Explore topic-wise InterviewSolutions in .

The correct option is (a) Formed by any SINGLE peptide chain in a whole protein molecule

To EXPLAIN I would say: Many proteins consist of a single polypeptide chain, and are DEFINED as monomeric proteins. Others may consist of two or more polypeptide chains that may be structurally IDENTICAL or totally unrelated. The ARRANGEMENT of these polypeptide subunits is called the quaternary structure of the protein.

Correct choice is (C) WEAK FORCES

Easiest explanation: Tertiary structure is formed by the folding and packing of super secondary structures. It gives a globular shape. Tertiary structures are stabilized by the bonds which are mostly formed between the R groups. Protein tertiary structures are mostly held by weak forces.

Correct answer is (C) Association between identical polypeptides

Easiest explanation: The biological function of some molecules is determined by MULTIPLE POLYPEPTIDE chains. Two kinds of quaternary STRUCTURES: both are multi-subunit proteins. Homotypic which is an association between identical polypeptide chains. Heterotypic which will be interactions between subunits of very different structures.

Right answer is (B) False

The best explanation: Adjacent polypeptide segments are stacked together is a rule of Secondary structure of proteins. Secondary structure composition will be all alpha and BETA motifs together or segregated. Motifs are stable arrangements which MAKES a secondary structure stable. Packing side chains from adjacent secondary ELEMENTS PRODUCES a super secondary structure.

Correct OPTION is (a) True

To explain: There are some of the rules of Secondary protein structure and ONE of them is that the Beta SHEET is the most STABLE. The beta sheet is a paper like structure formed MOSTLY by the hydrogen bonds between the NH molecule and CO molecule of different amino acids.

The correct option is (a) True

For explanation: There some of the rules of secondary STRUCTURE and these are hydrophobic SIDE groups must be buried inside the FOLDS, therefore, layers must be created (b-a-b; a-a). Alpha-helix and b-sheet, if occur TOGETHER, are found in different structural layers. Adjacent polypeptide segments are stacked together. The b-sheet is the most STABLE.

Correct choice is (a) POLAR covalent BOND

Explanation: A covalent bond is when a bond formed by the sharing of electrons. A nonpolar covalent n=bond is when electrons are shared EQUALLY such as H2 or Cl2. And Polar covalent BONDS are where the electrons are not shared equally such as H2O.

The correct choice is (B) Nonpolar covalent BOND

Explanation: When electrons between the atoms, while BONDING is shared equally, are known as non-polar covalent BONDS such as H2 or Cl2. And when the electrons are shared unequally they are called polar covalent bond such as H2O.

The correct choice is (d) Metallic bond

To EXPLAIN I WOULD say: Metallic bonds are FOUND in metals. It arises from the ELECTROSTATIC ATTRACTION between electrons. When metals are bonded with proteins they are known as metalloproteins. They usually coordinate with nitrogen, oxygen, etc.

Correct OPTION is (b) Ionic bond

The best I can explain: Bond FORMED between two ions by the TRANSFER of electrons. It involves electrostatic attraction between oppositely charged ions. In ionic bonds generally, a metal loses an electron becoming a POSITIVELY charged ION and a nonmetal accepts that ion becoming a negatively charged ion.

Correct option is (d) Covalent BOND

To elaborate: Covalent bond is the bond that occurs due to the SHARING of electrons between the molecules. This bond can form BONDS in any polyatomic ions or diatomic ions. This is ONE of the strongest bond and the energy required to break one such bond is 250 kJ/mol.

Right ANSWER is (a) True

Easy EXPLANATION: They are weak interactions CAUSED by momentary changes in electron density in a molecule. Thus they are the only force between non-polar molecules. Such as CH4 has no net dipole, at any one instant its electron density may not be completely SYMMETRICAL, RESULTING in a temporary dipole. This can induce a temporary dipole in another molecule. The weak interaction of these temporary dipoles constituents’ van der Waals forces.

The correct choice is (a) Vander WAALS force

To explain: Van der Waals forces are also known as London forces. They are weak interactions caused by MOMENTARY CHANGES in electron density in a molecule. They are the only attractive forces present in nonpolar COMPOUNDS. The surface area of a molecule determines the strength of the van der Waals interactions between MOLECULES.

Right OPTION is (b) False

The best explanation: In the tertiary structure of a PROTEIN the interactions of the R groups give a protein its specific three-dimensional tertiary structure. GLOBAL but restricted to the amino acid polymer. Formed and stabilized by hydrogen BONDING, covalent (e.g. disulfide) bonding, hydrophobic PACKING toward the core and hydrophilic exposure to solvent.

The correct answer is (d) The surface area of the molecule

For explanation: The surface area of a molecule determines the strength of the VAN der WAALS interactions between molecules. The LARGER the surface area, the larger the attractive force between two molecules, and the STRONGER the intermolecular forces. They are weak interactions caused by MOMENTARY changes in electron density in a molecule.

