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#	Question	Answer
1	What is the genetic material in the majority of organisms?	DNA (Deoxyribonucleic acid).
2	Name additional roles of RNA besides acting as a messenger.	Adapter, structural, and catalytic roles.
3	What are the three components of a nucleotide?	Nitrogenous base, pentose sugar, and phosphate group.
4	Which nitrogenous base is common to both DNA and RNA?	Cytosine.
5	What is formed when phosphate attaches to a nucleoside?	Nucleotide.
6	Which end of a polynucleotide chain has a free OH group?	3' end.
7	Which nitrogenous base is present in RNA in place of thymine?	Uracil.
8	Who proposed the Double Helix model of DNA?	James Watson and Francis Crick.
9	Why can the sequence of one DNA strand predict the sequence of the other strand?	Because the two strands are complementary.
10	In which direction do the two DNA strands run?	Anti-parallel direction.
11	In which fashion are the two DNA strands coiled?	Right-handed fashion.
12	Who proposed the Central Dogma of molecular biology?	Francis Crick.
13	Why is DNA packaging necessary in cells?	Because DNA length is far greater than the size of the nucleus.
14	Which proteins are responsible for DNA organisation in eukaryotes?	Histones.
15	What structure is formed when DNA wraps around histone octamer?	Nucleosome.
16	Which proteins are required for higher level chromatin packaging?	Non-histone chromosomal (NHC) proteins.
17	What was the major unanswered question before 1926 regarding inheritance?	Which molecule acts as the genetic material.
18	Why do R strain bacteria appear rough?	Because they lack the polysaccharide coat.
19	What happened when live R strain and heat-killed S strain were injected together into mice?	The mice died.
20	Which molecule transformed live R cells into S cells?	DNA.
21	Which scientists provided unequivocal proof that DNA is the genetic material?	Alfred Hershey and Martha Chase.
22	Why did Hershey and Chase use radioactive phosphorus in one set of viruses?	Because DNA contains phosphorus.
23	Why are proteins not labelled by radioactive phosphorus in Hershey-Chase experiment?	Because proteins do not contain phosphorus.
24	What was observed in bacteria infected with viruses having radioactive proteins?	The bacteria were not radioactive.
25	Which nucleic acid mainly performs dynamic functions like messenger and adapter roles?	RNA.
26	Why should genetic material be chemically and structurally stable?	So it does not change during life cycle, age, or physiological changes.
27	Which nitrogenous base provides additional stability to DNA?	Thymine.
28	Why is DNA dependent on RNA?	DNA requires RNA for protein synthesis.
29	Which essential life processes evolved around RNA?	Metabolism, translation, and splicing.
30	What is semiconservative DNA replication?	Each daughter DNA contains one parental and one newly synthesised strand.
31	How long does *E. coli* take to divide?	20 minutes.
32	Which enzyme is the main enzyme involved in DNA replication?	DNA-dependent DNA polymerase.
33	What is the approximate rate of DNA polymerisation in *E. coli*?	Approximately 2000 bp per second.
34	Besides DNA polymerase, what else is required for DNA replication?	Additional enzymes for high accuracy.
35	Which enzyme joins discontinuously synthesised DNA fragments?	DNA ligase.
36	Which strand undergoes discontinuous replication?	The strand with template polarity 5' → 3'.
37	Why are vectors required in recombinant DNA procedures?	Because they provide the origin of replication.
38	During transcription, adenine pairs with which base in RNA?	Uracil.
39	What are the three regions of a transcription unit?	Promoter, structural gene, and terminator.
40	Why is the coding strand called so?	Because its sequence resembles the RNA sequence.
41	What is the function of the terminator?	It defines the end of transcription.
42	What type of structural genes are mostly found in prokaryotes?	Polycistronic genes.
43	What are regulatory genes?	Regulatory sequences loosely defined as genes though they do not code for RNA or protein.
44	How many DNA-dependent RNA polymerases are present in bacteria?	One.
45	What happens when RNA polymerase reaches the terminator region?	Nascent RNA and RNA polymerase fall off, ending transcription.
46	Which RNA polymerase transcribes rRNA in eukaryotes?	RNA polymerase I.
47	Why are primary transcripts in eukaryotes non-functional?	Because they contain both exons and introns.
48	Where is processed mRNA transported after processing?	Out of the nucleus for translation.
49	How many codons are possible with a triplet code?	64 codons.
50	What is the nature of the genetic code?	Triplet.
51	How is the genetic code read in mRNA?	In a contiguous manner without punctuation.
52	Name the three stop codons.	UAA, UAG, and UGA.
53	What happens when one or two bases are inserted or deleted?	The reading frame changes from that point onward.
54	What was tRNA originally called?	sRNA (soluble RNA).
55	Are there tRNAs for stop codons?	No.
56	What is the effect of deleting one base from a genetic code sequence?	It alters the reading frame from the point of deletion.
