Section outline

  • What you will learn
    ::你会学到什么

    • Traits in humans that have Mendelian patterns of inheritance
      ::人类的悲剧 拥有孟德利的继承模式
    • Single- gene autosomal traits and their inheritance
      ::单基因自动溶性特征及其继承财产
    • What are charts and how they are used in studying inheritance patterns
      ::哪些是图表,它们是如何用于研究继承模式的?
    • Sex-linked traits and their inheritance in humans
      ::与性别相关的特征及其在人类中的继承权

    Circle composed of colored dots showing the number 12, illustrating color vision differences.

    What number can you see?
    ::你看到多少号码了?

    Red-green color blindness is a common inherited trait in humans. About 1 in 10 men have some form of color blindness, however, very few women are color blind. Why?
    ::红色绿色失明是人类常见的遗传特征。 大约十分之一的男性有某种颜色失明,然而,很少有女性是肤色失明。 为什么?

    Mendelian Inheritance in Humans
    ::人类的门德利人继承遗产

    Characteristics that are encoded in are called genetic traits . Different types of human traits are inherited in different ways. Some human traits have simple inheritance patterns like the traits that Gregor studied in . Other human traits have more complex inheritance patterns.
    ::各种人类特征以不同的方式传承。有些人类特征有简单的继承模式,如Gregor研究过的特征。其他人类特征有更复杂的继承模式。

    Mendelian inheritance refers to the inheritance of traits controlled by a single gene with two , one of which may be dominant to the other. Not many human traits are controlled by a single gene with two alleles, but they are a good starting point for understanding human heredity . How Mendelian traits are inherited depends on whether the traits are controlled by genes on autosomes or the X chromosome .
    ::门德利继承指的是由两种基因的单一基因所控制的特性的继承,其中一种可能是对另一种基因的主宰。 并不是许多人类特性都由两种等同的单一基因所控制,但它们是了解人类遗传性的良好起点。 门德利继承的方式取决于这些特性是受机体基因还是X染色体基因所控制。

    Autosomal Traits
    ::自动共解托盘

    Autosomal traits are controlled by genes on one of the 22 human autosomes. Consider earlobe attachment. A single autosomal gene with two alleles determines whether you have attached earlobes or free-hanging earlobes. The allele for free-hanging earlobes ( F ) is dominant to the allele for attached earlobes ( f ). 
    ::22个人类自体基因之一的基因控制着自动细胞特性。 考虑耳垂附物。 单个带有两个异形的自动细胞基因决定着您是否附有耳垂或自由挂耳垂。 自由挂耳垂( F) 的异型基因在耳垂( f) 的异型基因中占主导地位。

    The chart in the  Figure is called a pedigree . It shows how the earlobe trait was passed from generation to generation within a family. Pedigrees are useful tools for studying inheritance patterns.
    ::图表中的图表称为小儿科,显示了耳垂特征是如何在家庭中代代相传的。“小儿科”是研究继承模式的有用工具。

    Pedigree chart showing inheritance of earlobe traits across three generations, with genotype representation.
    Having free-hanging earlobes is an autosomal dominant trait. This figure shows the trait and how it was inherited in a family over three generations. Shading indicates people who have the recessive form of the trait. Look at (or feel) your own earlobes. Which form of the trait do you have? Can you tell which genotype you have?

     

     

    Other single-gene autosomal traits include widow's peak and hitchhiker's thumb. The dominant and recessive forms of these traits are shown in the  Figure . Which form of these traits do you have? What are your possible genotypes for the traits?
    ::其他单基因自体细胞特征包括寡妇的峰值和搭便车者的拇指。图中显示了这些特征的主要和消亡形式。这些特征的哪种形式?这些特征的基因类型是什么?

    Examples of widow's peak and hitchhiker's thumb traits shown in four illustrations.
    Widow's peak and hitchhiker's thumb are dominant traits controlled by a single autosomal gene. (a) widow's peak, (b) no widow's peak, (c) hitchhiker's thumb, (d) no hitchhiker's thumb.

