BMS 250 Chapter Notes - Chapter 4: Lipid Bilayer, Cell Membrane, Extracellular Fluid

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20 Jul 2018

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The proteins dispersed within the lipids make up about half of the plasma membrane by weight. Proteins can float and move about the fluid bilayer, and most of the membranes" specific functions are determined by its resident proteins. Membrane proteins are classified as one of two structural types: integral or peripheral. Integral proteins: are embedded within, and extended across, the phospholipid bilayer. Hydrophobic regions within the integral proteins interact with the hydrophobic interior of the membrane. In contrast, hydrophilic regions of the integral proteins are exposed to the aqueous environments on either side of the membrane. Many integral membrane proteins are glycoproteins that have carbs exposed to the interstitial fluid. Peripheral proteins are not embedded within the lipid bilayer. They are attached loosely either to the external or internal surfaces of the membrane are are often anchored to the exposed parts of an integral protein.

Related Questions

Hybridomas are the useful result of a fusion between _______________ and _________________ to obtain hybrid cells that can proliferate and produce _________________ against specific ________________.

	myeloma cells; B lymphocytes; monoclonal antibodies; epitopes
	myeloma cells; T lymphocytes; polyclonal antibodies; antigen
	T lymphocytes; B lymphocytes; monoclonal antibodies; antigen
	T lymphocytes; B lymphocytes; polyclonal antibodies; epitopes

With respect to mammalian cell culture, which of the following statements is true?

	Media used for cell growth contain proteases and a divalent cation chelator to help cells adhere to the surface.
	During the establishment of a cell line, senescence is the last stage of the cell's life.
	Rodent cells cultures undergo spontaneous transformation with similar frequency to human cell cultures.
	Embryonic cell lines do not undergo senescence nor do they have a finite life span.

Epithelial cells have distinct surfaces. Which of these surfaces tends to be involved in secreting proteins out of the cell and into the bloodstream?

	apical
	basal
	All of the answers are correct.
	lateral

Which of the following is NOT true of phospholipid bilayers?

		Phospholipid bilayers separate the cell from the exterior environment as well as from compartments within the cell.
		The interior of phospholipid bilayers is a highly hydrophobic environment.
		Membrane budding requires transient breakages in the bilayer membrane.
		The chemical properties of phospholipids lead to the spontaneous formation of bilayers.

Which of the following is true regarding membrane proteins?

		All peripheral membrane proteins contact the lipid bilayer by covalent attachment to the hydrophilic head groups on membrane lipids.
		Beta strands can assemble into a membrane-spanning barrel structure.
		Lipid-anchored membrane proteins always face the cell exterior.
		A protein with six hydrophobic helices is most likely a lipid-anchored membrane protein.

Which of the following statements is NOT true?

		The three types of lipid anchors responsible for tethering proteins to the bilayer are acylation, prenylation, and ubiquitinylation.
		Movement of lipids from the cytoplasmic to the exoplasmic leaflet of the membrane bilayer requires specialized transport proteins called flippases.
		Glycoproteins are the basis for blood type compatibility between donor and receiver.
		Glycoproteins are always oriented so that the carbohydrate moieties are exoplasmic.

Explain the cell theory; know the three basic tenets of the theory.

All cells have to carry out certain functions, what do all cells have in common?

Compare/contrast an Eukaryotic vs a Prokaryotic cell type.

Understand the concept of selective toxicity. What do all effective targets of an antimicrobial agent have in common? What are some characteristics of Prokaryotic cells that can be targeted?

Explain the unity and diversity of prokaryotic cells in terms of evolutionary theories.

Describe the three basic shapes (morphologies) of bacteria.

What are the functions of the plasma membrane, how does the structure of the plasma membrane aid in carrying out these functions?

Describe the fluid mosaic model of the plasma membrane. Draw out the plasma membrane, include the phospholipid bilayer (indicating polar/hydrophilic and nonpolar/hydrophobic components) and peripheral and integral proteins. Also indicate the intracellular (cytoplasmic) and extracellular regions.

What are the functions of the components of the plasma membrane? Phospholipids, proteins?

Transport. Compare/contrast the following mechanisms of transport in terms of the types of molecules transported, with or against the concentration gradient, if any Energy input is required, if a transport molecule is involved, and if Euk and or Prok use this mechanism.

Osmosis (explain the role of aquaporins)

Diffusion

Facilitated Diffusion

Active transport (proton motive force / ATP binding cassette system)

Group translocation

Cholesterol is transported in the bloodstream in lipoproteinparticles. There are several classes of lipoprotein particles, butone of the most important classes is called Low-densitylipoproteins (LDL). LDL particles are composed of a single moleculeof a large protein called apolipoprotein, as well as thousands ofcholesterols molecules and phospholipids. Part of theapolipoprotein forms the surface of the particles and faces theaqueous phase, while other parts face the hydrophobic interior ofthe particle where they interact with cholesterol and thehydrophobic tails of the phospholipids. When cells need additionalcholesterol, they produce a receptor protein on the surface oftheir plasma membrane that binds to the apolipoprotein andinitiates the uptake of LDL particles into the cell via a processcalled endocytosis.

1. What is the likely reason that LDL particles are used totransport cholesterol in the blood stream?

a. Cholesterol in LDL particles easily inserts into lipidbilayers

b. Cholesterol id largely insoluble in aqueous solutions

c. Cholesterol is synthesized within LDL particles

d. LDL particles can form lipid rafts in the lipid bilayer

2. What is the most likely location of phospholipids in LDLparticles?

a. Bound to the hydrophilic domain of apolipoprotein

b. In the lipid bilayer that surrounds LDL particles

c. On the surface interacting with the aqueous environment aswell as interacting with the hydrophobic core of the particle

d. Within the hydrophobic core of the particle

3. What best describes the class of protein that apolipoproteinbelongs to?

a. Amphipathic proteins

b. Cell surface proteins

c. Membrane associated protein

d. Multipass membrane proteins

4. What kind of molecule on the surface of the cell would bemost likely to serve as a receptor for LDL particles?

a. a cholesterol binding protein

b. a glycolipid

c. a phospholipid

d. trans membrane protein

5. What conditions would be most likely to trigger increaseduptake of LDL particles by cells?

a. increased glycolipid synthesis

b. increased plasma membrane growth

c. increased protein secretion

d. increase protein synthesis

BMS 250 Chapter Notes - Chapter 4: Lipid Bilayer, Cell Membrane, Extracellular Fluid

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