SlideShare a Scribd company logo
1 of 13
Molecular Biology
Lecture # 1
Introduction to Molecular Biology
Ms. Seerat-e-Fatima
M.Phil. Molecular Biology
Molecular Biology
• Molecular Biology is the branch of biology that deals with the study of
gene structure and function at molecular level
• The field of molecular biology overlaps with other fields especially
genetics and biochemistry.
• Molecular biology deals with the study of Central Dogma of Life
(DNA RNA Protein)
Transcription Translation
Central Dogma of Life
Introduction to Gene
• Introduction: In 1865, Gregor Mendel was the first one to describe
the elements of hereditary i.e., Gene. His observations and analysis of
the observation features of Peas led him to believe that specific traits
were passed on unchanged from parent plant to the next generation.
• Definition: Gene is a Greek work that means “to become” or “to
grow”. Genes make up the parts of DNA, acts as RNA instructors and
to make molecules called Protein.
• In humans, genes ranges in size from a few hundred to up to 2 billion
bases. Some genes are same in most people whereas some genes are
slightly different between different people
Characteristics
• Genes are the true carriers of heredity, responsible for the development
and structure of human body. They are physical substances passed on from
parents to children. The parents’ genes, in turn, have come from their
parents, grandparents and ancestors.
• Some genes are dominant, some are recessive.
• Genes do not act alone, they are influenced by genetic background of the
individual, and the external and internal environment.
• Each human somatic cell has around 30,000 genes present inside nucleus.
Some non-nucleated gene are also located inside the mitochondria in the
cell.
Terms associated with Gene
• Gene : A section of DNA that codes for specific trait.
• Trait : A trait is a specific characteristic that is unique. Traits determine how we
look, or how are body functions. They are inherited e.g., hair color, eye color,
etc.,
• Allele : Alternate form of gene are termed as alleles. The one pair of allele that
masks the effect of other when present in same cell is called dominant allele. The
allele that is masked by the other pair in the same cell is called the recessive
allele and is capable of producing a phenotype in organism only when two alleles
are present and identical.
• Locus : A fixed position of the chromosome where a certain gene resides.
•
• Exons and Introns : Most of the genes consists of short coding sequences called
exons, interrupted by short intervening non-coding sequences called introns.
History
• Introduced by Sutton in 1902 and elaborated by T.M Morgan in 1913 who
put forward gene theory that stated
“Chromosomes are bearer of hereditary units, and each chromosome carries
hundreds or thousands of genes. The genes are arranged on the
chromosomes in the linear order and on the special regions called locus”
• Features outlined by Bridge (1923), Muller (1927) and other scientists are
as follows:
Discrete particles inherited in mendelian fashion
Occupies a definite locus in chromosome
Responsible for expression of specific phenotypic character
Summary of evolution
Year Scientists Gene Concepts
1866 G.J. Mendel A unit factor that controls specific
phenotypic trait
1909 A.E. Garrod One gene – one product
1940 Beadle and Tatum One gene – one enzyme
1957 U.M. Ingram One gene – one polypeptide theory
1960s C. Yanofsky and co-workers Gene is a unit of recombination
Types of genes
Based on genetic phenomena
• Gene as a unit of transmission or cistron : The part of DNA specifying
a single polypeptide chain is termed as cistron. A cistron can have 100
nucleotide pairs in length to 30,000 nucleotide pairs. It transmits
characters from one generation to another as unit of transmission
• Gene as a unit of recombination or recon : The smallest segment of
DNA capable of being separated and exchange with another
chromosome is called recon. A recon consists of not more than two
pairs of nucleotides
• Gene as a unit of mutation of muton : Muton is a smallest unit of
genetic material which when changed or mutated produces a
phenotypic trait. It is delimited to single nucleotide
Based on activity
• Constitutive/House keeping genes : The genes which are constantly expressing themselves in a cell
because their products are required for normal cellular activities are called house keeping genes. For
example, genes for glycolysis, ATP etc.
• Non-constitutive/luxury genes : The genes which activate only according to the requirement of cellular
activities e.g., genes for lactose
• Inducible genes : The genes are switched on in response to the presence of a chemical substance or
inducer, which are required for functioning of the product of gene activity
• Cumulative Gene : Some genes have different effects on the action of other genes. These are called
cumulative genes
• Pleiotropic Gene : The genes which produce changes in more than one character is called pleiotropic
gene
• Modifying Gene : The gene which cannot produce a character by itself but interacts with other to
produce a modified effect is called modifier gene
• Inhibitory Gene : The gene which suppresses or inhibits the expression of another gene
Functions of genes
• Control the morphology or phenotype of an individual
• Control the structure and metabolism of body
• Replication of genes is essential for cell division
• Genes carry the hereditary information from one generation to next
• Reshuffling of genes at time of sexual reproduction produces
variations
Human Genome Project
• 1990 : American geneticists started an ambitious quest to map and
sequence the entire human genome.
• 1999 : the final draft of human chromosome 22
• 2000 : the final draft of human chromosome 21
• 2001 : working draft of whole human genome
• 2004 : the finished sequence of euchromatin part of human genome.

