Question

Describe the structure of a cell.

Answer 1

Explanation:

Ideas about cell structure have changed considerably over the years. Early biologists saw cells as simple membranous sacs containing fluid and a few floating particles. Today's biologists know that cells are infinitely more complex than this.

Illustration showing the structure of a cell

There are many different types, sizes, and shapes of cells in the body. For descriptive purposes, the concept of a "generalized cell" is introduced. It includes features from all cell types. A cell consists of three parts: the cell membrane, the nucleus, and, between the two, the cytoplasm. Within the cytoplasm lie intricate arrangements of fine fibers and hundreds or even thousands of miniscule but distinct structures called organelles.

Cell membrane

Every cell in the body is enclosed by a cell (Plasma) membrane. The cell membrane separates the material outside the cell, extracellular, from the material inside the cell, intracellular. It maintains the integrity of a cell and controls passage of materials into and out of the cell. All materials within a cell must have access to the cell membrane (the cell's boundary) for the needed exchange.

The cell membrane is a double layer of phospholipid molecules. Proteins in the cell membrane provide structural support, form channels for passage of materials, act as receptor sites, function as carrier molecules, and provide identification markers.

Nucleus and Nucleolus

The nucleus, formed by a nuclear membrane around a fluid nucleoplasm, is the control center of the cell. Threads of chromatin in the nucleus contain deoxyribonucleic acid (DNA), the genetic material of the cell. The nucleolus is a dense region of ribonucleic acid (RNA) in the nucleus and is the site of ribosome formation. The nucleus determines how the cell will function, as well as the basic structure of that cell.

Cytoplasm

The cytoplasm is the gel-like fluid inside the cell. It is the medium for chemical reaction. It provides a platform upon which other organelles can operate within the cell. All of the functions for cell expansion, growth and replication are carried out in the cytoplasm of a cell. Within the cytoplasm, materials move by diffusion, a physical process that can work only for short distances.

Cytoplasmic organelles

Cytoplasmic organelles are "little organs" that are suspended in the cytoplasm of the cell. Each type of organelle has a definite structure and a specific role in the function of the cell. Examples of cytoplasmic organelles are mitochondrion, ribosomes, endoplasmic reticulum, golgi apparatus, and lysosomes.

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Answer 2

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Cell Membrane

One of the most important parts of the cell is the cell membrane. The cell membrane acts as a semi-permeable barrier. It allows only a few molecules across it and fences the majority of organically produced chemicals inside the cell.

Cytoplasm

Another important part of the cell is the cytoplasm. It is a jelly-like substance that is present between the nucleus and the cell membrane. There are a number of other components or organelles of the cell that can be found in the cytoplasm. These are mitochondria, Golgi bodies, ribosomes, etc.

Nucleus

The nucleus is believed to be the most important component of the living cell. It is located in the centre of the cell and is usually spherical in shape. You can stain the nucleus and see it clearly by using a microscope. The nucleus is separated from the cytoplasm by a membrane known as the nuclear membrane. This membrane is also porous and allows the moment of materials between the cytoplasm and the inside of the nucleus.

In our body and in the body of every living organism, every organ is composed of smaller parts known as tissues. A tissue is a group of like cells that perform a specific function.