BIOLOGY: CELL AS LIVING FORM

BIOLOGY: CELL AS LIVING FORM

from Femosky110 on 06/11/2020 11:58 AM

Cells as Living Unit-Forms in which living things exit
The cell is the basic unit of organization for the majority of living things. Living things can be classified as multicellular ie organisms that are made up of varieties of cells, or unicellular-organisms that are made up of only a single cell.

 

Cells are the fundamental or basic unit of life both in plants and in animal. Cell can exist as a living unit as opposed to being part of a larger or multicellular organism. Thus cell can exist in various forms. The following are forms in which living cell exists:

Group of cells that form tissue are part of a living multicellular organism and cannot survive on their own. They would normally require the functions of other cells in the body to remain alive while the groups of cells that form colonies or filament are individual organism capable of carrying out all the body processes on their own.

Their existence as a colony or as a filament is for the sake of mutual and symbiotic relationship. These free living or colonial organisms that are single celled with different modes of nutrition, locomotion and reproduction is referred to as protista.

A group of cells that perform same or similar function are joined together to make tissue. A number of tissues joined together to perform a specific function join together to make up an organ like the the heart, the stomach, or the lungs.

A lot of organ that functions together to achieve one common purpose are referred to as System- Examples the cardiovascular system, which is made up of the heart, arteries, veins, capillaries, and blood, and the respiratory system, that is made up of the lungs.

Dissimilar organ systems that provide unlike purposes for the same effect, normally described as good health, are called an organism, like the human being. Therefore cell is in the lowest level, the most widespread denominator in this pecking order of cell structure and organization.

In unicellular organisms, all the processes of life are being carried out by a single cell while in multicellular organisms, the life processes are being carried out by the five various levels of organization-cell-organ-tissue-system-organism. The human body for an example is made up of contains 11 organ systems.

Single and free-living:
Single celled organisms are organisms that are consist of only a single cell. They are as well referred to as unicellular organisms. Examples of single celled organisms are amoebas, paramecium, volvox, protozoa, spirogyra, euglena, animalcule, diatoms, prokaryotes, bacteria (or bacterium), yeast, and archaea.

Again, xenophyophores are the largest single celled organism ever found. They were discovered in October 2011 in the Mariana Trench, 6 miles under the surface of the ocean. Another big single celled organism is the syringammina fragilissim .

These single celled organisms have the tendency to reach a diameter of up to 20 centimeters. Examples of organisms that exist as a single cell and are free living are Amoeba, Paramecium, Euglena and Chlamydomas.

Many life forms are composed of a single cell. In addition to simple bacteria, there are more composite organisms, referred to as protoctists. Dissimilar to bacteria, they have composite internal structures, like nuclei which contain organized strands of genetic material known as chromosomes.

The majority of them are single-celled, but some form colonies, with every one of the cell remaining independent.

Euglena is a single-celled organism that uses flagellum for locomotion. The single-celled organism that uses cilia or hair like projections for locomotion is Paramecium. Amoeba is a single-celled organism that makes use of pseudopods to surround and engulf their food.

A single-celled organism that is made up of a colony of ciliates with some containing chlorophyll is Volvox. Euglena is a single-celled organism that has a unique feature of an eye spot. Amoeba is a single-celled organism that moves by cytoplasmic streaming. The two types of single-celled organisms that have chlorophyll are Euglena and Volvox

Amoeba: This is a single-celled predator that does not possess a definite shape. It can make a projection of parts of its cell to form a gelatinous tentacle referred to as pseudopodia.

The amoeba makes use of the pseudopodia for locomotion for touching and grabbing a prey. They live in water and are found creeping along decaying vegetation. They prey on smaller cells like bacteria.

Algae are currently classified as protoctists, even though scientists formally classified them under plant kingdom. Algae can manufacture their own food through the process of photosynthesis since they contain green chloroplasts.

Euglena and algae live in ponds. When they are placed in the dark, they lose their chloroplasts and then feed like animals. Seaweeds are good examples of popular algae. They are composed of enormous communities of algae cells.

A few protoctists obtain their food by invading other organisms and living on them as parasites. Example is the malaria parasite which first enters its human host through the bite of the Anopheles mosquito.

As soon as it gets into the human system, it multiplies inside the blood and may cause liver infection. The parasite causes a fatal disease known as malaria fever.

Slime moulds begin like amoeba-like cells that searches for food in damp habitats. Eventually, the cells combine together to form spore-producing feature.

As a colony:
Example of single celled organism that exists as a colony is Volvox. In biology, a colony refers to a number of individual organisms of similar species existing together for mutual benefit.