More Related Content

Similar to Introduction to basic Molecular Biology.pptx

Genetics & mutations (every thing about DNA & Genes &Mutations )
Genetics & mutations (every thing about DNA & Genes &Mutations )Genetics & mutations (every thing about DNA & Genes &Mutations )
Genetics & mutations (every thing about DNA & Genes &Mutations )Hanan Ez
 
Genetics dentistry part 1 2017
Genetics dentistry part  1 2017Genetics dentistry part  1 2017
Genetics dentistry part 1 2017Lama K Banna
 
Gene- basics (Gene, nature of Gene, regulatory elements of Gene, Non coding D...
Gene- basics (Gene, nature of Gene, regulatory elements of Gene, Non coding D...Gene- basics (Gene, nature of Gene, regulatory elements of Gene, Non coding D...
Gene- basics (Gene, nature of Gene, regulatory elements of Gene, Non coding D...Dr. Naeem Ullah
 
GENETICS IN ORTHODONTICS WORD.docx
GENETICS IN ORTHODONTICS WORD.docxGENETICS IN ORTHODONTICS WORD.docx
GENETICS IN ORTHODONTICS WORD.docxsidharth779721
 
Genetics in orthodontics
Genetics in orthodonticsGenetics in orthodontics
Genetics in orthodonticsShweta Dhope
 
Concept of gene
Concept of geneConcept of gene
Concept of geneAman Ullah
 
AdiZareiGenetics1
AdiZareiGenetics1AdiZareiGenetics1
AdiZareiGenetics1Adi Zarei
 
Introduction to genetics for Neuroscience
Introduction to genetics for NeuroscienceIntroduction to genetics for Neuroscience
Introduction to genetics for NeuroscienceKadir Sümerkent
 
Diffrentiation,Cell diffrentiation,Types of differentiation,Mechanism,Factors...
Diffrentiation,Cell diffrentiation,Types of differentiation,Mechanism,Factors...Diffrentiation,Cell diffrentiation,Types of differentiation,Mechanism,Factors...
Diffrentiation,Cell diffrentiation,Types of differentiation,Mechanism,Factors...SoniaBajaj10
 
MolecularGeneticsUnit4-1_000.pptx
MolecularGeneticsUnit4-1_000.pptxMolecularGeneticsUnit4-1_000.pptx
MolecularGeneticsUnit4-1_000.pptxSrinivasaJagadesh1
 
Bacterial Genetics System
Bacterial Genetics SystemBacterial Genetics System
Bacterial Genetics SystemAnanyaGulbake
 
Genetics in orthodonics
Genetics in orthodonicsGenetics in orthodonics
Genetics in orthodonicsIrasolanki3
 

Similar to Introduction to basic Molecular Biology.pptx (20)

Genetics & mutations (every thing about DNA & Genes &Mutations )
Genetics & mutations (every thing about DNA & Genes &Mutations )Genetics & mutations (every thing about DNA & Genes &Mutations )
Genetics & mutations (every thing about DNA & Genes &Mutations )
 
Epigenetics
EpigeneticsEpigenetics
Epigenetics
 
Genetics dentistry part 1 2017
Genetics dentistry part  1 2017Genetics dentistry part  1 2017
Genetics dentistry part 1 2017
 
Gene- basics (Gene, nature of Gene, regulatory elements of Gene, Non coding D...
Gene- basics (Gene, nature of Gene, regulatory elements of Gene, Non coding D...Gene- basics (Gene, nature of Gene, regulatory elements of Gene, Non coding D...
Gene- basics (Gene, nature of Gene, regulatory elements of Gene, Non coding D...
 
