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Cell organelles


Cells are composed of various cell organelles that perform certain specific functions to carry out life’s processes. The different cell organelles, along with its principal functions, are as follows:
Cell Organelle and its Functions
Nucleolus
The nucleolus is the site of ribosome synthesis. Also, it is involved in controlling cellular activities and cellular reproduction
Nuclear membrane
The nuclear membrane protects the nucleus by forming a boundary between the nucleus and other cell organelles.
Chromosomes
Chromosomes play a crucial role in determining the sex of an individual. Each human cells contain 23 pairs of chromosomes
Endoplasmic reticulum
The endoplasmic reticulum is involved in the transportation of substances throughout the cell. It plays a primary role in the metabolism of carbohydrates, synthesis of lipids, steroids and proteins.
Golgi Bodies
Golgi bodies are called the cell’s post office as it is involved in the transportation of materials within the cell
Ribosome
Ribosomes are the protein synthesisers of the cell
Mitochondria
The mitochondrion is called “the powerhouse of the cell.” It is called so because it produces ATP – the cell’s energy currency
Lysosomes
Lysosomes protect the cell by engulfing the foreign bodies entering the cell and helps in cell renewal. Therefore, it is known as the cell’s suicide bags
Chloroplast
Chloroplasts are the primary organelles for photosynthesis. It contains the pigment chlorophyll
Vacuoles
Vacuoles stores food, water, and other waste materials in the cell

Cell Biology

Cells are the basic, fundamental unit of life. So, if we were to break apart an organism to the cellular level, the smallest independent component that we would find would be the cell.
Explore the cell notes to know what is a cell, cell definition, cell structure, types and functions of cells. These notes have an in-depth description of all the concepts related to cells.

Cell Definition
“A cell is defined as the smallest, basic unit of life that is responsible for all of life’s processes.
Cells are the structural, functional, and biological units of all living beings. A cell can replicate itself independently. Hence, they are known as the building blocks of life.
Each cell contains a fluid called the cytoplasm, which is enclosed by a membrane. Also present in the cytoplasm are several biomolecules like proteins, nucleic acids and lipids. Moreover, cellular structures called cell organelles are suspended in the cytoplasm

Discovery of Cells
Discovery of cells is one of the remarkable advancements in the field of science. It helps us know that all the organisms are made up of cells, and these cells help in carrying out various life processes. The structure and functions of cells helped us to understand life in a better way

Who discovered cells?
Robert Hooke discovered the cell in 1665. Robert Hooke observed a piece of bottle cork under a compound microscope and noticed minuscule structures that reminded him of small rooms. Consequently, he named these “rooms” as cells. However, his compound microscope had limited magnification, and hence, he could not see any details in the structure. Owing to this limitation, Hooke concluded that these were non-living entities.

Characteristics of Cells
Following are the various essential characteristics of cells:
• Cells provide structure and support to the body of an organism.
• The cell interior is organised into different individual organelles surrounded by a separate membrane.
• The nucleus (major organelle) holds genetic information necessary for reproduction and cell growth.
• Every cell has one nucleus and membrane-bound organelles in the cytoplasm.
• Mitochondria, a double membrane-bound organelle is mainly responsible for the energy transactions vital for the survival of the cell.
• Lysosomes digest unwanted materials in the cell.
• Endoplasmic reticulum plays a significant role in the internal organisation of the cell by synthesising selective molecules and processing, directing and sorting them to their appropriate locations

Types of Cells
Cells are similar to factories with different labourers and departments that work towards a common objective. Various types of cells perform different functions. Based on cellular structure, there are two types of cells:
• Prokaryotes
• Eukaryotes

Prokaryotic Cells

  1. Prokaryotic cells have no nucleus. Instead, some prokaryotes such as bacteria have a region within the cell where the genetic material is freely suspended. This region is called the nucleoid.
  2. They all are single-celled microorganisms. Examples include archaea, bacteria, and cyanobacteria.
  3. The cell size ranges from 0.1 to 0.5 µm in diameter.
  4. The hereditary material can either be DNA or RNA.
  5. Prokaryotes generally reproduce by binary fission, a form of asexual reproduction. They are also known to use conjugation – which is often seen as the prokaryotic equivalent to sexual reproduction (however, it is NOT sexual reproduction)

Eukaryotic Cells

  1. Eukaryotic cells are characterised by a true nucleus.
  2. The size of the cells ranges between 10–100 µm in diameter.
  3. This broad category involves plants, fungi, protozoans, and animals.
  4. The plasma membrane is responsible for monitoring the transport of nutrients and electrolytes in and out of the cells. It is also responsible for cell to cell communication.
  5. They reproduce sexually as well as asexually.
  6. There are some contrasting features between plant and animal cells. For eg., the plant cell contains chloroplast, central vacuoles, and other plastids, whereas the animal cells do not.