Question

How does plasma membrane differ between eukaryotes and prokaryotes?

Answer 1

Hint: Plasma membrane is the outermost layer in the animal cell and second outermost layer in the plant cell after the cell wall. Plasma membrane is a lipid bilayer, containing proteins and carbohydrates.

Complete answer:
-Cell is a basic structural, functional and biological unit of life. There are two types of cells: prokaryotic and eukaryotic cells depending on the presence (eukaryotic cells) or absence of true nucleus in a cell (prokaryotic).A cell contains cytoplasm which is surrounded by a thin membrane called plasma membrane. It helps in protecting the constituents of the cell from the outside environment. Selective materials are only permitted to enter the cell through plasma membranes. It involves many cell organelles like mitochondria, nucleus.
-Prokaryotic plasma membrane: Prokaryotic cells are single celled organisms with the deficiency of nucleus and it contains capsule, cytoplasm, cell wall, plasma membrane, ribosomes, nucleoid, plasmids and flagella like bacteria.
-In prokaryotes plasma membrane is the inner delicate structure which plays an important role in regulating the entry and exit of any substances in a cell. It acts as a permeable membrane which is about 6-10 nm in width which helps in the oozing of proteins and elimination of waste products. Therefore in prokaryotes there is lipid bilayer except in some bacteria.
-Eukaryotic plasma membrane: They are the cells with true nucleus like animals, plants. These organisms have membrane bound nuclei with many cell organelles to make cellular functions within the system. -In eukaryotes plasma membrane is semi-permeable membrane that behaves as a boundary of a cell which protects and splits up the cell from the outside environment.
-In the animal cells they support holding the cell together and control the entry and exit of nutrients in a cell. Plasma membrane is a lipid bilayer in eukaryotes.
-In 1972, Singer and Nicolson proposed a model of plasma membrane called fluid mosaic model. It states that plasma membrane is made up of bilayer of phospholipids with carbohydrates, proteins, glycolipids and glycoprotein embedded inside it.
-A phospholipid molecule has its head which is a phosphate containing group which has polar or negative charge and tail consists of fatty acids with no charge. Both the surfaces of the plasma membrane are hydrophilic.
-Proteins are of two types: integral proteins lie on the surfaces and extrinsic proteins are totally buried in the layer. Carbohydrates help in cell recognition and adhesion and act as a physical barrier.

Note: Functions of plasma membrane are:
- It is responsible for the structure of the cell and shelters mechanically and chemically.
- It maintains the differences in the concentration both inside and outside the membrane.
- It regulates the transport of substances through barrier
- It interacts with other cells for tissue formation.