MOLECULAR BASIS OF INHERITANCE
# DNA & RNA are the type of nucleic acids
Nitrogenous base:-
Are of two type purine (adenine and guanine) and pyrimidine (cytosine and thymine) ,In RNA uracil present instead of thymine
Double helical structure of DNA:-
Proposed by James Watson and Francis crack in 1953
Chargaff rule:-
- Amount of adenine= Amount of thymine & Amount of guanine = Amount of cytosine
- A (adenine) joint to T (thymine) and G (guanine) joint to C (cytosine) by two and there hydrogen bond respectively
- ratio of A/T=G/C=1
Central dogma-
Proposed by Francis Crick, states that genetic information flow from DNA to mRNA then mRNA form protein,
Packaging of DNA:-
In prokaryotes:-
# negative charged DNA is coiled with some positively charged non-histone basic protein
In Eukaryotes:-
Negativity charged DNA molecule wraps around the positively charged histone protein
Euchromatin :-
# Region of chromatin which is loosely packed during interphase
# lightly stained
# contain active gene
Heterochromatin:-
# densely packed during cell division
# appear intensely stained chromatin
# contain inactive gene
Transforming :-
Frederick Griffith, in 1928 conducted experiment with streptococcus pneumonia,
Experiment :-
1) take two type stains bacterium R and S type (non virulent and virulent type)
2) S type injected into mice, mice die
3) R type injected to mice, mice live
4) heat killed injected, mice survive
5) heat killed S type + R type injected mice, mice die
Conclusion:-
Heat killed S type bacteria cause transformation of R type into S type
Transforming principle:-
Oswald Avery, Colin MacLeod, Maclyn McCarty, repeat Griffth experiment in vitro
# they concluded that DNA is hereditary material
DNA as genetic material :-
Harshey and Chase conducted experiment on bacteriophage,
Genetic material character:-
# should able to generate own replica
# chemically and structurally stable
# able to store genetic information
# able to express itself in offspring
# present in all cell
RNA:-
# was first genetic material found
# behave as catalyst as well as genetic material in some viruses
# it can synthesis DNA in reverse transcription process
Ribose sugar+ Nitrogenous base---> Ribonucleoside
Ribonucleotide +phosphate group---> Ribonucleotide
DNA replication :-
# semiconservative in nature:-
Two parental stand separate ,each strands act as template for synthesising complementary stand
Enzyme used:-
1) DNA polymerase :-
Polymerisation of deoxynucleotides of DNA template
2) Helicase:-
Unwind The DNA strand to form replication fork
3) DNA ligase:-
Joints okazaki fragments, which formed from lagging strand
Process:-
1.) initiation:-
# unwinding of double-stranded DNA, form replication fork
2.) Elongation:-
# primase initiate replication oriented in 3' to 5' direction
# replication of lagging strand generates small polynucleotide fragments called 'Okazaki fragments'
# they fragments are then joined together by polynucleotide ligase
Transcription :-
Process of coping genetic information from one strand of DNA into RNA
Transcription unit:-
Of DNA contain 3 region
1) promoter:-
For initiation of transcription
2) structural gene:-
Code for enzyme
3) terminator :-
Where transcription ends
Ciston:-
Segment of DNA coding for polypeptide
Exon:-
In eukaryotes, gene split into coding or expressed sequence of DNA
Intron:-
Non-expressable sequence of DNA
Transcription :-
Process by which RNA formed From DNA..
Genetic code:-
Relationship between the sequence of nucleotides on mRNA and sequence of amino acid in polypeptide
Features:-
# Codon are in always in triplet
# out of 61 codon, 61 code for 20 amino acid
# UAA,UGA,UAG do not code for any amino acid, called stop and terminating codons
# some amino acid code for particular amino acid, hence called unambiguous
# codon read in contigous fashion, commaless without punctuation
# they are nearby universal
Mutation :-
Sudden inheritable change in genetic material
1) point mutation:-
Mutation in single base pair
2) Frameshift:-
Change in reading frame
# insertion :-
Addition of one or more nucleotide in DNA segment
# deletion :-
Removal one or more nucleotide from DNA segments
tRNA:-
Adapter molecule which could read the code on one end and on the other end would bind to specific amino acid
Structure :-
# Clover-leaf structure, 3-D tertiary structure, L-shaped molecule
# have five loops
1) Anticodon loop
2) Amino acid acceptor end
3) T loop
4) D loop
5) variable loop
Translation:-
Synthesis of protein from mRNA with help of ribosome
Steps:-
1) initiation :-
Assembly of ribosome from mRNA
2) Elongation :-
Repeated cycle of amino acid delivery
3) termination :-
Release of polypeptide chain
Regulation of gene expression:-
Controlling amount and time of formation gene products according to the requirement
Operon:-
Proposed by Jacob and Monod, operon is unit of prokaryotic gene expression which include coordinately regulated gene
Components :-
1) structural gene
2) promoter
3) operator
4) regulator gene
5) inducer
Human genome project (HGP):-
Is for development of new era of in biology
Goals:-
# identify 20,000 - 25,000 gene in human
# determine all 3 billion chemical base pair
# improve tools for data analysis
DNA fingerprinting :-
Is an attempt to identity DNA marker for inherited disease
Method:-
1) isolated cell or tissue centrifugation
2) produce many copies by polymerase chain reaction (PCR)
3) DNA fragments separated by agarose gel electrophoresis
4) separated DNA fragment are visualised under U.V after applying suitable dye
5) tranfer to electrophoresis plate or nylon sheet
6) prob's now added to bind specific nucleotide sequence
7) hybrid DNA fragment are detected by autobiography
Application :-
# used in forensic science
# settle paternity disputes
# determine genetic diversity to study evolution
# DNA & RNA are the type of nucleic acids
Nitrogenous base:-
