LifeLine

Every living organism on is made up of cells. They’re the building blocks of life. They are designed intricately to carry out all the essential processes needed for life. But what lies inside them? Let’s take a closer look.

The contents of the cell, or the structures of the cell, allow the cell to be “specialized.” Together with the cell’s proteins, they allow the cell to do specific things. They allow a cell to act like a neuron or a bone cell or a skin cell. The structure-function relationship describes a pattern evident throughout biological systems. Cells vary in shape. The variation in shape mainly depends on their function. 

Prokaryotic and eukaryotic cell 

There are two types of cells, prokaryotic and eukaryotic. Prokaryotic cells, bacteria, are simple and lack membrane-bound organelles. Eukaryotic cells, found in animals, plants, and fungi, are more complex and contain membrane-bound organelles, including a nucleus.

	Eukaryotes	Prokaryotes
Type of Cell	Unicellular and multicellular	Always unicellular
Cell size	Size ranges from 10 μm – 100 μm in diameter	Ranges in size from 0.1 μm – 0.5 μm in diameter
Cell wall	When present, chemically simple in nature	Usually present; chemically complex in nature
Cell membrane	Present	Present
Nucleus	Present	Absent. Instead, they have a nucleoid region in the cell
Ribosomes	Present. Comparatively larger in size and linear in shape	Present. Smaller in size and spherical in shape
DNA arrangement	Present	Present
Mitochondria	Present	Absent
Cytoplasm	Present, cell organelles present	Present, but cell organelles absent
Endoplasmic reticulum	Present	Absent
Plasmids	Very rarely found in eukaryotes	Present
Cytoskeleton	Present	Mainly absent
Microtubules	Present	Absent – Rare
No. of chromosomes	More than one	One – plasmid
Lysosome & Centrosome	Present	Absent
Vesicles and vacuoles	Present	Present
Cell division	Through mitosis	Through binary fission
Flagella	The flagella are larger in size	The flagella are smaller in size
Reproduction	Both asexual and sexual	Asexual
Example	Plant and Animal cell	Bacteria and Archaea

Organelles and cell function

Cell Membrane: A phospholipid layer, forms cell boundary, is partially permeable, acts as a barrier and controls movement in and out of cell

Cell Wall: Semi-rigid structure, made of cellulose, supports cell and prevents cell from bursting

Centrosome: Organizing the microtubule, cell division, structure

Chromatin: Tangles spread out form of DNA found inside the nucleus

Ctyoskeleton: Muscle and skeleton, made of 3 types of protein

Cytoplasm: Jelly fluid, holds cell organelles together, site of major chemical reactions, site for the metabolic activity of the organelles

Endoplasmic Reticulum (ER): Many chemical reactions, system of folded membranes, 2 types – Rough ER synthesizes protein, Smooth ER synthesizes lipid

Golgi apparatus: Helps make package material (protein) to be transported – post office of the cell 

Lysosome: Contains digestive enzymes are durable collectors and waste removers for the cell

Mitochondria: Powerhouse, site of respiration, break down sugar to make ATP

Nuelceolus: A structure where ribosomes are made

Nucleus: Membrane bound organelle, contains DNA material, carries information inherited through generation, has role in processes like growth and metabolism

Peroxisome: Involved in the metabolism of lipids and catabolism of long-chain fatty acids

Ribosomes: Form protein, made of RNA and protein
Vacuole: Large fluid sack, support cell, make cell turgid (swollen), if vacuole shrinks cells become smaller due to flaccidity (limp). Provides shape and help in storage of substances.

The structure of a cell is like a miniature city. As science advances, our understanding of deepens, reminding us of complexity in the building blocks of life.