Cytoplasm: Definition, Structure and Function (with diagram) (2023)

The cell is the basic component of living things.

cellsit can vary widely from one to another depending on the organism in which a particular cell is found, and in more specialized organisms in relation to the specific physiological function of that cell. But all cells have some elements in common, including acell membraneas the outer edge and the cytoplasm inside the cell.

prokaryotic cells– Think of bacteria: they have no nuclei or organelles, and therefore the cytoplasm is “everything” visible inside them. the cytoplasm ofeukaryotic cells, found in plants, animals, and fungi, is "everything" outside of the nucleus and any organelles present.

What is in the cytoplasm?

First, it is useful to distinguish between related terms in cell biology.

cytoplasmgenerally refers to the environment within more complex cells that is found within the cell but is not part of the cell's organelles.

Eukaryotic cells, in addition to having their genetic material contained within a nucleus, have structures and characteristicsorganellessuch as mitochondria and Golgi bodies, which have their own double plasma membrane similar in structure and content to the cell membrane itself.

citosol, on the other hand, is the specific jelly-like substance that makes up the cytoplasm and excludes everything inside, even the smallest components like enzymes.

Therefore, "cytoplasm" can be seen as "cytosol plus some impurities", while "cytosol" means "cytoplasm without organelles".

The cytoplasm is composed mainly of water, salts and proteins.

Most of these proteins areDifficultthat catalyze or assist chemical reactions. Although no general function can be attributed to the cytoplasm, it serves as the physical medium for the transport and processing of molecules within the cell that are essential for sustaining life from moment to moment.

Prokaryotic cells lack organelles (French for "little organs"); Hegenetic materialand the other extracytosolic components within these cells "float" freely in the cytoplasm.

plant and animal cellson the other hand, they are almost always part of multicellular and correspondingly more complex organisms.

HeKernIt's not usually grouped with other organelles because of its importance, but an organelle is just what the nucleus is, double plasma membrane and all.

Their size varies, but their diameter can range from 10 to 30 percent of the diameter of the entire cell.

It contains the organism's chromosomes along with the structural and enzymatic proteins necessary for the chromosomes to do their job of replication and ultimately pass information on to the gamete cells destined to create organisms in the next generation of members down the road to form.

organelles in the cytoplasm

Heorganelles in a cellthey are analogous to the various organs and structures of the human body.

Humans and other animals do not have a cytosol or cytoplasm, but the fluid that makes up blood plasma and fills much of the space between cells and organs could be seen as serving the same basic functions: a different physical scaffold on which metabolic and other reactions. it can happen.

mitochondriathey are perhaps the most fascinating organelles.

It is believed that before the arrival of eukaryotes, these "powerhouses" once existed as separate bacteria in which the processes are carried out.aerobic respirationoccur.

They are elongated, more like narrow footballs, and their double membrane contains a large number of folds, called cristae, which expand the mitochondria's functional area far beyond what a smooth membrane would allow.

This is important because of the number and variety of reactions that take place here, including the familiar tricarboxylic acid cycle (also known as theKrebs cycle or citric acid).

Although mitochondria are found in plants, their role in animals is more often emphasized since animals do not participate in photosynthesis.

HeEndoplasmatisches Retikulumit is a type of transport network whose double plasma membrane is connected to that of the cell as a whole and extends inward ("reticulum" means "small mesh").

The rough endoplasmic reticulum (RER) has a large number of ribosomes, or miniature protein factories, which give it its name, while the smooth endoplasmic reticulum has few or no ribosomes occupying its length.

I'm sure thatThey're like a cell's storage scales, able to store enzymes, fuel, and other substances until they're ready for use, just as your body can store items it needs later, like blood cells and glycogen, in specific locations.

Golgi apparatusit's like a processing center and is usually represented on cell diagrams as a pancake-shaped stack of disks.

As the SER and RER transport the crude products of ribosomal activity (ie, proteins), the Golgi apparatus refines and modifies these products based on where they will eventually end up in the physical system.

lysosomethey are a manifestation of a cell's need for maintenance and disposal functions.

They contain enzymes that can chemically lyse or digest the inevitable waste products of metabolic functions and reactions.

Just as strong industrial acids are stored in special containers, the cell sequesters the corrosive enzymes used by lysosomes in these special vacuoles scattered throughout the cytoplasm.

Finally,cloroplastenoThey are specific organelles of plant cells that contain a pigment called chlorophyll that converts sunlight into energy that allows plants to synthesize glucose. Obviously, unlike animals, plants cannot get fuel from food, so they have to make it themselves.

Under the microscope, these look a lot like mitochondria.

the cytosol

As described, the cytosol is essentially organelle-free cytoplasm.

It is a matrix, a gelatinous substance, in which organelles and solutes "swim". The cytosol contains theZitoskeleton, which is a network ofmicrotubulesThey help the cell maintain its shape. These microtubules are protein structures made up of different subunits called tubulins, which assemble at the centrioles of the two opposite centrosomes of the cell.

In addition to tubulin-rich microtubules, other elements are also mentioned.microfilamentssupport microtubules to ensure the structural integrity of cells.

Despite their name, which perhaps implies a filamentary character, microfilaments are made of globular proteins called actin, which are also found in the contractile apparatus of muscle cells.

Plants have so-called structuresPlasmodesmenthey run into and through the cytosol of your cells from the outside.

These are also small tubes, but they differ from microtubules in that they serve to connect different plant cells together. The immobile nature of plants makes these "living bridges" particularly important, as they allow processes to take place that might otherwise occur in normal animal locomotion.

What dissolves in the cytoplasm

Less easy to visualize microscopically are substances in the cytoplasm that help drive cell function, particularly enzymes.

Just as blood contains much more than the red blood cells and platelets that give it its color and basic consistency, the cytosol contains a number of "floating" elements and molecules that are metabolically active.

The cytoplasm can be rich in fuel sources, such as starches and other carbohydrates, particularly in bacterial cells that lack membrane-bound organelles.

One disadvantage of existing outside the endoplasmic reticulum system and other membrane structures is that materials in the cytoplasm can only move by simple diffusion, meaning they migrate down concentration gradients.

Of course, in situations that require rapid metabolic changes, dissolved elements in the cytoplasm cannot react quickly.

The cytosol also contains signaling molecules such as calcium, potassium, and sodium ions. These are often involved in triggering cell receptor activity on cell surfaces and the surfaces of the organelles they contain, initiating cascades of biochemical reactions.

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