Cell nucleus

Cell nucleus

Cell nucleus. The presence of cell nucleus is a principal feature in plants an animals. Nucleus contains the genetic information for that organism.

Cell nucleus.

Cell nucleus. The presence of cell nucleus is a principal feature in plants an animals. Nucleus contains the genetic information for that organism.

What is cell nucleus? What is the example of cell nucleus?

Cell nucleus. The large membrance enclosed organelle which contains the genetic material in the form of multiple linear DNA molecules with the structure of chromosome is called cell nucleus.

It’s a double-membraned organelle containing genetic material and other instructions required for celluar systems.Accordong to cell biology,the nucleus function is to act as the control center of the cell. Nucleus is specially found in eukaryotic cells.

When people look at a picture of the cell,it’s found in the middle of the cell.The nucleus bears all of the cell’s chromosomes, which encode the genetic material. So,this is really an important part of the cell to survive.

The nucleus has a membrane surrounding it that keeps all the chromosomes inside and makes the distinction between the chromosomes being inside the nucleus,the other organelles and components of the cell staying outside.

Sometimes things like RNA need to traffic between the nucleus and the cytoplasm.There are pores in this nuclear membrane that allow molecules to go in and out of the nucleus.

An array of holes, or pores, in the nuclear membrane allows for the selective passage of some certain molecules (such as proteins and nucleic acids) into and out of the nucleus. It used to be thought that the nuclear membrane only allowed molecules to go out, but now it’s realized that there is an active process also for bringing molecules into the nucleus.

Etymology:

The term nucleus came from the Latin nucleus, meaning “kernel” or “core”, a diminutive of nux (“nut”). The plural form is nuclei. Nuclear is the descriptive term that relates to a nucleus.

Example :

An example of a nucleus in real life is the nucleus of human skin cells. It contains all of our genetic information and only genes that are necessary for skin cells are expressed.Thus, producing the unique cell type needed for the epidermis.

On the other hand, in botany, the nucleus may also refer to the central kernel of a nut or seed, or the center of a starch granule. In neuroanatomy, a nucleus is a group of cell bodies of nerve cells in the brain or spinal cord.

There are so many examples of it.

Do all cells have nucleus?

No,all cells do not have a nucleus.When there is a lack of nucleus in a cell, the cell is termed as anucleated.
Cell biology breaks cell types into eukaryotic (those with a defined nucleus) and Prokaryotes(those with no defined nucleus). Prokaryotes(meaning ‘before nucleus’) are cells without a definite nucleus. The DNA floats in the cytoplasm and they divide through mitosis. RBC and platelets present in eukaryotes also do not have the nucleus. It’s RBC (Red Blood Corpuscles) and plateletdie.

But,a cell can’t survive without nucleus.

The nucleus is the control centre of the eukaryotic cell. It possesses DNA, which directs the formation of proteins and enzymes in the cell, it controls the gene expression and regulates other functions performed by the cell. It guides the cells to divide. So without the nucleus, most of the eukaryotic cells will die.

Why cell nucleus is important?

Why nucleus is called the brain of cell?

The nuclcleus controls & regulates the activities of cell. It helps in growth metabolism.It also carries the gens, structures that contain the hereditary information.

Nucleus is highly important for all the cells.
It is often called ‘Brain of cell’ as it Regulates the cell activities.

It contains the genetic material ( DNA OR RNA ) ,which is passed on to the next generation. It contains genetic information, which directs the synthesis of proteins and other cellular processes such as differentiation, growth, metabolism, cell division, reproduction, etc.

What are the types of nucleus?

Cells are normally diploid – this means that they have a pair – two sets of homologous chromosomes, and hence two copies of each gene or genetic locus.
For example : Mice only have 19 pairs plus XY chromosomes, whereas Humans have 22 plus XY.

However, cells can be haploid, polyploid or aneuploid. Haploid: only has one set of chromosomes – i.e. in a sperm or oocyte. Polyploid: Contains more than two sets of homologous chromosomes. Aneuploid: Have atypical chromosome numbers – can either have one or two extra chromosomes, or can lose chromosomes. This is abnormal, and can be diagnostic of cancer.

There are four types of nucleus. They are discussed below:

1. Uninucleate cell:

It is also referred to as monokaryotic cell. Mostly in plant cell contain single nucleus.

