What is a Cell Made Up of, and What is the Structural Organisation of a Cell

A cell is the most fundamental structural and functional unit of all living things. A cell is a structure with organelles that perform the essential tasks it needs to survive. But not every cell is the same. Animal cells are very different from plant cells. One of their main distinctions is the absence of cell walls in animal cells.

Additionally, different cells have different sizes; the egg or female ovum is the biggest cell in the human body. It is around 1 millimetre across. Granule cells are the tiniest cells, about 4.5 micrometres in size, and are found in the human cerebellum.

Types of Cells

Eukaryotic and prokaryotic cells make up the majority of cells.

Prokaryotic Cell

• The prokaryotic cell's primary characteristics are listed below.

• Bacteria, mycoplasma, and blue-green algae represent them.

• Different shapes multiply quickly.

• It is the naked genetic material.

• Organelles in cells are missing.

• Except in Mycoplasma, the presence of a cell wall around the cell membrane.

• The two components, the 50s and 30s of ribosomes, which are joined to form the 70s ribosomes and serve as locations for protein synthesis, are connected to the cell membrane.

• Polyribosomes are ribosomes that chain together with RNA.

• The cytoplasm contains reserved elements such as cell inclusion bodies.

The Eukaryotic Cell

The following lists the primary characteristics of eukaryotic cells.

• Animals, plants, fungi, and protists all have eukaryotic cells.

• Organelles bound to membranes cause the cytoplasm to be separated into compartments.

• A well-organised nucleus enclosed by a nuclear membrane is present.

• Chromosomes are structures that hold genetic material.

• In addition to the membrane, plant cells also have a cell wall. In contrast to animal cells, they have a sizable central vacuole.

• Animal cells have centrioles, which are distinctive.

The Structural Organisation of a Cell

We will now discuss the structural organisation of a cell in detail.

Cell Membrane

• One crucial component of the cell is the cell membrane.

• Composed of phosphoglyceride-containing lipids organised in a bilayer. Later, protein compounds were also found.

• Proteins exist in two forms: integral protein, which is submerged in the membrane, and peripheral protein, which is exposed.

• According to Singer and Nicholson's hypothesis, the membrane's quasi-fluid structure makes it possible for proteins to migrate across the bilipid layer.

• The plasma membrane's main job is to guarantee that chemicals are transported.

Cell Wall

Cell Wall

The following is a list of the cell wall's properties.

• It is composed of algae and plants.

• Plants use cellulose, hemicellulose, and pectin to make their cell walls.

• Galectins, minerals, and cellulose make up the algal cell wall.

• Plants' main cell walls can't expand, therefore, once they reach maturity, they quickly change into secondary cell walls.

• The endoplasmic reticulum, Golgi bodies, lysosomes, and vacuoles comprise the endomembrane system.

Endoplasmic Reticulum

Endoplasmic Reticulum

• The endoplasmic reticulum is involved in some of the most crucial processes.

• Ribosomes are not present on the surface of smooth ERs, which are involved in lipid production.

• Rough ER: Produces and secretes proteins and has ribosomes on its surface.

Golgi Apparatus

Golgi Apparatus

• The Golgi apparatus is a further crucial component of the cell.

• It is a site of glycoprotein and glycolipid production.

• Golgi Apparatus is involved in transporting and packaging materials.

• Golgi Apparatus consists of parallel stacks of flat, disc-shaped cisterns.

Lysosome

Lysosome

The membrane-bound structure. It has an abundance of hydrolytic enzymes like lipase and protease that can break down proteins, carbs, and lipids.

Mitochondria

Mitochondria

• The mitochondria are the next critical component of the cell structure. These characteristics are listed below.

• Mitochondria are found in areas where aerobic respiration occurs.

• Mitochondria produce ATP, which is the cellular energy currency.

• The matrix comprises ribosomes, circular DNA molecules, RNA molecules, and protein synthesis-related molecules.

Plastids

Plastids

• Another crucial component of the cell structure is the plastids.

• Plastids are available in plant cells.

• Plastids are organelles with a limited degree of autonomy and different genetic makeup.

• Depending on the type of pigment discovered, there are three types. As follows:

• Leucoplasts are nutrient-stored, colourless plastids of various shapes.

• Chromoplasts: Because soluble lipids are present, they have a yellowish or reddish colour.

• Double membranous structures are called chloroplasts. The term "stroma" refers to the inner membrane. The stroma contains stacks of thylakoids called grana. Enzymes for protein synthesis are present in the stroma.

Centrosome

Centrosome

• This is a crucial component of the cell structure.

• The centrosome consists of two centrioles, which are cylindrical structures.

• The spokes are the peripheral fibrils in the hub of the centriole.

Nucleus

Nucleus

• The nucleus is located further along in a cell's structure. It carries out several significant tasks.

• It has chromatin, nuclear matrix, and nucleoli, which are extremely extended nucleoprotein fibres.

• During cell division, chromatin material rearranges into chromosomes.

• It consists of proteins and histones.

• The centromere, or major constriction, is found at the centre of each chromosome on its disc.

• Chromosomes can be classified as metacentric, submetacentric, telocentric, or acrocentric, depending on where the centromere is located.

Interesting Facts

• The nerve cell are the only cell in the human body that will remain the same in number as they were at birth

• Telomeres present at the end of each chromosome decide the life span of the cell.

• All animal cells are self-sufficient, they have their own factory or machinery for the generation of essential components of the cell.

• Every human cell divides in 24 hours.

Important Questions

1. How are cells formed?

Mitosis or meiosis is the process by which one cell divides to form other cells; during these divisions, the whole content of a cell duplicates and divides into two daughter cells.

2. Do all cells contain DNA?

Yes, all cells contain DNA as genetic material. All cells contain the full set of DNA required for that organism.

3. What is the structure of a cell?

There are three main parts of a cell, nucleus, cell membrane, and cytoplasm; other than this, many organelles are also present in the cytoplasm.

Practice Question

1. What is the structural organisation of a cell?

2. What is a cell made of?

3. Who discovered the cell?

4. What are the various functions of a cell?

Key Features

• Cells are the fundamental biological, structural, and functional elements of all living organisms. A cell has the ability to reproduce on its own. They are, therefore, referred to as the basis of life.

• The cell organelles are the cellular constituents. These membrane-bound cell organelles are located inside cells and have unique shapes and roles.

• For the cell to function normally, they effectively coordinate with one another. A few of them give the cell structure and support, while others play a role in the cell's movement and reproduction.