Mitochondrion is the powerhouse of the cell. It generates energy in the form of ATP by breaking down glucose molecules. The outer membrane is freely permeable which allows the passage of ions, nutrient and energy molecules. The inner membrane, contrarily, is strictly permeable. It is permeable only to oxygen and ATP. It is folded into a number of folds, which is known as the cristae. The cristae contain proteins and molecules which aids in the production of ATP molecules. The main function of the rough endoplasmic reticulum is to manufacture proteins. Unlike smooth endoplasmic reticulum, ribosomes are attached to its membrane, hence appears rough. Ribosome serves as the site of protein synthesis. These proteins are then delivered to other …show more content…
Since the nuclear membrane is impermeable to most molecules, small holes called nuclear pores are present to allow the movement of molecules across the envelope. The nucleolus, additionally, is responsible for the production and assembly of subunits which form the ribosome.The cell membrane is a semi-permeable membrane which function is to protect the contents of the cell by controlling what substance enters and exits of the cell. Cell membrane is a double layer of phospholipids (lipid bilayer). The hydrophilic heads (water-loving) of the bilayer are arranged to face the cytosol and the extracellular fluid. The hydrophobic tails (water-fearing), on the other hand, are buried in the interior of the membrane, making the membrane impermeable to water-soluble molecules such as …show more content…
They help large molecules move across the cell membrane. Some proteins also form a channel which allows ions or other small molecules to cross.
The cell membrane is responsible for regulating the movement of substances in and out of the cell. It is selectively permeable which means that certain molecules can diffuse across the lipid bilayer but others cannot. Small hydrophobic molecules and gases like oxygen and carbon dioxide cross membranes rapidly. Small polar molecules, such as water and ethanol, can also pass through membranes, but they do so more slowly. On the other hand, highly charged molecules, such as ions, and large molecules, such as sugars and amino acid cannot diffuse across the membrane.

The transportation of substances across the membrane can either be passive or active. Passive transport occurs without the input of cellular energy, whereas active transport requires the expenditure of energy in transporting materials across the membrane. The membrane also maintains the cell potential. The cell membrane thus works as a selective filter that allows only certain things to come inside or go outside the cell. The cell employs a number of transport mechanisms that involve biological