Cell biology notes on Golgi appratus

                                       Golgi  Complex

The Golgi body is a membrane-bound organelle found in all the eukaryotic cells except RBCs. They remain scattered in the cytoplasm and called dictyosomes but in an animal cell they are localized. Camello Golgi in the year 1898 discovered it from the nerve cell of the cat and named it Golgi after discovery. It plays a significant role in the synthesis of large molecules of complex carbohydrates. Golgi Complex is also known by another name Lipchondria, Idiosome, Dalton Complex, and Golgi Apparatus.

Also, refer - Golgi body

Role Of Golgi Complex  -  Golgi Complex is responsible for transporting and packaging of protein & lipid molecules into vesicles for delivery to the target destination.  

Origin -  It is believed that Golgi Body arises from the vesicle of the endoplasmic reticulum.

Structure -  Golgi bodies are membrane-bound organelles. When it was studied in an electron microscope then the following structure was seen -

• Cisternae - These are flattened and tubular sacs filled with the fluid. There are 4- 7 cisternae arranged in a parallel bundle and the whole Golgi complex is supported by cytoplasmic microtubules.
• Vesicles -  These are in a bulb shape responsible for storing secretory material.
• Vacuoles - This rounded sac-like structure is found at the edge of the Golgi Complex.

Function -

• The main function of the Golgi complex is to secrete.
• It helps in cell plate formation.
• Golgi bodies also secrete carbohydrate and in this way, they help in the formation of cell walls.
• Lysosomes are also formed from Golgi Body.

Refer-  mitochondria - the powerhouse of the cell 

What Are Chromosomes? Definition, Function, and Structure

                                          Chromosome

Chromosomes are thread-like structures found inside the nucleus of every cell. These structures play a crucial role in heredity, which is why they are often called the carriers of heredity.

The word “Chromosome” comes from two Greek words:

• Chroma – meaning color

• Soma – meaning body

Chromosomes are usually present in pairs, and their number varies among different organisms:

• Humans have 23 pairs (46 chromosomes)

• Elephants have 28 pairs

• Cats have 19 pairs

These chromosomes carry genetic material in the form of DNA, which is passed on from one generation to the next.

Structure Of Chromosomes -   In 1888 W. Waldeyer called  this thread like structure a Chromosome as they could be stained with the help of stains like acetocarmine , acetoorcein etc . The structure of chromosome are composed of following parts -

• Pellicle -    Each chromosome is bounded by membrane called Pellicle .
• Matrix -  The  jelly like structure present inside chromosome enclosed by pellicle is known as Matrix
• Chromatids - Chromatids  is the  two strands of  DNA that make  Chromosomes . Two chromatids are joined by a centromere . During prophase and sometime during interphase , the chromosomal material becomes visible as very thin filaments called as Chromenemeta .
• Chromomere - Chromomere is one of the serially aligned beads that are linearly arranged along the chromosomes  They are also known by another name Idiomere .
• Telomere -  The round sealed tips of chromosomes are known as Telomere . It is derived from the two Greek words - Telos - End and Meros  - Parts.  Telomere protect the end of chromosomes from fusion with neighboring chromosomes .
• Centromere  or Primary Constriction -  It is the modified part of chromosomes where chromosomes threads are connected together .
• Secondry Constriction -  It is different from the  primary constriction by angular  deviation of chromosomal segment during anaphase stage . It is the morphological feature of some types of chromosomes which  helps in their identification .
• Satellite -  The terminal portion of chromosomes are known as Satellite . It is generally round in shape . The chromosome with satellite is known as SAT - Chromosome .

Function Of Chromosomes -

• Chromosomes are carrier of gene (DNA ) .
• Chromosomes are responsible for the transmission of parental character to their offspring .
• Changes in the number of chromosomes are result in the development of new character .
• They are responsible fro forming of new species .
• Some chromosomes are called as Sex Chromosomes are help in determining sex of the individual .

Types Of Chromosomes - Depending upon the number their are four types of chromosomes -

• Monocentric - When one centromere is present in each chromosomes then such type  of chromosomes are known as Monocentric .
• Dicentric - in this type of chromosomes their are two centromere is present .
• Polycentric - when their is more than two centromere present inside the chromosomes then the term polycentric is used .
• Acentric - In this type of chromosomes their is no centromere present inside the chromosome  .

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