2. Bi-nucleate cell:

It is also called as dikaryotic cell.It contains 2 nucleus at a same time. Example is:

(i) Paramecium (mega and micronucleus)

(ii) Balantidium

(iii) Liver cells and cartilage cells.

3. Multinucleate cells:

It is also known as polynucleate cell which contains more than 2 nucleus at a time e.g., in, plants latex cells and latex vessels. In animals, striated muscle cell and bone narrow cells.

4. Enucleate cells:

Cell without nucleus are called enucleate cells. However, some living cells like mature sieve tubes of phloem and RBCs of mature mammals lack nuclei.

 

What are the parts of nucleus?

What is the structure of cell nucleus?

The nucleus is the largest organelle in the human body having around 25 % of the cell volume.

Well, generally nucleus has four parts.

They are:
(a). Nuclear membrane or Nuclear envelope or Karyotheca.
(b). Chromatin threads or Nuclear reticulum.
(c). Nuclear sap or Nucleoplasm or Karyolymph.
(d). Nucleolus.

A detail description is given below:

(a). Nuclear membrane:

The nuclear envelope is made up of outer and inner membrane (2 unit membranes), made up of lipoproteins, perinuclear space, pores, annuli material and inner dense lamella. The outer membrane is continuous with ER. The outer membrane may be continuous with other organelles, such as the Golgi apparatus and the endoplasmic reticulum. The nuclear membrane has tiny gaps called pores. These pores allow the selective passage of substances between the nucleus and the cytoplasm (the matrix containing various organelles in the cell).The exchange of different substances between nucleus and cytoplasm takes place through minute pores already present in nuclear membrane.

(b). Chromatin threads:

The DNA is organized in the nucleus to form chromatin. The chromatin also contains proteins, the main proteins being histones. The chromatin further condenses to form the chromosomes. The human cell has 23 pairs of chromosomes.

This term was proposed by W. Flemming. Chromatin threads are intermixed with one another and form a network called chromatin reticulum. At the time of cell division the chromatin threads separate from one another and become thicker and smaller and are now termed as chromosomes.

It is basically nucleoprotein, made up of nucleic acid and basic protein histone. Nucleic acid contains sugar, phosphate, nitrogenous bases and are very complex organic acids.

Here, Again Nucleic acid are of two types.

1. DNA (Deoxyribonucleic acid).

Especially found in chromatin, also present in mitochondria and chloroplast.

2. RNA (Ribonucleic acid).

Especially found in cytoplasm in soluble form and is called soluble RNA or £RNA, also present to some amount in ribosomes of nucleus, chromatin and nucleolus. It is synthesized from DNA and is accumulated in nucleolus. Later, it travels to cytoplasm and gets attached to ribosomes.

Chromatin is basophilic in nature and most of the chromatin material is transformed into a specific number of chromosomes during cell division. The chromatin material may be heterochromatin, euchromatin and sex chromatin. Heterochromatin and Euchromatin terms were given by Emil Heitz.

Nuclear Sap (= Nucleoplasm):

The nucleoplasm is also called the karyoplasm or the nuclear sap. It is a semi-solid, granular substance that contains many proteins. The protein fibers form a crisscross matrix within the nucleus. This helps maintain the shape and structure of the nucleus. The nucleoplasm is the main site for enzyme activity within the nucleus. The appearance of nucleoplasm may vary during the different phases of the cell cycle. Besides proteins, the nucleoplasm also contains other substances, such as DNA, RNA, and minerals.

The nuclear membrane encloses the clear, homogenous, transparent, colloidal liquid of variable consistency. It is chiefly composed of nucleoproteins, a small amount of organic and inorganic substances like nucleic acids, proteins dissolved phosphorus, minerals, ribose sugars, enzymes and nucleotides.

Nucleolus:

It was first observed by Wagner and the term was proposed by Browman, subsequently described by Fontana.

The nucleolus is a well-defined spherical structure within the nucleus. It is the site for the synthesis and assembly of ribosomes. The ribosomes act as the site of protein synthesis within the cell.

Characteristics:

(i) One or more nucleoli may be present within a nucleus. Four nucleoli are present in each nucleus in onion.

(ii) Nucleolus disappears in late prophase stage.

