Must Remember Point BIOCHEMISTRY

 

BIOCHEMISTRY REVIEW

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1. Prokaryotic cells have:

                   i) Cell membrane

                  ii) Cytoplasm

                 iii) Nucleus

                 iv) RNA

 

2. Prokaryotic cells do not have DNA

 

3. Endoplasmic Reticulum is a double membrane organelle

 

4. Mitochondria are the major site for energy production

 

5. Ribosomes are sites for protein synthesis

 

6. The cytosol is the site for glycogen synthesis

 

7. Peroxisomes synthesize

                     i) Ether Glycerophospholipids

                    ii) Dolicols

                   iii) Cholesterol

 

8. Cellulose is the main constituent of the plant cell wall

 

9. Water is an ideal solvent because of its:

                    i) Dipolarity

                   ii) High melting point

                  iii) High boiling point

                  iv) Hydrogen bonds (weak bonds)

 

10. Water participates in the reactions:

                   i) Hydration

                  ii) Dehydration

                 iii) Hydrolysis

 

11. Buffers in the human body include:

                   i) Proteins & amino acids

                  ii) Carbonic acid & bicarbonate

                 iii) Phosphoric acid & phosphate

                 iv) Ammonium

 

12. Bonds mostly involved in interactions of biomolecules are covalent bonds.

 

13. A disulphide bridge is a covalent bond

 

14. The plasma membrane of a cell:

                   i) Contains proteins

                  ii) Is a lipid bilayer

                 iii) Is selectively permeable

                 iv) Is different from a mitochondrial membrane

 

15. The pH is the hydrogen ion concentration in solution

 

16. pH in humans is between 7.35-7.45

 

17. pH of a buffer solution can be determined by

pK + log [base]/[acid]

 

18. Metabolic Acidosisà Decrease in pH

        Caused by: i) Starvation

                         ii) Uncontrolled diabetes mellitus

                        iii) Lactic acidosis

 

19. Bicarbonate is regulated by the rate of respiration

 

20. Intestinal bicarbonate is produced in the colon

 

21. The main aldohexose in the blood is GLUCOSE

 

 

 

22. Glucose & Ribose:

            i) are both aldoses

                 ii) Form intramolecular hemiacetal bonds

          iii) Both are reducing sugars

          iv) Have functional groups that form glycosidic linkages

 

23. Sucrose & Trehalose are non-reducing sugars

 

24. Carbohydrates are polyhydroxyaldehydes or ketones

 

25. Benedict's test involves an oxidation-reduction reaction

 

26. Structural polymers of glucose include:

                    i) Cellulose

                   ii) Peptidoglycan

                  iii) Chitin

 

27. Isomers of glucose:

                  i) Have 6 carbon atoms

                 ii) Include mannose

                iii) Can be epimers or anomers

                iv) Differ only in configuration

 

28. RIBOSE and LACTOSE can be synthesized from glucose in the body

 

29. Galactose is an aldohexose

 

30. Carbohydrates include:

                 i) Starch

                ii) Proteoglycans

               iii) Cellulose

               iv) Peptidoglycans

 

31. Glycoproteins are considered as non-carbohydrates

 

32. GLYCOGEN is a branched sugar that is a polymer of glucose

 

33. GLYCOGEN synthesis occurs in the muscles and liver and excessively deposits in liver of Von Gierke's disease patient

 

34. PROTEOGLYCANS act as lubricants in joints

 

35. GLYCOSAMINOGLYCANS contain abundant negative charges and include Chondriotin Sulphate

 

36. GLUCONEOGENESIS occurs in the Kidneys during prolonged fasting

 

37. GLUCOSE-6-PHOSPHATE DEHYDROGENASE is activated by high levels of NADP+

 

38. In the TCA cycle 2 ATP's are produced at substrate-level phosphorylation

 

39. Succinyl CoA is a precursor for heme synthesis

 

40. Pyruvate is converted to oxaloacetate

 

41. Not all reactions in the TCA cycle are reversible

 

42. Glucose-6-phosphate deficiency leads to Von Gierke's disease

 

43. The deficiency of glucose-6-phosphate inhibits the last step of glycogenolysis and gluconeogenesis in the liver

 

44. Glucose-6-phosphate deficiency leads to hyperuricemia

 

45. In glycogenesis the enzyme Glycogen Synthase is the key enzyme

 

46. In glycogenesis ATP is not required

 

47. GLYCOGEN is responsible for maintenance of blood glucose level between meals

 

