Biochemistry is carried out at the cellular or subcellular level, generally on cell extracts. Biochemical methods are applied to the main chemical compounds of genetics—notably DNA, RNA, and protein. Biochemical techniques are used to determine the activities of genes within cells and to analyze substrates and products of gene-controlled reactions. In one approach, cells are ground up and the substituent chemicals are fractionated for further analysis. Special techniques (e.g., chromatography and electrophoresis) are used to separate the components of proteins so that inherited differences in their structures can be revealed. For example, more than 100 different kinds of human hemoglobin molecules have been identified. Radioactively tagged compounds are valuable in studying the biochemistry of whole cells. For example, thymine is a compound found only in DNA; if radioactive thymine is placed in a tissue-culture medium in which cells are growing, genes use it to duplicate themselves. When cells containing radioactive thymine are analyzed, the results show that, during duplication, the DNA molecule splits in half, and each half synthesizes its missing components.
Chemical tests are used to distinguish certain inherited conditions of humans; e.g., urinalysis and blood analysis reveal the presence of certain inherited abnormalities—phenylketonuria (PKU), cystinuria, alkaptonuria, gout, and galactosemia. Genomics has provided a battery of diagnostic tests that can be carried out on an individual’s DNA. Some of these tests can be applied to fetuses in utero.
The-initial-proposal-of-the-structure-of-DNA-by-JamesThe initial proposal of the structure of DNA by James Watson and Francis Crick, which was …[Credits : Encyclopædia Britannica, Inc.]
Sex-linked-inheritance-of-white-eyes-in-Drosophila-fliesSex-linked inheritance of white-eyes in Drosophila flies.[Credits : Encyclopædia Britannica, Inc.]
Steps-involved-in-the-engineering-of-a-recombinant-DNA-moleculeSteps involved in the engineering of a recombinant DNA molecule.[Credits : Encyclopædia Britannica, Inc.]
Dolly-the-sheep-was-successfully-cloned-in-1996-by-fusingDolly the sheep was successfully cloned in 1996 by fusing the nucleus from a mammary-gland cell of …[Credits : Encyclopædia Britannica, Inc.]
Mendels-law-of-independent-assortment-The-example-here-shows-aMendel’s law of independent assortment[Credits : Encyclopædia Britannica, Inc.]
Mendels-law-of-segregation-Cross-of-a-purple-flowered-andMendel’s law of segregation[Credits : Encyclopædia Britannica, Inc.]
Punnett-square-diagrams-are-used-to-predict-all-the-possiblePunnett square diagrams are used to predict all the possible gene combinations that could result …[Credits : Encyclopædia Britannica, Inc.]
James Watson and Francis Crick revolutionized the study of genetics when they discovered the …[Credits : Acquired from Vast Video]
Specific segments of DNA are amplified (copied) in a laboratory using polymerase chain reaction …[Credits : Encyclopædia Britannica, Inc.]
Studying bacteria has lead to the relatively new science of genetic engineering.[Credits : Acquired from Vast Video]
Advantages of budding and grafting.[Credits : Acquired from Vast Video]
Mendel’s discovery of the fundamental laws governing the science of genetics.[Credits : Acquired from Vast Video]
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