Are of two type purine (adenine and guanine) and pyrimidine (cytosine and thymine) ,In RNA uracil present instead of thymine
Double helical structure of DNA:-
Proposed by James Watson and Francis crack in 1953
Chargaff rule:-
- Amount of adenine= Amount of thymine & Amount of guanine = Amount of cytosine
- A (adenine) joint to T (thymine) and G (guanine) joint to C (cytosine) by two and there hydrogen bond respectively
- ratio of A/T=G/C=1
Central dogma-
Proposed by Francis Crick, states that genetic information flow from DNA to mRNA then mRNA form protein,
Packaging of DNA:-
In prokaryotes:-
# negative charged DNA is coiled with some positively charged non-histone basic protein
In Eukaryotes:-
Negativity charged DNA molecule wraps around the positively charged histone protein
Euchromatin :-
# Region of chromatin which is loosely packed during interphase
# lightly stained
# contain active gene
Heterochromatin:-
# densely packed during cell division
# appear intensely stained chromatin
# contain inactive gene
Transforming :-
Frederick Griffith, in 1928 conducted experiment with streptococcus pneumonia,
Experiment :-
1) take two type stains bacterium R and S type (non virulent and virulent type)
2) S type injected into mice, mice die
3) R type injected to mice, mice live
4) heat killed injected, mice survive
5) heat killed S type + R type injected mice, mice die
Conclusion:-
Heat killed S type bacteria cause transformation of R type into S type
Transforming principle:-
Oswald Avery, Colin MacLeod, Maclyn McCarty, repeat Griffth experiment in vitro
# they concluded that DNA is hereditary material
DNA as genetic material :-
Harshey and Chase conducted experiment on bacteriophage,
Genetic material character:-
# should able to generate own replica
# chemically and structurally stable
# able to store genetic information
# able to express itself in offspring
# present in all cell
RNA:-
# was first genetic material found
# behave as catalyst as well as genetic material in some viruses
# it can synthesis DNA in reverse transcription process
Ribose sugar+ Nitrogenous base---> Ribonucleoside
Ribonucleotide +phosphate group---> Ribonucleotide
DNA replication :-
# semiconservative in nature:-
Two parental stand separate ,each strands act as template for synthesising complementary stand
Enzyme used:-
1) DNA polymerase :-
Polymerisation of deoxynucleotides of DNA template
2) Helicase:-
Unwind The DNA strand to form replication fork
3) DNA ligase:-
Joints okazaki fragments, which formed from lagging strand
Process:-
1.) initiation:-
# unwinding of double-stranded DNA, form replication fork
2.) Elongation:-
# primase initiate replication oriented in 3' to 5' direction
# replication of lagging strand generates small polynucleotide fragments called 'Okazaki fragments'
# they fragments are then joined together by polynucleotide ligase
Transcription :-
Process of coping genetic information from one strand of DNA into RNA
Transcription unit:-
Of DNA contain 3 region
1) promoter:-
For initiation of transcription
2) structural gene:-
Code for enzyme
3) terminator :-
Where transcription ends
Ciston:-
Segment of DNA coding for polypeptide
Exon:-
In eukaryotes, gene split into coding or expressed sequence of DNA
Intron:-
Non-expressable sequence of DNA
Transcription :-
Process by which RNA formed From DNA..
Genetic code:-
Relationship between the sequence of nucleotides on mRNA and sequence of amino acid in polypeptide
Features:-
# Codon are in always in triplet
# out of 61 codon, 61 code for 20 amino acid
# UAA,UGA,UAG do not code for any amino acid, called stop and terminating codons
# some amino acid code for particular amino acid, hence called unambiguous
# codon read in contigous fashion, commaless without punctuation
# they are nearby universal
Mutation :-
Sudden inheritable change in genetic material
1) point mutation:-
Mutation in single base pair
2) Frameshift:-
Change in reading frame
# insertion :-
Addition of one or more nucleotide in DNA segment
# deletion :-
Removal one or more nucleotide from DNA segments
tRNA:-
Adapter molecule which could read the code on one end and on the other end would bind to specific amino acid
Structure :-
# Clover-leaf structure, 3-D tertiary structure, L-shaped molecule
# have five loops
1) Anticodon loop
2) Amino acid acceptor end
3) T loop
4) D loop
5) variable loop
Translation:-
Synthesis of protein from mRNA with help of ribosome
Steps:-
1) initiation :-
Assembly of ribosome from mRNA
2) Elongation :-
Repeated cycle of amino acid delivery
3) termination :-
Release of polypeptide chain
Regulation of gene expression:-
Controlling amount and time of formation gene products according to the requirement
Operon:-
Proposed by Jacob and Monod, operon is unit of prokaryotic gene expression which include coordinately regulated gene
Components :-
1) structural gene
2) promoter
3) operator
4) regulator gene
5) inducer
Human genome project (HGP):-
Is for development of new era of in biology
Goals:-
# identify 20,000 - 25,000 gene in human
# determine all 3 billion chemical base pair
# improve tools for data analysis
DNA fingerprinting :-
Is an attempt to identity DNA marker for inherited disease
Method:-
1) isolated cell or tissue centrifugation
2) produce many copies by polymerase chain reaction (PCR)
3) DNA fragments separated by agarose gel electrophoresis
4) separated DNA fragment are visualised under U.V after applying suitable dye
5) tranfer to electrophoresis plate or nylon sheet
6) prob's now added to bind specific nucleotide sequence
7) hybrid DNA fragment are detected by autobiography
Application :-
# used in forensic science
# settle paternity disputes
# determine genetic diversity to study evolution
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