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level: Level 1

Questions and Answers List

level questions: Level 1

Question	Answer
It is highly fluid, dynamic structures consisting of a lipid bilayer and associated proteins.	Membranes
They define cell boundaries, has selective permeabilities and acts as a barrier, thereby maintaining differences in composition between the inside and outside of the cell.	plasma membrane
Selective membrane molecular permeability is generated through the action of specific ______ and ______.	transporters, ion channels
Plasma membrane plays a key role in _______ and _______	cell-cell interactions; transmembrane signalling
Such intracellular membranes help shape many of the morphologically distinguishable structures (organelles)	specialized compartments
they function as integral elements in excitation-response coupling, and provide sites of energy transduction	localized enymes
Water makes up about ____ of the lean body mass of the human body and is distributed in two large compartments.	60%
This compartment constitutes two-thirds of total body water and provides a specialized environment for the cell	intracellular fluid ICF
they make, store, and utilize energy; to repair itself; to replicate; and to perform cell-specific functions.	ICF
This compartment contains about one-third of total body water and is distributed between the plasma and interstitial compartments	extracellular fluid ECF
serves as a delivery system. It brings to the cells nutrients (eg, glucose, fatty acids, and amino acids), oxygen, various ions and trace minerals, and a variety of regulatory molecules (hormones) that coordinate the functions of widely separated cells	ECF
removes CO2, waste products, and toxic or detoxified materials from the immediate cellular environment.	ECF
is rich in K+ and Mg2+, and phosphate is its major inorganic anion.	internal environment
The cytosol of cells contains a high concentration of _____ that acts as a major intracellular buffer	proteins
The _______ of cells contains a high concentration of protein that acts as a major intracellular buffer	cytosol
is characterized by high Na+ and Ca2+ content, and Cl− is the major anion.	extracellular fluid
contains the highest ratio of protein to lipid in its membrane	mitochondrial inner membrane
has the lowest ratio of protein to lipid in its membrane	myelin
the mass ratio of protein to lipid of mitochondrial inner membrane	3.2
the mass ratio of protein to lipid of mitochondrial outer membrane	1.1
concentration of Na+ in ECF	140 mmol /L
concentration of Na+ in ICF	10 mmol/L
concentration of K+ in ECF	4 mmol/L
concentration of K+ in ICF	140 mmol/L
sheet-like enclosed structures consisting of an asymmetric lipid bilayer with distinct inner and outer surfaces or leaflets.	membranes
These structures and surfaces are protein-studded, sheet-like, noncovalent assemblies that form spontaneously in water due to the amphipathic nature of lipids and the proteins contained within the membrane.	membranes
the nature of lipids that enables the membrane be protein-studded, sheet-like, noncovalent assemblies that form spontaneously in water	amphiphatic
Of the two major phospholipid classes present in membranes, _________ are the more common and consist of a glycerol-phosphate backbone to which are attached two fatty acids in ester linkages and an alcohol	phosphoglycerides
phosphoglycerides backbone is consist of:	glycerol-phosphate
attached to the backbone of phosphoglycerides	two fatty acids
the fatty acids attached to the backbone of phosphoglycerides have what linkage	ester linkage
usually even-numbered carbon molecules, most commonly containing 16 or 18 carbons.	fatty acids
The simplest phosphoglyceride	phosphatidic acid
a phosphatidic acid is a	1,2-diacylglycerol 3-phosphate
a key intermediate in the formation of other phosphoglycerides	phosphatidic acid
what phosphate is esterified to an alcohol in most phosphoglycerides in membranes	3-phosphate
is generally the major phosphoglyceride by mass in the membranes of human cells	phosphatidylcholine
The second major class of phospholipids comprises	sphingomyelin
A fatty acid is attached by an amide linkage to the amino group of sphingosine, forming______	ceramide
ceramide is formed when a fatty acid is attached to the amino group of sphingosine through what kind of linkage	amide linkage
What group of sphingosine is esterified to form phosphorylcholine, sphingomyelin	primary hydroxyl group
is prominent in myelin sheaths.	sphingomyelin
They are sugar-containing lipids built on a backbone of ceramide	glycosphingolipids
The glycosphingolipids (GSLs) are sugar-containing lipids built on a backbone of what substance	ceramide
The most common sterol in the membranes of animal cells	cholesterol
The majority of cholesterol resides within what part of the cell	plasma membrane
All major lipids in membranes contain both hydrophobic and hydrophilic regions is referred to as ______	amphiphatic
membrane region that is insoluble in water but soluble in organic solvents	hydrophobic
insoluble in organic solvents but soluble in water	hydrophilic