What are Cells?
As we know, all living organisms are composed of cells. So we are calling cells as building blocks of living organisms.
Wow! Fact, How many cells are in the human body?
We can’t count the exact number, because there are trillions of cells in our body. In one day, 50 to 70 billion cells are dying and again produced by our body. We can categorize two types of cells in living organisms.
Types of cells in living organisms:
1. Prokaryotic cells, Ex: bacteria
2. Eukaryotic cells, Ex: human cells, animal cells, plant cells.
Prokaryotic cells vs eukaryotic cells:
Prokaryotic cells are a single circular organism, whereas Eukaryotic cells are multicellular (i.e., they have many cells). Prokaryotic cells don’t have a nucleus and other membrane-bound organelles. Eukaryotic cells have a nucleus and membrane-bound organelles. Prokaryotic cells have a haploid genome; eukaryotes have a diploid genome. An organism with a prokaryotic cell is called prokaryotes. An organism with eukaryotic cells is called eukaryotes. Prokaryotes reproduce asexually; eukaryotes reproduce sexually.
Wow! Fact, which cells came to earth initially?
Prokaryotic cells emerged first (over 3.5 billion years ago) but evolved almost 1 -1.5 billion years back; eukaryotic cells evolved 2.7 billion years back.
Human cells :
Humans are eukaryotes. Human cells have a nucleus, cytoplasm, endoplasmic reticulum, mitochondria, Golgi apparatus, lysosomes, plasma membrane.
The function of membrane-enclosed organelles:
#nucleus – Nucleus is a house of the cell complement of genetic information. In light microscope nucleus visible usually round or oval. The core has a diameter of 2-20µm.
Wow! Fact – Red blood cell in our body has no nucleus.
#endoplasmic reticulum – Endoplasmic reticulum has two forms -rough and smooth. In the rough endoplasmic reticulum, ribosomes are present. Ribosomes are the primary site of protein synthesis. They can also present in the cytosol. On another hand, smooth endoplasmic reticulum produces lipid synthesis. The endoplasmic reticulum is the primary reservoir for calcium ions. Calcium is significant in the role of intracellular signaling.
#golgi apparatus – Golgi apparatus helps the protein to mature.
#mitochondria – Mitochondria is the power plant of the cell because it produces ATP(molecular unit of currency). It is about 0.2µm in diameter. It has two compartments: the outer membrane, inner membrane. The inner membrane has dramatic folds called cristae.
#lysosome – Lysosome function as the cell’s digestive organelle. It comprises many round vesicles called exosome.
#plasma membrane – Plasma membrane is the outer layer of the cell. It is primarily composed of plasma lipids. It doesn’t permit anything to go out and inside of the cell.
Surprising Things You Never Knew About Human Cells :
1. Atom vs Cell, which is bigger?
The answer is a cell in much bigger than an atom.
A cell contains 100 trillion atoms.
2.In humans which cell is the smallest and largest?
The smallest cell in the human – sperm cell.
The giant cell in the human – ovum.
3. The longest cell in the human body?
4. Are cells a positive or negative charge?
In resting cells inside, it is negatively charged and outside the cell is positively charged.