GENETICS IN ORTHODONTICS WORD.docx
GENETICS IN ORTHODONTICS WORD.docxGENETICS IN ORTHODONTICS WORD.docx
GENETICS IN ORTHODONTICS WORD.docx
 
Genetics in orthodontics
Genetics in orthodonticsGenetics in orthodontics
Genetics in orthodontics
 
Concept of gene
Concept of geneConcept of gene
Concept of gene
 
Gene mutation
Gene mutationGene mutation
Gene mutation
 
AdiZareiGenetics1
AdiZareiGenetics1AdiZareiGenetics1
AdiZareiGenetics1
 
Introduction to genetics for Neuroscience
Introduction to genetics for NeuroscienceIntroduction to genetics for Neuroscience
Introduction to genetics for Neuroscience
 
Vinay @ dna
Vinay @ dnaVinay @ dna
Vinay @ dna
 
Diffrentiation,Cell diffrentiation,Types of differentiation,Mechanism,Factors...
Diffrentiation,Cell diffrentiation,Types of differentiation,Mechanism,Factors...Diffrentiation,Cell diffrentiation,Types of differentiation,Mechanism,Factors...
Diffrentiation,Cell diffrentiation,Types of differentiation,Mechanism,Factors...
 
MolecularGeneticsUnit4-1_000.pptx
MolecularGeneticsUnit4-1_000.pptxMolecularGeneticsUnit4-1_000.pptx
MolecularGeneticsUnit4-1_000.pptx
 
Bacterial Genetics System
Bacterial Genetics SystemBacterial Genetics System
Bacterial Genetics System
 
Genetics FY ppt.pptx
Genetics FY ppt.pptxGenetics FY ppt.pptx
Genetics FY ppt.pptx
 
Biogenetic Analysis
Biogenetic AnalysisBiogenetic Analysis
Biogenetic Analysis
 
Epigenetics
EpigeneticsEpigenetics
Epigenetics
 
Pharmacogenetics
PharmacogeneticsPharmacogenetics
Pharmacogenetics
 
BIOCHEMISTRY
BIOCHEMISTRYBIOCHEMISTRY
BIOCHEMISTRY
 
Genetics in orthodonics
Genetics in orthodonicsGenetics in orthodonics
Genetics in orthodonics
 

Recently uploaded

Call Girls ITPL Just Call 7001305949 Top Class Call Girl Service Available
Call Girls ITPL Just Call 7001305949 Top Class Call Girl Service AvailableCall Girls ITPL Just Call 7001305949 Top Class Call Girl Service Available
Call Girls ITPL Just Call 7001305949 Top Class Call Girl Service Availablenarwatsonia7
 
Russian Call Girls Gunjur Mugalur Road : 7001305949 High Profile Model Escort...
Russian Call Girls Gunjur Mugalur Road : 7001305949 High Profile Model Escort...Russian Call Girls Gunjur Mugalur Road : 7001305949 High Profile Model Escort...
Russian Call Girls Gunjur Mugalur Road : 7001305949 High Profile Model Escort...narwatsonia7
 
Mumbai Call Girls Service 9910780858 Real Russian Girls Looking Models
Mumbai Call Girls Service 9910780858 Real Russian Girls Looking ModelsMumbai Call Girls Service 9910780858 Real Russian Girls Looking Models
Mumbai Call Girls Service 9910780858 Real Russian Girls Looking Modelssonalikaur4
 
97111 47426 Call Girls In Delhi MUNIRKAA
97111 47426 Call Girls In Delhi MUNIRKAA97111 47426 Call Girls In Delhi MUNIRKAA
97111 47426 Call Girls In Delhi MUNIRKAAjennyeacort
 
Hemostasis Physiology and Clinical correlations by Dr Faiza.pdf
Hemostasis Physiology and Clinical correlations by Dr Faiza.pdfHemostasis Physiology and Clinical correlations by Dr Faiza.pdf
Hemostasis Physiology and Clinical correlations by Dr Faiza.pdfMedicoseAcademics
 
