prokaryoatic gene structue and salient features of gene with definition , histroy.

1. Structure
of
prokaryotic gene
PRESENTED BY,
HARI PRASATH C.
M.Sc BIOCHEMISTRY

2. DEFINITION:
A gene is a specific sequence of DNA containing genetic
information required to make a specific protein.
TYPES OF GENE BASED ON ORGANISM:
 Prokaryotic gene – which is seen in the prokaryotes.
Example :- bacteria and cynobacteria.
 Eukaryotic gene – which is seen in the higher organisms.
Example :- plants and animals.
INTRODUCTION TO GENE

3. HISTROY OF GENE
 The classical principles of genetics were denoted
by Gregor Mendel in 1865.
 On the basis of breeding experiments with peas.
 He assumed that each traits is determined by a pair
of inherited “factors” which are now called as ‘gene’.
 In 1990 Wihelm Johannsen coined the term
“GENE”.

4. PROKARYOTIC GENE
STRUCTURE OF PROKERYOTIC GENE :

5. PROKARYOTIC GENE
Prokaryotic gene is composed of three regions :
1) Promoter region
2) RNA coding sequence
3) Terminator region.
 Prokaryotic gene is continues and uninterested where there
is no introns present.
 The region of 5’ of the promoter sequence is called
upstream sequence.
 The region of 3’ of the terminator sequence is called
downstream sequence.

6. PROKARYOTIC GENE
PROMOTER REGION :
 This is situated on upstream of the sequence
that codes for RNA.
 This is the site that interact RNA polymerase
before RNA primase (transcription).
 Promotor region provides the location and
direction initiate transcription.

7. PROKARYOTIC GENE
 At -10 there is sequence TATA or PRIBNOW BOX.
 AT -35 another consensus sequence TTGACA.
 These two are the most important promoter
elements recognized by transcription factors.

8. PROKARYOTIC GENE
RNA CODING SEQUENCE :
 The DNA sequence that will become copied into
an RNA molecule (RNA transcript).
 Starts with the initiator codon and with the
terminator codon.
 No introns (uninterrupted).
 Collinear to its mRNA.

9. PROKARYOTIC GENE
 Any nucleotide present on the left side is denoted by (-)
symbol and the region is called upstream elements.
Example : -10, -20, -35, etc,…..
 Any sequence present on the right side of the start is
denoted by (+) symbol called downstream elements.
Example : +10, +35, etc,….
TERMINATOR REGION:
 The region that signal the RNA polymerase to stop
transcription from DNA template.
 Transcription termination occurs through the Rho dependent
or Rho independent manner.

10. SALIENT FEATURES OF GENE
 Number of gene in each organism is more than the number of
chromosomes.
 Each gene occupies specific position called locus.
 If the position of gene changes, character also change.
 Genes can be transmitted from parents to off springs.
 Genes may exit in several alternate form called alleles.
 Genes are capable of combined together or can be replicated during a cell
division.
 Gene undergo for sudden changes in position and composition called
mutation.
 Genes are capable of self duplication producing their own exact copies.

11. References
 https://courses.lumenlearning.com/suny-wmopen-biology1/chapter/outcome-
prokaryotic-gene-
regulation/#:~:text=The%20DNA%20of%20prokaryotes%20is,together%20in
%20blocks%20called%20operons.
 https://en.wikipedia.org/wiki/Gene_structure
 The cells (fifth edition) by Geoffrey M. Cooper and Robert E. Hausman.
 Genes IX by Benjamin Lewin.