Right option is (a) DISULFIDE bond

Explanation: Disulphide bonds are strong covalent links between the sulfur atoms of 2 CYSTEINE molecules. When two sulfur atoms from 2 different cysteine molecules FORM bind they release a WATER MOLECULE. It is an oxidative reaction.

The correct choice is (c) Hydrophilic interaction

The explanation is: Hydrophilic attractions are attractions between polar or ionized R groups and the water on the SURFACE of the tertiary structure. Hydro means water and phallic means loving. These BONDS are water-loving bonds and THEREFORE ALWAYS takes into account the surrounding water.

Right choice is (b) HYDROGEN bond

Best explanation: This BONDS in protein structure occurs between the COO group on one side of amino acid and polar side groups of other amino ACIDS. They are WEAK forces. Hydrogen bonds are responsible for the structural changes in the protein.

Correct ANSWER is (b) False

Easy explanation: Hydrophobic attractions are an attraction between the nonpolar alkyl groups and AROMATIC groups form a non-polar CENTER that is REPELLED by water. Hydrophilic attractions are an attraction between polar or ionized R groups and water on the surface of the tertiary structure.

Correct answer is (d) 4-7 kcal/mol

Best explanation: The energy NEEDED to break a salt bridge is around 4-7 kcal/mol. Salt BRIDGES are electrostatic bonds between oppositely charged GROUPS. The ions on the R group of AMINO acids form salt bridges through electrostatic bonds.

Correct choice is (B) False

Explanation: Hydrogen bond is a very WEAK bond which is formed with the interaction between hydrogen and oxygen atoms. This although weak is a very important force for the STRUCTURE of a protein. This bond can EASILY BREAK and newly form by changing the structure of the protein.

Correct option is (B) H bond

Easy EXPLANATION: H bonds weak bonds ALLOWING to be broken and reformed easily. Allows STRUCTURAL change in the protein structure. Hydrogen bonds produce ‘functional’ molecules.

Right answer is (c) The covalent bond between sulfur atoms on TWO cysteine amino acids

Best explanation: Covalent bond between sulfur atoms on two cysteine amino acids. Two cysteine amino acids atoms in close proximity will come together and then FORM a covalent bond in between with the release of a water molecule. The bond formed is covalent bond RATHER than IONIC, Vander WAALS or non-ionic.

The correct answer is (a) True

Easiest EXPLANATION: The main forces that stabilize the covalent structures of the protein are an interaction between atoms within the protein chain and interaction between the protein and the SOLVENT. Interactions which helps in stabilizing the protein STRUCTURE are disulfide bonds, HYDROGEN bonds, salt BRIDGES, hydrophobic interactions, hydrophilic interactions, and ionic interaction.

Correct option is (c) Solvent

For explanation I would SAY: The interaction between the protein and the solvent around makes a protein structure stable. Also, the interaction between the protein atoms within the protein structure makes the structure stable. Most of the common interaction found in a protein structure are DISULFIDE bonds, HYDROGEN bonds, SALT bridges, hydrophobic interactions, HYDROPHILIC interactions, and ionic interaction.

The correct option is (a) True

To elaborate: Salt bridges are one of the SEVERAL types of interaction which helps in the stability of protein STRUCTURE. Salt bridges are IONIC INTERACTIONS between ionized R groups of the amino acids and the WATER on the surface of the tertiary structure.

Right answer is (b) There are three categories of matrix devices

To ELABORATE: The DRUG used in these devices has a large therapeutic index. Such that overdosing does not PRECIPITATE toxic reactions. There are two categories of matrix devices ONE is where the drug is dissolved in the polymer matrix and the other is where the drug is dispersed. The polymer employed for the matrix system MAY be hydrophilic or lipophilic. These polymers include PVC, PVP, and polysaccharides.

Right answer is (d) The DRUG is contained in a powder form FLOATING on liquid

The explanation: The drug is contained in a reservoir as a suspension liquid or gel carrier. The thin POLYMERIC membrane is MADE up of olefinic polymers or PVC. When applied on skin it shows rapid release at first and then zero order release as long as the solution inside the reservoir is saturated.

Correct answer is (d) Size of the eyeball

The BEST I can explain: The absorption of the OPHTHALMIC drug across the corneal membrane is a diffusion process and depends LARGELY on the physicochemical properties of the permeating molecule that is the drug. It also depends upon the drainage and output of tears. Drugs of ophthalmic USE are such as atropine, local ANESTHETICS, epinephrine, etc.

Right answer is (c) The drug-polymer MATRIX is layered by rate-controlling membrane

The explanation: This device has drug RELEASE KINETICS INTERMEDIATE between monolithic and reservoir systems. Here the drug-polymer matrix is layered by a rate controlling membrane. The release is CONTROLLED initially by the membrane but as the drug gets depleted the rate is controlled by diffusion of the drug.

