![Page 1: Section 2 Molecular and Morphological Structure of Chromosomal DNA Experiments proving that Chromosomes Posses the DNA: Chemical analysis (Ris & Marasky)](https://reader031.vdocument.in/reader031/viewer/2022012316/56649d6d5503460f94a4d029/html5/thumbnails/1.jpg)
Section 2Molecular and Morphological Structure of Chromosomal DNA
Experiments proving that Chromosomes Posses the DNA:•Chemical analysis (Ris & Marasky)•Feulgen’s reaction•Ultraviolet absorption•Enzymatic digestion Lambproush chromosomes•Autoradiography
![Page 2: Section 2 Molecular and Morphological Structure of Chromosomal DNA Experiments proving that Chromosomes Posses the DNA: Chemical analysis (Ris & Marasky)](https://reader031.vdocument.in/reader031/viewer/2022012316/56649d6d5503460f94a4d029/html5/thumbnails/2.jpg)
Section 2Molecular and Morphological Structure of Chromosomal DNA
1- Enzymatic Digestion of Lampbrush Chromosomes:
A Lampbrush chromosome is the largest chromosome known and is found in the amphibian oocytes (immature eggs). Lampbrush chromosomes occur during the diplotene stage of meiosis I. They are meiotic bivalents, each consisting of 2 sister chromatids. Lampbrush chromosomes are clearly visible even in the light microscope, where they are seen to be organized into a series of large chromatin loops emanating from a linear chromosomal axis.
Rnase +proteinase Matrix disappeared DnaseChromosome
lyses
![Page 3: Section 2 Molecular and Morphological Structure of Chromosomal DNA Experiments proving that Chromosomes Posses the DNA: Chemical analysis (Ris & Marasky)](https://reader031.vdocument.in/reader031/viewer/2022012316/56649d6d5503460f94a4d029/html5/thumbnails/3.jpg)
Section 2Molecular and Morphological Structure of Chromosomal DNA
2- Feulgen’s Reactiona specific staining procedure for DNA: mild acid hydrolysis makes the aldehyde group of deoxyribose available to react with schiffs reagent to give a purple colour.
Warm and diluted Acid
DNA hydrolysis
Schiff’s reagent+
Nucleic Acid Source(CHO- Ribose)
magenta or purple color
develops
![Page 4: Section 2 Molecular and Morphological Structure of Chromosomal DNA Experiments proving that Chromosomes Posses the DNA: Chemical analysis (Ris & Marasky)](https://reader031.vdocument.in/reader031/viewer/2022012316/56649d6d5503460f94a4d029/html5/thumbnails/4.jpg)
Section 2Molecular and Morphological Structure of Chromosomal DNA
3- Ultraviolet AbsorptionDNA can absorb UV waves in 2600 Å (260n.m) wave length due to the cyclic structure of the nitrogen bases.
High radiatio
n
Low
rad
iation
![Page 5: Section 2 Molecular and Morphological Structure of Chromosomal DNA Experiments proving that Chromosomes Posses the DNA: Chemical analysis (Ris & Marasky)](https://reader031.vdocument.in/reader031/viewer/2022012316/56649d6d5503460f94a4d029/html5/thumbnails/5.jpg)
Chemical Analysis (Ris and Marasky)
90 %
The main compound
10 %
The secondary compound
45 % DNA
55 % Histone proteins
14 % RNA
2.6 % DNA
80 % Non Histone Proteins
Animal
( Cow)
Thyroid
glands
![Page 6: Section 2 Molecular and Morphological Structure of Chromosomal DNA Experiments proving that Chromosomes Posses the DNA: Chemical analysis (Ris & Marasky)](https://reader031.vdocument.in/reader031/viewer/2022012316/56649d6d5503460f94a4d029/html5/thumbnails/6.jpg)
Autoradiography
![Page 7: Section 2 Molecular and Morphological Structure of Chromosomal DNA Experiments proving that Chromosomes Posses the DNA: Chemical analysis (Ris & Marasky)](https://reader031.vdocument.in/reader031/viewer/2022012316/56649d6d5503460f94a4d029/html5/thumbnails/7.jpg)
Genome Organization• Eukaryotes Vs. Prokaryotes• Genome• Haploid• Diploid
http://www.youtube.com/watch?v=ke7PDxrKbj8
![Page 8: Section 2 Molecular and Morphological Structure of Chromosomal DNA Experiments proving that Chromosomes Posses the DNA: Chemical analysis (Ris & Marasky)](https://reader031.vdocument.in/reader031/viewer/2022012316/56649d6d5503460f94a4d029/html5/thumbnails/8.jpg)
![Page 9: Section 2 Molecular and Morphological Structure of Chromosomal DNA Experiments proving that Chromosomes Posses the DNA: Chemical analysis (Ris & Marasky)](https://reader031.vdocument.in/reader031/viewer/2022012316/56649d6d5503460f94a4d029/html5/thumbnails/9.jpg)
Eukaryotic Chromosome
http://www.youtube.com/watch?v=ke7PDxrKbj8
![Page 10: Section 2 Molecular and Morphological Structure of Chromosomal DNA Experiments proving that Chromosomes Posses the DNA: Chemical analysis (Ris & Marasky)](https://reader031.vdocument.in/reader031/viewer/2022012316/56649d6d5503460f94a4d029/html5/thumbnails/10.jpg)
DNA Packaging Why package DNA?
Levels of Packing:
1-Nucleosome
2-30 nm fiber/Solenoid
3-Loops
4-Rossettes
5-Chromosome
![Page 11: Section 2 Molecular and Morphological Structure of Chromosomal DNA Experiments proving that Chromosomes Posses the DNA: Chemical analysis (Ris & Marasky)](https://reader031.vdocument.in/reader031/viewer/2022012316/56649d6d5503460f94a4d029/html5/thumbnails/11.jpg)
• ChromosomesNucleosome (Level 1)A nucleosome core particle contains: – 146 base pairs of supercoiled DNA– Around a core of eight histone molecules
Histone coreTwo copies of H2A, H2B, H3 and H4– Octamer
H1 resides outside of core– Linker histone– Binds to linker DNA– Connecting one nucleosome core particle
to next
![Page 12: Section 2 Molecular and Morphological Structure of Chromosomal DNA Experiments proving that Chromosomes Posses the DNA: Chemical analysis (Ris & Marasky)](https://reader031.vdocument.in/reader031/viewer/2022012316/56649d6d5503460f94a4d029/html5/thumbnails/12.jpg)
![Page 13: Section 2 Molecular and Morphological Structure of Chromosomal DNA Experiments proving that Chromosomes Posses the DNA: Chemical analysis (Ris & Marasky)](https://reader031.vdocument.in/reader031/viewer/2022012316/56649d6d5503460f94a4d029/html5/thumbnails/13.jpg)