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Evolution
The scientific theory according to which populations change gradually through a process of natural selection.
5,264 Questions
Traits, which we define as visible aspects of an organism (known as the organism's phenotype) , are coded for by an organisms DNA and are expressed through the proteins that that DNA codes for. Here's the indepth version:
Every living organism on this earth has DNA (or in some bacteria, RNA). These strands of DNA are made of nucleic bases (adenine, thymine, cytosine, and guanine), phosphates, and sugars. These components form DNA into the double helix shape we associate with DNA (the twisted ladder shape.) The nucleic bases are held together in the middle of the two strands by weak hydrogen bonds. This is what we know contemporarily as a strand of DNA.
Strands upon strands of DNA are then packaged together (with protein formations generally called histones) to form what we know as the chromosome. DNA must be packaged this way so that the extremely long strands of DNA can be easily moved during sexual (or asexual) reproduction. But that's another topic.
The expression of "traits" can be traced back specifically to the order of nucleic bases in the DNA, and the proteins those bases code for. Here's how it works.
Let Organism A have a certain part of their DNA that reads
ATCAGCATAGCAUAG
These nucleic bases would then be paired with their complement bases on the other strand of DNA. But let us then say that the cells in Organism A want to express this trait. A process known as transcription and translation must occur.
First, the DNA is "unzipped" by an enzyme. Then, another enzyme moves along the DNA and lays down a "primer strand" (this enzyme, fittingly, is called primase) of RNA. RNA is just like DNA, except that in RNA, Thymine is not existant and a particle known as ribose is present. There are different types of RNA, but in this instance, mRNA (messenger RNA) is used. Another enzyme will move along the DNA-mRNA strands, inserting completmentary bases on the RNA. But since thymine is not expressed in RNA, Adenine must match with another base (only present in RNA) called uracil. The above code would be expressed like this in mRNA:
UAGUCGUAUCGUAUC
(NOTE: Adenine always binds with Thymine or Uracil, Cytosine always binds with Guanine)
This particular strand of mRNA is almost ready to leave the nucleus to be translated. First, a 5' cap and poly-A tail must be added to either end of the strand to protect it during transport.
This mRNA is then taken to ribosomes in the cell, which are located outside the nucleus. This step is called translation.
When the mRNA arrives at the ribosome, it begins to slide "through" the ribosome. Now, it is important to know that DNA and mRNA is read in groups of three. Every three bases, known as a codon, has a matching anticodon. These mRNA codons will feed through the ribosome, and according to the particular order of the bases, a molecule called tRNA (transport RNA) will arrive at the ribosome with the matching anticodons. Attatched to these tRNA structures are the matching anticodons and an amino acid.
The above strand would then match with these anticodons. Note how the anticodons resemble the original DNA.
AUCAGCAUAGCAUAG
The only difference is the fact that thymine is replaced by Uracil. The amino acids that are brought to the ribosome by tRNA then bind to each other through peptide bonds, eventually forming a polypeptide chain (the beginnings of a protein).
Thus, we can see how DNA codes for RNA which then codes for specific amino acids. Scientists have developed a table that can determine which aminos are coded for according to the order of the bases.
So, the need to know is this: DNA codes for mRNA in a process called transcription. Then, that mRNA is translated at ribosomes. The anticodons that bind to the mRNA determine which proteins are made. Ultimately, those proteins express traits based on the function of the protein.
DNA codes for mRNA--> mRNA codes for tRNA anticodons---> the specific order of the assembled amino acids determines their function, thus expressing a trait.
What is the definition of positive mutation?
Last Answer: "Never! When would it be positive? It's a DEFORMATION!!!"
That's incorrect. Without mutations, evolution could never occur. For example:
Imagine a bird with a very small mouth. The seeds it eats are very large, and many birds die of starvation. Because of a mutation, one bird's mouth is larger than any other's, and it ends up surviving, passing on that "deformed" gene to its offspring who also survive because of their large mouths.
That is just one example of how a mutation can lead to positive evolutionary changes.
Origin of man on biblical theory?
Well there's the big bang theory then evolution which is scientifically proven also various religious beliefs regarding how man and the world was created for example christians belive that god created the world and mankind
Why is Darwin more famous than Wallace in the explanation of evolution?
The reason the focus, or major credit goes to Darwin is, though they both realized the principles of evolution, Wallace's presentation was little more than the realization. Darwin had had the realization and spent almost twenty years documenting and exploring the relations and complexities of said theory. Wallace himself had no difficulty with Darwin receiving the majority of the credit. Wallace had sent Darwin his paper on the topic, which kind of shocked Darwin that some one else might scoop his idea, he decided to present his idea to the Royal Society, and when he did so, he presented at the same time Wallace's paper, a very gracious thing to do on Darwins part. Wallace was at the time totally unaware of what was happening and only learned after the fact that he was presented to the Royal Society as co-discoverer of, The Theory Of Evolution By Natural Selection.
Which is an example of vestigial structure?
Most of the "higher evolved" animals I can think of have a vestigial structure or two. The most common example given is of the vestigial leg structures that can be found in the back of whales. Ostriches can't fly so i think their wings are considered vestigial. Humans have a vestigial tail bone.
