Md. Kawsar Ali Hawlader Senior Lecturer Dept. Of Biology Sub:Biology Second Paper

Chapter – 11 Genetics and Evolution

Genetics

After reading this lesson students should be able to…  tell the definition of genetics  tell the definition of heredity  explain the various terms of this lesson.

Genetics Inheritance Mendel Gene Allele Dominant character Recessive character Genotype Phenotype Homozygous Heterozygous Test-cross Back-cross

Willium Betson introduced the word‘Genetics.’. Genetics

Heredity Heredity is the transmission of characters from one generation to next.

Gene Allele Fragmentation of DNA which is responsible for character of organism. Two or more alternative form of a gene present in a locus of homologous chromosome are called allele.

 Dominant trait: Of the two alternating forms of a trait, the one which appears in the F1 hybrid is called dominant trait.  Recessive trait: Of the two alternating forms of a trait, the one which suppressed in the F1 hybrid is called recessive trait.

An individual possessing identical alleles for a trait is called homozygous. An individual receiving dissimilar alleles for a trait is called heterozygous. Homozygous Heterozygous

Monohybrid cross The cross between two parents differing in a single pair of contrasting characters is called monohybrid cross. Dihybrid cross The cross between two parents in which two pairs of contrasting characters are considered is called dihybrid cross.

Test cross An experimental cross of individual organism dominant phenotype but unknown genotype to an organism with a homozygous recessive genotype is called test cross. Back cross It is a crossing of a hybrid with one of its parents is called back cross.

TEAM WORK Group - A Write down the definition of genetics, heredity, homozygous, heterozygous and test- cross. Group-B Write down the definition of phenotype, genotype, allele, dominant character and back- cross.

a.Who is the father of genetics? b.What is meant by genetics c.What is phenotype? d. What is genotype? e. What is dominant character? f. What is recessive character?

Make a short note on the various terms on genetics.