Cell or Plasma Membranes

In a cell city analogy, the plasma membrane can be compared to the city walls as it surrounds and protects the cell, controlling what enters and exits the cell. Just like city walls, the plasma membrane also helps maintain the cell's shape and provides structural support.

The plasma membrane of a mucosal epithelial cell can form microvilli, which are finger-like projections that increase the cell's surface area for absorption. It can also have tight junctions, which are responsible for creating a barrier that prevents leakage of material between cells. Additionally, the plasma membrane may contain cilia, which are hair-like structures that help with movement and sensing in certain epithelial cells.

The area between the cell membrane (plasma membrane) and the nucleus is known as the cytoplasm. It is a gel-like substance that contains organelles, such as mitochondria and endoplasmic reticulum, and where many cellular processes occur. The cytoplasm also contains the cytoskeleton, which helps maintain cell shape and allows for intracellular transport.

To explain how a plant cell is eukaryotic rather than prokaryotic, consider the definition of both words. What are the similarities and differences between the two cell types? Here are two places to start: what is found inside each cell type and how does each type reproduce itself?

The most selective pores in the filtration membrane are located in the glomerulus of the nephron in the kidneys. These selective pores, known as podocytes, allow for the passage of small molecules like water, ions, and waste products while preventing larger molecules like proteins and blood cells from entering the filtrate. This selectivity is important for maintaining the body's fluid balance and eliminating waste products efficiently.

The cell membrane is a complicated structure layered rather like a sandwich. The two pieces of bread are the lipid bilayers (bilayers as in the two pieces), the meats and cheeses is the hydrophobic region, and proteins are like the toothpick that is sticking out of the sandwich (there are multiple) and there are various carbohydrate chains coming off of the proteins, like the plastic wrapper on the top of the toothpick.

A plasma membrane is most fluid if it contains a higher proportion of unsaturated fatty acids in its phospholipid bilayer. Unsaturated fatty acids have kinks in their hydrocarbon tails, which prevents them from packing tightly together, making the membrane more fluid. Additionally, a higher ratio of cholesterol can also contribute to fluidity by increasing flexibility and reducing rigidity in the membrane.

Fibroblasts have receptors for growth factors on their plasma membranes. Growth factors play a crucial role in regulating the proliferation and function of fibroblasts in various physiological processes such as wound healing and tissue regeneration.

Most cell membranes are composed principally of phospholipids, which have a hydrophobic tail and a hydrophilic head. These phospholipids form a lipid bilayer that acts as a barrier to control what enters and exits the cell. Additionally, cell membranes also contain proteins, cholesterol, and carbohydrates.

smooth endoplasmic reticulum

A cell membrane can be compared to a barrier or protective fence. It regulates the passage of materials in and out of the cell, just like a gatekeeper controls who enters and exits a space. Additionally, it is flexible and dynamically adjusts its shape, much like a stretchy security net.

Yes, the plasma membrane plays a role in self-recognition in the immune system. Cells use proteins on their plasma membranes, such as major histocompatibility complex (MHC) molecules, to distinguish self from non-self cells. This helps the immune system to target foreign invaders while not attacking the body's own cells.

Yes, Euglena has a cell membrane. The cell membrane surrounds the cell and helps regulate the movement of molecules in and out of the cell.

the cell membrane

The two principal types of molecules in plasma membranes are phospholipids and proteins. Phospholipids form the basic structure of the membrane, while proteins are embedded within or attached to the phospholipid bilayer and serve various functions such as transport, signaling, and cell recognition.

It is semi-permeable. Small, polar molecules (like water) can pass through, as can non- polar molecules (like steroids). However, since the inside of the double-layered plasma membrane is non-polar, large polar molecules require channels or transport proteins to get inside the cell.

If by why you mean how, then the answer lies in the fact that cell membranes have special transport channels for different materials. Essentially, the phospholipid bilayer means that the outside of the cell membrane is charged (polar) and the inside is uncharged (non-polar). Whilst uncharged molecules can easily squeeze in between the phospholipids, the charged molecules have a problem. Because they carry a charge it means that they cannot enter the area in the middle where there is no charge, so there are special protein channels. These channels are lined with charge and allow the passage of polar (charged) molecules through the cell membrane.

The compound that allows materials to move through cell membranes by osmosis is water. Water moves freely through cell membranes to maintain osmotic balance within the cell.

Ions, glucose, amino acids, and certain proteins are actively transported across plasma membranes. This process requires the use of energy in the form of ATP to move substances against their concentration gradient.

Cell membranes are selectively permeable, allowing certain molecules or ions to pass through while restricting the passage of others. This permeability is crucial for maintaining cellular homeostasis by controlling the movement of substances in and out of the cell. The lipid bilayer of the membrane and embedded proteins play key roles in regulating this permeability.

All cells have a cell membrane! Only "plant cells" have a cell wall, and a cell membrane!

Cell membranes are selectively permeable because they allow certain substances to pass through while blocking others. This selectivity is achieved through the presence of proteins and channels that regulate the movement of specific molecules into and out of the cell. The lipid bilayer structure of the membrane also plays a role in determining which substances can cross based on their size, charge, and solubility.