48. Ucoupling of oxidative phosphorylation increases oxygen consumption and releases heat

 

49. Enzymes found in glycolysis include:

                         i) Aldolase

                        ii) Endolase

                       iii) Pyruvate kinase

                       iv) Phosphoglycerate mutase

 

50. The following are glycolytic intermediates:

                         i) Glucose-6-phosphate

                        ii) Fructose-6-phposphate

                       iii) Dihydroxyacetone phosphate

                       iv) Pyruvate

 

51. ERYTHROCYTES utilize glucose as an energy exclusively under all conditions

 

52. DINTROPHENOL uncouples phosphorylation from electron transfer interfering in oxidative phosphorylation. Dintrophenol also enhances ATP synthesis

 

53. The following are part of the pyruvate dehydrogenase complex:

                    i) Thiamin Diphosphate

                   ii) Lipoamide

                  iii) CoA

                  iv) NAD+

                   v) FAD

 

 

 

 

54. UDP-Glucose can be formed from UDP-Galactose

 

55. GLYCOGEN PHOSPHORYLASE produces glucose-1-phosphate

 

56. FRUCTOSE 2,6-BISPHOSPHATE activates phosphofructokinase 1

 

57. PYRUVATE CARBOXYLASE converts pyruvate to oxaloacetate

 

68. In Glycogen Storage Diseases, TYPE 4 is called ANDERSONS DISEASE

 

69. Pyruvate dehydrogenase complex defect occurs in disorder BERIBERI

 

70. Deficiency of Glucose-6-phosphate dehydrogenase can cause hemolytic anemia

 

71. Synthesis of glucose from pyruvate by GLUCONEOGENESIS in the liver requires the participation of biotin

 

72. Fructose-6-phosphate is produced by FRUCTOKINASE

 

73. Oxidation of glucose by red blood cells gives LACTATE & NAD+

 

74. The importance of the PPP is reductive biosynthesis

 

 

 

 

 

 

 

75.  UDP Glucose:

          i) Is indirectly involved in bilirubin conjugation

         ii) Is a substrate for the enzyme EPIMERASE in     

             lactating mammary gland

        iii) Is an intermediate in sphingolipid synthase

        iv) Is required for galactose metabolism

 

76. Pyruvate is converted to alanine reversibly by the enzyme ALANINE AMINOTRANSFERASE

 

77. If there was biotin deficiency, the enzyme affected would be PEP carboxykinase

 

78. The PPP is important for fatty acid synthesis because it produces equivalents

 

79. A deficiency of the enzyme ALDOLASE B causes hereditary fructose intolerance

 

80. The rate of glycolysis in the liver is increased by glucose-6-phosphate

 

81. The preparative step of glycolysis first involves the reduction of NAD+ to NADH

 

82. Glucose-6-phosphatase is present in the liver but absent in the muscles

 

83. SUCCINATE DEHYDROGENASE utilizes FAD as a coenzyme

 

84. Painful cramps and easy fatigability is caused by deficiency in the debranching enzyme or muscle phosphorylase

 

85. MALONATE inhibits succinate dehydrogenase because it chelates a metal ion required by the enzyme

 

86. In oxidative phosphorylation, protons are pumped into the interspace between the inner and outer mitochondrial membranes

 

87. PHOSPHOFRUCTOKINASE-1 is activated by high levels of AMP

 

88. Energy consumption is high in gluconeogenesis

 

89. Glycogen synthesis requires uridine diphosphate-glucose as intermediate

 

90. Galactosemia:

         i) Causes mental retardation

        ii) Liver failure

       iii) Deficiency of galactose-1-phosphate uridyl transferase

       iv) CATARACT occurs from accumulation of galactose in

            lens

       iv) Is treated by restricting galactose from diet

 

91. TCA cycle intermediates produce:

       i) Fatty acids

      ii) Glucose

     iii) Cholesterol

     iv) Ketone bodies

      v) Heme

     vi) Glutamine

 

92. SKELETAL MUSCLES metabolize glucose, fatty acids & ketone bodies for ATP production

 

93. DIHYDROXYACETONE PHOSPHATE is a glycolytic intermediate that is a close precursor to TRIACYLGLYCEROL

 

 

 

 

94. The CARBON SKELETON of glucose can participate in the synthesis of:

          i) Purine ring

         ii) Pyrimidine ring

        iii) Fatty acid

        iv) Glutamine

 

95. OLIGOMYELIN inhibits electron transfer, interfering with oxidative phosphorylation

 

