Part I: What Evolution Is in VS .NET

Encoder QR in VS .NET Part I: What Evolution Is

At any given place (locus) on the DNA strand, the sequence of nucleotides (the alleles) that appears can be the same or different, with each particular sequence representing a different manifestation of a particular trait At the locus where the eye-color trait resides, for example, you find alleles representing the different colors: blue, green, brown, and so on Imagine a single locus with two alleles, A and a, each representing a different manifestation of a particular trait Because the locus has only two options, you can figure out pretty easily what individual combinations you may find in the population In this case, some people would have AA (having received A from both parents), Aa (having received A from one parent and a from the other), and aa (having received a from both parents) Here are a couple of other facts about alleles to keep in mind: As is the case with eye color (or blood type or a number of other traits, for that matter), you can have more than two alleles at a given locus in the population, but any particular individual can have at most only two alleles: one that came from the mother and one that came from the father When two alleles at a particular locus are the same, they re said to be homozygous When the alleles are different, they re heterozygous I don t throw these terms in just for kicks Whether the alleles are different or the same is an important factor in how, when, or even whether the heritable trait manifests itself, as the following sections explain

You probably won t be surprised that the genes you (or any other sexually reproducing organism) inherited from your parents can determine outward characteristics hence the idiom chip off the old block The scientific way of stating this rather obvious point is Genotype (genes) translates into phenotype (physical traits) Here are the possibilities: Each different genotype has different phenotypes Maybe AA makes red flowers, aa makes white flowers, and Aa makes pink flowers an easy-to-understand example if you know that the A allele codes for a redpigment protein, and the more of that protein the individual makes, the redder the pigment is The genes interact as dominant (represented by a capital letter) and recessive (represented by a small letter) When a recessive allele is paired with a dominant allele, the phenotype is the same as for an individual with two dominant alleles So in the AA, Aa, and aa example, AA and Aa have one phenotype, and aa has another To read more about genotype and phenotype two key terms in evolutionary biology go the later section Genotype and phenotype

The sum of all the DNA in an organism is called the organism s genome Studying the genome can reveal quite a bit Scientists know, for example, that a gene exists for a trait like eye color But sequence an entire genome, and they see that a lot of genes whose purpose isn t clear They scratch their heads and say I wonder what this one does or Wow, the sequence of that gene looks a lot like a particular fish gene whose function we do know Having a whole genome lets scientists asked questions about genes in a completely different way From an evolutionary point of view, the genome is intriguing because it presents evolutionary scientists with a bunch of deep questions to ponder like, if genome sizes are different for different organisms (and some in ways that make no obvious sense), then how did that happen Or why does so much of the genome seem to be junk (and why is this the case in some species but not others) Any why are similar genes in different places on the genomes of different species