GENE
Genes are unit of
inheritance. These are located on chromosome in linear form and carried
information from parents to offspring by gametes. Gene control the expression
of characters. Gene was first visualize by MENDEL and called it factor. The
word gene introduce by Johannsen in
1909. In a simple language gene is a segment of DNA with specific sequence of
nucleotide which has coded information for specific character or for specific
protein.
TYPES OF GENES
1.
House-keeping
genes-
Active in every organisms and all time (example glycolysis)
2. Luxury genes- Inactive for most of the time and expressed in certain cells or at certain time only when their products are needs.
3. Structure genes-These genes code for substances which are needed for the morphological or functional traits of the cell
4.
Control
genes-Positive and negative control on functioning of
structural genes.
a) Regulator
genes
b) Operator
genes
c) Promoter
genes
d) Terminator
genes
5. Interrupted gene and discontinuous
genes-
I.
Split genes
II. Introns
6. Alternative genes- These are form different discontinuous genes get connected forming several new combinations.
7.
Overlapping
genes- In overlapping sequence code for
more than two different proteins. Its means same specific nucleotide sequence
is shared in the transcription of two different mRNA for the synthesis of two
non-homologous proteins
8. Transposons genes- jumping genes (from one position to another position in in the genome of a cell)
9.
Smart
genes- Artificially constructed genetic molecules
composed of one or more genes code for functional protein or enzymes.
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