The correct option is (b) Drug permeation rate is high

Easiest explanation: These devices are used when the drug permeation through the stratum corneum is rapid than the rate of drug DIFFUSION from the device. It is suitable for drugs which have low therapeutic INDICES. When applied on SKIN it shows rapid release at first and then zero ORDER release as long as the solution inside the reservoir is SATURATED.

Right OPTION is (b) The square root of time

For explanation: The drug RELEASE from the matrix system of the monolithic device is rapid INITIALLY and FALLS as the matrix gets depleted. The rate is thus proportional to the square root of time. The polymers EMPLOYED for matrix system may be hydrophilic or lipophilic.

Right option is (a) The DRUG has a large therapeutic index

The explanation is: Monolithic devices are USED when the rate of drug diffusion from the device is higher than the rate of drug permeation through the STRATUM corneum. There are TWO categories of matrix devices one is where the drug is dissolved in the polymer matrix and the other is where the drug is dispersed.

Correct option is (C) Drugs with NARROW therapeutic indices

The best I can explain: The transdermal route is unsuitable when the drug dose is large when the drug has a large molecular size, the drug is skin SENSITIZING and irritating. It ALSO becomes a problem when the drug is metabolized in the skin, the drug GOES protein binding in the skin, or even if the drug is highly lipophilic or hydrophilic.

Right OPTION is (d) Drugs against peptic ulcer

The explanation is: Transdermal DELIVERY SYSTEMS are topically administered medications. Drugs with very short half-live example nitro-glycerine are administered as transdermal patches. Drugs with narrow THERAPEUTIC indices can be safely administered through transdermal patches. Problems for ORAL administration are not seen here.

Right OPTION is (b) Series of concentric bilayers of lipid

For EXPLANATION I WOULD say: MLV are also KNOWN as multilamellar vesicles. These liposomes are made of series of concentric bilayers of lipids enclosing a small internal volume. 2-10 bilayers are lipid is used to make OLV. A SINGLE bilayer of lipid is used to make ULV.

Right answer is (B) False

Best explanation: No the CELLS have to be immersed in a hypotonic SOLUTION. The cells must be immersed in a buffered hypotonic solution of drug which causes these cells to RUPTURE and release hemoglobin and trap the medication. The RESTORATION can be done by the restoration of the isotonicity and incubating them at 37°C, the cells reseal and are ready to use.

Correct answer is (b) The system is programmed to release drugs at a controlled rate

The best explanation: BATTERY powered PUMPS are such that they are programmed to release drugs of a certain AMOUNT when the RANGE of those components is differing from the normal value. Their design is such that the drug moves towards the exit and there is no BACKFLOW of the liquid. They are of two types these are peristaltic pump and solenoid driven reciprocating pump.

The correct choice is (b) False

To explain I WOULD say: After implantation, the VOLATILE liquid vaporizes at the body temperature and creates a vapor pressure that compresses and expels the drug through a series of flow regulators at a CONSTANT rate. Insulin and morphine have been successfully delivered by such implants. The disc-shaped device consists of two chambers. The infuscate chamber consists if the drug solution which will be separated by a freely movable flexible bellow from the vapor chamber CONTAINING vaporizable FLUIDS.

Correct answer is (c) Drug solution chamber is separated by rigid walls

For explanation I would say: The disc-shaped DEVICE consists of two chambers. The infuscate chamber consists if the drug solution which will be separated by a FREELY movable flexible bellow from the vapor chamber containing vaporizable fluids. The volatile liquid VAPORIZES at body temperature after IMPLANTATION thus creating vapour pressure which compresses and expels the drug through a series of flow regulators.

The correct CHOICE is (d) Morphine antagonist

To elaborate: Drugs which are generally used for such implants are steroids like contraceptives, morphine antagonists like naltrexone for opioid-dependent addicts. POLYMERS used for MAKING such implants are polymethacrylates, ELASTOMERS, etc. The system is generally prepared as implantable flexible or rigid rods or spherical tablets.

Right ANSWER is (a) True

The best explanation: Due to a very easy access for the implants the subcutaneous tissue became an ideal location for IMPLANTING. Moreover it has poor perfusion, slow drug absorption and less reactivity to many of the foreign materials. The system is generally prepared as implantable FLEXIBLE or RIGID rods or spherical tablets. Polymers used for making such implants are polymethacrylates, elastomers, ETC.

The correct ANSWER is (d) Need of microsurgery

Explanation: The advantages of implants are these are more effective, have prolonged ACTION, and a small dose is sufficient for the patient. The major disadvantage of such systems is that microsurgery is REQUIRED for the implantation DEVICE. Although some implants can be implanted by SPECIALLY designed implant syringe.