gene, dna and rna

1. Basic concepts of
Genes, DNA & RNA
Course: BSc Biotech Sem-I
Subject : Fundamentals of Biotechnology
Unit - 2
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2. BREAKTHROUGH DISCOVERY
• In 1953, James Watson and Francis Crick
discovered the double helical structure of the
DNA molecule
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3. The discovery was announced on
February 28, 1953
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4. The First Paper appeared in Nature on April
25, 1953
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5. 5

6. Watson and Crick - Awarded Nobel Prize
in 1962
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7. DNA
A purine always links with a pyrimidine base to maintain the structure of DNA.
Adenine ( A ) binds to Thymine ( T ), with two hydrogen bonds between them.
Guanine ( G ) binds to Cytosine ( C ), with three hydrogen bonds between them.
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8. 8

9. Chemical Structure Of DNA
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10. 10

11. Nucleoside & Nucleotide, the
fundamental building block of DNA
glycosidic bond
phosphoester bond
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12. 12

13. 13

14. Ribose
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15. DNA & RNA - Nucleotide Bases
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16. Nucleotide
adenine
deoxyribose
PO4
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17. Nucleotides
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14.

18. Chargaff's rule
• Chargaff's rules state that DNA from
any cell of all organisms should have a 1:1
ratio (base Pair Rule)
of pyrimidine and purine bases and, more
specifically, that the amount of guanine is
equal to cytosine and the amount
of adenine is equal to thymine.
• They were discovered by Austrian
chemist Erwin Chargaff
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19. Relative proportions (%) of bases in DNA
Organism %A %G %C %T A/T G/C %GC %AT
φX174 24 23.3 21.5 31.2 0.77 1.08 44.8 55.2
Maize 26.8 22.8 23.2 27.2 0.99 0.98 46.1 54
Octopus 33.2 17.6 17.6 31.6 1.05 1 35.2 64.8
Chicken 28 22 21.6 28.4 0.99 1.02 43.7 56.4
Rat 28.6 21.4 20.5 28.4 1.01 1 42.9 57
Human 29.3 20.7 20 30 0.98 1.04 40.7 59.3
Grasshoppe
r 29.3 20.5 20.7 29.3 1 0.99 41.2 58.6
Sea Urchin 32.8 17.7 17.3 32.1 1.02 1.02 35 64.9
Wheat 27.3 22.7 22.8 27.1 1.01 1 45.5 54.4
Yeast 31.3 18.7 17.1 32.9 0.95 1.09 35.8 64.4
E. coli 24.7 26 25.7 23.6 1.05 1.01 51.7 48.3
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20. CHEMICAL AND PHYSICAL PROPERTIES
OF DNA
• ABSORPTION
• The bases in DNA absorb ultraviolet light at
the wavelength of 260 nm
• This absorption can be monitored using a
spectrophotometer
• This is one method used to figure the
concentration of DNA in solution
• The more DNA present, the higher the
absorption
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21. • DENSITY
• Density can be measured by CsCl-density
ultracentrifugation
• can be used to estimate G+C content
• GC base pairs are more dense than AT base
pairs
• Density studies show the existence of satellite
DNA
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22. • DENATURATION
• DNA is considered denatured when the double
stranded DNA molecule is converted into two
single stranded molecules
• As thermal energy increases, the frequency of
hydrogen bonds breaking between the molecules
increases
• G-C base pairs are held together by three
hydrogen bonds (A-Ts by two) and it therefore
takes more energy (higher temperatures) to
separate molecules with high GC contents
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23. • Hydrophobicity of solvent
• Hydrophobic substances will allow the bases in
DNA to dissolve into the solvent
• Whereas hydrophilic substances will keep the
bases of DNA stacked upon one another in
the orientation that most favors hydrogen
bonding between DNA strands
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24. • pH
• Acidic pH cause breakage of phosphodiester
bonds between nucleotides and breakage of
the N-glycosidic bond between the sugar and
purine bases
• Alkali - Above pH 11.3, all hydrogen bonds
are disrupted and the DNA is totally
denatured
• Salts will stabilize the DNA double helix
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25. • Electrophoresis
• DNA has a negative charge that is proportional to
its size
• This is due to the negatively charged phosphates
in the sugar-phosphate backbone
• If DNA is placed in an electrical field it will migrate
towards the positive electrode (the cathode)
• smaller pieces will migrate faster than larger pieces
• Larger pieces have trouble squeezing through the
gel matrix and are hence retarded while smaller
pieces migrate easier
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26. • Type of gels
• Agarose is used to separate fairly large DNA
molecules
– 5 million to a few thousands base pairs
• Polyacrylamide is used to separate small pieces
of DNA
– 2 to several hundred base pairs
• The size of DNA is estimated by comparing
its migration through the gel to DNA
molecules of known size
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27. A, B and Z DNA
• A form – favored by
RNA
• B form – Standard
DNA double helix under
physiological conditions
• Z form – laboratory
anomaly,
– Left Handed
– Requires Alt. GC
– High Salt/ Charge
neutralization
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15.

28. 28
16.

