Histology Lecture 2: Cell Structure PDF

Histology Lecture no.2 : Cell structure  What is a Cell? Cell is the basic unit of life on earth. For ease of study, we divide the cell into Three main parts: 1. Cell membrane 2. Cytoplasm (Cytosol –Organelles- Inclusions - Cytoskeleton) 3. Nucleus  1-Cell membrane  is the o...

Histology Lecture no.2 : Cell structure  What is a Cell? Cell is the basic unit of life on earth. For ease of study, we divide the cell into Three main parts: 1. Cell membrane 2. Cytoplasm (Cytosol –Organelles- Inclusions - Cytoskeleton) 3. Nucleus  1-Cell membrane  is the outer coating of the cell (fluid lipid bilayer)  Which regulates the movement of substances in and out of the cell (allows substances to enter and leave the cell). Very thin 75-100 A° Elastic Dynamic Semipermeable Phospholipids  2- Nucleus It consists of  Nuclear envelope contains pores  Nucleoplasm  Nucleolus The nucleus contains the DNA Protects the genetic information Directs synthesis of ribosomes and expression of genes Location of transcription and DNA replication  3- Cytoplasm A. Cytosol: the fluid portion of cytoplasm. Jelly like Contains: (water, dissolved solutes, minerals and suspended particles). B. organelles (little organs). Each type of organelle has a specific shape and functions. Examples include: ( ribosomes , endoplasmic reticulum , Golgi complex , lysosomes and mitochondria ) C. Inclusions Intracellular non-living substances(stores nutrients ,secretory products and pigment granules) D. Cytoskeleton Complex dynamic of interlinking protein filaments oMicrotubules oIntermediate filaments oMicrofilaments  organelles Membranous Nonmembranous  Mitochondria the powerhouses of the cell Definition: a membranous organelle that breaks down nutrients to yield energy and produces a high-energy compound called ATP L.M: Can be seen only by using special stain E.M: Each mitochondria has two membranes: Outer membrane Inner membrane:provides the physical sites of energy production. Mitochondria Mitochondria Endoplasmic Reticulum (ER) Contains a network of tubules and vesicles. Acts as production unit And transport unit There are 2 types of endoplasmic reticulum Rough (granular) Protein production Smooth lipid production  The Golgi apparatus : Composed of membranous sacs: Flat vesicles Small vesicles (transport) Large vesicles (secretion) Membrane infolds called cisternae Has 2 faces Cis – receiving Trans – shipping Modify the cellular products and tag them for delivery By adding : phosphate , sulphate or carbohydrates Golgi Apparatus Ribosomes Each cell contains thousands Fabricate the proteins floating throughout the cell  Lysosomes (suicidal bag) Consist of vesicles It varies in size and function depending on the type of cell. Lysosomes contain enzymes that help with the digestion of nutrients in the cell and break down any cellular debris or invading microorganisms like bacteria.  Centrosome Is an organelle consisting of 2 centrioles. Make up of microtubules , cenexin ,tektin. Anchor spindle microtubules in order to form the spindle apparatus during the cell division  Cytoskeleton The cytoskeleton supports the cell, gives it shape has roles in molecule transport, cell division and cell signaling.  Cytoskeleton Three different types  Microfilaments Intermediate filaments Microtubules  Microfilaments are the narrowest protein fibers in the cytoskeleton. They function in cellular movement, have a diameter of about 7 nm, and are made of two strands of a globular protein called actin Microfilaments also provide some rigidity and shape to the cell. Intermediate filaments Intermediate filaments are made of several strands of fibrous proteins These filaments are maintaining the shape of the cell, and anchor the nucleus and other organelles in place.  Microtubules The largest structure in the cytoskeleton at about 25 nm thick. are hollow cylinders made up of repeating protein structures (dimers of alpha and beta tubulin) Function of Microtubules Cell Movement: cilia and flagella Cell Division: forming the mitotic spindle (the spindle apparatus) Cell Transport: help move organelles inside the cytoplasm. They also help various areas of the cell communicate with each other. Cilia and Flagella Flagella (1 = flagellum) are long, hair-like structures that extend from the plasma membrane and are used to move an entire cell. Cilia (1 = cilium) are short, hair-like structures that are used to move entire cells or substances along the outer surface of the cell 1. ___________ is a jellylike substance found floating inside the plasma membrane. (a) Cell sap (b) Cytoplasm (c) Karyoplasm (d) Mitochondria 2. Which of the following cell organelles is called the powerhouse of the cell? (a) Nucleus (b) Lysosomes (c) Chloroplast (d) Mitochondria 3. Which of the following cell organelles regulates the entry and exit of molecules to and from the cell? (a) Lysosomes (b) Golgi bodies (c) Cell membrane (d) Mitochondria 4. Which of the following cell organelles is called a suicidal bag? (a) Lysosomes (b) Golgi bodies (c) Cell membrane (d) Mitochondria 5. Which of the following cell organelles is involved in the storage of food, and other nutrients, required for a cell to survive? (a) Vacuoles (b) Lysosome (c) Mitochondria (d) Cell membrane 6. Which of the following statements is true about the Golgi bodies? (a) It is a sac-like organelle (b) It is located near the nucleus (c) It helps in the cellular transport (d) All of the above 7. The inside of the cell contains a jelly-like substance known as: A. Ribosome B. Nucleoplasm C. Cytoplasm D. None of the above 8. Which of the following cell organelle is responsible for transporting, modifying, and packaging proteins and lipids? a) RNA b) cell membrane c) Golgi Complex d) DNA 9. DNA is stored in which of the following cell organelle? a) Cell wall b) Cell Membrane c) Nucleus d) Cytoplasm 10. RNA is present in which of the following cell organelles? a) Cell wall b) Ribosome c) Nucleus d) Cytoplasm 11. Golgi bodies help in (a) Excretion of steroids (b)packaging products into vesicles for transport (c) Translation (d) Transcriptions 12. Golgi bodies are concerned with synthesis of (a) Photosynthetic pigments (b) Hydrolytic enzymes (c) Cell plate (d) All above 13. Which of the following organelles contain enzymes that have digestive action?: (a) Lysosomes (b) Ribosomes (c) Plastides (d) Polysomes 14. Infoldings of inner mitochondrial membrane are called: (a) Girana (b) Oxysomes (c) Cristae (d)microtubules 15. The cell organelle containing the flattened membrane bounded cisternae located near the nucleus are: (a) cytoplasm (b) Golgi (c) Centrioles (d)cytosol 16. Mitochondria are the store houses of : (a) ATP (b) Glycogen (c) Sucrose (d) None of the above 17. The cytoskeleton is a structure that provides A. mechanical support B. Division C. Movement D. All of the above 18. Name the scientist who discovered Golgi apparatus? a) Robert Remake b) Rudolf Virchow c) Camillo Golgi d) Theodor Schwann 19. The chemical products of the cell are shipped and distributed by_______ a) ER lumen b) Golgi apparatus c) Lysosome d) Endosome 20. SER produces a) Nucleic acid b) Carbohydrate c) Protein d) Lipid  Mitochondria The powerhouses of the cell that break down nutrients to yield energy. It also produces a high- energy compound called ATP Mitochondria are composed of two membranous layers: an inner membrane that provides the physical sites of energy production. The inner membrane has many folds where enzymes attach and oxidize nutrients. Endoplasmic Reticulum (ER)