Kinh Nghiệm Hướng dẫn What is the genotype of individual 3 in the second generation how do you know? Chi Tiết
Bùi Thành Tài đang tìm kiếm từ khóa What is the genotype of individual 3 in the second generation how do you know? được Update vào lúc : 2022-12-15 20:58:04 . Với phương châm chia sẻ Mẹo về trong nội dung bài viết một cách Chi Tiết 2022. Nếu sau khi tham khảo tài liệu vẫn ko hiểu thì hoàn toàn có thể lại phản hồi ở cuối bài để Mình lý giải và hướng dẫn lại nha.Genetic analysis predates Gregor Mendel, but Mendel's laws form the theoretical basis of our understanding of the genetics of inheritance.
Nội dung chính Show- What is the genotype of individual 3?Can you determine the genotype of son 3 in the Second Generation Why or why not?What would be the number of genotypes if there are 3 alleles in a gene?Which P cross would have an F2 generation always showing a 3 1 phenotypic ratio?
Mendel made two innovations to the science of genetics:
developed pure linescounted his results and kept statistical notesPure Line - a population that breeds true for a particular trait [this was an important innovation because any non-pure (segregating) generation would and did confuse the results of genetic experiments]
Results from Mendel's Experiments
Parental CrossF1 PhenotypeF2 Phenotypic RatioF2 RatioRound x Wrinkled SeedRound5474 Round:1850 Wrinkled2.96:1Yellow x Green SeedsYellow6022 Yellow:2001 Green3.01:1Red x White FlowersRed705 Red:224 White3.15:1Tall x Dwarf PlantsTalll787 Tall:227 Dwarf2.84:1Terms and Results Found in the Table
Phenotype - literally means "the form that is shown"; it is the outward, physical appearance of a particular trait
Mendel's pea plants exhibited the following phenotypes:
- - round or wrinkled seed phenotype- yellow or green seed phenotype- red or white flower phenotype- tall or dwarf plant phenotype
Seed Color: Green and yellow seeds.
Seed Shape: Wrinkled and Round seeds.
What is seen in the F1 generation? We always see only one of the two parental phenotypes in this generation. But the F1 possesses the information needed to produce both parental phenotypes in the following generation. The F2 generation always produced a 3:1 ratio where the dominant trait is present three times as often as the recessive trait. Mendel coined two terms to describe the relationship of the two phenotypes based on the F1 and F2 phenotypes.
Dominant - the allele that expresses itself the expense of an alternate allele; the phenotype that is expressed in the F1 generation from the cross of two pure lines
Recessive - an allele whose expression is suppressed in the presence of a dominant allele; the phenotype that disappears in the F1 generation from the cross of two pure lines and reappears in the F2 generation
Mendel's Conclusions
The hereditary determinants are of a particulate nature. These determinants are called genes.Each parent has a gene pair in each cell for each trait studied. The F1 from a cross of two pure lines contains one allele for the dominant phenotype and one for the recessive phenotype. These two alleles comprise the gene pair.One thành viên of the gene pair segregates into a gamete, thus each gamete only carries one thành viên of the gene pair.Gametes unite random and irrespective of the other gene pairs involved.Mendelian Genetics Definitions
- Allele - one alternative form of a given allelic pair; tall and dwarf are the alleles for the height of a pea plant; more than two alleles can exist for any specific gene, but only two of them will be found within any individualAllelic pair - the combination of two alleles which comprise the gene pairHomozygote - an individual which contains only one allele the allelic pair; for example DD is homozygous dominant and dd is homozygous recessive; pure lines are homozygous for the gene of interestHeterozygote - an individual which contains one of each thành viên of the gene pair; for example the Dd heterozygoteGenotype - the specific allelic combination for a certain gene or set of genes
Using symbols we can depict the cross of tall and short pea plants in the following manner:
The F2 generation was created by selfing the F1 plants. This can be depicted graphically in a Punnett square. From these results Mendel coined several other terms and formulated his first law. First the Punnett Square is shown.
Union of GametesAt RandomDdPunnett
SquareDDD
(Tall)Dd
(Tall)dDd
(Tall)dd
(Short)
The Punnett Square allows us to determine specific genetic ratios.
Genotypic ratio of F2: 1 DD : 2 Dd : 1 dd (or 3 D_ : 1 dd)
Phenotypic ratio of F2: 3 tall : 1 dwarf
Mendel's First Law - the law of segregation; during gamete formation each thành viên of the allelic pair separates from the other thành viên to form the genetic constitution of the gamete
Confirmation of Mendel's First Law Hypothesis
With these observations, Mendel could form a hypothesis about segregation. To test this hypothesis, Mendel selfed the F2 plants. If his law was correct he could predict what the results would be. And indeed, the results occurred has he expected.
From these results we can now confirm the genotype of the F2 individuals.
PhenotypesGenotypesGenetic DescriptionF2 Tall Plants1/3 DD2/3 DdPure line homozygote dominant
HeterozygotesF2 Dwarf Plantsall ddPure line homozygote recessive
Thus the F2 is genotypically 1/4 Dd : 1/2 Dd : 1/4 dd
This data was also available from the Punnett Square using the gametes from the F1 individual. So although the phenotypic ratio is 3:1 the genotypic ratio is 1:2:1
Mendel performed one other cross to confirm the hypothesis of segregation --- the backcross. Remember, the first cross is between two pure line parents to produce an F1 heterozygote.
At this point instead of selfing the F1, Mendel crossed it to a pure line, homozygote dwarf plant.
Backcross: Dd x dd
MaleGametesdFemale
GametesDDD
(Tall)ddd
(Short)
Backcross One or (BC1) Phenotypes: 1 Tall : 1 Dwarf
BC1 Genotypes: 1 Dd : 1 dd
Backcross - the cross of an F1 hybrid to one of the homozygous parents; for pea plant height the cross would be Dd x DD or Dd x dd; most often, though a backcross is a cross to a fully recessive parent
Testcross - the cross of any individual to a homozygous recessive parent; used to determine if the individual is homozygous dominant or heterozygous
So far, all the discussion has concentrated on monohybrid crosses.
Monohybrid cross - a cross between parents that differ a single gene pair (usually AA x aa)
Monohybrid - the offspring of two parents that are homozygous for alternate alleles of a gene pair
Remember --- a monohybrid cross is not the cross of two monohybrids.
Monohybrids are good for describing the relationship between alleles. When an allele is homozygous it will show its phenotype. It is the phenotype of the heterozygote which permits us to determine the relationship of the alleles.
Dominance - the ability of one allele to express its phenotype the expense of an alternate allele; the major form of interaction between alleles; generally the dominant allele will make a gene product that the recessive can not; therefore the dominant allele will express itself whenever it is present
What is the genotype of individual 3?
So, the genotype of the individual 3 is heterozygous.Can you determine the genotype of son 3 in the Second Generation Why or why not?
D) Can you determine the genotype of son 3 in the second generation of offspring? (fourth row) Why or why not? No, he is either AA of Aa.What would be the number of genotypes if there are 3 alleles in a gene?
With three alleles 1, 2, 3 there are six possible genotypes: 11, 12, 13, 22, 23, 33.Which P cross would have an F2 generation always showing a 3 1 phenotypic ratio?
In the offspring of monohybrid crosses, or F2 generation, Mendel repeatedly observed a phenotype ratio of three plants with the dominant phenotype to one plant with the recessive phenotype (3:1) in the F2 generation. Tải thêm tài liệu liên quan đến nội dung bài viết What is the genotype of individual 3 in the second generation how do you know?