Section outline

  • General

    Collapse all Expand all

  • 分子十字十字 - 高级

    lesson content

    What if this apple also came in two sizes: small or large?
    ::如果这个苹果也以两个大小出现:小的还是大的?

    What would you get if you crossed a small red apple and a large green apple? Possible a medium sized brown apple. Or you may still get mostly small red or large green apples, but possible some small green and large red apples. A dihybrid cross involves two traits, such as color and size.
    ::如果你跨过一个小红苹果和一个大绿苹果,你会得到什么? 可能是一个中等规模的棕苹果。 或者你仍然可能得到很多小红苹果或大绿苹果,但可能得到一些小绿苹果和大红苹果。 一个双环十字涉及两种特征,如颜色和大小。

    Dihybrid Crosses and Punnett Squares
    ::极分十字和普内特广场

    Punnett Squares and Dihybrid Crosses
    ::普内特广场和阴阳十字

    The also allows the determination of genotypes and phenotypes from dihybrid crosses . However, this process works only if the genes are independent of each other, that is, they are not linked, and they segregate independently of each other during . In other words, the inheritance of an of one gene does not effect the inheritance of an allele from another gene. This is usually true for alleles of genes on different , or genes that are not close together on the same chromosome. Genes that are close together on the same chromosome may not segregate independently of each other during meiosis, and are known as linked genes .
    ::也允许从二合金十字架上确定基因类型和苯型。 但是,这个过程只有在基因相互独立的情况下才能起作用,也就是说,基因没有相互连接,而且它们相互分离。 换句话说,一个基因的继承并不影响同一种基因的继承。 对于不同基因或不同染色体上不紧密相连的基因的所有基因来说,这通常都是如此。 在同一染色体上紧密相连的基因在美化期间可能不会彼此独立分离,而是被称为联系基因。

    Dihybrid crosses are more complicated than monohybrid crosses because more combinations of alleles are possible. For example, tracking the inheritance of pod color and pod form in a Punnett square requires that we track four alleles. R is the dominant allele for green pod color and r is the recessive allele for yellow pods. Y is the dominant allele for flat pod form and y is the recessive allele for constricted pod form.
    ::二环形十字比单环形十字更为复杂,因为可以使用更多的异类组合。例如,跟踪Punnett方形的缓冲色和缓冲形式遗产要求我们跟踪四个异类。 R是绿缓冲色的主要异类,r是黄色缓冲形的休眠异类。Y是扁缓冲形式的主要异类,y是紧凑型的缓冲形的休眠异类。

    If two are crossed, and one is true-breeding for green flat pods ( RRYY ), the other is true-breeding for yellow constricted pods ( rryy ), then all of the F 1 generation will be heterozygous for both traits ( RrYy ). Figure , shows the dihybrid cross of the dihybrid P generation and the F 1 generation. Those F 1 individuals will have gametes with four possible combinations of alleles: RY, Ry, rY and ry. If these individuals are allowed to self-pollinate , then 16 combinations of alleles are possible upon combination of gametes.
    ::如果横跨两个区域,一个是绿色扁豆(RRYY)的真种,另一个是黄色收缩舱(orry)的真种,那么所有F1代人将都是两种特性(RrYy)的异体曲菌。图中显示了二类P代和F1代的杂交交叉点。这些F1人将拥有四种可能组合的调子:RY、Ry、RY和ry。如果允许这些个人自我聚变,那么在组合调子时,16种异体组合是可能的。

    According to Mendel's Second Law , the Law of Independent Assortment , the inheritance of one trait will not affect the inheritance of another, meaning that alleles of each gene separate independently during gamete formation. If the genes are linked, then alleles will sort as a pair and not individually. Proper determination of genotypic and phenotypic ratios will not be possible without additional genetic analysis. This is the basis of linkage maps and determining how close genes are to each other, and will be discussed in additional concepts.
    ::根据Mendel的《第二法》,即《独立组别法》,一个特性的继承不会影响另一个特性的继承,也就是说,在基因形成期间,每种基因的异象在基因形成过程中独立分离。如果这些基因是相连的,那么所有异象将分为一对,而不是个别的。如果不进行进一步的基因分析,就不可能正确确定基因和胎儿比率。这是联系图和确定基因之间如何密切的基础,并将在更多的概念中加以讨论。

