Mutation and Its Types:- Mutation is a phenomenon which results in alternation of DNA sequences and consequently results in changes in the genotype and phenotype of an organism. In addition to recombination, mutation is another phenomenon that leads to variation in DNA. Causes of mutations :- There are many chemical and physical factors that induce…
Sex Determination in Human :- sex determination is a biological system that determines the development of sexual characteristic in an organism. Sex determination in human by chromosomal difference. Most organisms that created their offspring using sexual reproduction have two sexes. In human beings a sex chromosome that carries the genes for male characters is called…
Crossing Over :- Crossing over is a mechanism by which a group of genes on one chromosome changes it’s place with a similar group on it’s homologous chromosome. Term crossing over were first given by Morgan & Castle in 1912. Mechanism of crossing over :- Mechanism can be explained under the following steps – 1….
1. Incomplete dominance :- It is a post Mendelian discovery. In the case heterozygous condition of gene results in intermediate phenotype as one allele is only incompletely don’t over the other. The intermediate of flower colour in the Mirabilis jalapa is a good example to understand incomplete dominance. In a cross between true breeding red…
Mendel’s laws of inheritance :- Mendel’s present his paper on principles of heredity at the annual conventy on natural history society at Brun ( Austria ) in 1895. This paper use published in the proceeding on the conference in 1866. Tittle of this paper was experiment in plant hybridization. These principles are – 1. Law…
Monohybrid cross :- Monohybrid is the cross involves one character and single gene pair.It leads to monohybrid offspring in F₁ generation. Mendel proposed that in a true breeding, tall or dwarf pea variety the allelic pair of genes for height are identical or homozygous, TT and tt respectively. TT and tt are called genotype of…
It is a cross which involves two characters and two gene pair. it leads to dihybrid F₁ offspring. Mendel worked with and crossed pea plants that differed in two characters, as is seen in the cross between a pea plant that has seeds with yellow colour and round shape, one that had seeds of green…
Allele or Allelomorph :- Genes which code for a pair of contrasting traits are known as alleles, i.e. They are slightly different forms of the same gene. Example – In case of the character of height, T is used for the tall trait and t for the dwarf, T and t are alleles of each…
Genetics :- Genetics is the branch of biology concerned with the study of genes, genetic variation and heredity in organisms. Heredity :- It is the passing on of traits from parents to their offspring, either through asexual reproduction or sexual reproduction. The traits or characters are called hereditary characters. Gene :- A gene is the…
RNA and its structure :- RNA molecules are single stranded nucleic acids composed of nucleotides. Fig. 1. Structure of ( a ) DNA and ( b ) RNA. RNA molecules are polymer of nucleotides joined to one another by covalent bonds between the phosphate of one nucleotides and the sugar of another. These linkages are…
Replication of DNA :- Watson and Crick had proposed a scheme for Replication of DNA. The scheme suggested that the two strands would separate and as a template for the synthesis of new complementary strands. After the completion of replication, each DNA molecule would have one parental and one newly synthesised strand. This scheme was…
DNA and it’s structure :- DNA (Deoxyribose Nucleic Acid ) is a long polymer of deoxyribonucleotides. The length of DNA is usually defined as number of nucleotides present in it. This also is the characteristic of an organism. Example – Bacteriophase known as φ × 174 has 5386 nucleotides, Escherichia coli has 4·6 x10⁶ base…