    Sex-Linked Traits
    ::与性有关的悲剧

    Traits controlled by genes on the sex chromosomes are called sex-linked traits , or X-linked traits in the case of the X chromosome. Single-gene X-linked traits have a different pattern of inheritance than single-gene autosomal traits. Do you know why? It’s because males have just one X chromosome. In addition, they always inherit their X chromosome from their female parent, and they pass it on to all their female offspring but none of their male offspring. 
    ::由性染色体基因控制的染色体被性染色体的基因所控制,在X染色体中被称为性相关特性,或X染色体的X相关特性。 单基因X相联特性的继承模式不同于单基因自发性色素。知道为什么吗?这是因为男性只有一个X染色体。此外,他们总是从母母异体继承X染色体,并且将X染色体传给了所有女性后代,但没有任何男性后代。

    Because males have just one X chromosome, they have only one allele for any X-linked trait . Therefore, a recessive X-linked allele is always expressed in males. Because females have two X , they have two alleles for any X-linked trait. Therefore, they must inherit two copies of the recessive allele to express the recessive trait. This explains why X-linked recessive traits are less common in females than males. An example of a recessive X-linked trait is red-green color blindness . People with this trait cannot distinguish between the colors red and green. More than one recessive gene on the X chromosome codes for this trait, which is fairly common in males but relatively rare in females ( Figure ).
    ::因为雄性只有一个X染色体,所以它们只有一个与任何X相关特性的异差。 因此,一个休眠的X相联的异差总是用雄性表示。 由于雌性有两个X,它们有两个与X相关特性的异差。 因此,它们必须继承两个休眠异差的复制件来表达休眠特征。 这就解释了为什么与X相联的消亡性特征在雌性中比雄性少见。 一个与X相联的异差的例子就是红绿色失明。 具有这种特征的人无法区分红色和绿色的颜色。 在X染色体的编码中,这种特征的隐性基因不止一个,在雄性中相当常见,但在雌性中相对少见(图示 ) 。

    Punnett square showing inheritance patterns of color blindness and vision traits.
    Inheritance of Sex Chromosomes. Female parents pass only X chromosomes to their offspring. Male parents always pass their X chromosome to their female offspring and their Y chromosome to their male offspring. Color blindness is an X-linked recessive trait. Female parents pass the recessive allele for the trait to their male offspring, who pass it to their female offspring.

    Shown below is a pedigree chart of the inheritance of color blindness in a family. Can you predict the missing phenotype in the chart with the help of the given ?
    ::下面显示的是家庭彩色失明遗产的血统图。 您可以在给定的帮助下预测图表中缺少的pheno类型 ?

     

     

     

    Summary
    ::摘要

    • A minority of human traits are controlled by single genes with two alleles.
      ::少数人类特性受单基因和两种异基因的控制。
    • They have different inheritance patterns depending on whether they are controlled by autosomal or X-linked genes.
      ::他们有不同的继承模式,取决于他们是否受自制或X型相关基因控制。

    Review
    ::回顾

    1. Describe the inheritance pattern for a single-gene autosomal dominant trait, such as free-hanging earlobes.
      ::描述单基因自动溶液主要特征的继承模式,例如自由挂耳垂。
    2. Draw a pedigree for hitchhiker’s thumb. Your pedigree should cover at least two generations and include both dominant and recessive forms of the trait. Label the pedigree with genotypes, using the letter H to represent the dominant allele for the trait and the letter h to represent the recessive allele.
      ::给搭便车者的拇指画一个小指。 您的小指至少应该覆盖两代人, 并且包括该特性的主导形式和隐性形式。 带有基因型的小指标签, 使用字母 H 代表该特性的主导异端, 字母 h 代表休息异端 。
    3. Why is a recessive X-linked allele always expressed in males?
      ::为什么一个休眠的X-连线的异性通灵总是用男性表示?
    4. What is necessary for a recessive X-linked allele to be expressed in females?
      ::以女性表示的休眠X-连通的异性格有何必要?
    5. What is an example of a recessive X-linked trait?
      ::休眠X-连接特性的一个例子是什么?