(iii) Reappears in telophase stage.

(iv) It is store house of RNA.

What are the functions of cell nucleus?

The cell nucleus is a very notable organelle within the eukaryotic cell. Perhaps it is the most important and defining feature of the eukaryotic cells. Most of the genetic material (DNA) is contained in the nucleus, while a small amount of it is found in mitochondria. The majority of human cells have a single nucleus, although there are several cell types that have multiple nuclei (e.g. osteoclasts) or don’t have a nucleus at all (erythrocytes).

The nucleus is the largest, most prominent organelle inside the cell. The functions of the nucleus are that it houses genetic material (DNA). It is the site of RNA production and it helps regulate cell metabolism by generating various enzymes.

Since the structure of the nucleus is an important milestone for understanding citology and histology, this article will discuss the functions of the cell nucleus in an easy way.

• It contains the genetic information of the cell in the form of deoxyribonucleic acid (DNA) or chromosomes and thus, controls cell growth and multiplication. It is also the site of DNA replication (formation of an identical copy of DNA).

• Control of the protein and regulates cell metabolism by enzyme synthesis.

• Control of cell division and cell growth.

• Storage of DNA, RNA and ribosome.

• Regulation of the transcription of the mRNA to protein.

• Production of ribosomes.

• It is the site for the synthesis of ribonucleic acid or RNA that acts as a template for the synthesis of various proteins in the cell. It is also the site for the synthesis of the protein factories of the cell called the ribosomes.

 

Who first discovered cell nucleus?

In 1831,’Robert Brown’ discovered nucleus in cell for the first time.
It is heard that, he was working on orchids. Then,Under a microscope he observed an opaque area, which he called the areola or nucleus. It is a site for the genetic material.

But, Cell was first discovered by Robert Hooke in 1665.

Again,for the first time Dr. Joachim Hammerling determined that the nucleus controls the development of organisms by containing the hereditary information or DNA from his grafting experimentation on the green algae Acetabularia.

What is nucleus made of?

The nucleus contains nearly all of the cell’s DNA, surrounded by a network of fibrous intermediate filaments and enveloped in a double membrane called the “nuclear envelope”. The nuclear envelope separates the fluid inside the nucleus, called the nucleoplasm, from the rest of the cell.

 

Where is the nucleus found?

In 1665, Robert Hooke, a British scientist, discovered cells,the tiny compartments of DNA and proteins. Looking at a piece of cork under a microscope, Hooke coined the term “cells” for the different chambers that make up the piece of cork. The two types of cells are eukaryotes and prokaryotics. Eurkaryotic cells are more-advanced cells that have a nucleus while less-intricate prokaryotic cells do no cell.

The cell’s nucleus is in the middle of the cell’s cytoplasm, the liquid that fills the cell. The nucleus may not, however, be right in the middle of the cell itself. Taking up about 10 percent of the cell’s volume, the nucleus is usually around the center of the cell itself. As the nucleus directs all of the cell’s functionality, its central location is key to passing information to the other components of the cell.

The nuclear envelope contains pores which control the movement of substances in and out of the nucleus. RNA is selectively transported into the cytoplasm, and proteins are selectively transported into the nucleus. The nuclear membrane is supported by a meshwork of intermediate filaments, called nuclear lamins.

One or more darkly staining spherical bodies called the nucleoli are found inside the nucleus. These are the sites at which ribosomes are assembled. Nucleoli are most prominent in cells that are synthesising large amounts of protein.

Most cells have a single nucleus, though some have none (ie. red blood cells), and some have several (i.e. skeletal muscle).

Nuclei look different cell types, and when cells divide. For example, in different types of white blood cells, in interphase, the nucleus can have one, or more lobes, and the number of lobes is characteristic of the type of white blood cell.

 

What colour is a nucleus?

The color of the nucleus can differ depending on the type of the cell, but the nucleus is usually a clear, grayish color.

In some case, it is light blue too.

‘The nucleus’ considers the most spatially organized and probably the most dynamically active part of the cell.It is responsible for storing the cell’s hereditary material or the DNA. It is responsible for coordinating many of the important cellular activities.

It is a pivotal organelle responsible for regulating almost all forms of cellular activities.

So, this is really an important part of the cell to protect.

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