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nucleus
- 1. N U CL E U S B Y R AB I U L N O O R
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- 4. NUCLEOID • NUCLEUS IN PROKARYOTES •CHROMATIN AND PLASMID
- 5. TYPES OF EUKARYOTICCELLS
- 6. INTRODUCTION Discovered by Robertbrown in 1831 SHAPE OF NUCLEUS • Spherical • Elongated • Irregular • Oval
- 7. EXCEPTIONS • Cells withno nucleus • Plants ( sieve tube cells) • Animals ( red blood cells ) • More than one nucleus • Binucleate / Dikaryotic • At time of cellular division • Paramecium • Multi nucleated • Muscle cells • Endosperm tissue • Opalina
- 8. LOCATION • Plants cells •At side • Exception young cells • Animal cells • In centre • Except muscle cells
- 9. NUCLEAR ENVELOPE Outer membrane Inner membrane Perinuclearspace (10 –15 nm) Nuclear pores
- 10. NUCLEOPLASM Transparent semi groundsubstance • Composition Proteins (histone and non-histone) Enzymes (DNA and RNA polymerase) Nucleotides Metal ions (Mg )
- 11. NUCLEOLUS Composition • 85%protiens • 10%RNA • 5% DNA Function • Formation of ribosomes. Parts of nucleolus • Peripheral granular area (ribosomal sub units) • Central fibril area (rRNA and rDNA)
- 12. CHROMATIN Composition • DNA • RNA •PROTIENS (histone and non-histone) Function To convert loose strands of DNA into denser structures
- 13. CHROMOSOME Function To equally separategenetic material between newly forming cells. Structure • Primary constriction • Secondary constriction • Centromere • Satellite bodies
- 14. STRUCTURE OF CHROMOSOMES • Primaryconstriction o Thinner segments of chromosomes • Secondary constriction o Gives rise to nucleoli o Also called nucleolar organizer. Centromere Kinetochore
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- 16. KARYOTYPE Humans 46 Mucor 02 Pea14 Maize 20 Frog 26 Chimpanzee 48 Fruit fly 8 Ascaris round worm 02 The number of chromosomes in a cell is called karyotype.