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Cell Structure

Super Blue Berry Super Blue Berry: The Natural World’s Most Intense Color Have you ever wondered what renders the deep blue color to these blue berries? Blue berries are native to North America. Blueberries contain anthocyanins (water−soluble pigments that may appear red, purple, or blue depending on the pH), other pigments and various phytochemicals, which are under preliminary research for their potential role in reducing risks of diseases such as inflammation and cancer. Anthocyanin is one the most important pigments seen in chloroplasts. Find out the different structures and functions of all the cell organelles which helps one to discover such type of amazing facts.

Learning Objectives

After completing the topic, the student will be able to:

  • List out different cell organelles in prokaryotes and eukaryotes.
  • Compare and contrast the general structure of prokaryotic and eukaryotic chromosomes.
  • Understand and explore how plasma membrane acts as selective permeable membrane that regulates the steady traffic that enters and leaves the cell.
  • Deduce how nucleus acts as cell's genetic library and appreciate the importance of cytoplasm.
  • Discriminate between the membrane structures ER, Golgi complex and Lysosomes.
  • Discover how mitochondria acts as the energy factory of the cell.
  • Summarize the role of chloroplasts in plant cells and examine the role of peroxisomes, centrosomes and vacuoles in cellular function.
Cell Membrane Cell Membrane Structure This membrane is composed of both proteins & lipids and the proportion of it ranges from 40:60 accordingly. The lipid content is mainly composed of phospholipids (Lecithin, Cephalin, & Sphingomyelin) and glycolipids and sterols as well as some polysaccharides. This composition of plasma membrane gives rigidity and stability to the cell. Apart from all these, it is also made up of fats or other triglycerides. Hence this portion of cell plays a vital role in the influx and outflux of materials through this membrane.
Cell Structure

All the life processes take place in a cell. A cell itself is made of certain parts. Plant and animal cells are not exactly alike. Various kinds of cells show special differences, yet they all show some basic structural plan, which may be expressed in the term "generalized cell". A generalized cell consists of three essential parts: the cell membrane (plasma membrane), the cytoplasm and the nucleus.

Cell organelles: Most parts of a cell have a definite shape, a definite structure and a definite function. Such parts are called organelles. The organelles have the same status in a cell as the organs have in the entire body of an animal or plant. Cell organelles are living parts.

Cell membrane:

Cell membrane (plasma membrane or plasmalemma or phospholipid bilayer) is present in both plant and animal cells. Each cell is surrounded by a cell membrane. The cell membrane has fine pores through which substances may enter or leave the cell. It is living, thin, delicate, elastic and made of proteins and lipids (fats). Its function is to provide a mechanical barrier for the protection of the inner cell contents and to regulate the movement of molecules in and out of the cell. The permeability of the cell membrane is selective. The membranes that surround the nucleus and other organelles are almost identical to the cell membrane.

Cell membrane is a lipid bilayer, which contains a wide variety of biological molecules (primarily proteins and lipids) involved in a vast array of cellular processes. It also serves as the attachment point for both the intracellular cytoskeleton and, if present, the cell wall. The cell wall is present only in plant cells. It is made up of a complex polysaccharide (carbohydrate) called cellulose. Its function is to give strength and rigidity to the cell. It is non−living.

Fluid mosaic model Semi–permeable cell cover This is the most accepted model for plasma membrane proposed by Singer and Nicholson.
Fluid Mosaic Model

In 1972 Singer and Nicolson suggested a model, called fluid mosaic model, for explaining the ultra structure of the plasma membrane or any other membrane of the cell.

The plasma membrane is described to be fluid because of its hydrophobic integral components such as lipids and membrane proteins that move laterally or sideways throughout the membrane. That means the membrane is not solid, but more like a 'fluid'.

The typical membrane structure consists of a phospholipid bilayer with a number of proteins scattered throughout, along with some carbohydrates (glycoproteins), glycolipids and sterols. It is similar to the way in which one does a mosaic tile, hence the name.

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