    Heterozygous Dihybrid Cross
    ::切特罗兹古斯

    The phenotypes of the offspring from a heterozygous dihybrid cross with two independent traits, such as the RrYy x RrYy example, show a 9:3:3:1 ratio. In a cross involving pea plants heterozygous for green flat pods ( GgFf ), 9/16 plants have green flat pods, 3/16 have green constricted pods, 3/16 have yellow flat pods, and 1/16 have yellow constricted pods. Notice that two of these combinations are the original parental phenotypes (green flat pods, and yellow constricted pods) and two are new phenotypic combinations (green constricted pods, and yellow flat pods). What would be the suggestion if the 9:3:3:1 ratio was not obtained?
    ::具有两种独立特性(如RrYy x RrYy 示例)的异体二交体后代的苯型显示9:3:3:1比率。 在涉及绿扁豆(GgFf)的豆植物异体二交体的交叉体中, 9/16 植物有绿扁豆, 3/16 绿扁豆, 3/16 绿扁豆, 3/16 黄扁豆, 3/16 黄扁豆, 和 1/16 黄扁豆。 注意其中两种组合是原始的亲生酚型( 绿色扁豆和黄扁豆 ) , 两种是新的青扁豆组合( 绿扁豆和黄色扁豆 ) 。 如果没有实现 9: 3: 3: 1 比例, 那么建议是什么?

    lesson content
    Punnett Square for Two Characteristics. This Punnett square represents a cross between two pea plants that are heterozygous for two characteristics. G represents the dominant allele for green pod color, and g represents the recessive allele for yellow pod color. F represents the dominant allele for full pod form, and f represents the recessive allele for constricted pod form.

    Summary
    ::摘要

    • A dihybrid cross-examines the inheritance of two traits at the same time.
      ::一种分泌交叉质问 两种特征的继承 在同一时间。
    • Dihybrid crosses are more complicated than monohybrid crosses.
      ::两栖交叉比单栖交叉复杂得多。
    • With unlinked genes, a 9:3:3:1 phenotypic ratio will result in the offspring of a cross of two completely heterozygous individuals.
      ::与无关联基因,9:3:3:1的性别比例将导致两个完全异体阳性人十字的后代。

    Review
    ::回顾

    1. What is a dihybrid cross?
      ::半合金十字架是什么?
    2. What are linked genes? Why do genes need to be unlinked for a dihybrid cross to predict proper outcomes of crosses?
      ::连接的基因是什么?为什么基因需要没有连接,才能让两栖交叉体预测交叉体的适当结果?
    3. Mendel carried out a dihybrid cross to examine the inheritance of the characteristics for seed color and seed shape. The dominant allele for yellow seed color is Y, and the recessive allele for green color is y. The dominant allele for round seeds is R, and the recessive allele for a wrinkled shape is r. The two plants that were crossed were F1 dihybrids RrYy. Identify the ratios of traits that Mendel observed in the F2 generation, and explain in terms of phenotype what each number means. Create a Punnett square to help you answer the question.
      ::门德尔做了一个双环十字检查种子颜色和种子形状特征的遗传性。 黄色种子颜色的顶端是Y, 绿色颜色的底端线是y。 圆形种子的顶端是R, 皱纹形状的底端线是r。 横穿的两座植物是F1, 亚丁。 确定孟德尔在F2代中观察到的特征的比重, 并用苯型来解释每个数字意味着什么。 创建一个 Punnett 广场来帮助您回答问题 。
    4. If AaBb is crossed with aabb, what proportion of the offspring would be expected to be aabb?
      ::如果AaBb与Aabb交叉开来,预期后代的Aabb将占多大比例?
    5. Assume that you mated two individuals heterozygous for each of two traits and obtained 80 offspring. How many of them would be expected to look like their parents?
      ::假设你为两个特质各配了两个异体,并获得了80个后代,其中有多少会像父母一样?