Mcb Block 3- Organelles: Cell Membrane

1. What is a liposome?

A type of protein structure found in cells.

A small hormone released by the pituitary gland.

A type of carbohydrate used for energy storage.

A circular bilayer of phospholipids-used for drug delivery

A liposome is a spherical vesicle with a lipid bilayer structure composed of phospholipids. It is commonly used in drug delivery systems due to its ability to encapsulate both hydrophilic and hydrophobic molecules.

Explanation

A liposome is a spherical vesicle with a lipid bilayer structure composed of phospholipids. It is commonly used in drug delivery systems due to its ability to encapsulate both hydrophilic and hydrophobic molecules.

2. In Transmission Electron Microscopy (TEM), how do the membranes appear?

Hexalaminar. Displays a six-layered structure in TEM images

Trilaminar. Look trilaminar b/c outer dark + inner dark + middle clearPolar head groupsattract osmium tetroxide; become dark; center lipid section remains clear

Multilaminar. Shows multiple layers stacked on top of each other under TEM

Unilaminar. Appears as a single layer under TEM

In Transmission Electron Microscopy, membrane structures typically appear trilaminar due to the arrangement of the lipid bilayer. The polar head groups attract osmium tetroxide, causing them to appear dark, while the lipid section remains clear. Therefore, unilaminar, multilaminar, or hexalaminar appearances would not accurately describe the typical membrane structure under TEM.

Explanation

In Transmission Electron Microscopy, membrane structures typically appear trilaminar due to the arrangement of the lipid bilayer. The polar head groups attract osmium tetroxide, causing them to appear dark, while the lipid section remains clear. Therefore, unilaminar, multilaminar, or hexalaminar appearances would not accurately describe the typical membrane structure under TEM.

3. What are 5 functions of membrane proteins?

1.) Transport(nutrients, metabolites, ions across bilayer)2.) Anchormembrane to macromolecules on either side3.) Receptors:signal transduction4.) Enzymes(lactase in apical membrane of GI epithelial cells)5.) Cellidentity markers: MHC

3.) Storage of genetic material within the cell

2.) Regulation of gene expression

1.) Energy production in the cell

Membrane proteins have diverse functions beyond just energy production, gene expression regulation, and storage of genetic material within the cell. The correct functions include transport, anchoring, signaling, enzymatic activity, and cell identity markers.

Explanation

Membrane proteins have diverse functions beyond just energy production, gene expression regulation, and storage of genetic material within the cell. The correct functions include transport, anchoring, signaling, enzymatic activity, and cell identity markers.

4. What do Fatty acids form as a self assembling aggregate?

Liposomes: due to its spherical structure

Vesicles: due to its enclosed lipid bilayer structure

Bilayers: due to its dual layers arrangement

Micelles: due to its indiv. wedge shaped structure

Fatty acids form micelles due to their individual wedge-shaped structure, allowing them to spontaneously assemble into spherical aggregates in aqueous solutions.

Explanation

Fatty acids form micelles due to their individual wedge-shaped structure, allowing them to spontaneously assemble into spherical aggregates in aqueous solutions.

5. How are the leaflets of the phospholipid bilayer held together?

Ionic bonds

Covalent bonds

Van der waals interactions (weak bonds btw hydrophobic tails)

Hydrogen bonds

The correct answer is Van der Waals interactions, which are weak bonds between the hydrophobic tails of phospholipids in the bilayer. Ionic bonds, covalent bonds, and hydrogen bonds are not primarily responsible for holding the leaflets together in the phospholipid bilayer.

Explanation

The correct answer is Van der Waals interactions, which are weak bonds between the hydrophobic tails of phospholipids in the bilayer. Ionic bonds, covalent bonds, and hydrogen bonds are not primarily responsible for holding the leaflets together in the phospholipid bilayer.

6. Which organelles are involved with the membrane in Red Blood Cells?

1.) Lysosome 2.) Golgi Apparatus 3.) Nucleus

1.)Spectrin2.)Ankyrin3.)Protein 4.14.) Glycophorin5.) Band 3

The correct answer includes the organelles Spectrin, Ankyrin, Protein 4.1, Glycophorin, and Band 3, which are involved in maintaining the structure and function of the red blood cell membrane. The incorrect answers of Lysosome, Golgi Apparatus, and Nucleus do not play a role in the membrane of red blood cells.

Explanation

The correct answer includes the organelles Spectrin, Ankyrin, Protein 4.1, Glycophorin, and Band 3, which are involved in maintaining the structure and function of the red blood cell membrane. The incorrect answers of Lysosome, Golgi Apparatus, and Nucleus do not play a role in the membrane of red blood cells.

7. In the RBC, which membrane protein is single pass, and which is multipass?

CD47 - single pass transmembrane protein; CD59 - multipass transmembrane protein.

Glycophorin - single pass transmembrane glycoprotein-is linked to actin by protein 4.1

Band 3 : multipass transmembraneprotein

Hemoglobin - single pass transmembrane protein; Glucose transporter - multipass transmembrane protein.

Spectrin - single pass transmembrane protein; Ankyrin - multipass transmembrane protein.

In the RBC, glycophorin is an example of a single pass transmembrane protein that is linked to actin by protein 4.1, whereas Band 3 is a multipass transmembrane protein. Spectrin and Ankyrin are not membrane proteins in RBCs. Hemoglobin and Glucose transporter are not membrane proteins involved in the RBC membrane. CD47 and CD59 are not the specific single pass and multipass transmembrane proteins found in the RBC membrane.

Explanation

In the RBC, glycophorin is an example of a single pass transmembrane protein that is linked to actin by protein 4.1, whereas Band 3 is a multipass transmembrane protein. Spectrin and Ankyrin are not membrane proteins in RBCs. Hemoglobin and Glucose transporter are not membrane proteins involved in the RBC membrane. CD47 and CD59 are not the specific single pass and multipass transmembrane proteins found in the RBC membrane.