What is the smallest unit of life

what is the smallest unit of life

The cell is the smallest structural and functional smallest unit of life that can exist on its own. Therefore, it sometimes called the building block of life.

In other words, all cells have three things in common, no matter what type of cell they are and all cells have a cell membrane, which separates the inside of the cell from its environment.


Two types of cells

what is the smallest unit of life

Eukaryotic cell

In addition, they have organelles, which include the nucleus and other particular parts you carry. Eukaryotic cells are more advanced, complex cells such as those found in plants and animals.

what is the smallest unit of life

Prokaryotic cells

They don’t have a nucleus or membrane-enclosed organelles but they do have genetic material, However, it not contained within a nucleus. Prokaryotic cells are always one-celled or unicellular organisms, such as bacteria.

what is the smallest unit of life

What are organelles and why are they important

Organelle means little Organ. Organelles are the specialized parts of a cell that have unique jobs to perform.


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Let’s start with the Nucleus (The control center of the cell)


It’s a jelly-like fluid.


what is the smallest unit of life

DNA, the cell’s genetic material (I’ve explained the relationship below)

Nucleus contains DNA or genetic material. DNA dictates what the cell is going to do and how it’s going to do it.

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It’s the tangled spread out form of DNA found inside the nuclear membrane. When a cell is ready to divide, DNA condenses into structures known as chromosomes.



The nucleus also contains a nucleolus, which is a structure where ribosomes are made after ribosomes leave the nucleus. They will have the critical job of synthesizing or making proteins

Outside the nucleus, the ribosomes and the rest of the organelles float around in cytoplasm, which is the jelly-like substance. Ribosomes may wander freely within the cytoplasm or attach to the endoplasmic reticulum, sometimes abbreviated as ER.

There are two types of ER, (smallest unit of life)

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  • Rough ER (rER) has ribosomes attached to it
  • Smooth ER (sER) doesn’t have ribosomes attached to it.


The endoplasmic reticulum is a membrane-enclosed passageway for transporting material such as the proteins synthesized by ribosomes.

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Golgi apparatus (Golgi body)

Proteins and other materials that emerged from the endoplasmic reticulum in small vesicles where the Golgi apparatus receives them.

As protein Is moving through the Golgi body, they’re customized into forms that the cell can use.

The Golgi body does this by bolding the proteins into usable shapes or adding other materials onto them, such as lipids or carbohydrates.


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They are sack-like structures that store different materials. In this plant cell, the central vacuole stores water.


Going back to the animal cell, you will see an organelle called a lysosome.

Those are the garbage collectors that taken damaged or worn-out cell parts. They are filled with enzymes that breakdown these cellular debris.

what is the smallest unit of life


The mitochondrion is an organelle that is the powerhouse for both animal and plant cells during a process called cellular respiration. The mitochondria make ATP molecules. It provides the energy for all of the cells, activities. Cells need more energy, have more mitochondria.

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Meanwhile, the cell maintains its shape through a cytoskeleton. The cytoskeleton includes the thread, like microfilaments, which are made of protein and microtubules, which are thin hollow tubes. Some organisms, such as plants that are photoautotrophic meaning they capture sunlight for energy,



Have cells with an organelle called a chloroplast. The chloroplast is where photosynthesis happens.

It’s [highlight color=”green”]Green[/highlight] because it has a green pigment called chlorophyll Plant cells also have a cell wall outside of their cell membranes that shape, support, and protect the plant cell.


what is the smallest unit of life

Do animal cells have a cell wall

No. they haven’t. There are many other unique structures that only some cells have. Here are just a few. (smallest unit of life)

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  • In humans, for example, the respiratory tract is lined with cells that have cilia.
  • These are microscopic hair-like projections that can move in waves. This feature helps trap inhaled particles in the air and expels them when you cough.




Another unique feature in some cells is flagella. Some bacteria have flagella. A flagellum is like a little tail that can help us cell move or propel itself.

The only human cell that has a flagellum is a sperm cell.

what is the smallest unit of life
Hi, how are you?

In summary, remember

  • Eukaryotic cells: Plant and animal cells with a nucleus and membrane-enclosed organelles.
  • Prokaryotic cells: While, Prokaryotic cells are unicellular organisms without a nucleus and membrane-enclosed organelles.

Without these things,

  • All cells have a cell membrane, cytoplasm, and genetic material, and even though only plant cells have chloroplasts, both plant and animal cells have mitochondria.