GoConqr has a new look! Let us know what you think.

Sign up free

Quiz

Plasma Membrane

Fatima G. 11 questions Updated 15 Sep 2019

Take the quiz

This quiz has question types that open in the usual player.

Questions in this quiz (11)

  1. 1 • Phospholipid bilayer with embedded proteins
    ○ [blank_start]Hydrophilic[blank_end] (water-loving) polar [blank_start]heads[blank_end]
    § Face inside and outside of cell (water present)
    ○ [blank_start]Hydrophobic[blank_end] (water-fearing) nonpolar [blank_start]tails[blank_end]
    § Face each other, away from water
    ○ [blank_start]Cholesterol[blank_end] (animal cells) controls excess fluidity
    The tails have [blank_start]double bonds[blank_end].
    • Membrane proteins throughout membrane may be:
    ○ [blank_start]Peripheral[blank_end] proteins – associated with only one side of membrane
    ○ [blank_start]Integral[blank_end] proteins – span the membrane
    § Can protrude from one or both sides
    § Embedded within the membrane
    § Able to move laterally
    • Both phospholipids and protein can have attached carbohydrate chains.
    • [blank_start]Glycolipids[blank_end] are lipids attached to carbohydrates.
    [blank_start]Glycoproteins[blank_end] are proteins attached to carbohydrates.'
    1. Adouble bonds
    2. BCholesterol
    3. CHydrophobic
    4. Dtails
    5. Eheads
    6. FHydrophilic
    7. GPeripheral
    8. HIntegral
    9. IGlycolipids
    10. JGlycoproteins
  2. 2 • [blank_start]Flippases[blank_end]: transfer certain phospholipids from the inner to outer leaflet
    • Overview of Glycolipids
    ○ [blank_start]Glycolipids[blank_end] are molecules that contain both carbohydrate and lipid components.
    ○ Like the phospholipid sphingomyelin, glycolipids are derivatives of [blank_start]ceramides[blank_end] in which a long-chain fatty acid is attached to the amino alcohol sphingosine.
    ○ They are, therefore, more precisely called [blank_start]glycosphingolipids[blank_end]. [Note: Ceramides, then, are the precursors of both phosphorylated and glycosylated sphingolipids.]
    ○ Like the phospholipids, glycosphingolipids are essential components of all membranes in the body, but they are found in greatest amounts in [blank_start]nerve[blank_end] tissue.
    ○ They are located in the outer leaflet of the plasma membrane, where they interact with the extracellular environment.
    As such, they play a role in the regulation of cellular interactions (for example, adhesion and recognition), growth, and development.
    Glycolipids contribute to cells surface carbohydrates which form [blank_start]glycolax[blank_end].
    1. AFlippases
    2. BGlycolipids
    3. Cceramides
    4. Dglycosphingolipids
    5. Eglycolax
    6. Fnerve
  3. 3 • Membrane glycosphingolipids associate with cholesterol and GPI-anchored proteins to form [blank_start]lipid rafts[blank_end], laterally mobile microdomains of the plasma membrane that function to organize and regulate [blank_start]signaling[blank_end] and [blank_start]trafficking[blank_end] functions of membranes.
    Lipid rafts contain [blank_start]cholesterol[blank_end] and [blank_start]GPI[blank_end] anchor proteins.
    Lipid raft: specialized areas of outer leaflet of lipid bilayer enriched in [blank_start]cholesterol[blank_end] and [blank_start]sphingolipids[blank_end].
    • Structure of Phospholipids
    ○ There are two classes of phospholipids: those that have [blank_start]glycerol[blank_end] (from glucose) as a backbone and those that have [blank_start]sphingosine[blank_end] (from serine and palmitate).
    Both classes are found as structural components of membranes, and both play a role in the generation of [blank_start]lipid[blank_end]-signaling molecules.
    1. Alipid rafts
    2. Bsignaling
    3. Ctrafficking
    4. Dcholesterol
    5. EGPI
    6. Fcholesterol
    7. Gsphingolipids
    8. Hglycerol
    9. Isphingosine
    10. Jlipid
  4. 4 • Glycerophosholipids
    ○ Glycerophospholipids Phospholipids that contain [blank_start]glycerol[blank_end] are called glycerophospholipids (or phosphoglycerides).
    ○ [blank_start]Glycerophospholipids[blank_end] constitute the major class of phospholipids and are the predominant lipids in membranes.
    ○ All contain (or are derivatives of) [blank_start]phosphatidic acid[blank_end] (PA), which is DAG with a phosphate group on carbon 3.
    ○ [blank_start]PA[blank_end] is the simplest phosphoglyceride and is the precursor of the other members of this group.
    1. Glycerophospholipids from phosphatidic acid and an alcohol: The phosphate group on PA can be [blank_start]esterified[blank_end] to another compound containing an alcohol group. For example: Serine.
    1. Aphosphatidic acid
    2. BGlycerophospholipids
    3. Cglycerol
    4. Desterified
    5. EPA
  5. 5 • 2. Cardiolipin: formed by [blank_start]phosphatidylglycerol[blank_end] and synthesized from CDP-DAG.
    ○ Two molecules of PA esterified through their phosphate groups to an additional molecule of glycerol is called [blank_start]cardiolipin[blank_end], or diphosphatidylglycerol.
    PA is a precursor of phsophatidylglycerol which in turn gives rise to [blank_start]cardiolipin[blank_end].
