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organization of genome both full ppt.pptx

The document discusses the organization of genomes, focusing on genes as the basic units of heredity and their structure in prokaryotic and eukaryotic organisms. It explains gene components such as promoters, coding sequences, exons, introns, and regulatory elements, along with their functions in gene expression. The historical context of gene theory and terminology related to genes is also provided.

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JAI NARAIN VYAS UNIVERSITY JODHPUR Seminar topic – organization of genome Submitted to -: Dr. Harchand R. Dagla Submitted by -: Divya Department of botany
ORGANIZATION OF GENOME Gene basic physical or functional unit of heredity. its control a character. It transmits the character of from parents to their offspring A gene is a segment of DNA that specifies the sequence of amino acids in polypeptide chain. Gene is present in the chromosome of the nucleus or extra chromosome of the nucleus or extra chromosome DNA . A gene may exist in alternative forms called alleles.
HISTORY Gene was coined by Wilhelm Johansen Gene theory was proposed by T. H. Morgan in 1911 The fine structure of gene was proposed by ‘ Seymour benzere’ in 1962. Gene concept was given by ‘Sutton’
SPECIFIC FEATURES OF GENE • The term gene is often used to refer genetic material on the chromosome that code for a trait . • Example one person has a gene for hair colour. • It is a unit of recombination or capable of undergoing crossover. • A unit of heredity connected with somatic structure or functional that lead to a phenotype expression. • A gene is the basic physical and functional unit of heredity.
BASIC STRUCTURE OF GENE • Promoter:- region of gene where RNA polymerase bind • Start :- Transcription beings • Stop :- Transcription ends. • Regulatory sites :- near the promoter where regulatory proteins bind ( two gene on/off)
STRUCTURE OF GENE • On the basis of structure of gene is the classification of two type 1. prokaryotic gene 2. eukaryotic gene
PROKARYOTIC GENE • Prokaryotic gene is composed of three regions 1. promoter region 2. RNA recording sequence 3. Terminator region prokaryotic gene is continues and uninterested where there is no intron present The reason 5’ of the promoter sequence is called upstream sequence and reason 3’ of the Terminator sequence is called downstream sequence
PROMOTER REGION • This is situated on the upstream of the sequence that codes for RNA . • Promoter region provide the location and direction of initiate transcription. • At -10 there is a sequence TATAAT or PRIBNOW BOX. • At -35 another consensus sequence TTGACA RNA CODING SEQUENCE • The DNA sequence that will become copied into an RNA molecule ( RNA transcript) • Starts with an initiator codon and ends with termination codon . • No introns • Collinear to it’s m-RNA
TERMINATOR REGION • The region that signal the RNA polymerase is to stop transcription from DNA template. • transcription termination occur through RHO dependent or RHO independent manner
EUKARYOTIC GENE STRUCTURE • Eukaryotic gene are complex structure compare that prokaryotic gene • They are composed of following region -: • exons • intron , • promoter sequence , • Terminator sequence, • Upstream sequence, • downstream sequence, • Enhancers and silencers • Signals ( upstream sequence signal for addition of cap and downstream sequence signal for addition of poly a tail)
EXONS • Coding sequence transcribed and translated coding for amino acid in the polypeptide chain. • Very in number sequence and length. • A gene start and end with exon ( 5’ to 3’) • Some exons include translated (UTR) region. INTRONS • Coding sequence is separated by non coding sequence called introns. • They are removed when the primary transcript is processed to give the mature RNA. • All introns share the base sequence GT in the 5’ end and AG in the 3’ end.
PROMOTERS :- • Promoter is regulator region of DNA located upstream controlling gene expression. • CORE PROMOTER:- transcription start site (-35) binding site for RNA polymerase and it is a general transcription factor binding site. • PROXIMAL PROMOTER :- Contain element. primary regulatory elements. • These together and responsible RNA polymerase for binding of RNA polymerase 2nd which is responsible for the transcription.
• Upstream 5’ End) :- • 5’ UTR serve several functions including m-RNA transport and inhibitions of translation • Signal. For addition of of Cap (7 methyl I guanosine) to 5’ end and of the mRNA • The cap facilitates the inhibition of translation. • Stabilization of mRNA. • Downstream. 3’End):- • 3 UTR Serve to add .mRNA- • Stability and attachment site for poly-A-tail. • The translation termination codon TAA. • AATAR Sequence signal for addition of poly A tail. • Terminator:- • Recognized by RNA polymerase as a signal to stop transcription. • Enhancer:- • Enhances the transcription. of a gene upto few thousand bp upstream • Silencers:-. Reduce Or Shut down the expression a near by gene
FUNCTION OF GENE • Some genes encode for protein other encode for t-RNA, r-RNA etc. • gene control the function of DNA and RNA • Gene code for m-RNA, m-RNA code for protein. • The sequence of genes encoding for the protein directly determines , their functions ( amino acid sequence)