Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
mem struc and func
| Question | Answer |
|---|---|
| In biological membranes, the most numerous molecules are: | lipids |
| Which type of lipids are the most abundant in the plasma membrane? | phospholipids |
| phosphatidylcholine | most common phospholipid in plants and animals |
| phosphatidylethanolamine | most common phospholipid in bacteria |
| phosphatidylserine | most common phospholipid in cerbral cortex |
| cholesterol | functions in membrane fluidity |
| galactocerebroside | marker for oligodendrocytes in the brain |
| Which of the following is most likely to occur after the lipid bilayer is pierced? | the membrane reseals |
| Which of the following functions of the plasma membrane is possible without membrane proteins? | selective permeability |
| Formation of a lipid bilayer is energetically favorable. How does this arrangement result in higher entropy for the system, and thus make bilayer formation energetically favorable? | Water molecules form cage-like structures around hydrophobic molecules. |
| A bacterium is suddenly expelled from a warm human intestine into the cold world outside. Which of the following adjustments might the bacterium make to maintain the same level of membrane fluidity | produce lipids with hydrocarbon tails that are shorter and have more double bonds |
| Where does most new membrane synthesis take place in a eukaryotic cell? | in the endoplasmic reticulum |
| Membrane lipids are capable of many different types of movement. Which of these does not occur spontaneously in biological membranes? | moving between lipid layers |
| Most animal fats form a solid at room temperature, while plant fats remain liquid at room temperature. Which of the following is a feature of lipids in plant membranes that best explains this difference? | unsaturated hydrocarbons |
| New membrane phospholipids are synthesized by enzymes bound to the __________ side of the __________ membrane. | cytosolic; endoplasmic reticulum |
| Which enzyme regulates the growth and distribution of membranes by ensuring equal, but random, distribution of phospholipids in each layer. | scramblase |
| Which enzyme regulates the growth and distribution of membranes by the selective retention of certain types of lipids on one side or the other. | flippases |
| Red blood cells have been very useful in the study of membranes and the protein components that provide structural support. Which of the following proteins is the principal fibrous protein in the cortex of the red blood cell? | spectrin |
| Which best describes the process by which neutrophils are recruited by endothelial cells? | Proteins interact with the proteins on the surface of another cell. |
| Which best describes the process by which nutrients from the gut lumen are taken up at the apical surface of the intestinal epithelial cells that line the gut and released from their basal and lateral surfaces? | Protein movement is limited by the presence of a diffusion barrier. |
| The endothelial cells found closest to the site of an infection express proteins called lectins. Each lectin binds to a particular __________ that is presented on the surface of a target cell. | oligosaccharide |
| What percentage of the membrane mass is made up of lipids? | 50% |
| Which phospholipid is approximately 15% of phospholipids in the cerebral cortex? | Phosphatidylserine |
| What type of membrane protein passes through the membrane exactly one time? | Single-pass protein |
| How many times does a G protein coupled receptor pass through the membrane? | 7 times |
| Where are phospholipids synthesized? | On the cytosolic surface of the ER |
| What happens when bacteria experience increased temperatures? | They produce longer fatty acid chains with fewer double bonds |
| Which protein forms a mesh with actin to create the cell cortex that supports the cell membrane? | Spectrin |
| What is the glycocalyx composed of? | Proteins with attached sugars (glycoproteins and proteoglycans) |
| Which molecule is a marker for oligodendrocytes in the brain and is involved in myelination? | Galactocerebroside |
| What creates the "kinks" in unsaturated fatty acids? | Double bonds between carbons |
| Which of the following is found on the inner leaflet (cytosolic side) of the membrane and is involved in membrane fusion? | Phosphatidylethanolamine |
| Which component of phospholipids makes them amphipathic? | They contain both hydrophilic heads and hydrophobic tails |
| What are lectins? | Carbohydrate-binding proteins produced in response to infection/injury |
| Which example demonstrates how membrane asymmetry is preserved during vesicle transport? | Sugars on glycoproteins remain on the non-cytosolic side from Golgi to cell membrane |
| What is the typical length range of hydrocarbon tails in phospholipids? | 14-24 carbons |
| Which type of membrane protein uses beta-sheets to cross the membrane? | Beta barrel proteins |
| Why is membrane fluidity important? | It enables membrane protein movement, distribution to offspring, and cell fusion |
| What percentage of lipids by weight in the membrane is cholesterol? | 20% |
| What is the approximate thickness of a lipid bilayer membrane? | 5 nanometers |
| Which type of fatty acid would increase membrane fluidity? | Unsaturated fatty acids with kinks from double bonds |
| What is the most common phospholipid in plants and animals? | Phosphatidylcholine |
| How many times per second do individual lipids rotate in the membrane? | 500 revolutions per second |
| What role does cholesterol play in animal cell membranes? | Modulates fluidity by stiffening the membrane |
| Which enzyme performs random transfer of lipids to create symmetric growth of the membrane? | Scramblase |
| On which side of the cell membrane are glycolipids typically found? | Non-cytosolic side (outer leaflet) |
Created by:
user-1927187