GENETIC PROCESSES Through complex processes of transcription and translation, the genetic code is made into proteins. Transcription involves the copying of the DNA segment into ribonucleic acid or RNA. Translation is when the RNA message gets turned into a protein segment. Most recently, the human genome has been sequenced and the polymerase chain reaction was developed, which is a technique for amplifying and identifying DNA sequences. The patterns of inheritance can be determined by doing a genetic pedigree. This is a drawing that looks and the male and female parents, their offspring, and their own offspring. This can be done through many generations, highlighting which individuals in the pedigree carry the trait or disease state. Often, the pedigree will show the different patterns of inheritance of a particular trait or disease. Some genetic traits are the result of multiple genes, such as the height of one s offspring. These are called polygenic traits. This makes it more difficult to draw an actual pedigree chart. In many cases, scientists do not know exactly which genes get involved in the determination of the end result in the offspring. Remember that humans, and many multicellular eukaryotic organisms reproduce sexually so there are traits that can be passed on from both parents to each of their offspring. There are also complex traits that not only involve many genes but yield offspring that have features on a continuum between the two parents. This is true of human skin color. It doesn t mean that these are not heritable but rather that the actual inheritance of the feature is more complicated than can be explained by one gene. Heritability is the degree to which genetic factors determine a specific trait. Human height is an example of something that isn t 100 percent heritable. This is because the environment, such as nutrition, also plays a role in the end result. As mentioned, DNA is what makes up genes. DNA is itself made of nucleotides, which are a type of molecule that can easily form chains. There are four different nucleotides that make up DNA. These are adenine, guanine, cytosine, and thymine. The arrangement of the nucleotides determines the protein made by the gene. Figure 4 shows what the nucleotides look like:
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