Call Girls Service Nandiambakkam | 7001305949 At Low Cost Cash Payment Booking
Call Girls Service Nandiambakkam | 7001305949 At Low Cost Cash Payment BookingCall Girls Service Nandiambakkam | 7001305949 At Low Cost Cash Payment Booking
Call Girls Service Nandiambakkam | 7001305949 At Low Cost Cash Payment BookingNehru place Escorts
 
College Call Girls Vyasarpadi Whatsapp 7001305949 Independent Escort Service
College Call Girls Vyasarpadi Whatsapp 7001305949 Independent Escort ServiceCollege Call Girls Vyasarpadi Whatsapp 7001305949 Independent Escort Service
College Call Girls Vyasarpadi Whatsapp 7001305949 Independent Escort ServiceNehru place Escorts
 
call girls in paharganj DELHI 🔝 >༒9540349809 🔝 genuine Escort Service 🔝✔️✔️
call girls in paharganj DELHI 🔝 >༒9540349809 🔝 genuine Escort Service 🔝✔️✔️call girls in paharganj DELHI 🔝 >༒9540349809 🔝 genuine Escort Service 🔝✔️✔️
call girls in paharganj DELHI 🔝 >༒9540349809 🔝 genuine Escort Service 🔝✔️✔️saminamagar
 
Glomerular Filtration and determinants of glomerular filtration .pptx
Glomerular Filtration and  determinants of glomerular filtration .pptxGlomerular Filtration and  determinants of glomerular filtration .pptx
Glomerular Filtration and determinants of glomerular filtration .pptxDr.Nusrat Tariq
 
Kolkata Call Girls Services 9907093804 @24x7 High Class Babes Here Call Now
Kolkata Call Girls Services 9907093804 @24x7 High Class Babes Here Call NowKolkata Call Girls Services 9907093804 @24x7 High Class Babes Here Call Now
Kolkata Call Girls Services 9907093804 @24x7 High Class Babes Here Call NowNehru place Escorts
 
PERFECT BUT PAINFUL TKR -ROLE OF SYNOVECTOMY.pptx
PERFECT BUT PAINFUL TKR -ROLE OF SYNOVECTOMY.pptxPERFECT BUT PAINFUL TKR -ROLE OF SYNOVECTOMY.pptx
PERFECT BUT PAINFUL TKR -ROLE OF SYNOVECTOMY.pptxdrashraf369
 
Call Girls Kanakapura Road Just Call 7001305949 Top Class Call Girl Service A...
Call Girls Kanakapura Road Just Call 7001305949 Top Class Call Girl Service A...Call Girls Kanakapura Road Just Call 7001305949 Top Class Call Girl Service A...
Call Girls Kanakapura Road Just Call 7001305949 Top Class Call Girl Service A...narwatsonia7
 
Low Rate Call Girls Mumbai Suman 9910780858 Independent Escort Service Mumbai
Low Rate Call Girls Mumbai Suman 9910780858 Independent Escort Service MumbaiLow Rate Call Girls Mumbai Suman 9910780858 Independent Escort Service Mumbai
Low Rate Call Girls Mumbai Suman 9910780858 Independent Escort Service Mumbaisonalikaur4
 
Call Girls Jp Nagar Just Call 7001305949 Top Class Call Girl Service Available
Call Girls Jp Nagar Just Call 7001305949 Top Class Call Girl Service AvailableCall Girls Jp Nagar Just Call 7001305949 Top Class Call Girl Service Available
Call Girls Jp Nagar Just Call 7001305949 Top Class Call Girl Service Availablenarwatsonia7
 
Glomerular Filtration rate and its determinants.pptx
Glomerular Filtration rate and its determinants.pptxGlomerular Filtration rate and its determinants.pptx
Glomerular Filtration rate and its determinants.pptxDr.Nusrat Tariq
 
Measurement of Radiation and Dosimetric Procedure.pptx
Measurement of Radiation and Dosimetric Procedure.pptxMeasurement of Radiation and Dosimetric Procedure.pptx
Measurement of Radiation and Dosimetric Procedure.pptxDr. Dheeraj Kumar
 
Call Girls Frazer Town Just Call 7001305949 Top Class Call Girl Service Avail...
Call Girls Frazer Town Just Call 7001305949 Top Class Call Girl Service Avail...Call Girls Frazer Town Just Call 7001305949 Top Class Call Girl Service Avail...
Call Girls Frazer Town Just Call 7001305949 Top Class Call Girl Service Avail...narwatsonia7
 