Examples of such benefits they could get from each other include the strength or the ability to attack a bigger prey. Some insects like ants and bees live in colonies.

Colonial organisms are organisms that live intimately together, in a colony. For instance bacteria, Volvox, Pandorina, Sponges, algae and Salps are also examples of colonial organisms. Each organism/cell in the colony can exist on its own and may or may not benefit from other cells in the colony.

In biology, a colony refers to individual organisms of the same species living closely together, more often than not for mutual benefit, like stronger defense or the capacity to assault bigger prey. A few insects like ants and honey bees live only in colonies.

A colony of single-cell organisms is referred to as a colonial organism. Colonial organisms were almost certainly the first step toward multicellular organisms through natural selection.

A bacterial colony is defined as a observable cluster of bacteria that grows on the surface of or within a solid medium, most probably cultured from a single cell.

Due to the fact that every organism inside the colony descends from a single antecedent, they are genetically the same apart from mutations that usually take place at a small frequency, in addition to a possibility for them to be contaminated.

Getting hold of that type of genetically matching organisms or pure strains can be useful in loads of cases. It can be done by dispersing bacteria on a culture plate and starting a fresh stock of bacteria from a single colony.

A biofilm is a colony of microorganisms over and over again made up of a lot of species, with properties and abilities greater than the combinations of abilities of the individual organisms.

Types of cell colonies
In the process of evolution unicellular organisms began to co-exist in three different ways:

1. A colony is a group of related living organisms that are linked to each other through their own secretions, or cytoplasmic strands, but there isn't any suitable transportation system between the cells.

Colonies are formed due to daughter cells that stay together instead of separating apart from each other after the cell division. Any member of the colony has the capability to exist on its own.

2. Symbiosis is an inter-relationship between two or more different organisms which usually benefit from the relationship.

3. Endosymbiosis is a form of symbiosis where a colony member known as a microsymbiote lives within the other. Nowadays, scientists are of the opinion that the cell organelles mitochondria are, in reality, microsymbiotres that formally lived as free living bacteria cells. Ultimately these bacteria developed into a part, or organelle, of the host cell. This type of relationship is referred to as endosymbiotic.

As a filament:
Cell can as well exist as a filament. Example of single celled organism which exists as a filament is the Spirogyra. A few organisms exist as filaments with related cells are joined end to end to form unbranched filaments.

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Each cell in the filament works independently from the other. These types of organisms that exist as filament are multicellular. Other examples of filamentous organisms are the Zygnema, Oscillateria and Oedogonium.

Lastly a cell can as well exist as part of a living organism both in plant and in animal. Example of cases where the cell exists as part of a living organism is cheek cell, onion root tip cells and the epidermis of fleshy leaves.

A single cell can be the smallest possible unit and has the potential to grow into an entire colony.

Multicellular organisms are made up of many cells and in the majority of cases many organs where every cell that make up the organism cannot function as a whole organism and cannot as well exist independently of other cells.

The variation between a multicellular organism and a colonial organism is that individual organisms from a colony can, if alienated, survive on their own, while cells from a multicellular life form like cells from a brain cannot. Volvox which is technically referred to as a coenobium is an example of the boundary between the two states.

If onion epidermal tissue is engrossed into a solution of calcium nitrate, cells speedily lose water by osmosis and the protoplasm of the cells shrinks.

This happens due to the fact that the calcium and nitrate ions generously leak into the cell wall and come across the selectively permeable plasma membrane.

The large vacuole in the center of the cell at first contains a dilute solution which has a much lower osmotic pressure than that of the calcium nitrate solution on the other side of the membrane. The vacuole in this manner loses water and becomes smaller.

The space between the cell membrane and the cell wall then gets bigger and the plasma membrane together with the protoplasm inside it contract to the center of the cell.

Strands of cytoplasm expand to the cell wall due to the attachment points between the cell wall and the plasma membrane. Plasmolysed cells easily die except they are transferred fast from the salt or sugar solution to water.

Comparisons of Single-celled Organisms
Euglena
• Moves by flagellum

• It is known for a unique feature—eye spot

• Some Euglena contain chlorophyll

• A few of them are commonly found in fresh water

Amoeba
• They move through cytoplasmic streaming

• They surrounds food and engulfs it with the use of pseudopods

Paramecium
• Paramecium is the most complex and specialized of the protists

• They use their hairlike projections known as cilia for movement.

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Volvox
• Volvox is a colony of ciliates

• A few Volvox contain chlorophyll