All organisms, except for bacteria, blue green algae and E.coli are categorized into eukaryotes.
All types of species from the kingdoms of Protista, fungi, Plantae and Animalia are examples of eukaryotic organisms.An Example of Kingdom Fungi
Unicellular eukaryotes are those organisms, which consists of only one single cell and all types of functions in an organism are alone performed by this cell only.
Features of Unicellular Eukaryotes
- All unicellular eukaryotes are grouped in this family as they have a well developed nucleus followed by membrane bound organelles.
- All Unicellular eukaryotes move with the help of flagella.
- The unicellular eukaryotes possess similar characteristic features of multicellular.
- All Unicellular eukaryotes are aerobic and reproduce both by sexually and also by asexually.
- All types of functions including respiration, digestion, circulation, excretion, locomotion, reproduction, etc are all carried by a single cell only.
A eukaryotic cell consists of cell wall, endoplasmic reticulum and other membrane bounded organelles like mitochondria, Golgi bodies, lysosomes, plasma membrane, ribosome, cytoplasm, chromosomes and also has a well organized nucleus with a nuclear envelope. There are different activities in a cell that are carried out from the birth of organisms till death by these cell organelles.
Plant cells belong to the family of eukaryotic cell, which are most similar to the animal cells. Compared to the cell size, plant cell is larger than the animal cell. A plant cell consists of cell wall, vacuoles that are large, plastids, and nucleus. Listed below are the few important cell organelles of plant cell along with their functions.
Plasma membrane: A thin layered membrane, which protects the cell by acting as a barrier by surrounding the cell.
Cell wall: A rigid layered membrane, which is present just behind the cell membrane. It plays a vital role in providing a shape to the cell.
Chloroplast: A cell organelle, which helps in photosynthesis.
Cytoplasm: The jellylike membrane that helps in controlling all biological processes of an organism.
Nucleus: The dark coloured membrane, which controls all the activity of a cell. It is also called as a brain of the cell.
Animal cells belong to the family of eukaryotic cell with the presence of membrane bound nucleus. The DNA in animal cells is present within the nucleus. In addition to the presence of a nucleus, they also consist of other membrane-bound organelles with their specific functions, which are necessary for normal cellular operation. Animal cells are similar to that of a plant cells with the presence of similar organelles. Animal cells are smaller than plant cells.
Chromosomes are small, coloured thread like structures present in the nucleoplasm of living cells, which helps in the inheritance or transmission of characters in the form of genes from one generation to another generation. Chromosomes contain a single, long piece of DNA, a size of about 0.004mm long. There are 23 pairs of chromosomes in the nucleus of the cells. Each chromosome has a single strand of DNA (deoxyribonucleic acid) which carries the code for a couple of thousand genes. Our gender is also determined by the presence of chromosomes. The number of chromosomes per organism is always a definite number. In human beings, each cell contains 23 pair of chromosomes. Among these 23 pairs, 22 pairs of chromosomes are autosomes and the 23rd pair of chromosome is known as sex chromosomes, which differ in females and in males. Males have one “X “and one “Y” chromosome, whereas females have 2 copies of “X” chromosomes, among which one X-chromosome is active and other one is inactive. The size of each chromosome varies from 1 to 30µm in length and from 0.2 to 2µm in diameter. Chromosomes are made up of proteins- mainly protamines and histones and nucleic acids mainly DNA (deoxyribonucleic acid).
Functions of Chromosomes
- They are capable of self-duplication.
- They help in transmitting or transferring the characters from one generation to another generation (or) from parents to offspring.
- They play a vital role in controlling biological processes in the body of an organism.
- They control cell metabolism by directing the formatting of necessary proteins.
- They help in cell differentiation during development.