3. The science that deals with the study of
heredity and variations.
The science that studies the structure and
behavior of the gene.
INTRODUCTION GENETICS
4. The gene is an indivisible unit of structure,
unit of recombination, unit of mutation and
unit of function
gene
/dʒiːn/
Noun Biology
noun: gene; plural noun: genes
a unit of heredity which is transferred from a parent to offspring and is held
to determine some characteristic of the offspring
INTRODUCTION GENE
5. Genotype function
The genetic information is stored in the sequence of nitrogen bases
and is transmitted from one generation to another
Phenotype function
It controls the development of the phenotype of the organisms,
dictating the growth and differentiation from zygote to mature adult.
Evolutionary function
The genes undergo mutations giving rise to new alleles of a gene.
INTRODUCTION Characteristics of GENE
6. Structure of GENE
All genes are made up of DNA and RNA,
collectively called as Nucleic acids.
Nucleic acids are composed of repeating
units called Nucleotides.
Each Nucleotide is composed of –
A phosphate group
A five carbon sugar and
A cyclic nitrogen bases.
7. In DNA
The sugar is 2-deoxyribose. Double stranded consisting
Four nitrogen bases –
Adenine and Guanine (Purines),
Thymine and Cytosine (Pyrimidines)
In RNA
The sugar is Ribose. Single stranded consisting
Four nitrogen bases –
Adenine and Guanine (Purines),
Uracil and Cytosine (Pyrimidines)
8. Messenger RNA (mRNA):
carries genetic information from the DNA in the nucleus to the
cytoplasm for the synthesis of polypeptide.
Ribosomal RNA (rRNA)
Formation of peptide bond between amino acids during protein
synthesis when the ribosome moves along the mRNA.
Transfer RNA (tRNA)
Bind to specific amino acids and bring them to the site of protein
synthesis on the ribosome.
Small nuclear RNA (snRNAs)
Remove the noncoding regions (introns) and splice the coding region
(Exons) together to construct the functional mRNA molecules.
Types of RNA
10. A chromosome is a
structure of DNA, protein,
and RNA found in cells.
It is a single piece of coiled
DNA containing many
genes, regulatory elements
and other nucleotide
sequences.
CHROMOSOMES
11. Chromosomes were first described by E. Strasburger,1875.
A single-thread like structures with beaded (nucleosomes)
They are held together at Centromere (Prophase of mitosis)
They condensed into Chromatids (late prophase & metaphase).
They again appear as single threads due to separation of
Chromatids (Anaphase & early Telophase).
Elongate during Telophase.
Beaded appearance in Interphase.
The terminal ends of chromosomes are called Telomeres
Structure of chromosome
