Question

Short/long answer type questions.
What is the most widely accepted model to explain membrane structure today?
What percentage of organelles of a typical plant cell do you think are composed of membranes?

Answer 1

Cell theory emphasizes unity in the diversity forms. It is an organization of life forms. All organisms are composed of cells. As we knew that cell membrane is also known as plasma membrane. Anton Van Leeuwenhoek was the first person to see and describe a living cell. Cytoplasm is the gelatinous liquid that is filled inside of a cell. It is composed of salts, water and inorganic molecules. The organs are placed inside the cell separate from the cytoplasm.

Complete answer:
The most accepted model in today’s time to explain plasma membrane structure is Fluid mosaic model also known as fluid mosaic structure. A plasma membrane is the protective layer of the cell which holds the organelles intact. It should be having a proper rigid mechanism in order to protect the cell components from outside components.
Basically, the theory denotes a two-membrane layer around the cell, which is a lipid membrane bilayer with proteins embedded inside it. Behind the name of fluid mosaic model, the lipid layer is always in a locomotive form and fluid in nature hence it is named as fluid mosaic model.
The fluid mosaic model provides elasticity and fluidity to the cell organelles present inside it. The model was discovered by the scientists Singer and Nicolson in $1970$. It consists of various components called phospholipids, cholesterol, proteins and carbohydrates. The layer outside the layer is hydrophobic as to prevent the entry of liquid components from outside and inside its hydrophilic as for the smooth passage of the inner components to outside.
Almost all organelles present inside the cell are membrane bound as due to the above reason. The organelle ribosome, however, possesses an exception and it is lacking the plasma membrane. Except that all the organelles possess membranes.

Note:
As we discussed, Organelles like mitochondria, chloroplasts all are membrane bound organelles. Around ninety percent of organelles are membrane bound. The inner membrane of these organs is selectively permeable to the outer environment. So, the fluid mosaic model explains the theory of structures and functions of plasma membranes. How the PM works for a cell.