NUCLEUS- STRUCTURE & FUNCTION

1. NUCLEUS- STRUCTURE & FUNCTION Dr. R. Haritha Lecturer in Biotechnology Visakha Government Degree College for Women Visakhapatnam

2. Contents • Definition of Nucleus • Primary Functions • Structure of Nucleus • What have we learnt?

3. Nucleus The nucleus is a membrane bound structure that contains the cell's hereditary information and controls the cell's growth and reproduction.

4. Discovered by an English biologist Robert Brown in 1831. • Important part of the cell. • Spherical or oval structure. • Located in the Centre of the cell.

5. Primary Functions • Repository of genetic information • Enables synthesis of nearly all proteins • Houses the nucleolus • Responsible for production of ribosomes. • Selective transportation of regulatory factors and energy.

6. Composition of Nucleus

7. Structure of the nucleus Average diameter of nucleus is 6 um, which occupies around 10% of cell volume. • Nuclear Envelope • Nuclear Membrane • Nucleolus • Nucleoplasm • Chromosomes

8. Nuclear envelope • Double-layered membrane enclosing the nucleus of a eukaryotic cell. • Also called nuclear  membrane.

9. Nuclear Membrane • Nucleolemma or karyotheca • Phospho lipid bilayer membrane  •  Consists of two lipid bilayers— • 1. the inner nuclear membrane • 2. the outer nuclear membrane.

10. Nuclear Pore • composed of multiple proteins • allows the passage of molecules from inappropriate entering or exiting the nucleus.

11. NUCLEAR LAMINA • structural support for the nuclear envelope • anchoring sites for chromosomes and nuclear pores.

12. Progeria Defective Lamina protein makes the nucleus unstable. That nuclear instability appears to lead to the process of premature aging in Progeria.

13. Nucleolus • 25% of the volume of the nucleus. • Proteins and ribonucleic acids (RNA). • Site of transcription • Assembly of ribosomes

14. Nucleoplasm • Also known as karyoplasm. • Made up mostly of water, a mixture of various molecules, and dissolved ions. • Act as a suspension for organelles • Maintains the shape of the nucleus.

15. Chromatin • Long thin stands of DNA. • Contains instructions that control cell metabolism and heredity.

17. Which of the following parts of nucleus is responsible for the assembly of ribosomes? A • Nuclear • Pore C • chromosomes • Nucleolus D • Chromosomes B • Nuclear membrane

18. The genetic material complexes with proteins and is organized into linear structures called: A • nucleolus C • chromosomes • chromosomes D • plasmids B • histones

19. Provide structural support for the nuclear envelope and anchoring sites for chromosomes and nuclear pores. A • Nucleoplasm C • Nuclear Lamina • Nuclear Lamina B • Nucleolus D • Nuclear Membrane

20. The space between the two nuclear membranes is called: perinuclear space C A perinuclear space • nuclear space • internuclear space B D none of these

21. It prevents larger molecules, such as nucleic acids and larger proteins, from inappropriately entering or exiting the nucleus. C A nuleolus • nuclear lamina • nuclear envelope nuclear pores B D nuclear pores