Universe, Solar System, Earth, and Life: Key Concepts
The Universe
The universe encompasses all matter, energy, space, and time. Everything that exists is part of it. Matter in the universe is not destroyed but is uniformly distributed in places known as galaxies. Galaxies consist of matter that does not emit light (dark matter) and has gravitational attraction.
Location of Earth
Galaxies are large accumulations of matter in the form of dark matter and visible matter. The latter is formed by stars, nebulae, and dust. Our galaxy has millions of stars forming a black hole that engulfs old stars. Our solar system is located in the Orion arm, surrounded by dust and stars.
Celestial Bodies in the Solar System
Planets have sufficient mass for their gravity to make them round and attract other bodies. There are two main types:
- Inner planets: Small, formed by iron and silicates, with high density and high temperatures due to their proximity to the Sun.
- Outer planets: Large, consisting of hydrogen and helium, with a core composed of iron and silicates, and a vast atmosphere. They follow elliptical orbits.
Characteristics of Planets
- Mercury: Closest to the Sun, with extreme temperature variations due to the lack of an atmosphere. Daytime temperatures reach 480°C, while nighttime temperatures drop to -180°C. Its distance from the Sun varies between 46 million km and 76 million km, contributing to these temperature changes.
- Venus: Very dense, with an atmosphere full of CO2, resulting in a constant temperature of 470°C.
- Earth: Average temperature of 15°C, allowing for life due to its suitable atmosphere.
- Mars: Average temperature of -60°C. Water exists as ice, and the atmosphere is sparse.
- Jupiter: The largest planet, with a very large mass and numerous satellites.
- Saturn: The second-largest planet, with a vast atmosphere and 47 satellites.
- Uranus: Its atmosphere consists of gases like hydrogen, helium, and methane, giving it its distinctive color. It has a very dense atmosphere, and the temperature is -193°C.
- Neptune: Very similar to Uranus.
The Atmosphere
The atmosphere is the gaseous layer surrounding planets, maintained by gravity. It arises from the degassing of the hydrosphere. It maintains the color and provides the proper temperature for the existence of life. The first 80 km have a homogeneous blend, and from 80 km up to the limit, the composition varies by molecular mass.
Layers of the Atmosphere
- 0-12 km, Troposphere: Temperature decreases with altitude.
- 12-50 km, Stratosphere: Temperature increases; the ozone layer absorbs ultraviolet rays, maintaining the temperature.
- 50-90 km, Mesosphere: Temperature decreases.
- 90-500 km, Thermosphere: Temperature increases because it absorbs X-rays and gamma rays.
- 500 km – boundary, Exosphere
Greenhouse Effect
Greenhouse gases trap infrared radiation in the Earth and return it. These gases include CO2, CH4, and H2O. The troposphere and stratosphere play roles in this process, with clouds reflecting radiation.
Tectonic Plates
There are three types of tectonic plates:
- Oceanic: Composed only of oceanic lithosphere.
- Continental: Composed of continental lithosphere.
- Mixed: Formed by both oceanic and continental lithosphere.
Plate edges can be constructive, destructive, or neutral.
Ecosystems
The input and output of energy in an ecosystem are solar energy (input) and heat (output). The matter that makes up the ecosystem is found in the hydrosphere (H2O), atmosphere (O2), etc. Biocenosis refers to bound molecules that form larger structures such as carbon, oxygen, and hydrogen. Biocenosis is formed by carbon.
Genetic Processes
Transcription
During transcription, polymers are placed at the start of a gene. The double helix opens, breaking hydrogen bonds. A complementary strand of DNA is formed in the 5′ to 3′ direction. This complementary strand, called mRNA, leaves the nucleus to the cytoplasm through the nuclear membrane pores. (T pairs with A, A pairs with U, G pairs with C).
Translation
In the cytoplasm, the mRNA couples with a ribosome that creates anticodons. These anticodons are placed every three bases (codon), forming amino acids. Translation is the reading of the mRNA message and the production of a protein in the cytoplasm.
Nucleus -> DNA -> (chunk of DNA) gene -> transcription -> mRNA -> nuclear membrane -> ribosome in cytoplasm -> mRNA translation -> creation of anticodons (amino acids) -> protein formation -> specific function.
Key Genetic Terms
- Nucleus: Space bounded by the nuclear membrane, containing DNA.
- Gene: A segment of DNA with a specific function.
- DNA: A set of nucleotides containing an individual’s genetic information.
- Transcription: The process where DNA is copied into an RNA molecule within the nucleus.
- mRNA: A copy of a gene from DNA that leaves the nucleus to express its function.
- Ribosome: Located in the cytoplasm, it reads mRNA and facilitates translation.
- Translation: The process where mRNA is read by a ribosome in the cytoplasm to form a protein with a specific function.
- Protein: A molecule with a particular function, formed by the joining of amino acids (20 types).