Kingdom Fungi - Habitat , Features , Reproduction |Biology Blog

                                       Kingdom  Fungi 

Introduction - The Fungi are heterotrophic organisms, lacking the ability to produce their own food, as they are without chlorophyll. The term Fungi has been derived from the Latin word meaning -Mushrooms. They can be defined as chlorophyllous organisms with nucleated, somatic bodies and cell wall made of cellulose and chitin or both, and they reproduce sexually as well as asexually. The study of fungi is known as Mycology. Organisms of this group are parasites or saprophytes. It include about 1,00,000 species . They have thallus like structure,i.e., the body is not differentiated. 

Habitat -  The fungi grow in multiple habitats. In fact, they grow in every available habitat where organic matter, living or dead is found. Most of them are terrestrial. Some fungi are aquatic. The aquatic fungi are considered to be primitive. Many fungi are found in drinking water. They contaminate both our food and water. They are present all the time in the air we breathe. The fungi prefer to grow in damp, dark and humid places. 

Structure -  Fungi are simple thalli like organisms which are not differentiated into root, stem, and leaf-like structures. Their body consists of a thin branched threadlike structure called Hyphae. Many hyphae join together to form a network-like structure called mycelium. In some fungi hyphae are septate, i.e., the septum is not found in their hyphae, such hyphae are called Aseptate.  Aseptate fungi are multinucleated, in such condition, hyphae are called Coenocytic. 

Cells of fungi contain all membrane-bound cell organelles such as ribosomes, mitochondria, endoplasmic reticulum, Golgi complex, etc like other eukaryotic cells but chloroplasts are not found in them. 

Features - 

• They are either parasites or saprophytes. 

• They are found everywhere, where organic matter is found. Most of them are terrestrial. Some inhabitant the cells of living organisms and some are aquatic. 

• The cell wall is made up of chitin, but in some species, the cell wall is made of cellulose. 

• They absorb food and other substances, either through the entire surface of mycelium or by rhizoids. 

• Plastids are not found in their cells. 

• They have three types of reproduction; vegetative reproduction, asexual reproduction, sexual reproduction.

• They have food in the form of glycogen oil droplets. 

How Neurons Are Formed : Biology Blog

                                    Structure Of Neuron

All animals have a very important functional neural system in their body which is comprised of highly specialized cells called Neurons which can detect, receive and transmit different kinds of stimuli. Every neuron is made up of a cell body and cell process (Dendron and axon ).                                                   

• Cell Body or Cyton -   It contains uninucleated cytoplasm. Except for centriole, all cell organelles are found in the cytoplasm . The centriole is absent in the nerve cell thus cell division is absent .
• Nissl's granules - Endoplasmic Reticulum and ribosomes form granules like structures called Nissl's Granules.

• Cell Process -  

1. Dendron - The fine branches like structure extend out from the neuron is called dendrites . Some receptors are also present on it which receive the stimuli and produce Centripetal Conduction. The number of dendrites on neurons may vary.
2. Axon - It is the longest cell process of cyton . axon is covered by Axolemma . The terminal end is a button shape called Synaptic Knob. Each branch of Axon terminates on a  Synaptic Knob having  Neurotransmitter. Axon is covered by a layer of a phospholipid called Myelin Sheath . Myelin Sheath is covered by  thin cell membrane called Schwann Cells. Some gaps are found between the myelin sheath called Nodes of Ranvier.

Types Of Neurons - 

• Unipolar -  It is a single process arises from the cyton. It can be seen in the nervous system of the embryo.
• Bipolar -The two process arises from the cyton. It is found in the retina of our eyes. 
• Multipolar - The neuron which has one axon but many dendrons, just like most of the neurons of our body.