Cells, an Introduction: Prokaryotes, Eukaryotes and the Cell Theory

Summary

This video introduces the basics of cells, explaining their essential features, including the membrane, DNA, RNA, ribosomes, proteins, and cytoplasm. It compares prokaryotic cells (like bacteria) with eukaryotic cells (like those in humans and animals), highlighting differences such as the presence of a nucleus in eukaryotes. The video also covers the cell theory, stating that all living things are composed of cells, cells are the basic units of life, and all cells arise from other cells. It wraps up by encouraging further learning with additional resources.

Takeaways

• 😀 Cells are the basic units of life and come in two main types: eukaryotic and prokaryotic.
• 😀 A meter can be divided into 1000 millimeters, and a millimeter can be divided into 1000 micrometers (microns), the size range of most cells.
• 😀 The basic features of all cells include a membrane, DNA, RNA, ribosomes, proteins, and cytoplasm.
• 😀 Bacteria, such as E. coli, are prokaryotic cells, meaning they lack a nucleus and are simpler in structure than eukaryotic cells.
• 😀 Prokaryotic cells are typically between 0.5 and 5 micrometers in size, and their DNA is in the cytoplasm, not enclosed in a nucleus.
• 😀 Eukaryotic cells have a membrane-bound nucleus and various internal compartments, including organelles like mitochondria.
• 😀 Eukaryotic cells are generally larger than prokaryotic cells and include multicellular organisms like animals, plants, fungi, and algae.
• 😀 The largest eukaryotic cells, such as an egg cell, can be up to 100 micrometers in size.
• 😀 The cell theory has three main parts: (1) all living things are made up of one or more cells, (2) cells are the basic units of structure and function, and (3) all cells come from other cells.
• 😀 Cells are the fundamental units that perform all life functions and make up higher-level structures in organisms.
• 😀 The origin of life, or how the first cells emerged, remains an open question, with additional resources available for further learning.

Q & A

What are the basic features that all cells share?

All cells share a membrane that controls what enters and exits, DNA that carries genetic material, RNA that transmits instructions, ribosomes that synthesize proteins, and cytoplasm where most cellular activities occur.

How small can the smallest cells be?

The smallest cells can be less than a micrometer in size, with some bacteria being among the smallest.

What is the difference between prokaryotic and eukaryotic cells?

Prokaryotic cells are simpler and lack a nucleus, with their DNA located in the cytoplasm. Eukaryotic cells are more complex, containing a membrane-bound nucleus that houses their DNA and often have additional specialized organelles.

What is the size range of prokaryotic cells?

Prokaryotic cells range in size from about half a micrometer to five micrometers.

What structures do prokaryotic cells typically have?

Prokaryotic cells have a membrane, RNA, ribosomes, cytoplasm, and usually a cell wall. They may also have other features like a protective outer capsule or a flagellum for movement.

What is the significance of prokaryotic cells in the history of life on Earth?

Prokaryotic cells were the first form of life on Earth, existing for billions of years. They include bacteria that transformed Earth's atmosphere by producing oxygen through photosynthesis.

What is a key feature of eukaryotic cells that distinguishes them from prokaryotic cells?

Eukaryotic cells have a membrane-bound nucleus that contains their linear chromosomes, unlike prokaryotic cells which have circular chromosomes located in the cytoplasm.

What are some examples of multicellular eukaryotes?

Multicellular eukaryotes include animals, plants, fungi, and algae, all of which are made up of multiple eukaryotic cells.

What is cell specialization in multicellular eukaryotes?

Cell specialization refers to the differentiation of cells to perform specific functions in a multicellular organism, such as nerve cells and muscle cells in animals.

What is the cell theory?

The cell theory consists of three parts: 1) All living things are composed of one or more cells. 2) Cells are the basic units of structure and function in living organisms. 3) All cells come from pre-existing cells.