Types of Cells

Main thing

Cells are the fundamental units of life, and they come in two main types that are used to determine the three domains of life:

1. Prokaryotic cells - These cells lack a true nucleus and membrane-bound organelles. They make up the domains Archaea and Bacteria, which are simpler and more ancient forms of life. Example: E. coli bacteria, a prokaryotic cell.

2. Eukaryotic cells - These cells contain a nucleus and membrane-bound organelles like mitochondria, chloroplasts (in plants), and the endoplasmic reticulum, all suspended in the cytoplasm. They make up the domain Eukarya, which includes more complex organisms like plants, animals, and fungi. Example: Human skin cells, eukaryotic cells that are part of a multicellular organism.

Terms

• Cell - The fundamental structural and functional unit of all living organisms.

• Organelles - Specialized structures within eukaryotic cells that perform specific functions, such as mitochondria for energy production. Example: Chloroplasts in plant cells for photosynthesis.

• Cytoplasm - The jelly-like substance within cells where organelles are suspended. Example: The cytoplasm in an egg cell.

• Cell membrane - The protective barrier surrounding a cell that controls what enters and exits. Example: The cell membrane of a red blood cell.

An analogy

Cells can be compared to a factory, where different components (organelles) work together to produce the desired products (proteins, energy, etc.). Just like a factory has specialized machinery and workers, cells have specialized organelles and molecules to carry out their functions.

A main misconception

Many people think that all cells are generally similar in every living organism. However, there is a fundamental difference between prokaryotic and eukaryotic cells in terms of their complexity and internal structures. For example, people may incorrectly assume that a bacterial cell and a human cell have the same basic components.

The history

1. 1665: Robert Hooke first observed and named "cells" in cork tissue using a microscope.

2. 1839: Theodor Schwann and Matthias Schleiden proposed the cell theory, stating that all living things are made of cells.

3. 1855: Rudolf Virchow added that all cells arise from pre-existing cells.

4. 1930s: The distinction between prokaryotic (like archaea and bacteria) and eukaryotic cells was established.

5. 1953: The structure of DNA was discovered by Watson and Crick, revealing the genetic material within cells.

"The cell is the most fundamental unit of life." - Bruce Alberts, renowned biochemist and textbook author.

Three cases how to use it right now

1. Diagnosing diseases: Examining cells under a microscope can help doctors identify abnormalities or infections, such as cancer cells or bacterial infections.

2. Stem cell therapy: Stem cells can be used to regenerate damaged tissues or organs, such as using bone marrow stem cells to treat leukemia.

3. Genetic engineering: Modifying the genes within cells can produce desired traits, such as creating bacteria that produce insulin for diabetic patients.

Interesting facts

• The largest known cell is the ostrich egg cell, which can measure up to 5 inches (13 cm) in diameter.

• Mature red blood cells in humans lack a nucleus, making them more efficient at carrying oxygen.

• Nerve cells (neurons) can be up to 3 feet (1 meter) long in humans, with axons that transmit electrical signals.

• Plant cells can have different shapes, such as rectangular or cylindrical, depending on their function.

• Some bacteria can survive in extreme environments, such as hot springs or radioactive waste, due to their simple cellular structure.