Eukaryotic Cell Structure, Biology tutorial


Eukaryotes can be stated as the group of organisms which possess a membrane bound nucleus all along with the membrane bound organelles. Eukaryote comprises both the unicellular and multicellular organisms. The organisms having this kind of cell are known as eukaryotic organisms or simply eukaryotes.

Eukaryotes comprise plants, animals, fungi and protists. In general, eukaryotic cells are more complicated and much bigger than prokaryotic cells. On an average, prokaryotic cells are around 10 times smaller in diameter than the eukaryotic cells.

Eukaryotes grow up and reproduce via a procedure termed as mitosis. In organisms that as well reproduce sexually, the reproductive cells are generated by a kind of cell division termed as meiosis.

Main content of Eukaryotic cell:

1) Nucleus:

The nucleus is the most evident organelle of the eukaryotic cell. It is surrounded in a double membrane and communicates by the surrounding Cytosol through various nuclear pores. In each nucleus there is a nuclear chromatin which includes the organism's genome, that is, the collection of all the genes in the organism. The chromatin is made up of compound deoxyribonucleic acid (that is, DNA) and is well packaged in the small nuclear space. The DNA stores the whole encoded genetic information of the organism as genes.

2) Nucleolus:

The well-known structure in the nucleus is the nucleolus. The nucleolus generates ribosomes that move out of the nucleus and take positions on the rough endoplasmic reticulum where they are vital in the synthesis of protein.

3) Cytosol:

The Cytosol is the 'soup' in which all the other cell organelles reside and where most of the cellular metabolism takes place. However mostly water; the Cytosol is full of proteins which control the cell metabolism comprising signal transduction pathways, glycolysis, intracellular receptors and the transcription factors.

4) Cytoplasm:

This is a collective word for the Cytosol plus the organelles suspended in the Cytosol.

5) Centrosome:

The Centrosome, or Microtubule Organizing Center (that is, MTOC), is a region in the cell where microtubules are produced. Animal and Plant cell Centrosome play identical roles in cell division and both comprise collections of microtubules; however the plant cell Centrosome is simpler and doesn't have Centrioles.

6) Centriole (animal cells only):

Each and every Centriole is a ring of nine groups of fused microtubules. There are three microtubules in every group. Microtubules and Centrioles are segment of the cytoskeleton. In the complete animal cell Centrosome, the two Centrioles are set in such a way that one is perpendicular to the other.

7) Golgi:

The Golgi apparatus is a membrane-bound structure having a single membrane. It is in reality a stack of membrane-bound vesicles which are significant in packaging macromolecules for transport elsewhere in the cell. The stack of bigger vesicles is bounded by many smaller vesicles having such packaged macromolecules. The enzymatic or hormonal contents of Lysosomes, peroxisomes and secretory vesicles are packaged in the membrane-bound vesicles at the border of the Golgi apparatus.

8) Cell Membrane:

Each cell is surrounded in a membrane, a double layer of phospholipids. The exposed heads of the bilayer are 'hydrophilic' (that is, water loving), signifying that they are well-suited with water both in the Cytosol and outside of the cell. Though, the hidden tails of the phospholipids are 'hydrophobic' (that is, water fearing), therefore the cell membrane acts as a protective barrier to the uncontrolled water flow. The membrane built up is more complex by the presence of abundant proteins which are vital to cell activity.

9) Mitochondria:

Mitochondria give the energy a cell requires to move, split, produce secretory products, contract - in short, they are the power centers of the cell. They are approximate the size of bacteria however might have various shapes based on the kind of cell. Mitochondria are membrane-bound organelles and similar to the nucleus encompass a double membrane. The outer membrane is quite smooth. However the inner membrane is highly complicated, making folds (that is, cristae).

10) Vacuole:

A vacuole is a membrane-bound sac which plays roles in the intracellular digestion and the discharge of cellular waste products. In animal cells, vacuoles are usually small. Vacuoles tend to be big in plant cells and play numerous roles: storing nutrients and waste products, aid in increasing cell size throughout growth, and even acting much similar to Lysosomes of animal cells. The plant cell vacuole as well regulates turgor pressure in the cell.

11) Cell Wall (only in plant cells):

Plant cells encompass a rigid, protective cell wall build up of polysaccharides. In higher plant cells, the polysaccharide is generally cellulose. The cell wall gives and maintains the shape of such cells and serves as the protective barrier.

12) Chloroplast (only in plant cells):

Chloroplasts are particular organelles found in all the higher plant cells. Such organelles comprise the plant cell's chlorophyll accountable for the plant's green color and the capability to absorb energy from the sunlight. This energy is utilized to change water plus atmospheric carbon dioxide into metabolizable sugars through the biochemical procedure of photosynthesis. Chloroplasts encompass a double outer membrane.

13) Smooth Endoplasmic Reticulum:

All through eukaryotic cell, particularly those responsible for the production of hormones and other secretory products, is a huge network of membrane-bound vesicles and tubules termed as the endoplasmic reticulum or ER. The ER is a continuance of the outer nuclear membrane and its diverse functions recommend the complexity of the eukaryotic cell.

The smooth endoplasmic reticulum is so named as it emerges smooth in electron microscopy.

14) Rough Endoplasmic Reticulum:

Rough endoplasmic reticulum emerges 'pebbled' by electron microscopy due to the presence of many ribosomes on its surface. Proteins synthesized on such ribosomes gather in the endoplasmic reticulum for transport all through the cell.

15) Ribosomes:

Ribosomes are the packets of RNA and protein which play an essential role in both the eukaryotic and prokaryotic cells. They are the site of protein synthesis. Each ribosome contains two portions, a big subunit and a small subunit. Messenger RNA from the cell nucleus is moved systematically all along the ribosome where transfer RNA adds up separate amino acid molecules to the lengthening of protein chain.

16) Cytoskeleton:

As its name means, the cytoskeleton assists to maintain the cell shape. However the primary significance of the cytoskeleton is in the cell motility. The internal movement of cell organelles, and also cell locomotion and muscle fiber contraction couldn't occur devoid of the cytoskeleton. The cytoskeleton is an organized network of three primary protein filaments:

  • Microtubules
  • Actin filaments (microfilaments)
  • Intermediate fibers

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