682 Exercise 45 Group Challenge Odd Phenotype Out of phenotypes, discuss the pos
ID: 3520563 • Letter: 6
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682 Exercise 45 Group Challenge Odd Phenotype Out of phenotypes, discuss the possible candidates for the s based hin The following boxes each contain four phenotypes. One of the listed traits in each case does not belong with the odd phenotype" and which characteristic it lack other three for some reason. Working in groups of three, on your notes discuss the characteristics of the phenotypes in each set. On a separate piec characteristics for each phenotype in the set. For each set Once you have come to a consensus with your group, circle the trait that doesn't belong with the e of paper, one student will record the others, and explain how it is different from the others. 1. Which is the "odd phenotype"? Why is it the odd one out? Freckles Widow's peak Sickle cell trait Sodium benzoate "taster 2. Which is the "odd phenotype"? Why is it the odd one out? Blaze Type AB blood PTC "taster Widow's peak 3. Which is the "odd phenotype"? No proximal finger hair Straight hairline Color blindness Sodium benzoate "nontaster" 4. Which is the "odd phenotype" Dimpled cheek Straight hairline Freckles Blaze Why is it the odd one out? Why is it the odd one out?Explanation / Answer
So 1] Sickle cell trait is present in a person who has inherited one defective gene from a parent. Two genes are required to produce the phenotype.
Sodium benzoate taster is expressed by a single gene i.e presence of a single gene for this character is able to express itself in the individual.
Widows peak is a phenotype which shows a V shaped hairline. An individual with a single allele for this trait shows this phenotype.
Freckles are controlled by the MC1R gene. Scientists have found that the presence of even one copy of this is enough to produce the phenotype. If there are two such genes, the person will have freckles and red hair too.
Recent researches have shown that a gene present on chromosome 4 , can also cause freckles[ this was observed in a Chinese family]. In any case, scientists are certain that freckles is controlled by the presence of only one gene.
So, the odd one out will be sickle cell trait.
This is so because in sickle cell disease, two defective genes are required to produce the phenotype, while in all other cases only one gene can produce the phenotype.
2] Blaze is the presence of a lock of white hair that does not take a die. It is inherited and one dominant gene is capable of producing the phenotype.
PTC taster and Widows peak are also expressed by a single dominant gene.
Blood group is controlled by two dominant traits i.e they show co-dominance. This means that the genes responsible for producing antigen A and B respectively , co dominate and produce the phenotype blood group AB.
So, the odd one out will be blood group AB.
3] Absence of hair on fingers is controlled by two recessive genes.
Colour blindness is a sex linked disease and is carried on X chromosomes. It is expressed in males who have a inherited the defective X chromosome . In females, who mostly carry the gene, it can be expressed only if both the X chromosomes carry the defective gene.
So, the odd one out is colour blindness because it is a sex linked disorder while others are not .
4] Dimpled cheek, blaze and freckles , all are expressed by a single dominant gene. Straight hairline is expressed if two recessive genes are present because the gene for widow's peak is dominant.
So, the odd one out is the straight hairline phenotype because here two recessive alleles are present i.e. it is homozygous .
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