What’s smaller than a cell?


Ever wondered what the human body is composed of?

Well, the human body is made up of trillions of cells, and each cell has its own specialized function.

Before moving ahead we need to have a clear concept of cell.

A Cell is the basic building block of all living organisms and provides basic structure and support for the body. Cells draw in nutrients from the food and convert those nutrients to energy to carry out important functions such as growth and repair.

Cells can be thought of as minute packages that carry tiny factories and transport systems. Each cell works independently creating its own energy and is self-sustainable.

Cells are the smallest living parts of the body. Cells combine together to form tissues, tissues gather to form organs, and organs work together to keep the organism alive. Now, we can clearly understand why the cells are considered to be the basic unit of life.

Can we see cells with our eyes?

The average size of cells varies between 20 micrometer-30 micrometer which is extremely small. The human eye cannot see such minute structures with detail, therefore we need a microscope to examine these structures.

Is there anything smaller than a cell?

Yes, there are many things that are smaller than a cell. Cells contain floating structures within themselves called organelles. Organelles are specialized structures that perform certain tasks within a cell.

Human cells contain the following major parts:-

1. Nucleus:- Nucleus can be considered as the cell’s headquarters. In animal cells, there is only one nucleus present per cell. The nucleus is responsible to stimulate cells to grow, divide and die. The majority of a cell’s DNA is contained within the nucleus.

2. Mitochondria:- Mitochondria is referred to as the ‘powerhouse of the cell’. The most important function of mitochondria is to break down the food into energy. It is also responsible for calcium storage in the body.

3. Cytoplasm:- Cytoplasm is a jelly-like fluid that is present within the cell and surrounds the nucleus. The cytoplasm is essentially 80 percent water. Many important reactions that take place within cell occurs in the cytoplasm.

4. Ribosomes:- Ribosomes can be found within the cell and is one of the most structure present within the cell. The main function of the ribosome is to build up proteins.

5. Endoplasmic Reticulum:- It helps to transport the molecules to their specific destination either inside or outside the cell.

6. Lysosomes:- Lysosomes play important role in cell processes. They protect the cells by destroying the invading bacteria and also helps to remove the dying cell parts.

Fun Facts

  1. In humans, as many as 1011 cells die in each adult each day and are replaced by other cells.
  2. Animal cells are generally smaller than plant cells.

True or False

  1. Lysosomes protect the cell from invading bacteria and infections.      (T/F)
  2. Nucleus is considered to be the building block of the all organisms.   (T/F)
  3. Cells are responsible for growth, repair and reproduction.                    (T/F)
  4. Ribosomes is responsible for protein production in a cell.                     (T/F)
  5. Human body is made up of only one cell.                                                   (T/F)

Objective Quiz

  1. Which structure present within a cell is often termed as the ‘powerhouse of the cell’?
    (a) Mitochondria
    (b) Lysosome
    (c) Cytoplasm
    (d) Nucleus
  2. What are the main functions of a cell?
    (a)  Provides basic structure and support for the body.
    (b)  Helps in growth and repair of the body.
    (c) Both (a) and (b).
    (d) None of the above.
  3. What is the average size of cell in human body?
    (a) 100 μm
    (b) 50  μm
    (c) 20 μm
    (d) infinite size
  4. What is the basic unit of life?
    (a) Heart
    (b) Brain
    (c) Cells
    (d) Tissues
  5. Which organelle is termed as the headquarters of the cell?
    (a) Endoplasmic Reticulum
    (b) Nucleus
    (c) Lysosome
    (d) Cytoplasm

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