29. 29
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30. RNA
Three major classes of RNA:
Difference between RNA & DNA
RNA DNA
RNA nucleotides contain ribose sugar DNA contains deoxyribose
RNA has the base uracil DNA has the base thymine
presence of a hydroxyl group at the 2'
position of the ribose sugar.
Lacks of a hydroxyl group at the 2'
position of the ribose sugar.
RNA is usually single-stranded DNA is usually double-stranded 30

31. mRNA
• Transcripts of structural genes.
• Encode all the information necessary for the
synthesis of a polypeptide of protein.
• Intermediate carrier of genetic information;
deliver genetic information to the cytoplasm.
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32. mRNA to Amino Acid Dictionary
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33. 33
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34. tRNA
 RNA molecules 70- 100 nucleotide long.
 The secondary structure of the tRNA
resembles a D loop, anticodon loop,
and T loop and the acceptor stem.
 Carry correct amino acids to their
position along the mRNA template to be
added to the growing polypeptide chain.
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35. rRNA
• The central component of the
ribosome.
• Ribosome; factory for protein
synthesis; composed of ribosomal
RNA and ribosomal proteins.
• rRNA provides a mechanism for
decoding mRNA into amino acids.
• rRNA interact with the tRNAs during translation by
providing peptidyl transferase activity.
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36. RNA Helices are short, bulges, loops
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37. Organization of DNA in eukaryotes
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38. • Chromosome –
– double stranded DNA
molecule packaged by histone
& scaffold proteins
DNA double helix
nucleosome
30nm fiber
condensed chromosome
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39. Genome
Gene
• Is the basic units of
inheritance; it is a segment
within a very long strand of
DNA with specific
instruction for the
production of one specific
protein.
• Genes located on
chromosome on it's place or
locus.
Genome and Gene
• Totality of genetic information of an organism.
• Encoded in the DNA (for some viruses, RNA).
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40. Image refrences
1.http://www.bbc.co.uk/history/historic_figures/crick_and
_watson.shtml
2. http://m.harunyahya.com/tr/works/4159/Once-Upon-A-
Time-There-Was-Darwinism/chapter/4732/Once-there-
was-no-knowledge-of-biological-information
3. http://arabian-explorers.com/james-watson-francis-crick
4.https://www.bcps.org/offices/science/secondary/forensi
c/DNA.pdf
5.http://www.timerime.com/en/event/209438/Nobel+Prize
+for+Literature/
6. http://pixgood.com/dna-model-labeled-structure.html
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41. Image refrences
7.http://www.yourarticlelibrary.com/dna/deoxyribonucleic
-acid-dna-model-chemical-composition-and-
transformation-experiments/22676/
8.http://ircamera.as.arizona.edu/NatSci102/NatSci/text/nuc
leicacid.html
9. http://quizlet.com/11685525/chapter-8-slides-flash-cards/
10.http://biology200.gsu.edu/houghton%2704/4564%20%27
14/lecture6.html
11. http://www.slideshare.net/oreonixha/dna-11921134
12. http://www.bvgh.org/Current-Programs/Neglected-
Disease-Product-Pipelines/Global-Health-
Primer/Targets/cid/ViewDetails/ItemID/18.aspx
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42. Image refrences
13. http://smarttechno.net/tag/purine-bases
14. http://en.wikipedia.org/wiki/Nucleotide
15.http://biomedical.youngdong.ac.kr/sgkim/files/2013/06/P
OB_5e_ch08-SGKim.pdf
16. https://lh3.ggpht.com/b7SCiLAza-
c_D_wbjzOP86F4AnXyKu_wrviHfbF3GFqCWJXzuqHQvIG
7P51jXvJcNJnNfQ=s144
17.https://lh5.ggpht.com/uE2KYozDJ302Z1ScuRJwtmqjjthxv
ILPxYnYyxog8q75VSahpvcMgtztJl8qGrXKhgsugA=s136
18. https://lh4.ggpht.com/1cWohlnifUAe4-
WcqCCzkt3_GjfAmlbW1Tc7D0rcQXm9j5qW6Ns_xRv11VP
wLy1aOsRkaQ=s170
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43. Image refrences
19.https://lh4.ggpht.com/u0_RqejooRi2Vz7xOVJ7UkYuzUZquHOQ
nm4hSncWyNEOF0nAvJcM4WQlkYPuWaf2JiFN=s101
20. https://lh3.ggpht.com/ma2QHNXrMmoFjD-
RtySlsVEPZjKqVEh7dv2oytsVIXO570HJZUXABdFoleQeALL8wy1f
bg=s85
21.https://lh4.ggpht.com/rp027AgQNGhK99zk9t5qoLYRJgES8MDj
0tnom_OYqQbMbTepfE1UttFktW5mSDBKuzUQ=s85
22.https://lh4.ggpht.com/iFsbqDCWZz_IqdhnffJBMcOFPvy60Nzd
BMG9V8SF4hIzzPYpgOJj4uhhnOct-vCGCB1k=s85
23. http://people.csail.mit.edu/donglai/
24. http://www.jeansforgenesday.org/disorders/basicterms
25. http://carolguze.com/text/442-1-humangenome.shtml
26. http://science.howstuffworks.com/life/cellular-
microscopic/cell7.htm
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44. References
• Biochemistry by S C Rastogi
• Genes XI by Krebs, Goldstein and Kilpatrick
• Biotechnology by H K Das
• Biotechnology by John E. Smith (5th Ed.)
• http://www.genomicglossaries.com/
• http://biology-pages.info
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