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Genetics deals with the molecular structure and function of genes, with gene behavior in the context of a cell or organism (e.g. dominance and epigenetics), with patterns of inheritance from parent to offspring, and with gene distribution, variation and change in populations. Given that genes are universal to living organisms, genetics can be applied to the study of any living system from viruses and bacteria, through plants (especially crops) to humans (for example in Medical Genetics)

Basis and Importance of Genetics

Genes form the basis of genetic studies.DNA (Deoxyribonucleic acid) is a nucleic acid that contains the genetic information in all known living organisms. Genes are structural and functional units of the DNA (Deoxyribonucleic acid). Within every cell, DNA is organized into long structures called chromosomes. Genes are found on the chromosomes. There are 23 pairs of chromosomes in the human body, one derived from mother, the other from father. These chromosomes are arranged according to their size and shape. This arrangement is called Karyotype. Any variation in this order leads to genetic disorders and abnormalities. Genetic disorders are inborn since they are at the chromosome level.The most common cause for chromosomal abnormalities is mutations that occur due to exposure to radiation. Cancer is a common disease that is partly because of mutations. The advancement in medical sciences these days allow the detection of genetic disorders much before birth or soon after birth.

Branches of Genetics

  • Plant Genetics - The genetics of Plants.
  • Animal Genetics- The genetics of Animals.
  • Human genetics- The genetics of Human Beings.
  • Microbial genetics- The genetics of Microbes.
  • Viral genetics- The genetics of Viruses.
  • Immunogenetics- The study of production of various antibodies that has been found to be under the control of genetic regulation.
  • Molecular genetics- The molecular basis of Genetics.
  • Clinical Genetics- The genetics involved in the detection of the causes of genetic diseases.

Genetic Modification

Introduction to genetic modification:

Genetic modification is the manipulation of the organism’s genes. This genetic modification can be also be called as recombinant DNA technology, where the DNA recombination occurs.Gene modification or gene manipulation is another term where the genetic material is not particularly the DNA. Gene splicing is another term which implies genetic modification.

Procedure for Genetic Modification:

Genetic modification can be done by the help of molecular cloning and transformation. This follows a step-wise procedure.

  • Selection of the gene to be incorporated: this is done in relevance to the importance of the genes. Usually hormones like insulin, proteins like erythropoietin and new types of mouse production for the cancerous studies are being done world-wide.

In case of plants insect or pest resistant and drought resistance genes are been chosen and cloned.

  • Identification of the vector: the vector is the organism that multiplies the gene to a high copy number and carries to the target organism. Selection of the colonies of the bacteria or virus can  be done by the help of marker genes, that express the antibiotic resistance.

For example: viruses to transform bacteria, agrobacterium in case of plant genetic modification studies.

  • Cloning of the gene of interest: the cloning of the gene of interest into the vector is first carried out. This gives the recombinant bacteria. This recombinant bacteria now carries the desired gene into the plasmid. Plasmid is the extra chromosomal genetic material that takes up the desired gene.

Methods are

  1. Transformation
  2. Electroporation
  3. Microinjection


Formation of the genetically modified organisms(GMOs): the vector is capable of entering inside the host and multiplies a number of times giving raise to numerous copies of the gene.

This gene is now designated to enter the host and the host cell takes up the gene giving raise to the modified genome.

Thus producing the genetically modified organism, this is called a transgenic if the new gene is from different species. If the new gene is from same species then the GMO is called cisgenic.

Genetic Maps:--

Introduction to Genetic Maps

The linkage of the genes in a chromosome can be represented in the form of a genetic map, which shows the linear order of the genes along the chromosome with the distances between adjacent genes proportional to the frequency of recombination between them. A genetic map is also called a linkage map or a chromosome map.

The concept of genetic mapping was first developed by Morgan's student, Alfred H. Sturtevant, in 1913. The early geneticists understood that recombination between genes takes place by an exchange of segments between homologous chromosomes in the process now called crossing-over.

Each crossing-over is manifested physically as a chiasma, or cross-shaped configuration, between homologous chromosomes; chiasmata are observed in prophase I of meiosis.

Genetic Mapping

The unit of distance in a genetic map is called a map unit; 1 map unit is equal to 1 percent recombination. For example, two genes that recombine with a frequency of 3.5 percent are said to be located 3.5 map units apart.

One map unit is also called a centimorgan, abbreviated cM, in honor of T. H. Morgan. A distance of 3.5 map units therefore equals 3.5 centimorgans and indicates 3.5 percent recombination between the genes.

A frequency of crossing-over of 2 percent means that of the 200 chromosomes that result from meiosis in 50 cells, exactly 2 chromosomes (the two involved in the exchange) are recombinant for genetic markers spanning the particular chromosome segment.

Genetic map is the principal technique used in modern human genetics to identify the chromosomal location of mutant genes associated with inherited diseases.

The genetic markers used in human genetics are homologous DNA fragments, which differ in length from one person to the next and the principles are enumerated by Sturtevant.

Applications of Genetic Mapping

The common aspects of genetic mapping are (i) the determination of the linear order with which the genetic units are arranged with respect to one another (gene order) and (ii) the determination of the relative distances between the genetic units (gene distance).

The unit of distance that has the greatest utility in predicting the outcome of certain types of matings is an expression of the probability that crossing over will occur between the 2 genes under consideration.

Biotechnology Summary:--

Biotechnology is multidisciplinary applied science. Biotechnology is the appliance of scientific engineering. Dispensation of materials by biological agent to supply produce and services". Goods and services mean different processes such as waste and water treatment, fermentation. It has some of the fieldsin this summary. These are Genetic engineering, cloning, transgenic plants etc.

Genetic Engineering

  • In this summary genetic engineering is defined as "the extracellular creation of new forms or arrangement of DNA in such a way as to allow the incorporation or continued propagation of the altered genetic condition in nature."
  • In biotechnology Genetic engineering is very useful in the fields of medicine,industry,agriculture.
  • In medicine:Number of illness are caused by the failure of certain genes in the body to make specific proteins.
  • Scientists can produce large quantities of insulin in bacterial "factories" by splicing the insulin gene from isolated human cells to plasmids from cells of "Escherchia coli" bacterias.
  • In industry:Genetically engineered microbes have been used to improve the efficiency of food production of summary.
  • In agriculture:Large amounts of a growth hormone found in cows have been obtained from genetically engineered bacteria.
  • When treated with this hormone,cows increase their amount of milk,and beef cattle have leaner meat.

Cloning

  • Cloning is course of action of create an identical copy of an original organism.
  • Clone in the biological sense,single cell ot multi-cellular organism has been directly copied from another organism.
  • Cloning means form a fresh organism with the same genetic information as a cell from an existing one.
  • An asexual method of duplicate where fertilization or inter-gamete makes contact with does not obtain place in biotechnology.
  • This can involve somatic cell is transfered into an egg cell which has its nucleas removed.As the somatic nucleas contain almost all of the genetic information of a summary life form.

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