Cellular membranes, also known as plasma membranes, are biological membranes that separate and protect the interior of a cell from the outside environment. They are the outermost cell organ and act as a barrier and gate to control the transportation of materials and information between the cytoplasm and the external environment.  Cell membranes are made up of a lipid bilayer that is semipermeable. The major components of the cell membrane are phospholipids, proteins, carbohydrates, and other lipids such as cholesterol.  Cell membranes regulate the transport of materials entering and exiting... Show more

Cellular membranes, also known as plasma membranes, are biological membranes that separate and protect the interior of a cell from the outside environment. They are the outermost cell organ and act as a barrier and gate to control the transportation of materials and information between the cytoplasm and the external environment. 
Cell membranes are made up of a lipid bilayer that is semipermeable. The major components of the cell membrane are phospholipids, proteins, carbohydrates, and other lipids such as cholesterol. 
Cell membranes regulate the transport of materials entering and exiting the cell. Some forms of transport require no energy to perform, and these mechanisms are called passive transport. The most common forms of passive transport are diffusion and osmosis

Cell membranes have several functions, including:
Physical barrier
Selective permeability
Endocytosis and exocytosis
Cell signaling
Providing support and maintaining the shape of the cell
Helping in regulating cell growth through the balance of endocytosis and exocytosis 
 

Topics include: Membrane Lipids & Fluidity, Plasma Membrane, Membrane Potential, Membranes Composition, Membrane Protein Structure, & Cell Membranes Movement.

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Cell Biology Practice Test: Cellular Membranes

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25 Questions

1. The channel in a membrane protein by which an ion or molecule can be transported in and out of the cell membrane is known as ___________

Channel pathwayPermeation pathwayPermeation channelPermeate channel

2. How many H⁺ ions are transported by the vacuole H+-ATPase pump and the vacuole H+-phosphatase pump per hydrolysis of ATP and pyrophosphate respectively?

1, 21, 12, 22, 1

3. The model of a lipid bilayer lined by a layer of protein molecules on both sides was put forward by _____

Davson and DanielliNone of the mentionedWatson and CrickSinger and Nicolson

4. The first insights into the chemical nature of plasma membranes date back to __________

1790170018001890

5. Fluidity and viscosity are the same.

TrueFalseDon't KnowMaybe

6. Lipid rafts are patches of cholesterol and ________________

carbohydratesamino acidslipidssphingolipids

7. Cell fusion can be performed on two cells from different species.

TrueDon't KnowFalseMaybe

8. The use of optical tweezers in membrane biology was done to confirm the ________________ nature of membranes.

inelasticself-replicatingelasticphoto-responsive

9. Cytosol is the same as cytoplasm.

FalseDon't KnowMaybeTrue

10. Which of the following channels depend on forces such as stretch tension applied on the membrane?

Voltage-gated channelsTension-gated channelsLigand-gated channelsMechano-gated channels

11. FRAP can be used to analyze living cells.

FalseTrueDon't KnowMaybe

12. Energy transduction is the underlying process of which of the following?

TranslationDNAPhotosynthesisTranscription

13. The parts in the figure are a)__________, b)_____________, c)___________, d)____________.

dendrites, soma, cell body, axon hillock, myelin sheathsoma, axon hillock, myelin sheath, dendritessoma, axon hillock, axon, dendritesdendrites, soma, myelin sheath, nodes of ranvier

14. Which is the first membrane protein to have its amino acid sequence determined?

Glycophorin DGlycophorin CGlycophorin BGlycophorin A

15. The sperm cell is covered by a _____________

sheathcontinuous membranecell walldiscontinuous membrane

16. In the experiments to demonstrate the mobility of membrane proteins, which cells were fused with human cells?

mouse cellstumor cellsdrosophila cellsbacterial cells

17. The ratio of Na⁺ and K⁺ transported by Na⁺/K⁺-ATPase pump is ___________

3:22:31:12:1

18. Myelin sheath is composed mainly of _____________

nucleic acidsproteinslipidscholesterol

19. On which of the following organisms, the research on nerve cells was first carried out?

OctopusGiant squidDrosophila melanogasterGrasshopper

20. Membrane potential is present only in nerve cells.

TrueDon't KnowMaybeFalse

21. The concept of transmembrane proteins was obtained from the results of which technique?

Freeze-fraction replicationFraction replicationNone of the mentionedFreeze-fracture replication

22. The ___________ the degree of unsaturation of the fatty acids of the bilayer, the ___________ the temperature before the bilayer gels.

greater, moregreater, lowerlesser, higher

23. Which of the following attributes of the membrane is most affected at the transition temperature?

internal compositionsizefluidityinternal environment

24. Which of the following facilitates binding of positively charged amino acid residues?

Phosphatidyl serine (PS)Phosphatidyl inositol(PI)Phosphatidyl ethanolamine (PE)Phosphatidyl choline (PC)

25. Transverse diffusion (flip-flop) is the movement of _____________

cholesterol moleculephospholipidproteinamino acid