96.   The rate-limiting enzyme in the committed step to glycolysis is catalyzed by PHOSPHOFRUCTOKINASE-1

 

97. The pyruvate dehydrogenase complex is inactive when THIAMIN IS DEFICIENT

 

98. Activation of phosphofructokinase-1 in the liver results in accumulation of fructose-6-phosphate in the liver

 

99. GLYCOGEN PHOSPHORYLASE requires an inorganic phosphate

 

100. In OXIDATIVE PHOSPHORYLATION an increase in the rate of ATP synthesis will decrease electron transport

 

101. HYPOGLYCEMIA results from:

          i) Deficiency of debranching enzyme (Cori's disease)

         ii) Deficiency in glucose-6-phosphatase

        iii) Defects in beta-oxidation in liver

        iv) Insulin overdose

 

102. Features of glycolysis and the PPP is that they both occur in RBC's

 

103. GLUCONEOGENESIS is active during prolonged fasting

 

 

104. MUSCLE GLYCOGEN:

          i) Accumulates in lysosomes in POMP'S DISEASE

         ii) Is largely depleted by long-term exercise (marathon                 runner)

         iii) Provides phosphohexose for muscular glycolysis

 

105. GLYCEROL-3-PHOSPHATE:

          i) Is produced by reduction of dihydroxyacetone

             phosphate

          ii) Is a precursor of phosphatidic acid

         iii) Can be produced by glycerol kinase

         iv) Is intermediate in TAG synthesis

 

106. 24 hours after a meal, the primary source of glucose to brain is:

             i) Protein from skeletal muscle

            ii) Glycerol from adipose tissue

 

107. GLUCOSE-6-PHOSPHATASE and GLYCEROL KINASE are absent in the muscle but present in the liver

 

108. LINOLENIC and LINOLEIC ACIDS are essential amino acids.

 

109. ARACHIDONIC ACID is an unbranched fatty acid that is a precursor for eicosanoids and prostaglandins. It is Non-Essential.

 

110. SPHINGOMYELIN, CARDIOLIPIN, CEREBROSIDES, CERAMIDES and GANGLIOSIDES are membrane phospholipids that contains glycerol

 

111. Lipids are IMPORTANT in the human body because they act as an energy source and are source to many hormones

 

112. TRIACYLGLYCEROL is a simple lipid

 

113. FATTY ACIDS are obtained from the hydrolysis of triacylglycerol

 

114. OLEIC ACID and LAURIC ACID are saturated fatty acids

 

115. DOLICOL and COENZYME Q are derived lipids.

 

116. CEREBROSIDES and CHOLESTEROL are structural lipids

 

117. Lipids are stored in mammalian tissue as TRIACYLGLYCEROL

 

118. CHOLESTEROL in mammals, is a normal membrane constituent

 

119. BILE SALTS are important enhancers in digestion and absorption of lipids

 

120. Unlike prostaglandins, THROMBOXANES are released by platelets

 

121. COMPLEX LIPIDS include

          i) Phosphatadiylserine

         ii) Cholesterol   

 

122. LECITHIN is a membrane phospholipids that DOES NOT contain glycerol

 

123. LINOLENIC and ARACHIDONIC ACIDS are unsaturated fatty acids

 

124. PHOSPHATIDYLCHOLINE:

           i) Is also known as lecithin

          ii) Is a major constituent of lung surfactant

         iii) Occurs in cell membranes

         iv) Can be obtained from phosphatidyl ethanolamine

 

125. Cerebrosides include GLUCOSYLCERAMIDE

 

126. CHOLESTEROL is also a precursor for the synthesis of steroid hormones and bile acids.

 

127. SPHINGOMYELINS consist of phosphoric acid, choline and ceramide

 

128. EICOSANOIDS:

              i) PROSTACYCLINS inhibit platelet aggregation

             ii) THROMBOXANES activate platelet aggregation

            iii) PROSTAGLANDINS enhance smooth muscle

                 contraction

            iv) LYPOXINS regulate the immunoresponse

             v) LEUKOTRIENES are allergic mediators

 

129. COMPLEX LIPIDS are:

           i) Glycerophospholipids

          ii) Sphingolipids

         iii) Sterols

 

130. PANCREATIC LIPASE is the main enzyme for lipid digestion

 

131. The duodenum is the site of BICARBONATE EXCRETION

 

132. FATTY ACID OXIDATION is a significant source of energy for:

           i) Liver

          ii) Kidney

         iii) Heart

         iv) Skeletal muscle

 