57	Which part of tRNA reads the genetic code?	Anticodon loop.
58	What is required for peptide bond formation?	Energy.
59	In inactive state, ribosomes exist as what?	Large and small subunits.
60	What is a translational unit in mRNA?	Sequence between start codon and stop codon coding for a polypeptide.
61	Which tRNA recognises the start codon AUG?	Initiator tRNA.
62	What happens after translation termination?	Complete polypeptide is released from the ribosome.
63	Which level of gene expression regulation involves movement of mRNA from nucleus to cytoplasm?	Transport level.
64	Why is beta-galactosidase not synthesised in absence of lactose?	Because the enzyme is unnecessary without lactose as energy source.
65	What are regulatory proteins that increase transcription called?	Activators.
66	What is an operon?	Arrangement where polycistronic structural genes are regulated by common promoter and regulatory genes.
67	What does the i gene code for?	Repressor of the lac operon.
68	What does the y gene code for?	Permease.
69	Why is lactose called an inducer?	Because it switches the lac operon on and off.
70	Where does the repressor protein bind in lac operon?	Operator region.
71	Regulation of lac operon can also be viewed as regulation of what?	Enzyme synthesis by its substrate.
72	What does HGP stand for?	Human Genome Project.
73	Why is Human Genome Project called a mega project?	Due to enormous genome size, cost, and data involved.
74	Which new field of biology developed rapidly with HGP?	Bioinformatics.
75	Which sectors were expected to benefit from technologies developed during HGP?	Industries and other sectors.
76	Knowledge of DNA variations among individuals may help in what?	Diagnosis, treatment, and prevention of disorders.
77	Why is genomic DNA fragmented before sequencing?	Because very long DNA molecules cannot be sequenced directly.
78	What does YAC stand for?	Yeast Artificial Chromosome.
79	What were specialised computer programs used for in HGP?	Sequence alignment and analysis.
80	Which information helped generate genetic and physical maps of the genome?	Polymorphism of restriction endonuclease sites and microsatellites.
81	What is the size of the dystrophin gene?	2.4 million bases.
82	What makes up a large portion of the human genome?	Repeated sequences.
83	Which chromosome contains the fewest genes?	Y chromosome.
84	What will understanding DNA sequences help explain in future research?	Biological systems and interconnected gene/protein networks.
85	What are repetitive DNA sequences?	Small stretches of DNA repeated many times.
86	Name different categories of satellite DNA.	Microsatellites and minisatellites.
87	Why is DNA fingerprinting useful in paternity testing?	DNA polymorphisms are inherited from parents to children.
88	In which DNA regions are mutations more likely to accumulate without harmful effects?	Non-coding DNA sequences.
89	What does VNTR stand for?	Variable Number of Tandem Repeats.
90	Which technique separates DNA fragments in DNA fingerprinting?	Electrophoresis.
91	Why do VNTRs show high polymorphism?	Because the copy number varies among chromosomes and individuals.
92	In which individuals is DNA fingerprint pattern identical?	Monozygotic (identical) twins.
93	What is the major role of RNA in cells?	Transfer and expression of genetic information.
94	Which bases pair through three hydrogen bonds?	Guanine and Cytosine.
95	Why can bacterial mRNA be translated immediately after transcription?	Because it is already functional and requires no processing.
96	Which molecule reads the genetic code during translation?	tRNA.
97	Why is translation considered to have evolved around RNA?	Because RNA performs catalytic and informational roles.
98	Which metabolic process is controlled by lac operon?	Lactose metabolism.
99	Name major applications of DNA fingerprinting.	Forensic science, genetic biodiversity studies, and evolutionary biology.
100	If the coding strand sequence is 5'-ATGCATGCATGCATGCATGCATGCATGC-3', what will be the mRNA sequence?	5'-AUGCAUGCAUGCAUGCAUGCAUGCAUGC-3'.
101	Which experiment proved DNA as genetic material?	Hershey-Chase experiment.
102	What is the function of tRNA?	It transports amino acids and reads genetic code through anticodon.
103	What are exons?	Coding sequences that appear in mature RNA.