromosomes line up during meiosis I. Each chromosome pair orients independently of the others, so the maternal and paternal chromosomes can separate into different gametes in many combinations. This random separation helps create genetic...

chi-square analysis

Chi-Square Test in Genetics

The chi-square test in genetics helps compare expected and observed results. It is a statistical hypothesis test used to see whether a difference between an expected value and an observed value is significant. In genetics, it helps decide whether to accept or reject a hypothesis based on how far the observed data moves from the expected data. The test was developed by Pearson in 1990. The first step is to set up a null hypothesis. This hypothesis says there is no real difference between the...

pedigree analysis

Tracing Traits with Pedigree Charts

Pedigree analysis uses family trees, called pedigrees, to trace how traits and diseases pass from one generation to the next. A pedigree chart helps scientists and students see inheritance patterns clearly across relatives. The chart uses standard symbols to show family members and their relationships. It can reveal whether a trait is likely passed through dominant or recessive inheritance, and it can also help identify patterns linked to sex chromosomes. By studying a pedigree, it is...

multiple allele traits

Multiple Alleles in Trait Inheritance

Multiple alleles can shape how a trait is inherited in a population. A gene may have more than two allele forms, even though each person still carries only two alleles for that gene. These allele combinations can produce traits with more than two possible outcomes. The ABO blood group system is a common example of a multiple allele trait. It shows how different alleles can interact to determine an organism’s phenotype, or observable trait. Multiple allele traits help explain why inheritance...

incomplete dominance

Incomplete Dominance in Traits and Disease

Incomplete dominance is a pattern of inheritance where two alleles both affect a trait in a heterozygous organism. In this case, one allele is not fully dominant over the other. The result is a phenotype that looks like a blend or intermediate form. Gregor Mendel’s pea plant experiments helped explain the usual dominant and recessive pattern. He showed that each gene in a diploid cell has two alleles, one inherited from each parent. In his model, a dominant allele shows its effect with one or...

lethal alleles

When Genes Cause Embryonic Death

Lethal alleles can change inheritance patterns by causing death before birth. In mice, Lucien Cuénot studied the agouti gene, which helps control coat color through an agouti-signaling protein that affects melanin distribution in mammals. The wild-type allele produces a gray-brown coat, while the mutant allele produces a yellow coat. Cuénot also found that the yellow allele was linked to yellow mouse obesity syndrome. This syndrome is associated with early-onset obesity and tumors. When he...

polygenic traits

Traits Shaped by Many Genes

Polygenic traits are characteristics shaped by many genes acting together. This pattern is different from a single-gene trait, where one gene has a larger effect on the outcome. In polygenic inheritance, each gene adds a small contribution to the final trait. Height is a common example of a polygenic trait. Many genes influence human height, so the result can vary across a wide range. These small genetic effects combine to produce differences that are easy to see in a population. Polygenic...

background and environment affect phenotype

background-and-environment-affect-phenotype

How Genes and Environment Shape Traits

Genes and the environment work together to shape phenotype, or the visible traits of an organism. A phenotype can change because of genetic background, environmental conditions, or both. Factors such as temperature, oxygen availability, and mutagens can all influence how a trait appears. Horses show how one gene can affect coat color and how a modifier gene can change that result. The Extension gene controls pigment production in the coat. The wild-type genotype EE produces black pigment,...

x and y chromosomes

Sex Chromosomes in Human Inheritance

Sex chromosomes help determine biological sex in mammals, including humans. Humans have two sex chromosomes, X and Y. Each diploid cell has 22 pairs of autosomes and one pair of sex chromosomes. A female usually has two X chromosomes, while a male usually has one X chromosome and one Y chromosome. Egg and sperm cells carry only half the usual number of chromosomes. They contain 22 autosomes and one sex chromosome. Every egg has an X chromosome. Sperm cells can carry either an X or a Y...

the y chromosome determines maleness

Y Chromosome Structure and Male Traits

The Y chromosome is a sex chromosome that helps guide male development in humans and other vertebrates and mammals. Human males usually have one X chromosome and one Y chromosome, along with 22 pairs of autosomes. In these organisms, the presence or absence of the Y chromosome influences whether male traits develop. The Y chromosome evolved from an autosome about 300 million years ago, when two sex chromosomes began to diverge. Since then, it has lost most of its genes and become much smaller.

the ratio of x chromosome to autosomes

Drosophila Sex Determination by X:A Balance

In Drosophila, sex is determined by the balance between X chromosomes and autosomes, not by the X and Y chromosomes alone. The Y chromosome is active in these flies, but it does not set sex. Instead, it carries genes needed for sperm production in adult males. A normal male Drosophila has one X chromosome and two sets of autosomes. A normal female has two X chromosomes and two sets of autosomes. When this X:A ratio changes, flies can develop different sexual phenotypes, including metamales,...

