please can somebody answer these question for me correct I need to study for the
ID: 52616 • Letter: P
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please can somebody answer these question for me correct I need to study for the test there are 3 pages I need the whole answer and correct I been get in answer wrong from tutor please for exam is 3 question but each one have a parts unc ments Pa 4. With a human and non-human example where possible, describe and discuss the following genetic phenomena: a. partial (incomplete) dominance b. codominance c. multiple alleles d. penetrance e. expressivity f. age of onset 5. More problems: Assume the following in humans: free ear lobes (D), attached (d) widow's peak (W), no widow's peak (w) freckles (F), no freckles () Normal skin color (A), albino (a) The genes for A, B and no antigen are determined by IA,IB, and The gene for straight hair (S1) is incompletely dominant to the Normal blood clotting (xH), hemophilia (xh) a, A man with attached ear lobes and without freckles who has 1O, respectively. gene for curly hair (S2). SiS2 heterozygotes have wavy hair. a mother with free ear lobes and freckles marries a woman with free ear lobes and freckles who has a mother with attached ear lobes and no freckles. What will be the phenotypes and proportions among the offspring? b. Two people have children as indicated below. What must be the phenotypes of the parents? girl with freckles, attached ear lobes and widow's neatExplanation / Answer
4. A. Incomplete dominance:Incomplete dominance is a form of intermediate inheritance in which one allele for a specific trait is not completely expressed over its paired allele. This results in a third phenotype in which the expressed physical trait is a combination of the dominant and recessive phenotypes.
B. Codominance- Codominance is a relationship between two versions of a gene. Individuals receive one version of a gene, called an allele, from each parent. If the alleles are different, the dominant allele usually will be expressed, while the effect of the other allele, called recessive, is masked. In codominance, however, neither allele is recessive and the phenotypes of both alleles are expressed.
example in plants- inheritance of seed shape (pea shape) in peas. Peas may be round (associated with allele R) or wrinkled (associated with allele r). In this case, three combinations of alleles (genotypes) are possible: RR and rr are homozygous and Rris heterozygous. The RR individuals have round peas and the rr individuals have wrinkled peas. In Rr individuals the R allele masks the presence of the r allele, so these individuals also have round peas. Thus, allele R is dominant to allele r, and allele r is recessive to alleleR.
Example in human-codominant trait is ABO blood types. The IA allele encodes for red blood cells with the A antigen, while the IB allele encodes for red blood cells with the B antigen. The recessive allele (i) doesn’t encode for any antigens.Therefore a person with two recessive alleles (ii) has type O blood. As no dominant (IA and IB) allele is present, the person cannot have type A or type B blood.
There are two possible genotypes for type A blood, homozygous (IAIA) and heterozygous (IAi), and two possible genotypes for type B blood (IBi and IBIB). If a person is heterozygous for both the IA and IB alleles, they will express both and have type AB blood with both antigens on each red blood cell. This pattern of inheritance is significantly different than Mendel’s rules for inheritance because both alleles are expressed completely and one does not mask the other.
C. Multiple alleles
example in human-
Two human examples of multiple-allele genes are the gene of the ABO blood group system, and the human-leukocyte-associated antigen (HLA) genes.
The ABO system in humans is controlled by three alleles, usually referred to as IA, IB, and IO (the "I" stands for isohaemagglutinin). IA and IB are codominant and produce type A and type B antigens, respectively, which migrate to the surface of red blood cells, while IO is the recessive allele and produces no antigen.
In plants: petal colour of rose
D. penetrance- Penetrance is the frequency with which a dominant or recessive gene is expressed in a population.
example in human- neurofibromatosis type 1 - every person who has a mutation in the gene will show symptoms of the condition. The penetrance is 100%.
F.
example in plants; no plant character show 100% penetrance. But presence of chlorophyll in some unfoliate leaves is example oiof penetrance.
E.Expressivity: It is related to the penetrance. Expressivity is the extent to which a gene or trait is expressed in a single individual.
F, Age of o nset- pattern of development differs over the first 3 years of life between children with early- and later-onset autism spectrum disorder (ASD).
example in plants- Flowering capacity in the different populations was negatively correlated with rainfall in the original habitat and, consequently, also with the age at onset of dormancy, i.e. the lower the mean annual precipitation, the earlier the onset of dormancy and the higher the proportion of flowering plants and panicles per plant.
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