Question

Explain the postulates of cell theory​

Answer 1

Answer:

Cell theory states that living things are composed of one or more cells, that the cell is the basic unit of life, and that cells arise from existing cells.

Cell Theory

The microscopes we use today are far more complex than those used in the 1600s by Antony van Leeuwenhoek, a Dutch shopkeeper who had great skill in crafting lenses. Despite the limitations of his now-ancient lenses, van Leeuwenhoek observed the movements of protista (a type of single-celled organism) and sperm, which he collectively termed “animalcules. ”

In a 1665 publication called Micrographia, experimental scientist Robert Hooke coined the term “cell” for the box-like structures he observed when viewing cork tissue through a lens. In the 1670s, van Leeuwenhoek discovered bacteria and protozoa. Later advances in lenses, microscope construction, and staining techniques enabled other scientists to see some components inside cells.

Explanation:

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Answer 2

$\bigstar \bold{Cell \: Theory.}$

Cell Theory was proposed by Matthias Schleiden, Theodor Schwann, and Rudolf Virchow, who were German scientists.

The cell theory states that:

• All living species on Earth are composed of cells.

• A cell is the basic unit of life.

• All cells arise from pre-existing cells.

$\boxed{ \bold{LET'S \: EXPLORE \: MORE}}$

$\bigstar \overbrace{ \underbrace { { \bold{Cell}}}}$A Basic structural unit of an organ is known as cell

$\bigstar \overbrace{ \underbrace { { \bold{Discovery \: of \: Cell}}}}$

• Robert Hooke in 1665 Observed slices of cork under a simple magnifying device.

• Cork is a part of the bark of a tree.

• He took thin slices of cork and observed them under a microscope.

• He noticed partitioned boxes in cork slice.

• Hooke coined the term as Cell

$\bigstar \overbrace{ \underbrace { { \bold{Numbers \: of \: Cell}}}}$

• They are A billion and trillions of cells in a living organisms.

• Organisms made up of more than one cell are called multicellular Organisms (multi: many; Cellular: Cell)

• Organisms made up of a singled cell are called unicellular organisms (uni: One; Cellular:Cell)

$\bigstar \overbrace{ \underbrace { { \bold{Cell \: Structure \: and \: function}}}}$

☆Provides Support and Structure

All the organisms are made up of cells. They form the structural basis of all the organisms. The cell wall and the cell membrane are the main components that function to provide support and structure to the organism.

☆Facilitate Growth Mitosis

In the process of mitosis, the parent cell divides into the daughter cells. Thus, the cells multiply and facilitate the growth in an organism.

☆Allows Transport of Substances

Various nutrients are imported by the cells to carry out various chemical processes going on inside the cells.

☆Energy Production

Cells require energy to carry out various chemical processes. This energy is produced by the cells through a process called photosynthesis in plants and respiration in animals.

☆Aids in Reproduction

A cell aids in reproduction through the processes called mitosis and meiosis. Mitosis is termed as the asexual reproduction where the parent cell divides to form daughter cells.

$\bigstar \overbrace{ \underbrace { { \bold{Structure \: of \: the \: Cell}}}}$

$\pink \bigstar \bold\pink{Cell \: Membrane}$

• The cell membrane supports and protects the cell. It controls the movement of substances in and out of the cells.

• The cell membrane is the outer covering of a cell within which all other organelles, such as the cytoplasm and nucleus, are enclosed. It is also referred to as the plasma membrane.

• By structure, it is a porous membrane (with pores) which permit the movement of selective substances in and out of the cell. Besides this, the cell membrane also protects the cellular component from damage and leakage.

• It forms the wall-like structure between two cells as well as between the cell and its surroundings.

• Plants are immobile, so their cell structures are well-adapted to protect them from external factors. The cell wall helps to reinforce this function.

$\blue\bigstar \bold \blue{Cell \: Wall}$

• The cell wall is the most prominent part of the plant’s cell structure. It is made up of cellulose, hemicellulose and pectin.

• The cell wall is present exclusively in plant cells. It protects the plasma membrane and other cellular components. The cell wall is also the outermost layer of plant cells.

• It is a rigid and stiff structure surrounding the cell membrane.

• It provides shape and support to the cells and protects them from mechanical shocks and injuries.

$\red \bigstar\bold \red{Cytoplasm}$

• The cytoplasm is a thick, clear, jelly-like substance present inside the cell membrane.

• Most of the chemical reactions within a cell take place in this cytoplasm.

• The cell organelles such as endoplasmic reticulum, vacuoles, mitochondria, ribosomes, are suspended in this cytoplasm.

$\green \bigstar \bold \green{Nucleus}$

• It is important component of the living cell. It is generally spherical and located in the centre of the cell.

• Nucleus is separated from the cytoplasm by a membrane called Nuclear Membrane this membrane is also porous and allow the movement of materials between the cytoplasm and the inside of nucleus.

• We can see a smaller spherical body in the nucleus, It is called nucleolus.

• Nucleus contains thread like structures called Chromosomes.These carry genes and help in inheritance or transfer of characters from parents to offspring. the chromosomes can be seen only when cell divides.

• Nucleus role in inheritance,acts as a control center of the activities of the cell.

$\bigstar \overbrace{ \underbrace { { \bold{Types of Cells}}}}$

They are 2 types of cell they are

• Prokaryotic Cells
• Eukaryotic Cells