Previous Topic :Cell Theory
The Cell As A Living Unit
A cell is a living unit because it displays the characteristics of living things. The cell is the smallest unit that shows the characteristics of life.
Forms In Which Cells Exist
Living cells exist in different forms. Some exist as independent organisms, some as colonies, some as filament and some as part of living organisms.
The cell as a independent organisms
In some microscopic organisms, such as Amoeba, Paramecium, Euglena, Chlamydomonas and others, the body consists of one cell only. An organism that consists of only one cell are called unicellular. top↑
Unicellular organisms are also described as acellular or non-cellular because their bodies are not divided into cells.
What is paramecium
Paramecium is a unicellular microscopic organism
Characteristics Of Paramecium
a] Habitat: it is found in muddy ponds and stagnant or sluggish fresh water containing decaying organic matter.
b] Locomotion: paramecium moves by the means of cilia, which occur on the surface of the body. The cilia beats obliquely backwards, causing the organism to rotate on its axis as it moves forward, with blunt end leading.
c] Feeding: it feeds on microscopic organisms such as bacteria, protozoa amd algae. As the cilia in oral groove beat, food particles are carried towards the gullet.
Cilia in the gullet move in such a way that the food particles are carried to the bottom of the gullet. There at the mouth pore, food particles, from time to time, enter the endoplasm to form food vacuoles. As the food vacuoles circulate, the endoplasm secretes digestive enzymes into it. The food is digested and absorbed.top↑
The undigested or unabsorbed remains of the food are removed at a definite spot called The anal pore.
Reproduction In Paramecium
Asexual Reproduction In Paramecium
Asexual reproduction in paramecium is by a mature individual dividing into two, which is called binary fission, the meganucleus and micronucleus, each will divides into two and the cytoplasm also divides tranversely into two, which each half contains one meganucleus and one micronucleus.
Asexual reproduction by binary fission is rapid, and gives rise to large numbers of individuals called clones.
This process leads to gradual weakening of the offspring. And when this weakening goes on to a certain degree, sexual reproduction take place to make the young ones strong again.top↑
Sexual Reproduction In Paramecium
Sexual reproduction in paramecium takes place after weakening of the offspring by a complicated process called conjugation.
What Is Conjugation
Conjugation: is when two fully developed individuals called conjugants, come together and lie side by side. The two conjugants then attach to each other along their oral grooves. The meganuleus of each individual breaks down.
And the micronucleus of each individual divides into four parts. Out of that four pieces three breaks down, and the remaining piece of the micronucleus divides into two.top↑
One of the two pieces of the micronucleus in each individual migrates into the other individual and fuses with the stationary piece of micronucleus, to form the zygotic nucleus also called fusion nucleus.
Now, the conjugants separated. The fusion nucleus in each ex-conjugant then divides into eight parts. And the cytoplasm divides into four parts by binary fission to form four young paramecia each with meganucleus and micronucleus.top↑
let stop here for today next class will be on Euglena And Chlamydomonas
Next Topic :Euglena And Chlamydomonas
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