Genetics (from Ancient Greek γενετικός genetikos, "genitive" and that from γένεσις genesis, "origin") a discipline of biology, is the science of genes, heredity, and variation in living organisms.
Classical Genetics consists of the technique and methodologies of genetics that predate the advent of molecular biology. A key discovery of classical genetics in eukaryotes was genetic linkage.
FIELDS OF GENETICS Genetics is a broad discipline Encompasses molecular, cellular, organismal, and population biology Many researchers have training in supporting disciplines Biochemistry, biophysics, ecology, agriculture, etc. Traditionally divided into three areas Transmission genetics Molecular genetics Population genetics
FIELDS OF GENETICS Transmission genetics Oldest field of genetics Explores inheritance patterns of traits as they are passed from parents to offspring Modern understanding began with Gregor Mendel Provided conceptual framework for transmission genetics
Cytogenetics is a branch of genetics that is concerned with the study of the structure and function of the cell, especially the chromosomes. It includes routine analysis of G-Banded chromosomes, other cytogenetic banding techniques, as well as molecular cytogenetics such as fluorescent in situ hybridization (FISH) and comparative genomic hybridization (CGH).
Molecular Genetics is the field of biology and genetics that studies the structure and function of genes at a molecular level. The field studies how the genes are transferred from generation to generation. Molecular genetics employs the methods of genetics and molecular biology. It is so-called to differentiate it from other sub fields of genetics such as ecological genetics and population genetics. An important area within molecular genetics is the use of molecular information to determine the patterns of descent, and therefore the correct scientific classification of organisms: this is called molecular systematics
Molecular Genetics Seeks a biochemical understanding of the hereditary material Seek an understanding of DNA’s molecular features Seeks an understanding of gene expression Interfaces with numerous other disciplines Biochemistry, biophysics, cell biology, etc.
Molecular Genetics Seeks a biochemical understanding of the hereditary material Most work is done on a few model organisms Seek an understanding of Escherichia coli, DNA’s molecular Saccharomyces features cerevisiae, Drosophila Seeks an melanogaster, and understanding of Arabidopsis thaliana gene expression Often involves the study Interfaces with of mutant alleles numerous other disciplines Especially loss-of- function mutations Biochemistry, bioph ysics, cell biology, etc.
Population Genetics Foundations of the field arose in the early 1900s Concerned with genetic variation and its role in evolution Links the fields of classical genetics and evolutionary biology
Genomics a discipline in genetics concerned with the study of the genomes of organisms. The field includes efforts to determine the entire DNA sequence of organisms and fine-scale genetic mapping ncludes studies of intragenomic phenomena such as heterosis, epistasis, pleiotropy and other interactions between loci and alleles within the genome. In contrast, the investigation of the roles and functions of single genes is a primary focus of molecular biology or genetics and is a common topic of modern medical and biological research.
Proteomics the large-scale study of proteins, particularly their structures and functions. The term "proteomics" was first coined in 1997 to make an analogy with genomics, the study of the genes. The word "proteome" is a blend of "protein" and "genome", and was coined by Marc Wilkins in 1994 while working on the concept as a PhD student After genomics and transcriptomics, proteomics is considered the next step in the study of biological systems It is much more complicated than genomics mostly because while an organisms genome is more or less constant, the proteome differs from cell to cell and from time to time.
Behavioral Genetics the field of study that examines the role of genetics in animal (including human) behaviour. Often associated with the "nature versus nurture" debate, behavioural genetics is highly interdisciplinary, involving contributions from biology, genetics, ethology, psychology, and statistics. Traditional research strategies in behavioral genetics include studies of twins and adoptees, techniques designed to sort biological from environmental influences. Genetics and molecular biology have provided some significant insights into behaviors associated with inherited disorders.
Sir FrancisGaltona nineteenth-century intellectual, isrecognized as one of the firstbehavioural geneticists.a cousin of Charles Darwin, studied theheritability of human ability, focusing onmental characteristics as well aseminence among close relatives in theEnglish upper-class. In 1869, Galtonpublished his results in HereditaryGenius.[
Psychiatric genetics subfield of behavioral neurogenetics, studies the role of genetics in psychological conditions such as alcoholism, schizophrenia, bipolar disorder, and autism. The basic principle behind psychiatric genetics is that genetic polymorphisms, as indicated by linkage to e.g. a single nucleotide polymorphism (SNP), are part of the etiology of psychiatric disorders.
Developmental Genetics Scientists in the Developmental Genetics Program study a number of diverse developmental questions including: Establishment of the body axis by morphogen gradients, Regionalization of the embryonic xbrain into different structural and functional regions, Neural stem cell allocation and differentiation, Axon navigation and branching, Development of the embryonic eye, Heart development and analysis of heart function, Germ line development.
Conservation genetics an interdisciplinary science that aims to apply genetic methods to the conservation and restoration of biodiversity. Researchers involved in conservation genetics come from a variety of fields including population genetics, molecular ecology, biology, evolutionary biology, and systematics.
Metagenics it means "the creation of something which creates.“ the practice of engineering organisms to create a specific enzyme, protein, or other biochemicals from simpler starting materials.
Ecological Genetics is the study of genetics in natural populations. This contrasts with classical genetics, which works mostly on crosses between laboratory strains, and DNA sequence analysis, which studies genes at the molecular level.
