Cytology 2nd Lab HELWAN NATIONAL UNIVERSITY PDF

HELWAN NATIONAL UNIVERSITY FACULTY OF SCIENCE BIOTECHNOLOGY & GENETIC ENGINEERING PROGRAM Cytology First year students 2024-2025 Internal cell structure Internal cell structure Structure of cell 2- Nucleus ...

HELWAN NATIONAL UNIVERSITY FACULTY OF SCIENCE BIOTECHNOLOGY & GENETIC ENGINEERING PROGRAM Cytology First year students 2024-2025 Internal cell structure Internal cell structure Structure of cell 2- Nucleus  It is the control center of the cell What is the nucleus ? which acts like the brain of the cell Nucleus is the largest organelle seen Size of nucleus clearly as it stains deeply Nucleus is mostly spherical (round) and Shape of nucleus contains the genetic material (DNA) Cell with one nucleus (uni-nucleated) or Number of nucleus with many nucleus (multinucleated) It controls on all cellular activities, Function of nucleus movement, reproduction  Parts of nucleus Nuclear membrane Chromatin Nucleolus (A) Nuclear membrane It is a double membrane with many pores (nuclear pores) It is as plasma membrane as it is formed from proteins and lipids Ribosomes are attached on the outer membrane of nuclear membrane (rough outer membrane) The pores allow transportation of large molecules (from and to nucleus)  Karyolymph (nucleoplasm) is a jelly like substance rich in proteins contains a chromatin (B) Chromatin It is fibrillar structures or network which found in the karyolymph which condensed to forming chromosomes during cell division  1- Eu-chromatin (less coiled DNA, more On staining of active genetically) chromosomes, there are 2 types of chromatin 2- Hetero-chromatin (more coiled DNA, less active genetically) (C) Nucleolus (nucleoli) Membrane-less and spherical body in all eukaryotic cells (dark area of nucleus) Nucleolus has DNA, RNA and proteins It is considered as a store house for RNA and proteins It regulates the synthetic activity of nucleus Nucleolus contains ribosomal RNA (rRNA) and makes ribosomes  Structure of cell 2- Endoplasmic reticulum (ER), Golgi body and ribosomes  Smooth ER Endoplasmic reticulum (ER) Rough single membrane bound structure ER formed from protein and lipid (as plasma membrane) Golgi apparatus Golgi apparatus (Golgi bodies) Ribosomes single membrane bound structure formed from protein and lipid (as plasma membrane) These three Ribosomes organelles operate This structure do not have membranes together Found on nucleus and on rough ER  Endoplasmic reticulum (ER) It is a network of membranes distributed through cytoplasm in contact with plasma membrane and nuclear membrane, has 2 types Rough endoplasmic reticulum (RER) Smooth endoplasmic reticulum (SER) when ribosomes are attached when no ribosomes are present ER provides as internal framework of the cell ER transports enzymes and other material in the cell RER is the site for protein synthesis Functions SER is the site of steroid synthesis, stores carbohydrates  Golgi apparatus (bodies) It is a group of membranous sacs exhibit great diversity in size and shape It is 3-7 in number and present around the nucleus Functions It is a site of synthesis and secretion of enzymes Sorting, packing, secreting and modification of RER products Participate in transformation of membranes to give other membrane structures as lysosomes  Ribosomes The smallest structures in cytoplasm in all Definition of ribosomes types of cells (from bacteria to plants and animals) They are spherical structure made up of Structure of ribosomes large molecules of rRNA (ribosomal RNA) and proteins Ribosomes as free particles (in cytoplasm) or attached (in RER or outer nuclear Location of ribosomes membrane) Also stored in nucleolus inside the nucleus Ribosomes can be considered as the site of Function of ribosomes protein synthesis