133. MALONYL-COA is the committed step of fatty acid synthesis

 

134. During prolonged fasting, the rate of production of KETONE BODIES increases dramatically

 

135. LANOSTEROL and SQUALINE are intermediates in cholesterol biosynthesis

 

136. LIPOPROTEIN LIPASE hyrdolyses TAG in chylmicrons and VLDL

 

137. 3HMG-CoA is an intermediate in CHOLESTEROL SYNTHESIS and KETOGENESIS

 

138. APOPROTEIN B-48 is one of the contents of chylomicron

 

139. CHOLESTEROL serves as a precursor for:

             i) Aldosterone

            ii) Corticosterone

           iii) Cholic acid

           iv) Testosterone

 

140. PROSTAGLANDINS are synthesized by cyclooxygenase from unsaturated fatty acids

 

141. MEVALONATE is an intermediate in CHOLESTEROL SYNTHESIS

 

142. Long chain fatty acids are attached to the CARNITINE which transports the chain across the inner mitochondrial membrane

 

143. The activity of LIPOPROTEIN LIPASE is stimulated by APO-CII

 

144. The rate-limiting step in the conversion of cholesterol to bile acids is 7-ALPHA-HYDROXYLATION

 

145. CHOLESTEROL is converted to CHOLIC ACID by intestinal bacteria

 

146. The rate limiting enzyme in cholesterol biosynthesis is

3-HYDROXY-3-METHYL GLUTAMYL-CoA REDUCTASE

 

147. TRIACYLGLYCEROL in chylomicron is mainly hyrdrolysed by Lipoprotein lipase

 

148. The oxidation of MALIC ACID is coupled to the production of NAD+H in the cytosol

 

149. LOW-DENSITY LIPOPROTEINS contain endogenous cholesterol

 

150. APO B100 interacts with LDL receptor

 

151. MALONYL CoA is synthesized by acetyl CoA carboxylase

 

152. PROSTAGLANDINS:

             i) Enhance smooth muscle contraction

            ii) Local hormones

           iii) Control of inflammation and blood pressure

           iv) Closely related to Thromboxanes

           v) Primarily synthesized from eicosanoic acids

 

153. KETONE BODIES:

            i) Are synthesized in the mitochondria of the liver

           ii) Increase in the blood during starvation

          iii) Are good fuels for cardiac muscle

          iv) Increase in the blood in uncontrolled diabetes

               mellitus

 

154. DIABETIC KETOACIDOSIS is caused by a rise of plasma free fatty acids

 

155. DENOVO synthesis of cholesterol takes place in the intestine & the liver.

 

156. LIPOPROTEIN LIPASE:

          i) Activated by insulin

         ii) Active during the fed state

        iii) Hydrolyses TAG

        iv) Activated in presence of APO CII

 

157. Gaucher's disease and Tay-Sacchs disease are examples of SPHINGOLIPODOSES

 

158. ACETYL CoA- CARBOXYLASE catalyzes the committed step in fatty acid synthesis and requires biotin as a coenzyme

 

159. CARNITINE is needed in fatty acid synthesis to transport fatty acid to mitochondria

 

160. The contents of HDL include:

             i) Apo A

            ii) Cholesterol

           iii) Apo E

           iv) Apo C

 

161. TAG and glycerol can be synthesized from glucose

 

162. CHYLOMICRON

            i) Carry cholesterol from the intestine

           ii) Contain many TAG

          iii) Has Apoprotein B48

          iv) Lower density than HDL

 

163. CITRIC ACID:

           i) Is produced in the mitochondria as a member of the

              TCA cycle

          ii) Is an allosteric activator of acetyl CoA carboxylase

         iii) Is a source of cytoplasmic acetyl CoA

         iv) Is cleaved in the cytosol by an ATP-dependent lyase

 

164. DICARBOXYLIC ACIDURIA is an inherited disorder of Beta oxidation

 

165. ACETYL CoA CARBOXYLASE converts Acetyl CoA to Malonyl CoA

 

166. Malonyl CoA is the activated form of acetyl CoA

 

167.  LIPOLYSIS in adipose tissue produces fatty acid & glycerol

 

168. GLUTAMINE can be synthesized from GLUTAMATE

 

169. The most important function of proteins in the human body is CATALYSIS

 

170. VALINE (V) and ISOLEUCINE (I) are Aliphatic non-polar amino acids

 

171.  ASPARTATE (D) and GLUTAMATE (E) contain two carboxylic groups (negatively charged; acidic)

 