    ○ Cardiolipin is found in membranes in [blank_start]bacteria[blank_end] and [blank_start]eukaryotes[blank_end].
    ○ In eukaryotes, cardiolipin is virtually exclusive to the inner [blank_start]mitochondrial[blank_end] membrane, where it maintains the structure and function of certain [blank_start]respiratory[blank_end] complexes of the electron transport chain.
    [Note: cardiolipin is antigenic and is recognized by antibodies raised against Treponema pallidum, the bacterium that causes syphilis.]
    1. Aphosphatidylglycerol
    2. Bcardiolipin
    3. Ccardiolipin
    4. Dbacteria
    5. Eeukaryotes
    6. Fmitochondrial
    7. Grespiratory
  6. 6 • 3. Plasmalogens
    ○ When the fatty acid at carbon 1 of a glycerophospholipid is replaced by an [blank_start]unsaturated[blank_end] alkyl group attached by an ether (rather than by an ester) linkage to the core [blank_start]glycerol[blank_end] molecule, an ether phosphoglyceride known as a plasmalogen is produced.
    ○ For example, phosphatidalethanolamine, which is abundant in [blank_start]nerve[blank_end] tissue (Figure 17.3A), is the plasmalogen that is similar in structure to phosphatidylethanolamine.
    [blank_start]Phosphatidalcholine[blank_end] (abundant in heart muscle) is the other quantitatively significant ether lipid in mammals. [Note: Plasmalogens use "al" rather than "yl" in their names.]
    1. Aunsaturated
    2. Bglycerol
    3. CPhosphatidalcholine
    4. Dnerve
  7. 7 • 4. Platelet-activating factor
    ○ A second example of an ether glycerophospholipid is platelet-activating factor (PAF), which has a [blank_start]saturated[blank_end] alkyl group in an ether link to carbon 1 and an acetyl residue (rather than a fatty acid) at carbon 2 of the glycerol backbone ( (see p. 148).
    ○ It also [blank_start]lowers[blank_end] blood pressure. [Note: PAF is one of the most potent bioactive molec Figure 17.3B).
    ○ PAF is synthesized and released by a variety of cell types.
    ○ It binds to surface [blank_start]receptors[blank_end], triggering potent thrombotic and acute inflammatory events. For example, PAF activates [blank_start]inflammatory[blank_end] cells and mediates hypersensitivity, acute inflammatory, and anaphylactic reactions.
    It causes platelets to [blank_start]aggregate[blank_end] and activate, and neutrophils and alveolar macrophages to generate superoxide [blank_start]radicals[blank_end] to kill bacteria ules known, causing effects at concentrations as low as 10-11 mol/l.]
    1. Aaggregate
    2. Bradicals
    3. Creceptors
    4. Dinflammatory
    5. Elowers
    6. Fsaturated
  8. 8 • Sphingophospholipids
    ○ Sphingomyelin The backbone of sphingomyelin is the amino alcohol [blank_start]sphingosine[blank_end], rather than glycerol.
    ○ A long-chain fatty acid is attached to the amino group of sphingosine through an amide linkage, producing a [blank_start]ceramide[blank_end], which can also serve as a precursor of glycolipids.
    ○ The alcohol group at carbon 1 of sphingosine is esterified to phosphorylcholine, producing [blank_start]sphingomyelin[blank_end], the only significant sphingophospholipid in humans.
    Sphingomyelin is an important constituent of the [blank_start]myelin sheath[blank_end] of nerve fibers. [Note: The myelin sheath is a layered, membranous structure that insulates and protects neuronal fibers of the central nervous system (CNS).]
    1. Asphingosine
    2. Bceramide
    3. Csphingomyelin
    4. Dmyelin sheath
  9. 9 • Role in membrane protein anchoring
    ○ Specific proteins can be covalently attached through a carbohydrate bridge to membrane-bound PI.
    ○ Alkaline phosphatase, a digestive enzyme found on the surface of the small intestine that attacks organic phosphates, is an example of a protein attached to such a glycosyl phosphatidylinositol ([blank_start]GPI[blank_end]) anchor.
    § [Note: GPI-linked proteins are also found in a variety of parasitic protozoans, such as, trypanosomes and leishmania.]
    ○ Being attached to a membrane lipid (rather than being an integral part of the membrane) allows GPI-anchored proteins increased lateral [blank_start]mobility[blank_end] on the surface of the plasma membrane.
    The protein can be cleaved from its anchor by the action of [blank_start]phospholipase C[blank_end], releasing [blank_start]DAG[blank_end]. [Note: A deficiency in the synthesis of GPI in hematopoietic cells results in the hemolytic disease paroxysmal nocturnal hemoglobinuria.]
    1. AGPI
    2. Bmobility
    3. Cphospholipase C
    4. DDAG
  10. 10- Some proteins preferentially bind to sphingolipids so they can contribute to the [blank_start]asymmetry[blank_end].
    - [blank_start]Peripheral[blank_end] proteins are bound to the hydrophilic regions of specific integral proteins and head groups of phospholipids.
    1. Aasymmetry
    2. BPeripheral

Information

Description
Biochemistry Quiz on Plasma Membrane, created by Fatima G. on 15/09/2019.
Author
Fatima G.
Language
English
Views
2
History
Created on 15 Sep 2019 · updated on 15 Sep 2019
Rating
No ratings yet
Rate this quiz
Rate this quiz

Feedback

What is it about?

What do you think of the new look?

How do you like it?