Pedigree Analysis ||Class 12 Biology

By -
     Pedigree analysis is an analysis of traits in several generations of a family. In this analysis, the inheritance of a particular trait is represented in the family tree over generations. 
       Importance of pedigree analysis are as follows: 
1. It is used to know the possibility of expressive or recessive allele which may cause genetic disorders.
2. It shows the origin of trait and flow of that trait in a family.
3. It predicts the harmful effects of marriage between close relatives.
4. It is extensively used in medical research.


      Pedigrees use a standardized set of symbols, squares represent males and circle represent females. It the sex of the person is unknown a diamond is used as symbol. Affected individuals is represented by a filled in (darker symbol). Heterozygotes, when identifiable, are indicated by a shade dot inside a symbol or a half filled symbol. Relationships in pedigree are shown as a series of lines. Parents are connected by a horizontal line and a vertical line leads to their offspring. The offspring are connected by a horizontal sibship (all the siblings of a family) line and are listed in birth order from left to right. If the offspring are twins they will be connected by a triangle. Each generation is identified by a Roman numeral (I, II, III, IV and so on).


Location: India

Comments

Post a Comment

If you have any doubts,please let me know

Popular posts from this blog

Spermatogenesis : Definition & Process ||Class 12 Biology

By -
Image
    Spermatogenesis is the process of formation of spermatozoa (sperms) in the testes which originate from the primordial germ cells (PCGs).     The process of Spermatogenesis initiates at puberty and continues even in the old age.       The process of Spermatogenesis comprised the following two main stages- 1. Formation of spermatids 2. Spermiogenesis 1. Formation of spermatids : It include the following three phases- i) Multiplication Phase ii) Growth Phase iii) Maturation Phase   i) Multiplication Phase : During this phase, the immature germ cells present in the Seminiferous tubules of the testes known as spermatogonia increases in number by mitotic divisions and so that the newly formed spermatogonium possesses the same number at chromosomes.  ii) Growth Phase : Each spermatogonium is diploid (2n) and contains 46 chromosomes. Some of the spermatogonia called primary spermatocytes.  iii)  Maturation Phase : Primary spermatocytes periodically undergo meiosis  division. A primary sper
Read more

Sperm: Structure ||Class 12 Biology

By -
Image
     A mature spermatozoa or a sperm cell is a microscopic, tadpole-shaped structure of about 2-5 micrometer in diameter and 50 micrometer long. A plasma membrane encloses the whole body of sperm.      Sperm consists of head, neck, middle piece and tail.       1. Head: It is flat, oval and composed of a large haploid nucleus and a small cap-like structure called acrosome. It lies at the tip of the nucleus and is formed from the Golgi complex. It contains hydrolytic enzymes and is used to contact and penetrate the egg (ova) during fertilization.       2. Neck: Neck is the smallest part, it is short structure that contains two centrioles- one parallel to the base of the nucleus and called proximal centriole and other distal centriole perpendicular to the previous one. The proximal centriole enters into the egg during fertilization and starts the first cleavage division of the egg which has no centriole. The distal centriole gives rise to the axial filament which forms the tail.       3.
Read more

Placenta: Structure & function ||Class 12 Biology

By -
Image
     The placenta is an organ attached to the lining of womb during pregnancy. Structure:       After implantation, finger-link projections appears on the trophoblast called chorionic villi which surrounded by the uterine tissues and maternal blood. The chorionic villi and the uterine tissue become interdigitated with each other and jointly form a structural and and functional unit between foetus and maternal body called placenta. Placenta is forms from the chorian and allantois. In human, the placenta averages 22cm (9 inch) in length and 2-2.5cm (0.8-1inch) in thickness. it has dark reddish-blue or crimson colour. It connects to the foetus by an umbilical cord. Function:      1. It facilitates the supply of oxygen and nutrients to the embryo.     2. Responsible for the removal of carbon dioxide and waste materials produced by the foetus.    3. The placenta is connected to the embryo through the umbilical cord which helps in the transport of substances to and from the embryo.    4. It
Read more