Células (Cells)

Teoria Celular (Cell Theory)

The Cell Theory is a fundamental concept in biology, describing the basic properties and functions of cells. It states:

• All living organisms are composed of cells.

• Cells are the basic morphological and functional units of life.

• Cells arise only from pre-existing cells.

Exception: Viruses are considered acellular because they lack cellular structure and do not perform all functions of living cells.

Partes Básicas da Célula (Basic Parts of the Cell)

All cells share certain fundamental components:

• Membrana plasmática (Plasma membrane): The boundary that separates the cell from its environment and regulates the movement of substances in and out.

• Citoplasma (Cytoplasm): The internal fluid containing organelles and molecules.

• Material genético (Genetic material): DNA or RNA, which carries hereditary information.

Classificação das Células (Classification of Cells)

Cells are classified based on the presence or absence of a nucleus:

• Sem núcleo (Without nucleus): Procarionte (Prokaryotic) cells, such as bacteria, lack a defined nucleus.

• Com núcleo (With nucleus): Eucarionte (Eukaryotic) cells, such as plant and animal cells, have a true nucleus enclosed by a membrane.

Organelas (Organelles)

Organelles are specialized structures within cells that perform distinct functions. Major organelles include:

• Mitocôndria (Mitochondria): Site of cellular respiration and energy production.

• Ribossomo (Ribosome): Responsible for protein synthesis.

• Retículo endoplasmático (Endoplasmic reticulum): Involved in protein and lipid synthesis.

• Complexo golgiense (Golgi complex): Modifies, sorts, and packages proteins and lipids.

• Lisossomo (Lysosome): Contains digestive enzymes for breaking down waste.

• Centriolo (Centriole): Important for cell division in animal cells.

• Vacuolo (Vacuole): Stores substances; prominent in plant cells.

Tipos de Células (Types of Cells)

• Célula Vegetal (Plant Cell): Contains chloroplasts, a cell wall, and a large central vacuole.

• Célula Animal (Animal Cell): Lacks a cell wall and chloroplasts, but contains centrioles and smaller vacuoles.

Example: Plant cells perform photosynthesis due to the presence of chloroplasts, while animal cells rely on mitochondria for energy production.

Additional info: The diagram visually compares plant and animal cells, highlights the main organelles, and summarizes cell theory, which is foundational for understanding cell biology.