ATP, Cells, and Cellular Processes: A Comprehensive Look
ATP: The Universal Energy Currency
ATP is a molecule found in all living things and is the main source of energy usable by cells to perform their activities.
The Cell Theory
- The cell is the structural unit of living beings; all living things are made of one or more cells.
- The cell is the functional unit of living things; it is the smallest unit capable of performing the vital functions of a living being.
- All cells come from another pre-existing cell by division.
Basic Structures of Cells
All cells have three basic structures:
- Plasma membrane: A thin membrane that covers the entire cell. It regulates the passage of substances between the outside and inside of the cell.
- Cytoplasm: The cell interior, where the organelles are located. Organelles are structures responsible for carrying out cell functions.
- Genetic material: A substance that controls and regulates the functioning of the cell.
Types of Cells
Based on how the genetic material is found, two types of cells are distinguished:
- Prokaryotic cells: These cells have no nucleus. Their genetic material is dispersed throughout the cytoplasm. Bacteria are prokaryotic unicellular organisms.
- Eukaryotic cells: These cells possess genetic material contained in the nucleus. Their organization is more complex and larger in size. Animal and plant cells are eukaryotic.
Cell Size and Shape
The unit of length used to measure cell size is called the micrometer. Cell shapes vary, including spherical and star-shaped.
Nutrition and Respiration
Nutrition is the process by which living beings incorporate substances from their environment. These substances are transformed by chemical reactions inside the cells into the energy needed for vital functions, growth, and repair of damaged parts.
Respiration is the process by which living beings obtain energy from ingested food. This process requires oxygen and produces energy and waste substances, mainly carbon dioxide and water.
Growth and Reproduction
Growth is an increase in cell size, cell number, or both.
Reproduction is the process by which living beings produce offspring that are identical or similar to themselves.
Chemical Composition of Living Things
The majority bioelements are carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur.
Inorganic Biomolecules
These are present in both living matter and inert matter.
- Water: The most abundant substance in all living things.
- Mineral salts: Perform various functions in living beings, such as forming skeletal structures in vertebrates.
Organic Biomolecules
These are unique to living things.
- Carbohydrates: Molecules composed of monosaccharides, such as glucose.
- Lipids: Very diverse molecules that perform different functions, such as fats.
- Proteins: Macromolecules formed by the union of many molecules called amino acids.
- Nucleic acids: Large biomolecules formed by the union of many molecules.
Cellular Nutrition
Cellular nutrition is the set of processes by which cells obtain the matter and energy necessary to perform vital functions.
Metabolism
Metabolism is the set of chemical processes that nutrients undergo.
Nutrients are substances that the cell takes from the exterior.
- Catabolism: The transformation of complex organic substances into simpler compounds. Catabolism releases energy.
- Anabolism: The conversion of smaller, simpler substances into complex organic substances.
Types of Nutrition
- Autotrophic nutrition: Present in cells capable of producing their own organic matter from inorganic substances.
- Heterotrophic nutrition: Present in cells that need to incorporate organic matter produced by other organisms.