Biology 2382B Lecture Notes - Action Potential, Lipophilicity, Ion Channel

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9 Dec 2012

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Since pure phospholipid membranes are only semipermeable to a few small molecules and gases and also function only to form a closed compartment many biological functions of membranes are carried out by membrane embedded/associated proteins . Three types of membrane proteins: integral, lipid-linked, peripheral. All are asymmetric (i. e. not found in equal abundance on both sides but rather localized to one leaflet or the other ) Inside is hydrophobic, outside is hydrophilic: integral membrane proteins. Hydrophobic secondary or tertiary structures that span the lipid bilayer . Arg and lys (charged aas) near cytosolic side (+)ive charge cannot cross membrane of er during synthesis = hydrophilic (interact w/ polar head groups) Barrels (another transmembrane structure composed of layered beta sheets) Mostly glycosylated in exoplasmic domain (provides specificity for extracellular interactions) . Can act as adapter proteins and allow cytoskeletal filaments to associate with bilayer (i. e. dystrophin & ankyrin that link integral membrane proteins to cytoskeleton)

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.

Biology 2382B Lecture Notes - Action Potential, Lipophilicity, Ion Channel

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