Origin and Composition of Life on Earth (STEAM)
Living beings on Earth originated from primitive conditions, evolving from the Last Universal Common Ancestor (LUCA). All life shares a complex hierarchical composition, starting from atoms and molecules, building up to specialized cells and organisms. Scientific understanding relies heavily on tools like optical and electronic microscopes for detailed observation.
Key Takeaways
Early Earth conditions—volcanic activity and radiation—led to the first life.
LUCA, the first prokaryotic cell, is the common ancestor of all life.
Life is organized hierarchically: atoms, molecules, organelles, cells, tissues, organs.
Biomolecules like lipids, carbohydrates, proteins, and nucleic acids are essential components.
Microscopes (optical and electronic) are crucial for observing cellular structures.
How did life form on Earth?
The formation of life on Earth, known as Challenge 1, occurred under extreme primitive conditions approximately 3.5 billion years ago. The early planet lacked oxygen and had an atmosphere filled with gases, intense volcanic activity, frequent electrical storms, and high solar radiation. These harsh environmental factors acted upon the 'Primitive Soup'—a mixture of inorganic molecules and toxic substances in the oceans—allowing for the chemical reactions necessary for the emergence of the first life form, LUCA, which is the ancestor of all current life.
- Conditions on Earth included no oxygen, a gas-filled atmosphere, volcanic activity, electrical storms, and solar radiation.
- The Primitive Soup was a mixture of inorganic molecules and toxic substances present in the oceans 3.5 billion years ago.
- LUCA (Last Universal Common Ancestor) appeared due to geothermal activity, chemical reactions, electrical discharges, and solar radiation acting on the primitive soup.
- LUCA Characteristics: A simple, small prokaryotic cell without a nucleus, living in an anaerobic environment and nourished by energy from its surroundings.
What is the hierarchical composition of living beings?
Living beings exhibit a complex hierarchical structure, starting from the most basic chemical components and building up to the complete organism. This organization begins at the atomic level, progressing through molecules and macromolecules, which include essential organic and inorganic biomolecules. These components assemble into specialized organelles, which in turn form the fundamental unit of life: the cell. Cells then aggregate to form tissues, organs, systems, and finally, the complete organism capable of performing all vital functions necessary for survival and reproduction.
- ÀTOM: The fundamental building block of all matter.
- MOLÈCULA: Formed by the attraction and union of different atoms.
- MACROMOLÈCULA: Long chains of molecules essential for life, categorized as:
- Organic Biomolecules:
- Lipids (fats): Crucial for energy storage, body protection, and forming the structure of cellular membranes.
- Carbohydrates (sugars): The primary source of energy required for bodily functions.
- Proteins: Essential for building and protecting the body, defending against diseases, and forming muscle tissue.
- Nucleic Acids (DNA/RNA): Contain the genetic information necessary for the body to function and regulate processes.
- Inorganic Biomolecules:
- Water: Transports substances so cells can perform their functions and helps maintain stable body temperature.
- Mineral Salts (Cl, Na, Mg, Fe): Participate in chemical reactions, and form important skeletal and molecular structures.
- ORGÀNUL: Specialized parts within the cell, each performing a specific function, formed by different biomolecules. Key organelles include:
- Nucleus: The cell's control center, housing genetic information to manage growth and functions.
- Endoplasmic Reticulum (ER): The rough part manufactures proteins using attached ribosomes; the smooth part synthesizes lipids and eliminates toxic substances.
- Ribosomes: Proteins created in the nucleus that assist in cellular repair.
- Mitochondria: The powerhouses responsible for supplying energy to the cell.
- Lysosomes: Clean and recycle the cell by digesting waste and unusable substances.
- Plasma Membrane: A thin layer surrounding the cell, controlling what enters and exits.
- Golgi Apparatus: Flattened sacs that help transport substances outside the cell.
- Plant-Specific Organelles:
- Cell Wall (Paret vegetal): A rigid layer providing structure and resistance to plant cells (made of cellulose).
- Chloroplast: Contains chlorophyll, responsible for photosynthesis, creating energy from light, and giving plants their green color.
- Vacuole: Water deposits that store nutrients and waste; they are very large in plant cells.
- Animal-Specific Organelles:
- Centrioles: Protein cylinders that aid in moving chromosomes during cell division.
- CÈL·LULA: The smallest unit of life capable of performing the three main vital functions: Nutrition, Reproduction, and Relation.
- Cell Parts: Plasma membrane, Genetic material (DNA or RNA), and Cytoplasm.
- Types of Cells: Prokaryotic (simpler, no nucleus, e.g., Archaea, Bacteria) and Eukaryotic (complex, defined nucleus, e.g., Animal, Plant, Fungi, Protist).
- Organism Types: Unicellular (single cell, like bacteria) or Pluricellular (many cells, like plants and animals).
- TEIXIT: A collection of cells working together.
- ÒRGAN: A structure composed of tissues united to fulfill a common function.
- SISTEMA O APARELL: A set of structures made up of different organs distributed throughout the organism.
- ORGANISME: The complete living being capable of executing all vital functions.
What tools are used for microscopic observation in biology?
Microscopic observation is essential for studying the detailed structure and composition of living beings, utilizing two primary types of microscopes. The Optical Microscope allows for observation at a microscopic scale, providing color images with various magnification levels, although the image is inverted compared to how the sample is placed. Conversely, the Electronic Microscope enables extremely detailed observation of cellular organelles, producing high-resolution, black-and-white images, functioning much like an X-ray of the cell structure to reveal fine details.
- Microscopi Electrònic: Allows detailed observation of organelles in black and white, providing an X-ray-like view of the cell structure.
- Microscopi Òptic: Allows microscopic observation in color with magnification, but the sample appears inverted.
- Key Parts of the Optical Microscope include the Foot, Arm, Eyepieces, Objectives, Optical tube, Macro/Micrometric screw, Revolver, Slide holder, Coverslip, Stage, Diaphragm, and Illumination focus.
Frequently Asked Questions
What was the 'Primitive Soup' and how did it contribute to life?
The Primitive Soup was a mixture of inorganic molecules and toxic substances present in the early oceans about 3.5 billion years ago. It provided the chemical environment necessary for the first organic molecules to form under the influence of early Earth conditions.
What are the four main types of organic biomolecules found in living beings?
The four main types are Lipids (fats), Carbohydrates (sugars), Proteins, and Nucleic Acids (DNA/RNA). They fulfill vital roles such as energy storage, structural support, defense against disease, and carrying genetic information.
What is the key difference between a prokaryotic and a eukaryotic cell?
Prokaryotic cells are simpler, smaller, and lack a defined nucleus; their genetic material is dispersed in the cytoplasm. Eukaryotic cells are larger, more complex, and have a defined nucleus containing the genetic information and specialized organelles.
