IMPORTANT POINTS
DNA :- Deoxy ribonucleic acid is the largest biomolecule which has polynucleotide chains with specific arrangement of nitrogen bases that posses coded information of Cryptogram of a large number of hereditary traits History
1. Friedrich Miescher - isolated nucleic acid and named nuclein
2. Zacharis - Found nuclein to be restricted to chromatin
3. Alt man - named nuclein of nucleic acid
4. Fisher - discovered purine and pyrimidine bases
5. Chargoff - found purine and pyrimidine content of DNA to be equal with A = T and G = C ( = equal to )
6. Franklin - found DNA to be helix
7. Watson Crick & Wilkins - Double helical model of DNA
8. Linus Pauling - a Nobel Laurete for unravelling protein structure
Functions of DNA :-
1. Autocatalytic Function :- DNA direct its own biosynthesis at the time of DNA replication
2. HeteroCatalytic Function :- Directing Synthesis of another biochemical is called heterocatalytic function
Ex :- Synthesis of RNA over DNA template
In 1948 Beadle and Tatum proposed one-gene one engyme hypothesis which states that a gene controls metabolic machinery of the organism through synthesis of an enzyme. This laid foundation of biochemical genetics One - Gene and one Polypeptide hypothesis was proposed by Yanofsky (1965). It states that a structural genes specifies the synthesis of a single polypeptide Ex :- Haemoglobin is made of two α and two β chains (polypeptides) Two separate genes play vital role in synthesis of two different (α and β ) Chains.
Cistron - In biochemical genetics the term gene is replaced by cistron Regulatory gene - Which controls the functioning of structural genes Structural gene - Produces biochemicals required for cellular machinery.
M.C.Q.
1. Name the conjugated protein used as genetic material in living cells
(A) Glyco protein (B) Nucleo protein (C) Metallo protein (D) Lip oprotein
2. Who supported Griffith effect by molecular explanation ?
(A) Hershay and chase (B) Watson, crick Ninenberg
(C) Avery , Mc Carty and Macleod (D) Griffith and Avery
3. Synthesis of nucleic acids always takes place in
(A) 31 - 51 dicectioon (B) 51 - 31 direction (C) Both ways (D) in any direction
4. DNA Chain initiation phase during replication is
(A) formation of stepping stone (B) Activation of deoxy ribonucleotides
(C) Formation of Okazaki fragments (D) Formation of replication fork stage
5. What is called Griffith effect ?
(A) DNA transcription (B) RNA translation
(C) Bacterial transformation (D) Bacterial transduction
6. Genetic information is carried by the long chain molecules which are made up of
(A) Amino acids (B) Nucleotides (C) Chromosomes (D) Enzymes
7. By which bonds the purine & pyrimidine pairs of Complementary Strands of DNA held together?
(A) H - bonds (B) O - bonds (C) C - bonds (D) N - bonds
8. State the nature of the 2 Strands of DNA duplex.
(A) identical & Complementary (B) Anti parallel & complementary
(C) Disimilar & non - complementary (D) Anti parallel & Non - complementary
9. The code AUG stands for
(A) Glycine (B) Methionine (C) N-formyl methionine (D) A lanine
10. A Sequence of three Consecutiue bases in a t- RNA molecule which Specifically binds to a complementary Codon Sequence in m - RNA is known as
(A) Triplet Codon (B) Non - Sense Codon
(C) Anti Codon (C) Termination Codon
11. A Codon is made up of
(A) Single nucleotide (B) two nucleotides (C) three nucleotides (D) Four nucleotides
12. Nucleus of a cell is the site of Synthesis of
(A) DNA (B) m - RNA (C) t - RNA (D) All
13. DNA replication requires
(A) DNA polymerase only (B) DNA polymerase and ligase
(C) Ligase only (D) RNA polymerase
14. The enzyme involved in transcription is
(A) RNA polymerase (B) DNA polymerase I(C) DNA polymerase II (D) DNA polymerase III
15. Enzymes needed for formation of repliction fork
(A) RNA polymerase and DNA polymerase I (B) Helicase and gyrase
(C) Hexokinase and aldolase (D) Ligase and endo nuclease
16. Okazaki fragments are Synthesized on
(A) Leading strands of DNA only (B) Lagging Strands of DNA only
(C) Leading and LaggingStrands (D) Complementary DNA Strand
17. Which of the following is used in DNA multiplication?
(A) RNA polymerase (B) DNA endonuclease (C) DNA exonuclease (D) DNA Polymerase
18. t - RNA attaches aminoacid at its
(A) 31 end (B) 51 end (C) Anticodon (D) Loop
19. DNA acts as a template for synthesis of
(A) RNA (B) DNA (C) Both ‘a’ and ‘b’ (D) Protein
20. Antiparallel strand in DNA is due to
(A) Disulphide linkage (B) Hydorgen bond (C) Phosphodiester bond (D) Ionic bond
21. Multiplication of DNA is called
(A) Translation (B) Replication (C) Transduction (D) Transcription
22. Which is the smallest RNA ?
(A) r RNA (B) m RNA (C) t - RNA (D) nuclear RNA
22. Which is the smallest RNA ?
(A) r RNA (B) m RNA (C) t - RNA (D) nuclear RNA
23. Genetic information are transfered from nucleus to cytoplasm of cell through
(A) DNA (B) RNA (C) Lysosomes (D) Anticodon
24. The information from RNA to DNA are transfered by which process
(A) Replication (B) Transcription (C) Translation (D)Reverse transcription
25. Which statement is correct ?
(A) Degeneracy of code is related to third member of codon
(B) Single codon, codes for more than one aminoacid
(C) In codon first two bases are more specific
(D) In codons third base is wobble
(E) code is universal
(A) A,B,C,D,E (B) A, B, D (C) A., C, D (D) A, C, D, E
26. DNA molecule has uniform diameter due to ?
(A) Double stranded
(B) Presence of phosphate
(C) Specific base pairing between purine and pyrimidine
(D) Specific base pairing between purine and purine
27. In a transcription unit promotor is said to be located towards
(A) 31 end of structural gene (B) 51 end of structural gene
(C) 51 end of template strand (D) 31 end of template strand
28. In DNA replication the primer is
(A) A Small deoxyribonucleotide polymer
(B) A small ribonucleotide polymer
(C) Helix destalilizing protein
(D) Enzyme taking part in joining nucleotides of new strands
29. Non - sense codons take part in
(A) formation of unspecified aminoacids
(B) Terminating message of gene controlled protein synthesis
(C) Releasing t-RNA from polynucleotide chain
(D) Conversion of sense DNA in to non-sense one
30, select the correct sequence of following in DNA replication
(A) single stranded binding proteins - Helicase - Topoisomerase - DNA polymerase
(B) Helicase - single stranded binding proteins -Topoisomerase - DNA polymerase
(C) Helicase - DNA polymerase - Topoisomerase - Single stranded binding proteins
(D) Helicase - Topoisomerase - DNA polymerase - Single stranded binding proteins
