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                              MOLECULAR GENETICS

 

 

 

          

 

 

 

 

INTRODUCTION-

 

      That  is the field of biology and genetics that studies the structure and function of genes at the molecular level. Molecular genetics employs the methods of molecular biology and genetics to elucidate molecular function and interactions with genes. It is so called to differentiate it from other sub fields of genetics such as population genetics and ecological geneticspopulation geneticsAlong with determining the pattern of descendants, molecular genetics help to explain developmental biology, genetic mutations that can create certain types of diseases. 

 

About the molecular genetics we can say the study of the agents that pass information from generation to generation. These molecules, genes are polymers of deoxyribonucleic acid. Just four chemical building blocks—adenine (A)guanine (G), thymine (T), and cytosine (C) is are placed in a unique order to code for all of the genes in all organisms. Genes determine hereditary traits, such as the color of our eyes and hairs. They do this by providing instructions for how every activity in every cell of our body should be carried out. eg. a gene may tell a liver cell to remove excess cholesterol from our blood. How does a gene do this? It will instruct the cell to make a individual protein. It is this protein that then carries out the real work. In the case of excess blood cholesterol, it is the receptor proteins on the outside of a liver cell that bind to and remove cholesterol. The cholesterol molecules can then be transported into the cell, where they are further processed by others proteins.

 

Many diseases are caused by mutations, When the information coded for by a gene changes, the resulting protein may not function properly or may not even be made at all. In either case, the cells have that genetic change may no longer perform as expected. We now know that changes in genes code for the cholesterol receptor protein create a disease called familial hypercholesterolemia. The cells of an particular with this disease end up having reduced receptor function and cannot remove a sufficient amount of low density bad cholesterol, or lipoprotein (LDL), from their blood. A person may then develop dangerously high levels of cholesterol, putting them at increased risk for both heart stroke and attack.

 

 

Defination-

 

The field of genetics that focuses on the chemical structure and the functions, ,mutations and replication of the molecules involved in the transmission of genetic information, namely DNA or RNA. Molecular genetics is concerned with the arrangement of genes on DNA molecule, the replication of DNA, the transcription of DNA into RNA, and the translation of RNA into proteins. 

 

 

 

MOLECULAR GENETICS SYLLBUS-

 

 

The molecular genetics is major field of biotechnology so according student facilty it divided in to two sections-

 

Section A- macromolecular synthesis: chromosom structure and applicaion, DNA structure, DNA replication, replication of bacterial chromosome, gene expression: genetic code and its features deciphering of genitic code. RNA structure and functions, transcription, processing of mRNA, rRNA, tRNA, Reverse transcrption, ribosome structure. translation, details of protien synthesis, regulation of protien synthesis with Lac operons as model, inhibition of translation, post translation, modification of theprotien.

 

 

Section B- Mutation elementory concept, types of mutations, point mutation ( base pair change fram shift deletion ) , plasmid- properties (replication, functions, of Ori regions, incompatibility, palsmid genetics plasmids cloning vectors, conjugation transformation, bacteriophage-transposition, and non-homologous recombination, recombinant DNA techniques andcloning, restriction endonuclease and recombinant DNA, DNA  cloning with restriction endonucleases, cloning bacterial genes, polymerase chain reaction (PCR) , GENOMIC AND cDNA library.

 

 

 

MOLECULAR GENETICS BOOOK-

 

 

     These books have three types of information. The main part of each book chapter is the text. Following each chapter are references and problems. References are arranged by topic, and one topic is “Suggested Readings”. The additional references cited permit a student or expert to find many of the fundamental papers on a topic. Some of these are on topics not directly covered in the text. Because solving problems helps focus one’s stimulates and attention understanding, many thought-provoking problems or paradoxes are provided. Some of these require use of material in addition to the text. Solutions are provided to about half of the problems.

 

 

These are some important books witch suit to study-

 

 

1.   Human Molecular Genetics, Fourth Edition by Tom Strachan and Andrew Read (Apr 2, 2010).

 

2.   Molecular Genetics of Bacteria by Larry Snyder, J. E. Peters, Tina M. Henkin and Wendy Champness (Dec 28, 2012).

 

3.   Molecular Genetics of Bacteria, Third Edition (Snyder, Molecular Genetics of Bacteria) by Larry Snyder and Wendy Champness (May      

     31, 2007).

 

4.   Introduction to Genetics: A Molecular Approach by T A Brown (Aug 5, 2011).

5.  BRS Biochemistry, Molecular Biology, and Genetics, Fifth Edition (Board Review Series) by Todd A. Swanson M.D. Ph. D, Sandra I.

