Cell and its types is among very essential topics in SSC CGL GK. Today we are here with the study notes of Cell and its types covering all aspects and important points regarding the topic.
Cell and its Types
About Cell: First cell was discovered by Robert Hook in 1665. It is the structural and functional unit of all living organism. The organisms which are made up of a single cell are known as Unicellular and those which are made up of multiple cells like human are known as multi-celullar cell.
A cells contains three basic structures:
- Cytoplasm: It is a fluid like substance that contains Cytosol and cell organelles such as mitochondria, chloroplast etc.
- Nucleus : It is the main parts of the nucleus as it contains the genetic information as DNA present in it. Fluid inside the nucleus is Nucleoplasm.
- Plasma membrane: It is made up of lipids and proteins and help in the transportation of nutrients form the external environment to inside the cell.
*Protoplasm = Nucleoplasm + Cytoplasm.* Deutoplasm = The Non-living things inside the cell.
Cell Theory:
Cell theory was given by T Schwann (a British Zoologist) and M Schleiden (a German Botanist).
Vital points of cell theory are as follow-
- A cell is a basic and functional unit of any organism and All living organisms are made of it (one or multiple cells).
- All cells arise from the pre-existing cell (Omnis cellula e cellula).
- Cell theory doesn’t apply to virus.
Detailed of Animal and Plant Cell
| Cell parts | Functions | Presence in animal cell | Presence in plant cell |
| Nucleus | Largest cell organelle of the cell and was discovered by Fontana. | yes | No |
| Mitochondria | Its called as power house of cell and is covered by two cell membranes | yes | Yes |
| Large Central Vacuole | It regulate the water and mineral transportation | yes | No |
| Chloroplast | It has double structure body and responsible for photosynthesis. It has its own DNA. | yes | No |
| Cell wall | It is made up of cellulose and present only in plant cells. | yes | No |
| Ribosome | It helps in protein syntheses and found in Endoplasmic reticulum. It is spherical body. | yes | Yes |
| Lysosome | Known as suicidal bad or atom bomb of the cell because it destructs the cell. | yes | Yes |
| Centriole | It has sac like body. It is involved in cell division. |
No | Yes |
| Golgi Bodies | It helps in protein secretion. | Yes | Yes |
| Endoplasmic Reticulum | Helps in transportation and also helps in protein and lipid synthesis. | Yes | Yes |
Classification of cells:
Primarily, cells are of two types, i.e. prokaryotic and eukaryotic cells.Difference between the two cells
| Prokaryotic cell | Eukaryotic cell |
| Nucleus without nuclear membrane | Nucleus with nuclear membrane |
| Membrane bound organelles area absent | Membrane bound organelles like endoplasmic reticulum, mitochondria are present |
| Vacuole is generally absent | Vacuole is generally present |
| Both transcription and translation occur in cytoplasm | Transcription occurs in nucleus while, translation occur in cytoplasm |
| Ribosome are 70S type only | Ribosome are 70S and 80S types |
| Enzymes of respitory are associated with the plasma membrane. | Enzymes of respitory are associated with the cytoplasm and mitochondria. |
Chromosome:
The condensed form of the DNA is known as Chromosome. A special type of protein known as histones is responsible for this condensation. When DNA is not condensed, it is known as chromatids. Centromere is a point where the chromatids held together during cell division and Telemores are the end points of the chromosomes. Based on position, centromere can be metacentric (present at the centre), sub metacentric (little away from the centre), acrocentric (situated close to the end), and telocentric (terminal centromere).
Different Types of Chromosomes are:
- Polytene Chromosomes: discovered by Balbiani in salivary gland of Chionomus larvae.
- Lampbrush Chromosomes: It was first discovered by the Balbiani, and it resemble the shape of the lamp brush.
- Genes:Gene is a unit of inheritance in living organisms. These are contained by genes. It controls the transfer of genetic information from one generation to the next generation.
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