The Lipid Bilayer quiz #1 Flashcards
The Lipid Bilayer quiz #1
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What are the main types of lipids found in the lipid bilayer, and what are their primary functions?
The main types of lipids in the lipid bilayer are phospholipids (form the foundation and provide structure), sphingolipids (contribute to membrane stability and protection), glycolipids (involved in cell recognition), and sterols like cholesterol (regulate membrane fluidity and stability). How does the lipid bilayer maintain its asymmetry, and what roles do flipases and scramblases play in this process?
The lipid bilayer is asymmetric, with different lipid compositions on each side. Flipases are specific enzymes that move certain lipids to one side of the bilayer, helping maintain this asymmetry. Scramblases, in contrast, randomly transfer lipids between layers during membrane synthesis, creating a more even distribution before flipases establish the final asymmetry. What structural feature makes phospholipids the primary building blocks of the lipid bilayer?
Phospholipids have amphipathic properties, with hydrophobic tails and hydrophilic heads, allowing them to form the bilayer structure that separates the cell from its environment. How do sphingolipids contribute to the function of the lipid bilayer?
Sphingolipids help maintain membrane stability and protect the cell from environmental factors by reinforcing the bilayer structure. What is the main role of glycolipids in the cell membrane?
Glycolipids are involved in cell recognition, acting as markers that help cells identify each other, such as determining blood cell types. How does cholesterol affect the fluidity of the lipid bilayer?
Cholesterol regulates membrane fluidity by preventing the bilayer from becoming too rigid in cold temperatures or too fluid in warm temperatures, maintaining an optimal state. What are the three main types of lipid movement within the bilayer, and which is the rarest?
The three types are lateral diffusion, rotational diffusion, and transverse (flip-flop) diffusion, with transverse diffusion being the rarest. How does the saturation of lipid tails influence membrane fluidity?
Saturated tails (no double bonds) make the membrane more rigid, while unsaturated tails (with double bonds) introduce kinks that increase fluidity. What is the difference between flipases and scramblases in maintaining bilayer asymmetry?
Flipases specifically move certain lipids to one side of the bilayer to establish asymmetry, while scramblases randomly transfer lipids between layers during membrane synthesis to initially mix them. Where does lipid synthesis primarily occur in the cell, and how are new bilayers formed?
Lipid synthesis occurs on the cytosolic surface of the endoplasmic reticulum (ER), where scramblases help distribute lipids to both sides to form a bilayer before vesicles transport them to their destinations.
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