172. LYSINE (K), ARGININE (R) and HISTIDINE (H) are positively charged amino acids (basic)

 

173. The PRIMARY STRUCTURE of proteins refers to the sequence of amino acids in the polypeptide chain

 

174. DENATURATION of a protein involves loss of its secondary and tertiary structures

 

175. The ALPHA-HELIX and BETA-SHEETS refer to the secondary structure of a protein

 

176. GLYCOPROTEINS contain sugar residues covalently bonded to ASPARAGINE & GLYCINE

 

177. CYSTEINE (C), SERINE (S), THREONINE (T) and METHIONINE (M) are sulphur containing amino acids (polar uncharged)

 

178. ALBUMIN is an important carrier of fatty acids, bilirubin and calcium

 

179. HEMOGLOBIN & MYOGLOBIN are multimeric protein structures that have the same prosthetic group

 

180. Branched chain amino acids undergo TRANSAMINATION and OXIDATIVE DECARBOXYLATION by similar reactions

 

181. HEMOGLOBIN & CYTOCHROMES contain heme as prosthetic group

 

182. The PEPTIDE BOND is a covalent double bond

 

183. PROTEINS are also important in hormonal function

 

184. SULPHUR CONTAINING AMINO ACIDS:

            i) Include Methionine, serine, threoserine & cysteine

           ii) Non-essential amino acids

          iii) Found at the carboxy-terminal of polypeptide chain

 

185. ALBUMIN IS:

           i) Synthesized in the liver

          ii) Water-soluble protein

         iii) Decreased in blood and in protein calorie malnutrition

         iv) Carrier of fatty acid, bilirubin & calcium

 

 

 

 

186. HEMOGLOBIN:

          i) Has a quaternary structure

         ii) Contains porphyrin ring

        iii) Contribute to pH maintenance in the blood

        iv) Affinity for oxygen increases with cooperativety

 

187. GLOBULAR PROTEINS are functional & water-soluble (enzymes, hormones, neurotransmitters)

 

188. FIBROUS PROTEINS are structural (collagen, elastin)

 

189. GLUTATHIONE and VASOPRESSIN are peptides

 

190. Enzymes involved in protein digestion are produced in the pancreas

 

191. PROLINE is an immino acid

 

192. GYRATE ATROPHY of the retina:

            i) Is inherited as autosomal recessive trait

           ii) Involves chorioretinal degeneration

          iii) Results in loss of peripheral vision and tunnel vision

          iv) Can cause blindness

 

193. A KETOGENIC amino acid will be able to produce

               i) Fatty acids

              ii) Ketone bodies

             iii) Energy

 

194. Compounds involved in TRANSAMINATION REACTIONS:

              i) Oxaloacetate

             ii) Pyruvate

            iii) Aspartate

            iv) Alanine

 

195. SUCCINATE does not participate in TRANSAMINATION

 

196. AMMONIA is mainly transported from extrahepatic tissues to the liver in the form of GLUTAMINE and ALANINE

 

197. HEME is synthesized from GLYCINE and SUCCINYL CoA

 

198. PROTOPORPHYRINOGEN IX is the immediate precursor of heme in its biosynthesis

 

199. PHEUKETONURIA & ALKAPTONURIA are in-born errors of aromatic amino acid metabolism

200. Deficiency of CARBAMOYL PHOSPHATE SYNTHASE 1 causes hyperammonemia type 1

 

201. The carbon skeletons of PHENYLALANINE and TYROSINE are catabolized to fumerate

 

202. The committed step in heme biosynthesis is ALA Synthase

 

203. GLYCINE participates in the synthesis of Heme & Purine

 

204. An immediate precursor of SERINE is PHOSPHOSERINE

 

205. UROBILINOGEN is formed in the intestine

 

206. Arginine participates in the synthesis of CREATINE and UREA

 

207. OXALOACETATE is converted to ASPARTATE in direct transamination

 

208. URINARY AMMONIUM IONS are derived by the enzymatic reaction of GLUTAMIC ACID

 

209. TYROSINEMIA and ALKAPTONURIA are in-born errors of tyrosine catabolism

 

210. If a person was deficient in PYRIDOXINE, the conversion of alanine to glucose would be decreased during starvation

 

211. MAPLE SYRUP URINE DISEASE is due to defective branched-chain KETO ACID DECARBOXYLASE

 

212. The one-carbon unit in METHYL-TETRAHYDROFOLATE is mainly obtained from S-ADENOSYLMETHIONINE

 