x-linked traits

X-Linked Inheritance in Families

X-linked inheritance in families explains how traits linked to the X chromosome pass from parents to children. These traits are often tracked through family trees because the pattern can differ between males and females. A male has one X chromosome and one Y chromosome. A female has two X chromosomes. Because of this difference, a trait on the X chromosome can show up in a different way depending on the sex of the child. Family examples often include traits such as color blindness. Studying...

sex linked disorders

Sex-Linked Disorders and Inheritance Patterns

Sex-linked disorders are genetic conditions that follow inheritance patterns tied to the sex chromosomes. These disorders help explain how certain traits can appear more often in one sex than the other. The transcript focuses on examples of sex-linked disorders, including Y-linked infertility, Fragile X syndrome, and Duchenne muscular dystrophy. Y-linked infertility is passed through the Y chromosome, while Fragile X syndrome and Duchenne muscular dystrophy are associated with sex-linked...

dosage compensation

X-Chromosome Balance in Animals

X-chromosome balance in animals helps equalize gene expression between males and females. Sex can be determined by the number and type of sex chromosomes. In humans, females have two X chromosomes and males have one X and one Y chromosome. In C. elegans, one X chromosome is male, while two X chromosomes make a hermaphrodite. The X chromosome carries more than sex-related genes. It also includes genes involved in body functions such as brain development and the immune system. Because males and...

x-inactivation

X-Inactivation and Barr Bodies

X-inactivation is a process that reduces gene activity on one X chromosome. It helps balance gene expression in cells that have more than one X chromosome. A key result of this process is the formation of a Barr body, which is the inactive X chromosome seen in the nucleus. This topic also includes Xist, a gene linked to X-inactivation. Xist produces RNA that coats the X chromosome and helps turn it off. Together, Xist and the Barr body show how cells control X-linked genes during development...

blood types

Blood Types and Transfusion Matching

Human blood types help determine safe blood transfusion matching. Blood is classified by antigens on the surface of red blood cells and antibodies in the plasma. Correct blood typing matters because an unsafe match can affect transfusion success. The International Society of Blood Transfusion has identified 38 human blood types, and ABO, Rh, and MNS are among the most common. The ABO blood group depends on antigens made by genes on chromosome 9. Red blood cells carry a base glycoprotein called...

blood transfusion and agglutination

Matching Blood Types for Safe Transfusion

Blood transfusion is a medical treatment used to restore blood volume after major blood loss from an accident or a medical procedure. It works by taking blood from a suitable donor and giving it to a recipient. Safe transfusion depends on matching blood types and checking for immune compatibility. The history of blood transfusion began in the 17th century, when early experiments were done in animals. In 1818, James Blundell, a British doctor, performed the first successful human blood...

key terms and concepts

Learn how the forked line method simplifies trihybrid crosses, predicts the 27:9:9:9:3:3:3:1 ratio, and uses 2n and 3n rules for gametes and genotypes.

Forked Line Method for Trihybrid Crosses | JoVE K12

molecular biology

JoVE Core 분자생물학은 명확하고 간결한 애니메이션을 통해 분자 단계에서 일어나는 세포 과정을 설명합니다.또한, 과학자가 직접 실험을 진행하는 실사 영상을 통해 분자생물학 개념의 응용 사례를 보여줍니다.

Louisiana Student Standards for Science

High School

Life Sciences

Heredity: Inheritance And Variation Of Traits

HS-LS3-1

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Heredity

Structure and function of DNA in cells

Genetic mechanisms and inheritance

Alabama Course of Study Science

Heredity: Inheritance and Variation of Traits

9-12.B.3.11.a

Next Generation Science Standards

Life Science

Florida Department of Education

SC.912.L.16

SC.912.L.16.2

Texas Essential Knowledge and Skills

BIO.8

BIO.8.B

new-york-state-science-learning-standards

New York State Science Learning Standards

Inheritance and Variation of Traits

HS-LS3-1.

What is Meiosis?

Meiosis is the process by which diploid cells divide to produce haploid daughter cells. In humans, each diploid cell contains 46 chromosomes, half from ...

Meiosis I

Meiosis II

Meiosis vs. Mitosis

Crossing Over

Crossing over is the exchange of genetic information between homologous chromosomes during prophase I of meiosis I. Genetic recombination gives rise to ...

Nondisjunction

Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate correctly and move to the opposite poles of the cells. This ...

Spermatogenesis

Spermatogenesis is the process by which haploid sperm cells are produced in the male testes. It starts with stem cells located close to the outer rim of ...