Book Call Girls in Kasavanahalli - 7001305949 with real photos and phone numbers
Book Call Girls in Kasavanahalli - 7001305949 with real photos and phone numbersBook Call Girls in Kasavanahalli - 7001305949 with real photos and phone numbers
Book Call Girls in Kasavanahalli - 7001305949 with real photos and phone numbersnarwatsonia7
 
epilepsy and status epilepticus for undergraduate.pptx
epilepsy and status epilepticus  for undergraduate.pptxepilepsy and status epilepticus  for undergraduate.pptx
epilepsy and status epilepticus for undergraduate.pptxMohamed Rizk Khodair
 
Call Girls Hebbal Just Call 7001305949 Top Class Call Girl Service Available
Call Girls Hebbal Just Call 7001305949 Top Class Call Girl Service AvailableCall Girls Hebbal Just Call 7001305949 Top Class Call Girl Service Available
Call Girls Hebbal Just Call 7001305949 Top Class Call Girl Service Availablenarwatsonia7
 

Recently uploaded (20)

Call Girls ITPL Just Call 7001305949 Top Class Call Girl Service Available
Call Girls ITPL Just Call 7001305949 Top Class Call Girl Service AvailableCall Girls ITPL Just Call 7001305949 Top Class Call Girl Service Available
Call Girls ITPL Just Call 7001305949 Top Class Call Girl Service Available
 
Russian Call Girls Gunjur Mugalur Road : 7001305949 High Profile Model Escort...
Russian Call Girls Gunjur Mugalur Road : 7001305949 High Profile Model Escort...Russian Call Girls Gunjur Mugalur Road : 7001305949 High Profile Model Escort...
Russian Call Girls Gunjur Mugalur Road : 7001305949 High Profile Model Escort...
 
Mumbai Call Girls Service 9910780858 Real Russian Girls Looking Models
Mumbai Call Girls Service 9910780858 Real Russian Girls Looking ModelsMumbai Call Girls Service 9910780858 Real Russian Girls Looking Models
Mumbai Call Girls Service 9910780858 Real Russian Girls Looking Models
 
97111 47426 Call Girls In Delhi MUNIRKAA
97111 47426 Call Girls In Delhi MUNIRKAA97111 47426 Call Girls In Delhi MUNIRKAA
97111 47426 Call Girls In Delhi MUNIRKAA
 
Hemostasis Physiology and Clinical correlations by Dr Faiza.pdf
Hemostasis Physiology and Clinical correlations by Dr Faiza.pdfHemostasis Physiology and Clinical correlations by Dr Faiza.pdf
Hemostasis Physiology and Clinical correlations by Dr Faiza.pdf
 
Call Girls Service Nandiambakkam | 7001305949 At Low Cost Cash Payment Booking
Call Girls Service Nandiambakkam | 7001305949 At Low Cost Cash Payment BookingCall Girls Service Nandiambakkam | 7001305949 At Low Cost Cash Payment Booking
Call Girls Service Nandiambakkam | 7001305949 At Low Cost Cash Payment Booking
 
College Call Girls Vyasarpadi Whatsapp 7001305949 Independent Escort Service
College Call Girls Vyasarpadi Whatsapp 7001305949 Independent Escort ServiceCollege Call Girls Vyasarpadi Whatsapp 7001305949 Independent Escort Service
College Call Girls Vyasarpadi Whatsapp 7001305949 Independent Escort Service
 
call girls in paharganj DELHI 🔝 >༒9540349809 🔝 genuine Escort Service 🔝✔️✔️
call girls in paharganj DELHI 🔝 >༒9540349809 🔝 genuine Escort Service 🔝✔️✔️call girls in paharganj DELHI 🔝 >༒9540349809 🔝 genuine Escort Service 🔝✔️✔️
call girls in paharganj DELHI 🔝 >༒9540349809 🔝 genuine Escort Service 🔝✔️✔️
 
Glomerular Filtration and determinants of glomerular filtration .pptx
Glomerular Filtration and  determinants of glomerular filtration .pptxGlomerular Filtration and  determinants of glomerular filtration .pptx
Glomerular Filtration and determinants of glomerular filtration .pptx
 
