What Do Membranes Do? Cell membranes serve as barriers and gatekeepers. They are semi-permeable, which means that some molecules can diffuse across the lipid bilayer but others cannot. Small hydrophobic molecules and gases like oxygen and carbon dioxide cross membranes rapidly.

The primary function of the plasma membrane is to protect the cell from its surroundings. Composed of a phospholipid bilayer from tail to tail with embedded proteins, the plasma membrane is selectively permeable to ions and organic molecules and regulates the movement of substances in and out of cells.

The labeling method could help researchers track membrane proteins in living animals. When a scientist labels a membrane protein with a dye, she has to wash the cells a few times to remove dye molecules that aren’t bound to the protein.

– exposed to parts of integral proteins. Why are some cell types more permeable to a substance (for example, sodium ions) than others? – the cell is able to take up a variety of small molecules and ions while excluding others. – substances that move through the membrane at different rates.

Why do cells not have membrane transport proteins for O2? Because oxygen can dissolve in water and leak in via water channels. C. Because oxygen can dissolve in the lipid bilayer and diffuse in and out rapidly without the need for a transporter.

Cell membrane is fluid because individual phospholipid molecules and proteins can diffuse within their monolayer and thus move around. The fluidity is affected by: The length of the fatty acid chain. Here, the shorter the chain the more fluid is the membrane.

The membranes create two compartments. The intermembrane space, as implied, is the region between the inner and outer membranes. It has an important role in the primary function of mitochondria, which is oxidative phosphorylation. The matrix contains the enzymes that are responsible for the citric acid cycle reactions.

Functions

• control of the genetical information of the cell and thus the heredity characteristics of an organism,
• control of the protein and enzyme synthesis.
• control of cell division and cell growth.
• storage of DNA, RNA and ribosome.
• regulation of the transcription of the mRNA to protein.
• production of ribosomes.