Oogenesis

In human women, oogenesis produces one mature egg cell or ovum for every precursor cell that enters meiosis. This process differs in two unique ways from ...

Fertilization

During fertilization, an egg and sperm cell fuse to create a new diploid structure. In humans, the process occurs once the egg has been released from the ...

Cleavage and Blastulation

After a large-single-celled zygote is produced via fertilization, the process of cleavage occurs while zygotes travel through the uterine tube. Cleavage ...

Gastrulation

Gastrulation establishes the three primary tissues of an embryo: the ectoderm, mesoderm, and endoderm. This developmental process relies on a series of ...

Neurulation

Neurulation is the embryological process which forms the precursors of the central nervous system and occurs after gastrulation has established the three ...

Cell Migration

Cell migration, the process by which cells move from one location to another, is essential for the proper development and viability of organisms ...

Determination

During embryogenesis, cells become progressively committed to different fates through a two-step process: specification followed by determination. ...

Use models to explain how DNA is passed from parents to offspring through the processes of meiosis and fertilization in sexual reproduction.

LS.Bio.6.1

Mutations

Mutations are changes in the sequence of DNA. These changes can occur spontaneously or they can be induced by exposure to environmental factors. Mutations ...

genome-size-and-the-evolution-of-new-genes

Genome Size and the Evolution of New Genes

types-of-genetic-transfer-between-organisms

Types of Genetic Transfer Between Organisms

Base-pairing and DNA Repair

The DNA Replication Fork

Lagging Strand Synthesis

The Replisome

Proofreading

Synthesis of new DNA molecules is carried out by the enzyme DNA polymerase, which adds nucleotides on the daughter strand complementary to the template ...

Replication in Prokaryotes

DNA replication has three main steps: initiation, elongation, and termination. Replication in prokaryotes begins when initiator proteins bind to the ...

Replication in Eukaryotes

In eukaryotic cells, DNA replication is highly conserved and tightly regulated. Multiple linear chromosomes must be duplicated with high fidelity before ...

Overview of DNA Repair

Base Excision Repair

Nucleotide Excision Repair

DNA Distortion and Damage
Cells are regularly exposed to mutagens&#8212;factors in the environment that can damage DNA and generate mutations. UV ...

Mismatch Repair

Organisms are capable of detecting and fixing nucleotide mismatches that occur during DNA replication. This sophisticated process requires identifying the ...

Fixing Double-strand Breaks

Homologous Recombination

Gene Conversion

Restarting Stalled Replication Forks

Construct an explanation to summarize how inheritable genetic variations may result from: new genetic combinations in meiosis, mutations during replication, or mutations caused by environmental factors.

LS.Bio.6.2

An Overview of Genetic Analysis

An organism&#8217;s physical traits, or phenotype, are a product of its genotype, which is the combination of alleles (gene variants) inherited from its ...

Genetic Crosses

To dissect genetic processes or create organisms with novel suites of traits, scientists can perform genetic crosses, or the purposeful mating of two ...

Punnett Squares

Monohybrid Crosses

Dihybrid Crosses

Trihybrid Crosses
Some of Mendel&#8217;s crosses examined three pairs of contrasting characteristics. Such a cross is called a trihybrid cross. A ...

Law of Independent Assortment

Chi-square Analysis

The chi-square test is a statistical hypothesis test. It is used to check whether there is a significant difference between an expected value and an ...

Pedigree Analysis

Multiple Allele Traits

Incomplete Dominance

Gregor Mendel&#39;s work (1822 - 1884) was primarily focused on pea plants. Through his initial experiments, he determined that every gene in a diploid ...

Lethal Alleles

Agouti: A Lethal Allele
Lucien Cu&#233;not discovered lethal alleles in 1905 while studying the inheritance of coat color in mice. The agouti gene is ...

Polygenic Traits

Background and Environment Affect Phenotype

Although the genetic makeup of an organism plays a major role in determining the phenotype, there are also several environmental factors, such as ...

Use mathematics and computational thinking to predict the variation and distribution of expressed traits based on: Mendelian inheritance, co-dominance, incomplete dominance, multiple alleles, and sex-linked inheritance.

Overview

A pedigree is a diagram displaying a family&#x2019;s history of a trait. Analyzing pedigrees can reveal (1) whether a trait is dominant or ...

Probability Laws

Overview

The probability of inheriting a trait can be calculated using the sum and product rules. The sum rule is used to calculate the probability of ...

The Concept of Multiple Allelism

Multiple allelism describes genes that exist in three or more allelic forms. Although diploid organisms, like humans, ...

Analyze and interpret data to explain how polygenic traits result in a wide range of phenotypes.

LS.Bio.7.2

Understand genetic mechanisms for variation.

Forked Line Method for Trihybrid Crosses

Description

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