Fundamental Concepts in Cellular Biology and Life Processes

Cellular and Structural Organization

Eukaryotic Cell

An organism or cell that possesses a clearly defined nucleus.

Prokaryote

A single-celled organism lacking a nucleus and membrane-bound organelles (e.g., bacteria).

Organism

Any living thing.

Cell

The smallest basic unit of life responsible for all life processes.

Tissue

An aggregate of cells in an organism that have similar structure and function.

Organs

A collection of tissues that structurally form a functional unit specialized to perform a particular function.

Organ System

A biological system consisting of a group of organs that work together to perform one or more functions.

Key Cellular Components and Specialized Functions

• Ribosome

  The site where protein synthesis occurs.

• Mitochondria

  The site where cellular respiration occurs (energy production).

Specialized Cell Functions

• Palisade Mesophyll Cells: Specialized for photosynthesis in plants.
• Neurons: Function in the conduction of electrical impulses.
• Red Blood Cells: Specialized for the transport of oxygen.

Nutrients and Membrane Transport

Nutrient Definitions

Nutrient

Materials required by an organism for energy and growth.

Nutrition (Process)

The process of taking in food and converting it into energy and other vital materials required for life.

Passive Transport Mechanisms

Movement of substances into and out of cells occurs primarily through the cell membrane.

• Diffusion: The movement of substances down a concentration gradient.
• Importance of Diffusion: The diffusion of gases is what makes gas exchange possible.
• Osmosis: The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.

Active Transport and Biomolecules

Active Transport

Defined as the movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration (a process that requires energy).

Importance: This process is vital for the movement of molecules and ions across membranes, including nutrient uptake by root hairs in plants.

Proteins and Amino Acids

Proteins, like carbohydrates, are complex molecules made of long chains of smaller units. In proteins, these small molecules are called amino acids.

Metabolism: Enzymes and Photosynthesis

Enzymes (Biological Catalysts)

Enzymes are proteins involved in all metabolic reactions where they function as biological catalysts.

Function: Enzymes break down molecules and significantly speed up (catalyze) chemical reactions.

Photosynthesis

The process by which plants synthesize carbohydrates from raw materials (carbon dioxide and water) using energy derived from light.

Photosynthesis Equations

Chemical Equation:

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Word Equation:

Carbon Dioxide + Water (+ Light Energy) → Glucose + Oxygen

Storage of Carbohydrates

The main advantage of using insoluble substances, such as starch, for storage (rather than soluble substances like sucrose) is that they do not affect the water potential inside the cell.