Key Theories of Evolution and the Origin of Life
Hybridization (general technique for detecting a specific gene, allowing a labeled probe with the complementary sequence to bind to the target molecule)
Recombination of DNA (the technology to transplant genes from one species to the genome of another)
Abiogenesis (study of how new biological life would arise from inorganic matter through natural processes)
Lamarck:
His theory considered that species proceeded one from another through transformation.
Causes of transformation:
- Species are constantly making an effort to adapt to their environment, which leads to the transformation of their organs.
- New acquired characteristics are hereditary and passed on to descendants.
Darwin:
In 1859 he published The Origin of Species, which explained the theory of natural selection of variations brought about at random.
Conclusion: Changes are produced in life, generating variety. Those varieties which have more possibilities of survival until they reach the reproductive period will transmit their features to their descendants.
Principles:
- Of variation (changes in the characteristics of individuals are constantly produced in all populations)
- Of heredity (individuals of a species are like their progenitors as they inherit those characteristics)
- Of selection (the environment will select those individuals which accumulate the advantageous variations)
Neo-Darwinism:
A theory about evolution that includes Darwin and Mendel's conclusions. The theory defines species as a group of populations that have a set of common genes. Mutations are frequent in species:
- Advantageous for the species (they survive better and the mutation is inherited)
- Lethal (they do not survive and the mutation tends to disappear)
Natural Selection:
It favors the survival of individuals with an advantage over others in a population. The least well-adapted members do not survive to reproduce, and the population becomes increasingly adapted to its environment. When two populations are so different that they cannot interbreed, we consider them separate species.
Origin of Species:
Different geographical zones can host the same species. If a population becomes isolated and stops exchanging its genome, mutations will occur.
Isolation:
- That prevents sexual union (two animals of the same species but of different varieties do not recognize each other because of color or behavior)
- Reproductive isolation after fertilization (inability of the zygote to develop, or sterility of the descendants)
Spontaneous Generation
The belief that living organisms appear from dead meat or humid earth, due to worms.
- Redi: He put a piece of meat in a jar. People said it was because there was no oxygen, so he covered the jar with a cloth.
- Pasteur: He prepared meat broth and heated it to eliminate microorganisms. He put it into jars and curved their endings. The jars were open to air, but microorganisms were trapped.
Origin in the Universe:
Resistant bacteria can support harsh conditions and may travel through space.
Oparin:
Life began in the seas due to the interaction of atmospheric components with ultraviolet radiation. These components accumulated in the seas and recombined into macromolecules thanks to the energy from lightning.
Miller:
He created conditions similar to Earth's 3,500 million years ago. The sample he obtained contained substances that form proteins and nucleic acids.
Vents:
Life began at submarine hydrothermal vents.
Clay:
The concentration of organic molecules in the primordial soup might be low, but high on the clay at the bottom of the sea.