Evolutionary Genetics the broad field of studies that resulted from the integration of genetics and Darwinian evolution, called the ‘modern synthesis’ (Huxley 1942), achieved through the theoretical works of R. A. Fisher, S. Wright, and J. B. S. Haldane and the conceptual works and influential writings of J. Huxley, T. Dobzhansky, and H.J. Muller. This field attempts to account for evolution in terms of changes in gene and genotype frequencies within populations and the processes that convert the variation with populations into more or less permanent variation between species
Medical Genetics is the specialty of medicine that involves the diagnosis and management of hereditary disorders medical genetics refers to the application of genetics to medical care. Example: gene theraphy
Human genetics describes the study of inheritance as it occurs in human beings Human genetics encompasses a variety of overlapping fields including: classical genetics, cytogenetics, molecular genetics, biochemical genetics, genomics, population genetics, developmental genetics, clinical genetics, and genetic counseling.
Microbial Genetics a subject area within microbiology and genetic engineering. It studies the genetics of very small (micro) organisms. This involves the study of the genotype of microbial species and also the expression system in the form of phenotypes.It also involves the study of genetic processes taking place in these micro organisms i.e., recombination etc
Archaeogenetics a term coined by Colin Renfrew, refers to the application of the techniques of molecular population genetics to the study of the human past. the analysis of DNA recovered from archaeological remains, i.e. ancient DNA; the analysis of DNA from modern populations (including humans and domestic plant and animal species) in order to study human past and the genetic legacy of human interaction with the biosphere; and the application of statistical methods developed by molecular geneticists to archaeological data.
QuantitativeGeneticsthe study of continuously measured traits (such as height or weight)and their mechanisms.It can be an extension of simple Mendelian inheritance in that thecombined effects of one or more genes and the environments in whichthey are expressed give rise to continuous distributions of phenotypicvalues.
Quantitative Traits Mendel worked with traits that were all discrete, either/or traits: yellow or green, round or wrinkled, etc. Different alleles gave clearly distinguishable phenotypes. However, many traits don’t fall into discrete categories: height, for example, or yield of corn per acre. These are “quantitative traits”. The manipulation of quantitative traits has allowed major increases in crop yield during the past 80 years. This is an important part of why today famine is rare, a product of political instability rather than a real shortage of food. Until very recently, crop improvement through quantitative genetics was the most profitable aspect of genetics. Early in the history of genetics is was argued that quantitative traits worked through a genetic system quite different from Mendelian genetics. This idea has been disproved, and the theory of quantitative genetics is based on Mendelian principles.
Types of Quantitative Trait In general, the distribution of quantitative traits values in a population follows the normal distribution (also known as Gaussian distribution or bell curve). These curves are characterized by the mean (mid-point) and by the variance (width). Often standard deviation, the square root of variance, is used as a measure of the curve’s width. 1. continuous trait: can take on any value: height, for example. 2. countable (meristic) can take on integer values only: number of bristles, for example. 3. threshold trait: has an underlying quantitative distribution, but the trait only appears only if a threshold is crossed.
Punchline and Basic Questions The basic tenet of quantitative genetics: the variation seen in quantitative traits is due to a combination of many genes each contributing a small amount, plus environmental factors. Or: phenotype = genetics plus environment. Basic questions (plus answers): 1. What is the genetic basis of quantitative traits? (they are caused by normal genes following Mendel’s rules). 2. How can we separate the effects of genetics from the effects of the environment? (by inbreeding to eliminate genetic variation). 3. How can we predict and control the outcome of a cross? (by artificial selection).
Quantitative Traits are Caused byMendelian Genes In 1909 Herman Nilsson-Ehle from Sweden did a series of experiments with kernel color in wheat. Wheat is a hexaploid, the result of 3 different species producing a stable hybrid, an allopolyploid. There are thus 3 similar but slightly different genomes contained in the wheat genome, called A, B, and D. Each genome has a single gene that affects kernel color, and each of these loci has a red allele and a white allele. We will call the red alleles A, B, and D, and the white alleles a, b, and d. Inheritance of these alleles is partially dominant, or “additive”. The amount of red pigment in the kernel is proportional to the number of red alleles present, from 0 to 6.
References http://en.wikipedia.org/wiki/Molecular_genetics http://en.wikipedia.org/wiki/Genomics n.wikipedia.org/wiki/Genetics http://en.wikipedia.org/wiki/Cytogenetics http://www.google.com.ph/url?sa=t&rct=j&q=branches and field of genetics ppt&source=web&cd=5&ved=0CEkQFjAE&url=http%3A%2F%2Ffaculty.inverhills.edu%2Fbiw http://www.ornl.gov/sci/techresources/Human_Genome/elsi/behavior.shtml http://en.wikipedia.org/wiki/Behavioural_genetics http://en.wikipedia.org/wiki/Classical_genetics http://saturn.med.nyu.edu/research/dg http://www.google.com.ph/imgres?q=developmental+genetics&um=1&hl=tl&sa=N&biw=1280& bih=801&tbm=isch&tbnid=K85hrCRHQs4t6M:&imgrefurl=http://www.craniodevgen.org/&docid =DozRD--s7bbcmM&imgurl=http://www.craniodevgen.org/Images/home- graphic.jpg&w=476&h=332&ei=HphXT5riKoa0iQe- sa3JDQ&zoom=1&iact=rc&dur=372&sig=104111655101932247338&page=1&tbnh=135&tbnw=180 &start=0&ndsp=24&ved=1t:429,r:6,s:0&tx=121&ty=92 http://en.wikipedia.org/wiki/Conservation_genetics http://en.wikipedia.org/wiki/Metagenics http://en.wikipedia.org/wiki/Ecological_genetics