Cell or Plasma Membranes

The movement of water and dissolved materials through a cell membrane is called Osmosis.

Lipid molecules are what make up the cellular membrane. Lipids are mostly composed of phospholipids creating a phospholipid bilayer. Each phospholipid has a polar head and a non polar tail. There are two layers of phospholipids composing the bilayer with non polar tails facing towards eachother. Each layer is known as a leaflet. The phospholipid translocators are designated to 'flip-flop' the phospholipids between each leaflet to increase fluidity of the membrane.

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If the receptors of the plasma membrane are damaged, the cell may not be able to receive signals from the external environment, which can disrupt important cellular processes like cell communication, growth, and metabolism. This can lead to various functional impairments and affect the overall health and functioning of the cell.

The plasma membrane uses selective permeability, by which a membrane allows some substances into the cells while keeping others out. Picture a butterfly net, the holes in the allow knats and other bugs to pass through, while capturing others.

Proteins in the cell membrane serve various functions such as transporting molecules in and out of the cell, acting as receptors for signaling molecules, and providing structural support for the membrane. They also help in cell-cell communication and adhesion, as well as in cell recognition and identification.

It depends on what is in the water. If the water in the cell has the same concentration of ions as there is outside the cell, nothing will happen. This solution is said to isotonic. Iso- means the same.

If the concentration is lower, then water will move into the cell and can cause it to burst. This solution is hypotonic. Hypo- means lower.

And if it higher, water will leave the cell and the cell will look like prune (crenated). The solution outside is hypertonic. Hyper- means above or higher.

"Water always follows salt" is a good idea to remember as water always goes to where the salt concentration is higher.

Of the major biomolecules, lipids, carbohydrates, proteins and nucleic acids, only nucleic acids are not present in cell membranes. Lipids make up the bilayer; proteins craete pumps and channels; carbohydrates are part of glycoproteins but no RNA or DNA is present.

Among others, yes, they serve as membrane receptors.

No.

The cell would dispose of the smaller substance later.

There are generally two types of mechanisms that allow a cell to move substances across the cell membrane. One is called active transport and the other is passive transport.

In passive transport the cell membrane is semipermeable and allows substances of smaller sizes to enter or leave the cell by diffusion, filtration, or osmosis.

In active transport the cell membrane uses energy in the form of ATP molecule to move either atoms, molecules, or even larger things like parts of other cells, bacteria, or virus across the membrane. With the larger particles, the cell wall actually engulfs the object, surrounds it, and then collapses onto it so it is inside the cell. Then organelles called lysosomes, eat away at the foreign particle until it breaks down and gets digested inside the cell. These processes are called phagocytosis (for solids) and pinocytosis (for liquids).

The implication of non-polar molecules being faster than polar molecules through the cell membrane is seen in the transport of essential molecules like glucose. This is made possible through the gradients that are established as a result of this.

Of course they have a cell membrane.Every living organism have a membrane.

The phospholipid tails of the plasma membrane are hydrophobic, meaning they repel water molecules. This non-polar characteristic prevents water and other hydrophilic substances from easily passing through the membrane. The arrangement of these tails in a bilayer creates a barrier, allowing the membrane to maintain its integrity and regulate the movement of materials in and out of the cell.

Membranes consist of lipid bilayers rather than lipid monolayers because bilayers provide a stable barrier that effectively separates the interior of the cell from the external environment. The amphipathic nature of lipids, with hydrophilic heads facing outward and hydrophobic tails facing inward, creates a dual-layer structure that minimizes exposure of hydrophobic tails to water. This arrangement also allows for the formation of various membrane proteins and facilitates essential functions such as transport and signaling. Monolayers would be less stable and could not enclose cellular compartments effectively.

Small, nonpolar molecules such as oxygen and carbon dioxide can pass freely through a plasma membrane. These molecules can diffuse directly through the lipid bilayer due to their size and hydrophobic nature. Additionally, small uncharged polar molecules like water can also cross the membrane, albeit at a slower rate, often facilitated by specific channels.

The plasma membrane is composed mostly of phospholipids

Yes, the hydrogen ion (H⁺) concentration is higher outside the thylakoid membrane than inside during the light-dependent reactions of photosynthesis. As electrons are transferred through the electron transport chain, protons are pumped from the stroma into the thylakoid lumen, creating a proton gradient. This gradient is then utilized by ATP synthase to produce ATP as protons flow back into the stroma.

During continuous conduction, the action potential is regenerated at each successive segment of the neuronal plasma membrane through the opening of voltage-gated sodium channels. When an action potential travels along the axon, the depolarization of one segment triggers the channels in the adjacent segment to open, allowing sodium ions to flow in and depolarize that segment. This process continues sequentially down the axon, ensuring the action potential propagates without decreasing in strength. The subsequent repolarization occurs as potassium channels open, restoring the membrane potential before the next segment is activated.

K

The gel-like substance inside the cell membrane is called cytoplasm. It is a semi-fluid matrix that contains water, salts, and various organic molecules, providing a medium for biochemical reactions. Cytoplasm plays a crucial role in maintaining cell shape and supporting organelles, allowing nutrients to be transported throughout the cell.

Virtually all cells contain a cell membrane, including plants and animals.