生物专业英语-第十一章.pptVIP

Foundations of Genetics Genetics (from Ancient Greek , genitive and that from , origin), a discipline of biology, is the science of genes, heredity, and variation in living organisms. Genetics deals with the molecular structure and function of genes, gene behavior in context of a cell or organism (e.g. dominance and epigenetics), patterns of inheritance from parent to offspring, and gene distribution, variation and change in populations, such as through Genome-Wide Association Studies. Given that genes are universal to living organisms, genetics can be applied to the study of all living systems, from viruses and bacteria, through plants and domestic animals, to humans (as in medical genetics). Genome-Wide Association Studies In genetic epidemiology, a genome-wide association study (GWA study, or GWAS), also known as whole genome association study (WGA study, or WGAS), is an examination of many common genetic variants in different individuals to see if any variant is associated with a trait. GWAS typically focus on associations between single-nucleotide polymorphisms (SNPs) and traits like major diseases. These studies normally compare the DNA of two groups of participants: people with the disease (cases) and similar people without (controls). Each person gives a sample of DNA, from which millions of genetic variants are read using SNP arrays. If one type of the variant (one allele) is more frequent in people with the disease, the SNP is said to be associated with the disease. The associated SNPs are then considered to mark a region of the human genome which influences the risk of disease. Epigenetics The study of the processes involved in the unfolding development of an organism. This includes phenomena such as X chromosome inactivation in mammalian females, and gene silencing within an organism. The study of heritable changes in gene function that occur without a change in the sequence of nuclear DNA. This includes the