Topic content:
Drosophila is an important experimental material in genetic research. Please answer the following questions: (1) Drosophila is similar to human beings and belongs to type ____ sex determination. The above table lists the relationship between sex chromosome composition and sex of human and drosophila. It can be seen from the table that the Y chromosome only plays a leading role in the sex determination of ____ (fill in "human" or "fruit fly").
(2) The grey body (B) of Drosophila is dominant to the black body (b), and the gene is located on the autosome; Red eye (R) is dominant to white eye (r), and the gene is located on the X chromosome. If both male and female Drosophila melanogaster are red eyed and grey bodied, their offspring will have four phenotypes: red eyed and grey body, red eyed and black body, white eyed and grey body, and white eyed and black body. Q:
① The genotypes of the two parents are female _________ and male _________.
② The genotype of spermatozoa produced by male parents is _________, and the proportion is _________.
(3) In nature, there are both male and female Drosophila melanogaster individuals with yellow wings and some individuals with gray wings. The apparent and recessive relationship between yellow wings and gray wings is unknown, but it is known that this trait is controlled by an allele. Please design a scheme to judge whether the allele is located on the autosome or the X chromosome through two pairs of hybridization experiments (hint: one pair is orthogonal, and the other pair is reciprocal).
Positive and negative cross experiment: orthogonal ____________; Counter delivery _____________.
Inference and conclusion: ___________________________________.
(4) In genetics, a certain segment of the chromosome and the genes it carries are lost together, and the resulting variation is called deletion. The viability of the deleted heterozygote is reduced but it can survive. The deletion of homozygote (the deletion of X chromosome segment in male individuals is also regarded as the deletion of homozygote) often leads to individual death. Now a red eyed male drosophila XAY crosses with a white eyed female drosophila XaXa, and a white eyed female drosophila appears in the offspring. Please use two methods to determine whether the appearance of this white eyed female drosophila is caused by deletion or gene mutation
Method 1: _______________________________________.
Method 2: _______________________________________.
Best answer:
(1) XY person
(2)①.BbXRXr BbXRY ②.BXR、 BY、bXR、bY 1:1:1:1
(3) Male yellow wing × female grey wing male grey wing × female yellow wing
Inference and conclusion: If the phenotype of any trait of the filial generation in the orthogonal and reverse cross groups is not related to sex (the same trait accounts for the same proportion in male and female individuals), it means that the allele is located on the autosome. If the phenotype of any trait in one group of offspring in the orthogonal and reverse cross groups is not related to gender, but the other group is related to gender (the same trait in one group accounts for the same proportion in male and female individuals, while the same trait in the other group accounts for different proportions in male and female individuals), it means that this allele is located on the X chromosome.
(4) Method 1: Take the cells of the Drosophila melanogaster with the ability to divide and make them into slides, and observe the chromosome structure under the microscope. If the chromosome is normal, it may be caused by gene mutation; Otherwise, it may be caused by chromosome loss
Method 2: The white eyed female drosophila melanogaster was selected to cross with the red eyed male drosophila melanogaster. If the ratio of the number of female drosophila melanogaster to the number of male drosophila melanogaster in the hybrid offspring was 1:1, the appearance of the white eyed female drosophila melanogaster was caused by gene mutation; If the ratio of female drosophila to male drosophila in hybrid offspring is 2:1, the appearance of this white eyed female drosophila is caused by the absence
Answer analysis:
There is no explanation for this question
Test core:
Biological characteristics:
1. Biological characteristics: physiological characteristics, morphological characteristics and behavioral characteristics.
2. Character type:
(1) Relative character: Different performance types of the same character of an organism.
(2) Character separation: dominant and recessive characters appear simultaneously in hybrid offspring. For example, in the DD × dd cross experiment, the dominant characters (DD and Dd) and recessive characters (dd) appeared in the F2 generation formed after self crossing of hybrid F1 generation.
(3) Dominant trait: the trait shown by F1 in DD × dd cross test; For example, the F1 generation pea in the textbook shows a high stem, that is, a high stem is dominant. Dominant genetic factors (genes) determine dominant traits, which are represented by capital letters. For example, high stems are represented by D.
(4) Recessive traits: traits not shown by F1 in DD × dd cross test; For example, F1 generation pea does not show dwarf stem in the textbook, that is, dwarf stem is recessive. It is the recessive gene that determines the recessive character, which is represented by lowercase letters, for example, dwarf stem is represented by d. Allele: A gene that controls a relative trait.
(5) Dominant relativity: when parents with the same traits cross, hybrid seeds do not show recessiveness in the first generation, showing the intermediate traits of both (incomplete dominance) or colleagues showing the traits of two parents (co dominance).