213. TYROSINE and PHENYLALANINE are amino acids that are both glucogenic and ketogenic

 

214. The formation of BILIRUBIN from HEME occurs in the RETICULOENDOTHELIAL SYSTEM

 

215. An increase in plasma conjugated bilirubin concentration occurs from COMMON BILE DUCT OBSTRUCTION

 

216. POSITIVE NITROGEN BALANCE is a characteristic of growing children and pregnant women

 

217. TYROSINOSIS and ALBINISM are in-born errors of aromatic amino acid metabolism

 

218. In the UREA CYCLE, FUMERATE and UREA are released

 

219. MYOCARDIAL INFARCTION increases the serum level of ASPARTATE TRANSAMINASE (AST)

 

220. KINASES modify phosphorylation of specific amino acid residues

 

221. In hemoglobin S, the mutation in the beta chain results from replacement of glutamate by valine in position 6

 

222. GLUCOSE-ALANINE CYCLE:

         i) Serves to carry amino group from skeletal muscle to

            liver

        ii) Requires the participation of GLUCONEOGENESIS in

            the liver

        iii) Provides the working muscle with glucose made by the

             liver

        iv) Requires participation of transamination reactions in

             both skeletal muscle and liver

 

 

223. Pancreatic enzymes involved in protein digestion are:

              i) Carboxypeptidase

             ii) Trypsin

            iii) Elastase

            iv) Chymotrypsin

 

224. The cells active in heme biosynthesis are ERYTHROCYTE PRECURSORS

 

225. GUANYLATE MONOPHOSPHATE (GMP) and ADENYLATE DIPHOSPHATE (ADP) are PURINE NUCLEOTIDES

 

226. Watson & Crick Model implies that THYMINE base pairs with ADENINE

 

227. RNA is usually SINGLE-STRANDED

 

228. PHOSPHODIESTER and HYDROGEN BONDS stabilize the structure of DNA

 

229. A NUCLEOSIDE is composed of:

            i) Deoxyribose

           ii) Ribose sugar

          iii) Pentose sugar

          iv) Purine base

 

230. PURINES= Adenine & Guanine

 

231. PYRIMIDINES= Cytosine & Thymine

 

232. NUCLEOSIDE= -sine (for purines)

                                 -ine (for pyrimidines)

 

233. NUCLEOTIDE= -ylate

 

234. ADENINE-THYMINE

 

235. GUANINE-CYTOSINE

 

236. MESSANGER RNA

           i) Is translated in direction 5'to 3'

          ii) Has a Poly A tail in eukaryotes

         iii) Is a heterogenous molecule

         iv) Is extensively processed post-transcriptionally in

              eukaryotes

 

237. NUCLEOTIDES in nucleic acids are linked together by 3' to 5' PHOSPHODIESTER BONDS

 

238. The two DNA strands are COVALENTLY LINKED

 

239. The opposing strands of DNA are said to be COMPLEMENTARY

 

240. RIBOSOMAL RNA has a catalytic function in protein synthesis

 

241. TRANSFER RNA act as adaptors during protein synthesis

 

242. The GENETIC CODE:

           i) 62 codons can code for amino acids

          ii) It is universal

         iii) Four codons can terminate protein synthesis

         iv) Many amino acids have multiple codons

 

243. In the genetic code, each triplet codes for one amino acid

 

244. MITOCHONDRIAL DNA:

            i) Has a circular duplex of RNA

           ii) Accounts for 25% of total human DNA

          iii) Codes for all mitochondrial enzymes

          iv) Inherited from the mother

 

245. DNA LIBRARY differs from the GENOMIC DNA LIBRARY in only having introns excluded from genes

 

246. The GENETIC CODE is degenerate

 

247. RNA POLYMERASE works in the 5' to 3' direction

 

248. DNA POLYMERASE works in the 3' to 5' direction

 

249. A PROMOTOR SITE on DNA initiates transcription

 

250. INTRON is the portion of the DNA that is transcribed but not translated

 

251. tRNA reacts specifically with free amino acids

 

252. A POLYMERASE CHAIN REACTION (PCR) requires

                 i) a double stranded DNA at least of partially known

                    sequence

                ii) pair of synthetic RNA PRIMERS

               iii) REVERSE TRANSCRIPTASE

 

253. 5-PHOSPHORIBOSYL-1-PYROPHOSPHATE (PRPP):

      i) de novo synthesis of pyrimidine & purine nucleotides

     ii) the salvage pathways for purine nucleotides

    iii) biosynthesis of nucleotide coenzymes

    iv) biosynthesis of NAD+ and NADP+

 