Kolkata Call Girls Services 9907093804 @24x7 High Class Babes Here Call Now
Kolkata Call Girls Services 9907093804 @24x7 High Class Babes Here Call NowKolkata Call Girls Services 9907093804 @24x7 High Class Babes Here Call Now
Kolkata Call Girls Services 9907093804 @24x7 High Class Babes Here Call Now
 
PERFECT BUT PAINFUL TKR -ROLE OF SYNOVECTOMY.pptx
PERFECT BUT PAINFUL TKR -ROLE OF SYNOVECTOMY.pptxPERFECT BUT PAINFUL TKR -ROLE OF SYNOVECTOMY.pptx
PERFECT BUT PAINFUL TKR -ROLE OF SYNOVECTOMY.pptx
 
Call Girls Kanakapura Road Just Call 7001305949 Top Class Call Girl Service A...
Call Girls Kanakapura Road Just Call 7001305949 Top Class Call Girl Service A...Call Girls Kanakapura Road Just Call 7001305949 Top Class Call Girl Service A...
Call Girls Kanakapura Road Just Call 7001305949 Top Class Call Girl Service A...
 
Low Rate Call Girls Mumbai Suman 9910780858 Independent Escort Service Mumbai
Low Rate Call Girls Mumbai Suman 9910780858 Independent Escort Service MumbaiLow Rate Call Girls Mumbai Suman 9910780858 Independent Escort Service Mumbai
Low Rate Call Girls Mumbai Suman 9910780858 Independent Escort Service Mumbai
 
Call Girls Jp Nagar Just Call 7001305949 Top Class Call Girl Service Available
Call Girls Jp Nagar Just Call 7001305949 Top Class Call Girl Service AvailableCall Girls Jp Nagar Just Call 7001305949 Top Class Call Girl Service Available
Call Girls Jp Nagar Just Call 7001305949 Top Class Call Girl Service Available
 
Glomerular Filtration rate and its determinants.pptx
Glomerular Filtration rate and its determinants.pptxGlomerular Filtration rate and its determinants.pptx
Glomerular Filtration rate and its determinants.pptx
 
Measurement of Radiation and Dosimetric Procedure.pptx
Measurement of Radiation and Dosimetric Procedure.pptxMeasurement of Radiation and Dosimetric Procedure.pptx
Measurement of Radiation and Dosimetric Procedure.pptx
 
Call Girls Frazer Town Just Call 7001305949 Top Class Call Girl Service Avail...
Call Girls Frazer Town Just Call 7001305949 Top Class Call Girl Service Avail...Call Girls Frazer Town Just Call 7001305949 Top Class Call Girl Service Avail...
Call Girls Frazer Town Just Call 7001305949 Top Class Call Girl Service Avail...
 
Book Call Girls in Kasavanahalli - 7001305949 with real photos and phone numbers
Book Call Girls in Kasavanahalli - 7001305949 with real photos and phone numbersBook Call Girls in Kasavanahalli - 7001305949 with real photos and phone numbers
Book Call Girls in Kasavanahalli - 7001305949 with real photos and phone numbers
 
epilepsy and status epilepticus for undergraduate.pptx
epilepsy and status epilepticus  for undergraduate.pptxepilepsy and status epilepticus  for undergraduate.pptx
epilepsy and status epilepticus for undergraduate.pptx
 
Call Girls Hebbal Just Call 7001305949 Top Class Call Girl Service Available
Call Girls Hebbal Just Call 7001305949 Top Class Call Girl Service AvailableCall Girls Hebbal Just Call 7001305949 Top Class Call Girl Service Available
Call Girls Hebbal Just Call 7001305949 Top Class Call Girl Service Available
 

