Mobile Structures and Life Processes
Mobile Structures: The Foundation of Life
Mobile structures, including DNA, atoms, and molecules, are the fundamental building blocks of life. These structures form the basis of cells, the smallest units of life.
Types of Cells
There are two main types of cells:
- Prokaryotic cells: These are primitive cells with a single, circular DNA molecule called a chromosome.
- Eukaryotic cells: These are more complex cells with a defined nucleus containing multiple linear chromosomes.
Modes of Nutrition
Organisms obtain nutrients through various methods:
- Holozoic: Ingesting solid food and breaking it down internally.
- Saprophytic: Absorbing nutrients from the surrounding environment.
- Parasitic: Obtaining nutrients from a living host.
Classification of Mobile Structures
Mobile structures within cells can be classified into two categories:
- Organelles: Membrane-bound structures within the cell, such as the nucleus, mitochondria, and endoplasmic reticulum.
- Microstructures: Smaller structures within the cell, such as ribosomes, centrioles, and cilia.
Cellular Components and Processes
Cell Membrane:
A selectively permeable membrane composed of lipids and proteins that regulates the passage of substances into and out of the cell.
Osmosis:
Passive transport of substances across a permeable membrane without energy expenditure.
Active Transport:
Energy-requiring transport of substances across a membrane.
Phagocytosis:
Engulfing solid particles by the cell membrane.
Pinocytosis:
Engulfing liquids or small molecules by the cell membrane.
Cell Wall:
A rigid structure found in plant cells that provides support and protection.
Cytoplasm:
A viscous, gelatinous substance that fills the cell and contains organelles and microstructures.
Endoplasmic Reticulum:
A network of folded membranes involved in protein and lipid synthesis.
Nucleus:
The control center of the cell, containing the genetic material.
Golgi Apparatus:
Processes and packages proteins and lipids.
Mitochondria:
The powerhouse of the cell, responsible for energy production.
Plastids:
Found in plant cells and involved in photosynthesis and storage.
Lysosomes:
Contain enzymes that break down waste materials.
Vacuoles:
Storage compartments within the cell.
Ribosomes:
Synthesize proteins.
Nucleolus:
Produces ribosomes.
Centrioles:
Involved in cell division.
Cilia and Flagella:
Hair-like structures that aid in cell movement.
Metabolism
Metabolism encompasses all the chemical reactions that occur within a living organism. It includes:
- Anabolism: Building up complex molecules from simpler ones, requiring energy.
- Catabolism: Breaking down complex molecules into simpler ones, releasing energy.
Autotrophic Nutrition
Autotrophs are organisms that produce their own food. They can be:
- Chemosynthetic: Obtain energy from chemical reactions.
- Photosynthetic: Obtain energy from sunlight.