Cell Bio Exam 3
Liposomes are: a) not very useful to biological chemists as models for biomembranes. b) a drug-carrying vehicle for disease treatment c) enzymes that de-esterify cholesterol in late endosomes d) membranes of single layered phospholipids with hydrophobic regions attached at their tails
a drug-carrying vehicle for disease treatment
A peptide bond forms between which two functional groups? a) Hydroxyl and amino b) Hydroxyl and carboxyl c) Hydroxyl and methyl d) Carboxyl and amino
Carboxyl and amino
We can estimate the relative mobility of a population of molecules along the surface of a living cell by fluorescently labeling the molecules of interest, bleaching the label in one small area, and then measuring the speed of signal recovery as molecules migrate back into the bleached area. What is this method called? a) SDS b) SPT c) GFP d) FRAP
FRAP
A protein that spans the plasma membrane once: a) Has a hydrophobic extracellular domain b) Has a hydrophobic cytoplasmic domain c) Has hydrophobic extracellular and cytoplasmic domains separated by a hydrophilic transmembrane domain d) Has hydrophilic extracellular and cytoplasmic domains separated by a hydrophobic transmembrane domain e) Has a hydrophilic extracellular domain followed by hydrophobic transmembrane and cytoplasmic domains
Has hydrophilic extracellular and cytoplasmic domains separated by a hydrophobic transmembrane domain
What is a prion? a) Chaperone protein b) Protein that cleaves DNA c) Protein that converts normal protein into abnormal protein d) Enzyme
Protein that converts normal protein into abnormal protein
Enzymes catalyze the many reactions in a cell. There are hundreds of different enzymes in a cell—each with a unique three-dimensional shape. Why do cells have so many different enzymes? a) Each enzyme molecule can only be used once. b) The shape of enzyme's active site generally fits a specific substrate. c) The substrate molecules react with enzymes to create new enzymes. d) Enzymes are randomly produced. With thousands of different shapes—one is likely to work.
The shape of enzyme's active site generally fits a specific substrate.
The process of generating monoclonal antibodies is labor-intensive and expensive. An alternative is to use polyclonal antibodies. A subpopulation of purified polyclonal antibodies that recognize a particular antigen can be isolated by chromatography. Which type of chromatography is used for this purpose? a) affinity b) ion-exchange c) gel-filtration d) any of the above
affinity
Membrane proteins, like membrane lipids, can move laterally by exchanging positions with other membrane components. Which type of membrane proteins is expected to be the least mobile, based on their function? a) channels b) anchors c) receptors d) enzymes
anchors
You are asked to provide data that support the hypothesis that protein structure and function are correlated. The best set of data to support this hypothesis is _____. a) denatured proteins do not function normally b) enzymes tend to be globular in shape c) proteins function best at certain temperatures d) proteins have four distinct levels of structure and many functions
denatured proteins do not function normally
Haemoglobin has 4 identical subunits a) True b) False
false
Membrane proteins that pump ions in and out of the cell are classified as enzymes. a) True b) False
false
What maintains the secondary structure of a protein? a) peptide bonds b) hydrogen bonds between the amino group of one peptide bond and the carboxyl group of another peptide bond c) disulfide bonds d) hydrophobic interactions e) hydrogen bonds between the R groups
hydrogen bonds between the amino group of one peptide bond and the carboxyl group of another peptide bond
Which of the following is not true of the plasma membrane? a) contains receptors for communication b) forms intercellular connections c) is a rigid sheet of molecules with little flexibility d) regulates material movement into and out of the cell
is a rigid sheet of molecules with little flexibility
Cholesterol serves several essential functions in mammalian cells. Which of the following is not influenced by cholesterol? a) membrane permeability b) membrane fluidity c) membrane rigidity d) membrane thickness
membrane thickness
Which type of lipids are the most abundant in the plasma membrane? a) Phospholipids b) Glycolipids c) Cholesterol
phospholipids
You observe a cluster of intestinal cells under a microscope and notice that the ECM connecting the cells is crystalline and dry as opposed to being soft-gel like. Which ECM protein is mutated in these cells? a) Collagens b) Proteoglycans c) Fibronectins d) Laminins e) Integrins
proteoglycans
The bonding of two amino acid molecules to form a larger molecule requires which of the following? a) removal of a water molecule b) addition of a water molecule c) formation of a glycosidic bond d) formation of a hydrogen bond e) both removal of a water molecule and formation of a hydrogen bond
removal of a water molecule
When urea is removed from proteins dissolved in urea detergent, the protein a) Denatures b) Renatures c) Both denatures and renatures d) No effect
renatures
Membrane lipids are capable of many different types of movement. Which of these does not occur spontaneously in biological membranes? a) switching between lipid layers b) lateral movement c) rotation d) flexing of hydrocarbon chains
switching between lipid layers
An Antibody heavy and light chains are held together by di-sulfide bonds a) True b) False
true
Which of the following methods would be the most suitable to assess levels of expression of your target protein in different cell types? a) gel-filtration chromatography b) gel electrophoresis c) western blot analysis d) ion-exchange chromatography
western blot analysis