Introduction to Earth Sciences and Biology
1. Evolution of the Atmosphere
The atmosphere is a mixture of gases surrounding the Earth up to 1,000 km in height. As we move away from the surface, we find different gases. Initially, colliding bodies formed the planet, incorporating various gases and water in the form of ice. Many of these components were lost in space. In the last phase of the planet’s creation, massive volcanic eruptions expelled large amounts of gas. The densest gases settled at the surface, while the least dense remained higher,
Read MoreIntroduction to Cell Biology
CELL THEORY
- All living organisms are made of one or more cells.
- Cellular life is simpler. In other words, the cell is the basic unit (structural and functional) of living beings.
- All cells arise from a pre-existing cell. There is no spontaneous generation.
- Each independent cell is capable of feeding itself, interacting, and reproducing, although in multicellular beings it must be coordinated with other cells.
Basic Cellular Functions
Nutrition
Food provides nutrients: building material and energy to work,
Read MoreGenetics and Biotechnology: A Deep Dive into Heredity and DNA
Heredity and Genes
Sons inherit parental characters. The world comprises two types of objects, both made of atoms and molecules. Living beings can create copies of themselves, unlike inert matter. Children inherit characteristics from their parents because living beings store and transmit information about themselves and how to reproduce.
Living beings evolve. Copies are nearly identical, yet slight variations are key to diversity and the evolution of species. Natural selection favors the fittest,
Human Sensory System and Locomotion: A Comprehensive Guide
Receiver Sensitivity
Stimulus
Environmental changes detectable by our body are called stimuli. These stimuli are detected by sensitive nerve cells called receptors.
Types of Receptors
There are two types of receptors: internal receptors (interoreceptors) and external receptors (exteroreceptors).
Internal receptors inform us about the state and function of our internal organs. External receptors, located on the body’s surface, detect external stimuli.
Receptor Classification
- Mechanoreceptors: React to pressure
The Biology of Monera, Protista, Fungi, and Plants
Kingdom Monera
Bacteria: These organisms are prokaryotic, unicellular, and the first on Earth. They include:
- Eubacteria: Green bacteria are photoautotrophs that don’t produce O2 and have bacteriochlorophyll.
- Proteobacteria: A broad group of gram-negative bacteria, including photosynthetic and heterotrophic types like Legionella.
- Spirochetes: Gram-negative bacteria without chlorophyll (e.g., Spirochaeta sicilis).
- Cyanobacteria (Blue-Green Algae): Photosynthetic bacteria with chlorophyll, ancestors of
Protein and Carbohydrate Classification and Functions
Proteins and Carbohydrates
Holoproteins
Fibrous Proteins
Coiled along a single dimension. Insoluble in water, with structural or protective functions.
- Collagen: The main component of connective tissue, and is present as one of the main components of the extracellular matrix of the skin.
- Myosin: A fibrous protein responsible for muscle contraction.
- Keratins: A large group of animal proteins that are synthesized and stored in the cells of the epidermis: they form horns, nails, hair, and wool in many animals.