254. RESTRICTION ENDONUCLEASES have sequence specifity

 

255. DNA:

          i) Synthesis of a new strand occurs 5' to 3' direction

         ii) Temple strand is 3' to 5' direction

        iii) Lagging strand synthesis is discontinuous

        iv) Synthesis occurs in both strands

 

256. The end product of purine catabolism is URIC ACID

 

257. RESTRICTION ENDONUCLEASES II cut double-stranded DNA from any source

 

258. To construct a cDNA library:

        i) Reverse Transcriptase is needed

       ii) mRNA is the starting material

      iii) Synthetic linkers with restriction sites are needed

      iv) Restriction enzymes are used to cut the vector base on             the linker choice

 

259. In HYPERURICEMIA

       i) Gouty Artheritis is a common feature

      ii) High level of urate in blood

     iii) Allopurinol is used for treatment

     iv) The defect in purine nucleotide metabolism

 

260. Inhibition of purine biosynthesis de novo is caused by:

      i) Inhibition PRPP aminotransferase

     ii) Inhibition PRPP synthase

    iii) Depletion of PRPP

 

261. The SIGMA SUBUNIT of PROKARYOTIC RNA POLYMERASE is required for proper recognition of prometer

 

262. AN ANTICODON is a specific nucleotide sequence of tRNA molecule

 

263. GOUT is characterized by high level of URATE in blood

 

264. Biosynthesis of PURINES involves

           i) GLY

          ii) GLU

         iii) ASP

 

265. HGPRTase enzyme is involved in the SALVAGE PATHWAY

 

266. PYRIMIDINES are non-essential in the human diet

 

267. CPS-1 is involved in pyrimidine biosynthesis

 

268. ALLOPURINOL may precipitate OROTIC ACIDURIA

 

269. ASPARTATE is important for pyrimidine nucleotide biosynthesis

 

270. The formation of dATP for DNA synthesis occurs primarily by conversion of ADP to dADP using ribonucleotide reductase

 

271. HYPERURICEMIA can be caused by:

        i) High level of PRPP

       ii) Inhibition of xanthine oxidase

      iii) Deficiency of HGPRTase

      iv) Leukemia

 

272. LAGGING DNA STRAND:

          i) There are several RNA PRIMERS

         ii) DNA synthesis is discontinuous

        iii) Polymerization is in 5' to 3'direction

        iv) DNA polymerase III is needed

 

273. RESTRICTION SITES of RESTRICTION ENDONUCLEASES:

        i) Are on double-stranded DNA

       ii) Can be 4-7 bp long

      iii) Provide blunt & sticky ends

      iv) Are less when the enzyme recognizes longer DNA 

           sequences

 

 

 

 

274. POLYMERASE CHAIN REACTION:

    i) Requires specific primers to amplify a DNA sequence

   ii) Involves cyclic thermal denaturation and reannealing of 

      DNA  

  iii) Help diagnosing sub-clinical infections

  iv) Exploits TAQ POLYMERASE for DNA replication

 

275. LIGASES are employes in DNA sequencing

 

276. cDNA is composed of DNA, end labeled primer, dNTP's, Dideoxynucleotides, DNA Polymerase

 

277. OXYGENASES and DEHYDROGENASES are OXIDOREDUCTASES

 

278. MICHAELIS CONSTANT (Km) of an enzyme is the substrate concentration which gives 1/2 the maximal velocity

 

279. A COMPETITIVE INHIBITOR increases the Km of the enzyme

 

280. The NON-PROTEIN part of the enzyme is called COENZYME

 

281. CLASSES OF ENZYMES are

          i) OXIDOREDUCTASES

         ii) TRANSFERASES

        iii) HYDROLASES

        iv) LYASES

        v) ISOMERASES

       vi) LIGASES

 

282. Enzyme activity is subject to regulation

 

283. COENZYMES:

        i) Non protein part of enzyme

       ii) Needed for enzyme activity

      iii) Usually vitamin derivatives

      iv) Termed prosthetic group if bonded tight to their

           enzymes

 

284. At Vmax of an enzyme catalyzed reaction ALL ENZYME MOLECULES are combined with SUBSTRATE

 

285. IN NON-COMPETITIVE INHIBITION of enzymes, Vmax cannot be reached

 

286. ISOENZYMES are important tools in the diagnosis and prognosis of disease

 