What evidence is used to support evolutionary theory?
Darwin noted similarities in species far removed from each other. His observations of finch beaks on the Galapagos Islands was one key piece of information helping him formulate his theory. Darwin did not realize these birds were finches to begin with. Only after he brought specimens back to England did an ornithologist point out what his birds were. The adaptations in beaks was one of the things that helped him piece together his theory.
Other evidence existed in the numerous fossils Darwin accumulated. These fossils showed gradual changes in species over vast periods of time. Birds and reptiles are diapsids, whereas all mammals (including humans) are synapsids. Darwin conjectured some fossil might exist to show a link between reptiles and birds, and that fossil was Archeopteryx. Since then we have found numerous other examples of transitions between species.
Yet more evidence is found in genetic similarities. On the basis of their anatomy organisms can be grouped into tree like structures of nested hierarchies. These nested hierarchies are evidence of common ancestry. Any other classification system would constitute evidence against common ancestry, and hence against evolution. However, genetic analysis produces identical overlapping tree structures. This is considered excellent evidence for the soundness of the foundational theory of biology.
The human heart is one example of an tissue or organ?
The levels or organization are: cells -->tissues--->organs--->organ systems--->organism. The heart is an organ of the organ system called the cardiovascular system. This includes the heart, veins and arteries and blood.
Can you compare and contrast gradualism and punctuated equilibrium?
punctuated equilibria accounts for the gaps in the fossil record. Species evolve quickly during relatively short periods. Tiny changes in a species gradually add up to major changes over very long periods of time.
Gradualism proposes that evolution occurs slowly but steadily. These periods of rapid change are separated by long periods of little or no change.
What are the direct evidence of evolution?
Evolution is the change in allele frequency over time in a population of organisms. This is observed and observable. In plant this can be seen in one generation by the process of polyploidy. Where chromosome number can double, for example, in one mating and thus fulfill the definition of both evolution and speciation.
What was the mechanism for evolution according to Darwin?
Survival of the species in a changing environment. A species evolves when its survival is threatened by its environment.
EX: Ho-mo sapiens evolved from primitive hominids by natural selection of those hominids with the larger brains. So gradually the primates acquired larger brains and were better able to survive by out-thinking their predators, including other hominids.
Ho-mo sapiens means "wise man" in Latin.
Why is evolution important to organisms?
It isn't. Evolution is just something that happens where you have populations of organisms. To any individual organism doesn't matter one hoot that its distant ancestor was different than itself, or that its remote descendants will be different again.
How have humans evolved in the last 1000 years?
What are the 5 conditions required for non evolving populations?
1) every large population
2) no emigration or immgration (no gene flow)
3) no mutations: no new alleles added to the gene pool
4) random mating: no sexual selection
5) no natural selection: all genotypes have equal chance at surviving
We often say the theory of evolution when we refer to the idea that life evolved through natural selection.
Note that the theory of evolution, at least as it is expressed in modern evolutionary synthesis, is far and away the bestexplanation for the countless facts we've discovered about life on earth and its long history here. In that light, modern evolutionary synthesis (MES) is considered fact by almost all of the scientific community.
The fact that the ideas expressed have not been proved false does not keep some from trying. And though the questions raised and the contrary opinions expressed are, in general, healthy for science on the whole, there is an undercurrent of desperate intent on the part of some investigators who attack the theory. These exchanges are spoken to in other posts here on WikiAnswers. Links can be found below.
What scientist developed theories on evolution?
Alfred Russel Wallace independently came up with the theory of evolution. His and Darwin's papers on evolution were jointly presented in 1858, and so both are credited with the discovery of evolution by natural selection.
How do you compute the Pharmaceutical evolution index?
ID in pharma talks about Growth of individual brand in relation to growth of a molecule or combination for a particulat period of Time in a .
Like amoxycillin oral growing x percent and Brand aaa Containg amoxycillin growing by y percent.Then ID =Y/D
Trait that improves a species chance of survival?
Adaptation is a trait or structure that improves an organism's chance for survival and reproduction. Benthos is organisms that live on or near the ocean bottom, sometimes attached to surfaces.
What is necessary for natural selection?
External selection forces that make survival hard.
To get the fastest rate of evolution these forces should kill or disable 50% to 90% of the individuals in each generation before they are able to reproduce. But these forces should not kill so many as to make the species go extinct. In most cases these forces only kill or disable less than 10% of the individuals in each generation before they are able to reproduce.
What principle states that living things change gradually over time through natural selection?
The theory of evolution by natural selection.
What did Darwin assert in his book On The Origin of Species as the mechanism of evolution?
Due to genes and mutations, organisms show variation within a species. Changes in the environment can put a selective pressure on the species - certain mutations may be more beneficial, therefore more individuals with that mutation will exist, as they survive and breed. This process is called Natural Selection.
What is Darwin's measure of success in origin of species?
Success in the context of natural selection means reproductive success, or fitness. It refers to the average number of fertile offspring raised by any variant, lineage or population as a whole.
Why are creationist skeptical about evolution?
They are against it because it goes against their beliefs, so they try to prove it wrong but only end up losing.