 

6. Kim MD PhD and Marc J. Glucksman PhD (Dec 7, 2009).

 

7. Molecular Biology of the Gene, Sixth Edition by James D. Watson (Dec 18, 2007).

 

                                 

 

 

 

 

MOLECULAR GENETICS TECHNIQUES-

 

 

  The methods used by molecular geneticists to gain and study to DNA have been developed through keen adaptation and observation of the chemical reactions and biological processes that occur naturally in all livingcells. Many of the enzymes that copy DNA, form RNA from DNA, and synthesize proteins from an RNA template were first characterized in bacteria. These basic research results have become fundamental to our understanding of the function of human cells and have led to immense practical uses for studying a gene and its corresponding protein.There are three general techniques used for molecular genetics: amplification, separation and detection, and expression. Specifically used for amplification is polymerase chain reaction (PCR), which is an “indispensable tool in a great variety of applications”.In the separation and detection technique DNA and mRNA are isolated from their living cells. Gene expression in cells is done in a place or time that is not normal for that particular gene.

 

Amplification-

There are other methods for amplification besides polymerase chain reaction. Cloning DNA in bacteria is also a way to amplify DNA in genes.

 

Polymerase chain reaction-

The main materials used in PCR are DNA nucleotides, primers and template DNA, Taq polymerase. DNA nucleotides are the base for the new DNA, the template DNA is the specific sequence being amplified, primers are complementary nucleotides that can go on either side of the template DNA, and Taq polymerase is an heat stable enzyme that jump-starts the production of new DNA at the high temperatures needed for reaction. This technique no need to use living cells; all that is needed is the base sequence of the DNA and materials.

 

Cloning DNA in bacteria-

 

Cloning for this type of amplification entails making multiple identical xerox of a sequence of DNA. The target DNA sequence is then inserted into a cloning vector. Because this vector originates from a self-replicating virus, plasmid, or higher organism cell when the appropriate size DNA is inserted the “target and vector DNA fragments are then ligated” and create a recombinant DNA (rDNA) molecule. The rDNA molecules are then put into a bacteria strain (usually E. coli) which produces several identical copies by transformation. Transformation is the DNA uptake mechanism possessed by bacteria. However, only one rDNA molecule can be cloned within a single bacteria cell, so each clone is of just one DNA insert.

 

Separation and detection-

In separation and detection DNA and mRNA are isolated from cells and then detected simply by the isolation. Cell cultures are also grown to provide a constant supply of cells ready for isolation.

Cell cultures-

Mean that culture is grown in artificial conditions. Some cell types grow well in cultures such a skin cells, but other cells are not as productive in cultures. There are many techniques for each type of cell, some only recently being found to foster growth in stem and nerve cells. Cultures for molecular genetics are frozen in order to preserve all xerox of the gene specimen and thawed only when needed. This allows for a steady supply of living cells.

DNA Isolation-

It extracts DNA from a cell in a pure form. First, the DNA is separated from cellular components like proteins, RNA, and lipids. This is done by placing the chosen cells in a tube with a solution that chemically, mechanically, breaks the cells open. This solution contains enzymes, chemicals, and salts that breaks down the cells except for the DNA. It haves enzymes to dissolve proteins, chemicals to destroy all RNA present, and salts to help pull DNA out of the solution liquid.

 

mRNA isolation-

Expressed DNA that codes for the synthesis of an protein is the final aim for researchers and this expressed DNA is obtained by isolating mRNA. First, lab use a normal cellular modification of mRNA that adds up to 200 adenine nucleotides to the end of the molecule . Once this has been added, the cell is ruptured and its cell contents are exposed to synthetic beads that are coated with thymine string nucleotides. Because Adenine and Thymine pair together in DNA, the poly(A) tail and synthetic beads are attracted to one another, and once they bind in this process the cell components can be washed away without removing the mRNA. Once the mRNA has been isolated, reverse transcriptase is employed to change it to single-stranded DNA, from which a stable double-stranded DNA is produced using DNA polymerase enzymeComplementary DNA is much more stable than mRNA and so, once the double-stranded DNA has been produced it represents the expressed DNA sequence.

 

 

                                                                                                   

 

 

 

 

MOLECULAR GENETICS OF BACTERIA-

 

Bacteria strongly regulate their activities Bacteria must respond quickly to changes in the environment.  Bacteria are small compared to their environment, have no real capacity for energy storage. Simultaneous transcription and translation allows them to synthesize the proteins witch they need quickly. Wasteful activities are avoided.  If there are sufficient amounts of some metabolite, bacteria will avoid making more and avoid making the enzymes that make the metabolite. Biosynthesis costs! genetic regulation and Biochemical regulation .

 

Bacteria are successful because
 
1. They carefully regulate their use of energy in metabolic processes by shutting down unneeded pathways at the biochemical and genetic levels.
 
2. They share genetic information with other bacteria,increasing their ability to adapt to their environment.
 
 
in Genetic regulation of bacteria possess many genes that they are not using at any particular time. Transcription and translation are expensive; why spend ATP to make an enzyme you don’t need? Induction of lactose operon and diauxic growth with sugars. In biochemical regulation, processes like feedback inhibition prevent wasteful synthesis.To save more energy, bacteria prevent the synthesis of unneeded enzymes by preventing transcription. In operons, several genes that are physically adjacent are regulated together.Two important patterns of regulation: Induction and repression. In induction, the genes are off until they are needed. In repression, the genes normally in use are shut off when no longer needed.
 

 

 

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