Cell Structure and Function: Eukaryotes vs. Prokaryotes

Cell: Basic Unit of Life

1_Celula: The fundamental unit of structure and function in living organisms, forming the lower portion of the material that meets the functional vitales.

2_Difference: Variations arise from differing degrees of specialization. While all cells share a similar chemical composition and structure, some remain undifferentiated, specializing for specific functions.

3_Structures: All cells possess a plasma membrane, a cytoplasmic matrix, and genetic material, enabling self-replication and transmission of species characteristics.

Cell Types: Eukaryotic and Prokaryotic

4_Eukaryotic: Cells with a true nucleus and various organelles enclosed by a plasma membrane. Prokaryotic: Cells lacking a nucleus, with the plasma membrane as the sole boundary.

5_Cytoplasm: Molecular aggregates within the cytoplasm are organized specifically, forming organelles and the nucleus. The nucleus consists of a karyoplast surrounded by a double membrane called the nuclear envelope.

6_Prokaryotic Cells: Smaller cells lacking a nucleus and specific organelles. Chromatin, typically not bound to histones, forms circular chromosomes.

Organelles in Animal and Plant Cells

7_Animal Cells: Include plasma membrane, nucleus, endoplasmic reticulum, dictyosomes, mitochondria, ribosomes, lysosomes, centrioles, vacuoles, and cytoskeleton.

Plant Cells: Possess chloroplasts, vacuoles (instead of lysosomes), leucoplasts, dictyosomes, and a cell wall.

Cellular Transport Mechanisms

Passive Transport

• Occurs without energy expenditure.
• Substances move along a concentration gradient.
• Facilitated diffusion uses special transporter proteins.

Active Transport

• Requires energy expenditure.
• Substances move against a concentration gradient, are insoluble, or are large lipid molecules.
• Primary or secondary transport systems based on energy source.
• Group translocation: Molecules are chemically altered during transport.
• Mass transport: Mechanism for large molecules.