Multiple alleles, Biology

Assignment Help:

MULTIPLE ALLELES

(i)         More than two alternative forms (alleles) of a gene in a population occupying the same locus on a chromosome or its homologue are known as multiple alleles.

(ii)         There are more than two alleles of the same gene.

(iii)        All multiple alleles occupy the corresponding loci in the homologous chromosomes. (iv)  A chromosome or a gamete has only one allele of the group.

(v)         Any one individual contains only two of the different alleles of a gene, one on each chromosome of the homologous pair carrying that gene.

(vi)        Multiple alleles express different alternatives of a single trait.

(vii)        Different alleles may show codominance, dominance - recessive behaviour or incomplete dominance among themselves.

Example :-

Human Blood Groups

(i)         ABO blood group system in human beings is an example of multiple alleles.

(ii)         Human beings have four blood groups or blood group phenotypes - A, B, AB and O.

(iii)        The blood groups are determined by two types of antigens present in the surface coating of red blood cells-A and B.

(iv)        Blood group A persons have antigen A, group B have antigen B, AB have both antigens while blood group O

persons do not carry antigen in the coating of their erythrocytes.

(v)         Presence, absence and type of antigens are determined by three immunogen alleles IA, IB and i. (vi)            IA forms antigen A, IB antigen B while allele i is recessive and does not form any antigen.

(vii)        Both IA and IB are dominant over i, but not over each other.

(viii)       When both IA and IB are present in a person, both the alleles are able to express themselves forming antigens A and B. Such alleles which are able to express themselves in the presence of each other are called codominant. Thus blood group alleles show both codominant and dominant recessive relationships (IA = IB >> i).

(ix)        A human being carries two of the three alleles, one from each parent. The maximum number of possible genotype is six for the four phenotypes. The phenotypes are tested by two antisera, anti-A and anti-B.

1158_multiple alleles.png

S .No.

Blood Group P he notype

Ge notype

Re a ction w ith  Anti-A      Anti-B

1

O

ii

-       -

2

A

IA IA , IA i

+       -

3

B

IB IB, IB i

-       +

4

AB

IA IB

+       +

(x)        Blood groups being a hereditary character, the knowledge of blood groups of the parents can give information about the possible blood groups of children and vice versa.


Related Discussions:- Multiple alleles

Prior to the solving of the structure of dna, Prior to the solving of the s...

Prior to the solving of the structure of DNA, Erwin Chargaff calculated the amounts of the four nucleotides (A, T,G,C) and made which of the following conclusions? A. All four

Explain the cladosporium - fungi and yeast, Explain the Cladosporium - Fung...

Explain the Cladosporium - Fungi and Yeast? Classification Kingdom - Mycetae Division - Amastigomycota Form - Class - Deauteromycetes Form - Order - Moniliales F

Listeriosis, List er i o si s The disease is caused by Listeria m...

List er i o si s The disease is caused by Listeria monocytogenes - Gram positive small non spore- forming bacilli seen in soil, silage, sewage and feces of animals and b

What are the major plant tissues, What are the major plant tissues that for...

What are the major plant tissues that form the rings observed on stem sections of some trees? The rings observed on a stem cross section of the dicot trees are made of conducti

Implantable cardioverter defibrillator, Patients with aborted sudden death,...

Patients with aborted sudden death, hemodynamically unstable ventricular arrhythmias, and unexplained cardiogenic syncope are at high risk for fatal ventricular arrhythmias. If the

Polypeptide chains of hemoglobin, Q. In sickle cell anemia, a hereditary di...

Q. In sickle cell anemia, a hereditary disease, there is replacement of one amino acid by another in one of the four polypeptide chains of hemoglobin. In this case are all of the s

What are the etiological agents of malaria, Q. What are the etiological age...

Q. What are the etiological agents of malaria? The etiological agents of malaria are protozoans of the genus Plasmodium. There are four different kinds of plasmodia that cause

Explain about the pregnancy and obesity, Explain the Pregnancy and Obesity?...

Explain the Pregnancy and Obesity? Obesity is associated with increased risk for gestational diabetes, hypertension, pre- eclampsia, perinatal mortality and the need for induce

Explain causes of shigellosis, Q. Explain causes of Shigellosis? Shigel...

Q. Explain causes of Shigellosis? Shigellosis is caused by the genus Shigella and is a common enteric (intestinal) infection. The genus has four serological groups,

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd