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Molecular biology

Like anatomical structures, the structures of the molecules of life reflect descent with modification. Evidence of a common ancestor for all of life is reflected in the universality of DNA as the genetic material and in the near universality of the genetic code and the machinery of DNA replication and expression. Fundamental divisions in life between the three domains are reflected in major structural differences in otherwise conservative structures such as the components of ribosomes and the structures of membranes. In general, the relatedness of groups of organisms is reflected in the similarity of their DNA sequences—exactly the pattern that would be expected from descent and diversification from a common ancestor.

DNA sequences have also shed light on some of the mechanisms of evolution. For example, it is clear that the evolution of new functions for proteins commonly occurs after gene duplication events that allow the free modification of one copy by mutation, selection, or drift (changes in a population’s gene pool resulting from chance), while the second copy continues to produce a functional protein.

Misconceptions of evolution

Although the theory of evolution generated some controversy when it was first proposed, it was almost universally accepted by biologists, particularly younger biologists, within 20 years after publication of On the Origin of Species . Nevertheless, the theory of evolution is a difficult concept and misconceptions about how it works abound.

This site addresses some of the main misconceptions associated with the theory of evolution.

Evolution is just a theory

Critics of the theory of evolution dismiss its importance by purposefully confounding the everyday usage of the word “theory” with the way scientists use the word. In science, a “theory” is understood to be a body of thoroughly tested and verified explanations for a set of observations of the natural world. Scientists have a theory of the atom, a theory of gravity, and the theory of relativity, each of which describes understood facts about the world. In the same way, the theory of evolution describes facts about the living world. As such, a theory in science has survived significant efforts to discredit it by scientists. In contrast, a “theory” in common vernacular is a word meaning a guess or suggested explanation; this meaning is more akin to the scientific concept of “hypothesis.” When critics of evolution say evolution is “just a theory,” they are implying that there is little evidence supporting it and that it is still in the process of being rigorously tested. This is a mischaracterization.

Individuals evolve

Evolution is the change in genetic composition of a population over time, specifically over generations, resulting from differential reproduction of individuals with certain alleles. Individuals do change over their lifetime, obviously, but this is called development and involves changes programmed by the set of genes the individual acquired at birth in coordination with the individual’s environment. When thinking about the evolution of a characteristic, it is probably best to think about the change of the average value of the characteristic in the population over time. For example, when natural selection leads to bill-size change in medium-ground finches in the Galápagos, this does not mean that individual bills on the finches are changing. If one measures the average bill size among all individuals in the population at one time and then measures the average bill size in the population several years later, this average value will be different as a result of evolution. Although some individuals may survive from the first time to the second, they will still have the same bill size; however, there will be many new individuals that contribute to the shift in average bill size.

Questions & Answers

what is abiotic and biotic factors?
Hira Reply
which of the following shows the correct sequence of the cell cycle
Kameishia Reply
who is name virus
Shivam Reply
centromere consist of
Shivam
meeting point of two chromatids
Cffrrcvccgg
Explain the function of nematocysts in cnidarians?
Israel Reply
The nemotocyst is used by Cnidarians (hydra, jellyfish, sea anemones) to sting their prey and any threatening enemy.
Lee
photosynthesis in plants is an example of what ? (a) excretion (b) irritability (c) nutrition (d) reproduction
Lee Reply
If a Hox 13 gene in a mouse was replaced with a Hox 1 gene, how might this alter animal development?
Israel Reply
Which of the following organisms is most likely to be a diploblast?
Israel
what are reactions of photosynthesis?
Maria Reply
what are the probabilities of blood genotypes for the offspring from a cross between a mother lAlA blood and a father with lBi blood?
dayana Reply
what is matter
Emmanuel Reply
matter is anything that has mass and can occupied space
Alice
weight
Alice
example of matter
Oyekemi
You serves as an example of matter Because matter is anything that has mass and occupy space e.g man and every other things that exist on earth.. So think of every other things around you ...
Biola
and you too
Oyekemi
We generally
Biola
What is ecological management
Oyekemi
how the kidney functions as osmoregulatory organ
Sam Reply
That true
Banda
what is the major connection for sugars in glycolysis?
Ibrahim Reply
Simple term of science
Palesa Reply
what does it mean
gopal
it's means what do u know about biology?
Phathu
what is immunisation
Melysa
the action of making a person immune to infections ,for immunisation
Kalia
what is the biology? what do you know about biology
Phathu Reply
biology is the study of living organisms, divided into many specialized fields that cover their morphology, physiology, anatomy, behavior, origin, and distribution.
Julia
The study of all aspects of life. The study of all living organisms (such as animal cells and plant cells) in greater detail (their structure and how they function). It's a very broad science.
juanita
what is prokaryotic
Bhaskar Reply
what is pathogens
Bhaskar
pathogens are a bacterium, virus, or other microorganism that can cause disease.
Lee
transistion metals....
Wasik Reply

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Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
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