Temperature Transition in Lipid Bilayers and Membrane Fluidity

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Questions and Answers

What is the role of kinks in the tails of phospholipids in the plasma membrane?

  • They increase the permeability of the membrane to ions
  • They provide a barrier to the entry of water
  • They keep the plasma membrane fluid across a range of temperatures (correct)
  • They help to regulate the movement of proteins within the membrane

What is the characteristic feature of steroids?

  • They contain four fused carbon rings (correct)
  • They are composed of a single carbon ring
  • They have a long chain of fatty acids attached to a glycerol backbone
  • They have a polar head and a nonpolar tail

What is the function of cholesterol in the cell membrane?

  • It is a precursor molecule for the synthesis of other steroids
  • It provides a barrier to the entry of water
  • It helps to regulate the movement of proteins within the membrane
  • It is a component of the cell membrane, providing structural support and regulating fluidity (correct)

What is the characteristic of the functional groups attached to the carbon skeleton of steroids?

<p>They can be polar or nonpolar (A)</p> Signup and view all the answers

What is the relationship between testosterone and estrogen?

<p>They differ only in the functional groups attached to the same carbon skeleton (B)</p> Signup and view all the answers

What is the main difference between saturated and unsaturated fatty acids?

<p>The presence or absence of carbon-carbon double bonds (A)</p> Signup and view all the answers

What is the characteristic of most membrane lipids?

<p>They are amphipathic, having a non-polar end and a polar end (A)</p> Signup and view all the answers

What is the primary function of lipids in cell membranes?

<p>To provide structural support and fluidity (B)</p> Signup and view all the answers

Which type of lipid is commonly found in biological membranes?

<p>Phospholipids (C)</p> Signup and view all the answers

What is the main characteristic of fatty acids in terms of their carbon atom number?

<p>They usually have an even number of carbon atoms (A)</p> Signup and view all the answers

What is the primary force driving the formation of lipid bilayers?

<p>Hydrophobic interaction (A)</p> Signup and view all the answers

Which type of fatty acids are more likely to make a membrane more fluid?

<p>Unsaturated fatty acids (C)</p> Signup and view all the answers

What is a characteristic of animal membranes that is not typical of plant membranes?

<p>Presence of cholesterol (D)</p> Signup and view all the answers

What is the term used to describe the difference in lipid composition between the inner and outer layers of a lipid bilayer?

<p>Lipid bilayer asymmetry (D)</p> Signup and view all the answers

Which type of cell membranes are the most fluid?

<p>Prokaryotic cell membranes (C)</p> Signup and view all the answers

What is the primary function of cholesterol in biological membranes?

<p>To affect the fluidity of the membrane (C)</p> Signup and view all the answers

Which type of membrane protein is associated with one side of the membrane and bound by electrostatic interactions?

<p>Peripheral protein (B)</p> Signup and view all the answers

What is the characteristic of the lipid bilayer structure in the fluid mosaic model of biological membranes?

<p>A double layer of lipids with proteins and cholesterol embedded in it (D)</p> Signup and view all the answers

What is the difference between integral and peripheral membrane proteins in terms of their binding to the membrane?

<p>Integral proteins are bound tightly to the interior of the membrane, while peripheral proteins are bound by electrostatic interactions (A)</p> Signup and view all the answers

What is the characteristic of the fluidity of biological membranes in the fluid mosaic model?

<p>There is lateral motion of components in the membrane, with proteins and lipids moving along the plane of the membrane (C)</p> Signup and view all the answers

Which type of protein is rhodopsin?

<p>Integral protein (D)</p> Signup and view all the answers

What is the primary source of energy for primary active transport?

<p>Hydrolysis of ATP (A)</p> Signup and view all the answers

What is the primary difference between saturated and unsaturated fatty acids?

<p>Number of double bonds between carbon atoms (C)</p> Signup and view all the answers

In which type of transport is a molecule or ion carried across the membrane by a carrier/channel protein?

<p>Facilitated diffusion (B)</p> Signup and view all the answers

What is the arrangement of phospholipids in a lipid bilayer?

<p>Polar phosphate heads oriented towards the water, nonpolar fatty acid tails oriented away from water (C)</p> Signup and view all the answers

What is the role of the modified phosphate group in a phospholipid?

<p>Acts as a polar and hydrophilic head (B)</p> Signup and view all the answers

What is the driving force behind secondary active transport?

<p>Electrochemical gradient (B)</p> Signup and view all the answers

What is the result of the binding of Na+ ions to the enzyme in the Na+/K+ ATPase mechanism?

<p>Phosphorylation and release of ADP (D)</p> Signup and view all the answers

What is the function of phospholipids in cells?

<p>Forming the plasma membranes of cells (C)</p> Signup and view all the answers

What is a characteristic of triglycerides?

<p>They are composed of a glycerol molecule linked to three fatty acids (C)</p> Signup and view all the answers

What is the primary function of HDL cholesterol in the bloodstream?

<p>To absorb cholesterol in the blood and carry it back to the liver (A)</p> Signup and view all the answers

What is the consequence of high levels of LDL cholesterol in the bloodstream?

<p>Increased risk of heart disease and stroke (A)</p> Signup and view all the answers

What is the primary characteristic of lipids in an aqueous environment?

<p>Low solubility in water, forming structures such as monolayers and bilayers (B)</p> Signup and view all the answers

What is the relationship between lipid bilayers and biological membranes?

<p>Lipid bilayers are a component of biological membranes (B)</p> Signup and view all the answers

What is the role of the liver in HDL cholesterol function?

<p>To flush HDL cholesterol from the body (C)</p> Signup and view all the answers

What is the effect of high levels of HDL cholesterol on the risk of heart disease and stroke?

<p>Reduced risk of heart disease and stroke (A)</p> Signup and view all the answers

What is the primary function of lipoproteins in the bloodstream?

<p>To transport cholesterol throughout the body (B)</p> Signup and view all the answers

What is the consequence of high levels of LDL cholesterol in the arteries?

<p>Increased risk of heart disease and stroke (B)</p> Signup and view all the answers

What is the relationship between lipoproteins and cholesterol in the bloodstream?

<p>Lipoproteins carry cholesterol throughout the body (A)</p> Signup and view all the answers

What is the primary characteristic of HDL cholesterol?

<p>HDL cholesterol absorbs cholesterol in the blood and carries it back to the liver (A)</p> Signup and view all the answers

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