Questions
What is not true about fluid mosaic model?
- Plasma membrane looks like a mosaic.
- It was proposed by Robertson.
- It highlights the presence of extrinsic and intrinsic proteins.
- Proteins and substances such as cholesterol become embedded in the bilayer, giving the membrane the look of a mosaic.
- The molecules that are embedded in the plasma membrane also serve a purpose.
What is common between active transport and facilitated transport?
- Use of ATP as a source of energy.
- Occurrence along the concentration gradient.
- Both the above options are correct.
- Occurrence of carrier protein.
- Transports chemicals against their concentration gradients.
Transport proteins _______________.
- are invariably integral proteins
- are sometimes called permeases
- are highly specific often for a single compound or small groups of closely related compounds
- are often globular proteins
- all of the above
Which one of the following amino acids would most likely be found in a membrane spanning alpha helix?
- Glutamine
- Alanine
- Phenyl alanine
- Aspartate
- Arginine
In coupled type of transport mechanism, two solutes are moved simultaneously in the same direction
- and are called symport
- which needs the use of ATP as it is a type of active transport
- as in case of movement of glucose by interstitial cells coupled to passive movements of Na+
- a symporter is an integral membrane protein that is involved in movement of two or more different molecules or ions across a phospholipid membrane
- all of the above
Flip flop movement is influenced by the enzyme flippase which causes the movement of ___________ to move from one side of the bilayer to the other.
- lipids
- lipoproteins
- oligosaccharides
- intrinsic proteins
- proteolipids
Which one of the following is absent from the cytoplasmic membrane of gram positive bacteria?
- Phosphatidylethanolamine.
- Phosphatidyl choline.
- Phosphatidyl inositol.
- Phosphatidyl glycerol.
- Peptidoglycan.
Chitin is an important constituent of cell wall of
- Mucor
- Porphyra
- Dunaliella
- Ulothrix
- Streptococcus
The bilayer nature of the lipids in the plasmamembrane and the occurrence of transient, temperature dependent localized non bilayer phases in cytoplasmic membrane has been studied by
- NMR
- PET
- X-ray crystallography
- CT scan
- MRI
The most common microfibrillar component of algal cell wall is
- hemicellulose
- keratin
- chitin
- celluose
- peptidoglycan
Which one of the following substances is known to inhibit the functioning of Na+K+ pump?
- Chalone
- Ricin
- Oubain
- Lauryl sulfate
- Rifampicin
The unit structure of gap junctions is named as connexin. What is not true about it?
- An aspect of connexins is that they have a relatively short half life of only a few hours.
- Connexins are also called as gap junctions.
- Connexins contain only single termini.
- The connexin gene family is diverse, with twenty-one identified members in the sequenced human genome.
- It is in the ER that connexins are properly folded, yielding two extracellular loops.
The cytoskeletal protein of microtubules is
- tubulin
- tubulin and actin
- actin and ankyrin
- myosin
- tropomyosin
Chose the incorrect statement.
- Activation of Na+ k+ ATPase transports 3 Na+ into the cell and 2K+ out of the cell.
- It is an antiporter enzyme (an electrogenic transmembrane ATPase) located in the plasma membrane of all animal cells.
- The sodium-potassium pump was discovered in the 1950s by a Danish scientist, Jens Christian Skou.
- Na+ K+-ATPase helps maintain resting potential, avail transport, and regulate cellular volume.
- The Na+K+ pump has been shown to control and set the intrinsic activity mode of cerebellar Purkinje neurons.
Which pair of chemicals would prevent the formation of microtubules in cytoplasm?
- Nicotine and cyanide
- Ricin and cocavalin
- Rotenone and vinchristine
- Colchicine and vinblastin
- Oubain and ricin