287. PEPTIDASES and LIPASES are HYDROLASES

 

288. ENZYMES lower the activation energy for conversion of substrate to product

 

289. ALLOSTERIC EFFECTOR influences enzyme activity by binding to a sight on the enzyme distinct from the catalytic site

 

290. DEFICIENCY of VITAMIN A gives rise to XEROPHTHALMIA

 

291. VITAMIN D can lower the calcium level in the blood

 

292. VITAMIN K is synthesized by intestinal flora

 

293. BERIBERI affects the nervous system & heart

 

294. VITAMIN B12 requires the intrinsic factor for absorption

 

295. PYRIDOXAL PHOSPHATE is needed by the enzyme ALANINE TRANSAMINASE

 

296. 25-HYDROXYCHOLECALCIFEROL is formed in the liver

 

297. PERNICIOUS ANEMIA is caused by deficiency of the intrinsic factor

 

298. VITAMIN A:

          i) Is important for growth & reproduction

         ii) Is obtained from beta-carotene

        iii) Retinol & Retinoic acids are known forms

        iv) Is required for keratin synthesis

 

299. PELLAGRA is due to deficiency of RIBOFLAVIN

 

300. ASCORBIC ACID:

          i) Deficiency causes HYPOCHROMIC MICROCYTIC

             ANEMIA

         ii) Is required for synthesis of epinephrine and collagen

        iii) Is required for synthesis of bile acids

        iv) Promotes iron absorption in GIT

 

301. COBALAMIN:

        i) Active form is METHYLCOBALAMIN

       ii) Absorption requires glycoprotein factor

      iii) Is required for metabolism of propionate

      iv) Is involved in folate metabolism

 

302. In GEL FILTERATION, biomolecules are separated according to difference in molecular weight

 

303. RADIOIMMUNE ASSAY requires antibodies and radioactive elements for the quantitative measurements of hormones using a pure antigen of known concentration

 

304. ELECTROPHORESIS can be used for purification of proteins & nucleic acids involving the use of a polyacrylamide gel and provided and electrical source

 

305. WESTERN BLOTTING for PROTEINS

 

306. SOUTHERN BLOTTING for DNA

 

307. NORTHERN BLOTTING for RNA

 

308. To separate a mixture of 20 amino acids the best technique is a TWO-DIMENSIONAL ELECTROPHORESIS

 

309. CHROMATOGRAPHY is a separation technique that involves a mobile phase and stationary phase and is exemplified by gel filteration

 

310. DIALYSIS involves diffusion across a POROUS MEMBRANE

 

311. ION EXCHANGE CHROMATOGRAPHY is used for sequencing of proteins

 

312. IN ELECTROPHORESIS the rate of migration depends on NET ELECTRIC CHARGE of a molecule & the SIZE and SHAPE of the molecule

 

313. CHROMATOGRAPHY can be used to separate proteins & amino acids

 

314. DNA Replication begins with DNA helicase unwinding the hydrogen bonds between the nucleotides

315. DNA Polymerase III replicates the new nucleotides of the leading strand (from 5' to 3')

 

316. DNA Polymerase III also replicates in the lagging strand but in Okazaki fragments because (from 3' to 5')

 

317. RNA Primase sets down RNA Primers to form nucleotides between the fragments in the lagging strand

 

318. DNA Polymerase I replaces the RNA Primers with DNA nucleotides

 

319. Finally DNA Ligase closes off the Okazaki Fragments

 

320. RNA Synthesis occurs when RNA Polymerase II and some protein factors temporarily denature the helix of the DNA

 

321. There is a starting end and a termination end on the DNA to synthesize RNA

 

322. RNA is synthesized by RNA Polymerase until it reaches the termination end to be released as an mRNA

 

323. RNA splicing is when small snRNA and other proteins split parts of the coding part in the mRNA to release the introns and bring together the exons

 

325. The mRNA leaves the nucleus where it is met by a small and large subunit of ribosomes

 

326. The large subunit holds an A site, a P site and a small E site for tRNA to come into

 

327. The t RNA has a head for the amino acid and a leg for the codons of the m RNA called the anti-codons

 

328. Each codon translates to an specific amino acid

329. As each t RNA moves from the A site to the P site, the new amino acids bond with each other by peptide bonds

 

330. The t RNA then reaches the E site empty and is thrown out of the ribosome

 

331. The new polypeptide chain continues growing until a stop codon is reached in the t RNA and the polypeptide chain is released into the cytosol to form a protein with other polypeptides