Introduction to basic Molecular Biology.pptx

  • 1. Molecular Biology Lecture # 1 Introduction to Molecular Biology Ms. Seerat-e-Fatima M.Phil. Molecular Biology
  • 2. Molecular Biology • Molecular Biology is the branch of biology that deals with the study of gene structure and function at molecular level • The field of molecular biology overlaps with other fields especially genetics and biochemistry. • Molecular biology deals with the study of Central Dogma of Life (DNA RNA Protein) Transcription Translation
  • 4. Introduction to Gene • Introduction: In 1865, Gregor Mendel was the first one to describe the elements of hereditary i.e., Gene. His observations and analysis of the observation features of Peas led him to believe that specific traits were passed on unchanged from parent plant to the next generation. • Definition: Gene is a Greek work that means “to become” or “to grow”. Genes make up the parts of DNA, acts as RNA instructors and to make molecules called Protein. • In humans, genes ranges in size from a few hundred to up to 2 billion bases. Some genes are same in most people whereas some genes are slightly different between different people
  • 5. Characteristics • Genes are the true carriers of heredity, responsible for the development and structure of human body. They are physical substances passed on from parents to children. The parents’ genes, in turn, have come from their parents, grandparents and ancestors. • Some genes are dominant, some are recessive. • Genes do not act alone, they are influenced by genetic background of the individual, and the external and internal environment. • Each human somatic cell has around 30,000 genes present inside nucleus. Some non-nucleated gene are also located inside the mitochondria in the cell.
  • 6. Terms associated with Gene • Gene : A section of DNA that codes for specific trait. • Trait : A trait is a specific characteristic that is unique. Traits determine how we look, or how are body functions. They are inherited e.g., hair color, eye color, etc., • Allele : Alternate form of gene are termed as alleles. The one pair of allele that masks the effect of other when present in same cell is called dominant allele. The allele that is masked by the other pair in the same cell is called the recessive allele and is capable of producing a phenotype in organism only when two alleles are present and identical. • Locus : A fixed position of the chromosome where a certain gene resides. • • Exons and Introns : Most of the genes consists of short coding sequences called exons, interrupted by short intervening non-coding sequences called introns.
  • 7.
  • 8. History • Introduced by Sutton in 1902 and elaborated by T.M Morgan in 1913 who put forward gene theory that stated “Chromosomes are bearer of hereditary units, and each chromosome carries hundreds or thousands of genes. The genes are arranged on the chromosomes in the linear order and on the special regions called locus” • Features outlined by Bridge (1923), Muller (1927) and other scientists are as follows: Discrete particles inherited in mendelian fashion Occupies a definite locus in chromosome Responsible for expression of specific phenotypic character
  • 9. Summary of evolution Year Scientists Gene Concepts 1866 G.J. Mendel A unit factor that controls specific phenotypic trait 1909 A.E. Garrod One gene – one product 1940 Beadle and Tatum One gene – one enzyme 1957 U.M. Ingram One gene – one polypeptide theory 1960s C. Yanofsky and co-workers Gene is a unit of recombination
  • 10. Types of genes Based on genetic phenomena • Gene as a unit of transmission or cistron : The part of DNA specifying a single polypeptide chain is termed as cistron. A cistron can have 100 nucleotide pairs in length to 30,000 nucleotide pairs. It transmits characters from one generation to another as unit of transmission • Gene as a unit of recombination or recon : The smallest segment of DNA capable of being separated and exchange with another chromosome is called recon. A recon consists of not more than two pairs of nucleotides • Gene as a unit of mutation of muton : Muton is a smallest unit of genetic material which when changed or mutated produces a phenotypic trait. It is delimited to single nucleotide
  • 11. Based on activity • Constitutive/House keeping genes : The genes which are constantly expressing themselves in a cell because their products are required for normal cellular activities are called house keeping genes. For example, genes for glycolysis, ATP etc. • Non-constitutive/luxury genes : The genes which activate only according to the requirement of cellular activities e.g., genes for lactose • Inducible genes : The genes are switched on in response to the presence of a chemical substance or inducer, which are required for functioning of the product of gene activity • Cumulative Gene : Some genes have different effects on the action of other genes. These are called cumulative genes • Pleiotropic Gene : The genes which produce changes in more than one character is called pleiotropic gene • Modifying Gene : The gene which cannot produce a character by itself but interacts with other to produce a modified effect is called modifier gene • Inhibitory Gene : The gene which suppresses or inhibits the expression of another gene
  • 12. Functions of genes • Control the morphology or phenotype of an individual • Control the structure and metabolism of body • Replication of genes is essential for cell division • Genes carry the hereditary information from one generation to next • Reshuffling of genes at time of sexual reproduction produces variations
  • 13. Human Genome Project • 1990 : American geneticists started an ambitious quest to map and sequence the entire human genome. • 1999 : the final draft of human chromosome 22 • 2000 : the final draft of human chromosome 21 • 2001 : working draft of whole human genome • 2004 : the finished sequence of euchromatin part of human genome.