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

Nervous system - brain, BRAI N (ENCEPHELON) Shape - Oval Positio...

BRAI N (ENCEPHELON) Shape - Oval Positio n - Situated in cranial cavity of skull. Medulla oblongeta comes out of foramen magnum in the form of spinal cord. Colou

Show defense mechanism when inflammation fails, Q. What is the defense mech...

Q. What is the defense mechanism that begins to work when inflammation fails to stop an infection? If the inflammatory attack is not sufficient to halt the infectious process t

Prevention from infective endocarditis, Prevention of endocardial infection...

Prevention of endocardial infection by the use of antimicrobial agents, although desirable, is not always possible. By identifying the patients at  risk, the causative bacteria and

Which aqueous solution has the lowest ph, The aqueous solution with the low...

The aqueous solution with the lowest pH is: Select one: a. 0.01 M HCl. b. 0.1 M acetic acid (pKa = 4.86). c. 0.1 M formic acid (pKa = 3.75). d. 0.1 M HCl. e. 10 t

Can you explain mitotic apparatus, Q. What is mitotic apparatus? Mitoti...

Q. What is mitotic apparatus? Mitotic apparatus is the set of aster fibers, radial structures around each centriole pair, plus the spindle fibers, fibers that extend across the

Sinece, modes of nutrition in animals?

modes of nutrition in animals?

Explain disadvantage of colonies at different dilution, Explain the Disadva...

Explain the Disadvantages of Colonies Obtained At Different Dilution 1. Heat sensitive microorganisms may be damaged by melted agar, giving low viable count as compared to spre

Available and non-available water, Available and Non-available Water Yo...

Available and Non-available Water You have seen above that water is present even in the apparently dry soils but it is of not much use as far as the plants are concerned. They

What is the etiology of cholera, Q. What is the etiology of cholera? T...

Q. What is the etiology of cholera? The most common cause of cholera is consumption of food or drinking water that has been contaminated with the bacteria. It is important to

Agro industrial-proteins, Proteins Protease inhibitors: Protease inh...

Proteins Protease inhibitors: Protease inhibitors are protein-based substances widely distributed within the plant kingdom, including the seeds of most cultivated legumes wh

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