Section outline

  • Depicts a cell with a chromosome and a DNA double helix, illustrating molecular genetics.

    Did know about ?
    ::知道吗?

    No, people did not understand that DNA is our hereditary material until long after Mendel's time. Our modern understanding of DNA and helped to explain how Mendel's rules worked.
    ::不,人们直到曼德尔时代很久之后才明白DNA是我们的遗传物质。 我们对DNA的现代理解有助于解释曼德尔规则是如何运作的。

    Modern Genetics
    ::现代遗传学

    Mendel laid the foundation for modern genetics , but there were still a lot of questions he left unanswered. What exactly are the dominant and recessive factors that determine how all organisms look? And how do these factors work?
    ::门德尔为现代遗传学打下了基础,但仍然存在许多他没有回答的问题。 确定所有生物的外观的主导性和休眠性因素究竟是什么? 这些因素是如何起作用的?

    Since Mendel’s time, scientists have discovered the answers to these questions. Genetic material is made out of DNA . It is the DNA that makes up the hereditary factors that Mendel identified. By applying our modern knowledge of DNA and chromosomes, we can explain Mendel’s findings and build on them. In this concept, we will explore the connections between Mendel’s work and modern genetics.
    ::自从曼德尔时代以来,科学家们已经发现了这些问题的答案。 遗传材料是由DNA制成的。 DNA是Mendel所认定的遗传因素的构成因素。 通过运用我们现代DNA和染色体知识,我们可以解释Mendel的发现并在此基础上发展。 在这个概念中,我们将探索门德尔的工作和现代遗传学之间的联系。

    Traits, Genes, and Alleles
    ::, 基因, 阿莱勒斯

    Recall that our DNA is wound into chromosomes . Each of our chromosomes contains a long chain of DNA that encodes hundreds, if not thousands, of genes . Each of these genes can have slightly different versions from individual to individual. These variants of genes are called . Each parent only donates one allele for each gene to an offspring .
    ::回顾我们的DNA是染色体中的伤口。我们的染色体中,每个染色体都含有长长的DNA链,它编码了成百上千个基因,如果不是千个基因的话。这些基因的每种基因的个性可能略有不同。这些基因的变异被称为 。 父母的每一个只向后代捐赠每个基因的异种。

    For example, remember that for the height gene in there are two possible factors. These factors are alleles. There is a dominant allele for tallness (T) and a recessive allele for shortness (t) .
    ::例如,请记住,对于身高基因来说,有两个可能的因素。 这些因素是异长。 高高( T)和短短( t)之间有主要的异长( T)和短短( t)之间有间歇的异差( t ) 。

    Genotype and Phenotype
    ::基因型和基因型

    Genotype is a way to describe the combination of alleles that an individual has for a certain gene ( Table  ). For each gene, an organism has two alleles, one on each chromosome of a homologous pair of chromosomes (think of it as one allele from Mom, one allele from Dad). The genotype is represented by letter combinations, such as TT , Tt , and tt .
    ::Genotype是一种描述个人对某一基因(表 ) 所持有的异系物组合的方法。 对于每个基因,生物体有两个异系物,一个在一对同质染色体的染色体的染色体上(视之为来自母亲的异系物,另一个来自爸爸的异系物 ) 。 基因型由字母组合(如TT、Tt和t)来代表,例如字母组合(TT、Tt和tt)。

    When an organism has two of the same alleles for a specific gene, it is homozygous ( homo means "same") for that gene. An organism can be either homozygous dominant (TT) or homozygous recessive (tt). If an organism has two different alleles (Tt) for a certain gene, it is known as heterozygous ( hetero means different).
    ::当一个有机体对特定基因有两个相同的异变物时,它就是该基因的同质(homo ) , 意思是“相同 ” (same ) 。 一种有机体可以是同质(TT ) , 也可以是同质(tt ) 。 如果一个有机体对特定基因有两个不同的异变物(Tt ) , 它被称为异体(hetero ) 。

    Genotype Definition Example
    Homozygous Two of the same allele TT or tt
    Heterozygous One dominant allele and one recessive allele Tt
    Homozygous dominant Two dominant alleles TT
    Homozygous recessive Two recessive alleles tt

    Phenotype is a way to describe the traits you can see. The genotype is like a recipe for a cake, while the phenotype is like the cake made from the recipe. The genotype expresses the phenotype. For example, the phenotypes of Mendel’s pea plants were either tall or short, or they were purple-flowered or white-flowered.
    ::基因类型是描述你所看到的特征的一种方式。 基因类型就像蛋糕的配方,而人型则像食谱做的蛋糕。 基因类型代表了基因类型。 比如,门德尔的豆子植物的配方要么高要么短,要么紫花,要么白花。

    Can organisms with different genotypes have the same phenotypes? Let’s see.
    ::具有不同基因型的生物能否具有相同的苯型?

    What is the phenotype of a pea plant that is homozygous dominant (TT) for the tall trait? Tall. What is the phenotype of a pea plant that is heterozygous (Tt)? It is also tall. The answer is yes, two different genotypes can result in the same phenotype. Remember, the recessive phenotype will be expressed only when the dominant allele is absent, or when an individual is homozygous recessive (tt) ( Figure  ).
    ::豆类植物的阳性类型是什么? 高。 豆类植物的阳性类型是什么? 高。 属于异性曲性( Tt) 的豆类植物的阴性类型是什么? 也是高的。 答案是是是, 两种不同的基因型可以产生相同的阴性类型。 记住, 只有当主要异性( TT) 不存在时, 或当个体是同性( t) ( Figure ) 时, 才会表示阴性苯性类型 。

    Comparison of tall and dwarf pea plants alongside genetic representations of traits.
    Different genotypes (AA, Aa, aa or TT, Tt, tt) will lead to different phenotypes, or different appearances of the organism.

    Summary
    ::摘要

    • Mendel's hereditary "factors" are variants of genes called alleles.
      ::孟德尔的遗传“因素”是基因的变种,叫做异形基因。
    • Genotype describes the combination of alleles that an individual has for a certain gene, while phenotype describes the traits that you can see.
      ::Genotype 描述一个人对某一基因拥有的异灵的组合,而 peno type 则描述您可以看到的特性。

    Explore More
    ::探索更多

    Use the resources below to answer the questions that follow.
    ::利用以下资源回答以下问题。

    Explore More I
    ::探索更多

    • Link Between Genotype and Phenotype at
      ::Genotym 和 Pheno 类型之间的联系
    1. When geneticists look at genotype, what are they really studying?
      ::当遗传学家看基因类型, 他们到底在学习什么?
    2. Why do geneticists like to turn genes off? What question(s) do they ask?
      ::基因学家为什么喜欢关闭基因?他们问什么问题?

    Explore More II
    ::探索更多情况二

    • iPlant Genotype to Phenotype at (3:49)
      ::iPlant Genotype 到(3: 49) 的基因型
    1. Do most of the complex phenotypes we observe come from a single gene?
      ::我们所观察到的 大部分复杂的苯型 都来自单一基因吗?
    2. What has led to the rapid analysis of DNA? Where do scientists now hope to apply these tools?
      ::是什么导致对DNA的快速分析?科学家现在希望在哪里应用这些工具?
    3. What are some of the phenotypic plant traits that scientists are investigating? Why do you think these traits were chosen?
      ::科学家们正在调查的几种植物特征是什么?你为什么认为这些特征是被选中的?

    Review
    ::回顾

    1. What is an allele?
      ::什么是埃莱尔?
    2. What type of allele can only affect the phenotype in the homozygous condition?
      ::哪种阿雷尔只能够影响同质古斯条件下的苯型?
    3. If two individuals have a certain phenotype, does that mean they must have the same genotype?
      ::如果两个人有某种苯型, 是否意味着他们一定有相同的基因型?
    4. A tall, green plant is homozygous for each trait. If T is the tall allele, and G is the green allele, what is the genotype and the phenotype of this plant?
      ::一个高高的绿色植物是每种特性的同质。 如果T是高的异质,G是绿色异质,那么这个植物的基因型和苯型是什么?