Cells and Organelles PDF

Cells and organelles by Siu Wai (Phyllis) TSANG, PhD TUNG WAH COLLEGE email: [email protected] Office#: 3190-6713 Prepared by SWT 2023 email: [email protected] 1 Organelles Prepared by SWT 2024 email: [email protected] 2 Overview of org...

Cells and organelles by Siu Wai (Phyllis) TSANG, PhD TUNG WAH COLLEGE email: [email protected] Office#: 3190-6713 Prepared by SWT 2023 email: [email protected] 1 Organelles Prepared by SWT 2024 email: [email protected] 2 Overview of organelles 細胞器 Organelles are the “tiny organs” of the cell Organelles serve specific functions to keep a cell alive Some organelles are membrane-bound while some are not Single membrane-bound: vacuole, lysosome, Golgi apparatus, endoplasmic reticulum (present in eukaryotic cells only) Double membrane-bound: nucleus, mitochondria and chloroplast (present in eukaryotic cells only) Organelles without membrane: cell wall, ribosomes, cytoskeleton (present in both prokaryotic and eukaryotic cells) The presence of organelles is one of the distinctive features of a eukaryotic cell Prepared by SWT 2024 email: [email protected] 3  Organelles – nucleus  Nucleus 細胞核  present in eukaryotic cells only  surrounded by a double membrane called nuclear envelope  contains the majority of the cell’s DNA  DNA in the form of chromosomes  “headquarters” / “brain” of the cell  controls the activities of the cell  controls inheritance and metabolism  normally one nucleus per cell https://tmrwedition.files.wordpress.com/2017/04/cells-in-the-human-body-5.jpg (>1 in skeletal muscle cells) Prepared by SWT 2024 email: [email protected] 4  Organelles – nucleolus  Nucleolus 核仁  pl. nucleoli  a spherical structure present in the nucleus of a eukaryotic cell  produces and assembles the cell’s ribosomes content/uploads/2018/09/Cell-OrganellesNUCLEUS.png https://cdn1.byjus.com/wp- https://tmrwedition.files.wordpress.com/2017/04/cells-in-the-human-body-5.jpg Prepared by SWT 2024 email: [email protected] 5  Organelles – plasma membrane  Plasma membrane 質膜 / 細胞膜  present in both prokaryotic and eukaryotic cells  the barrier between the inside of the cell and the outer environment  predominantly made of phospholipids  selectively permeable  allows the entry of selective materials in and out of the cell according to the requirement  contains a range of receptors (protein molecules) and transport proteins, which carry https://tmrwedition.files.wordpress.com/2017/04/cells-in-the-human-body-5.jpg out a number of cellular tasks Prepared by SWT 2024 email: [email protected] 6 Prepared by SWT 2024 email: [email protected] 7  Organelles – cytoplasm  Cytoplasm 細胞質  everything found inside the plasma membrane (in prokaryotic cells) or the interior of the cell that surrounds the nucleus (in eukaryotic cells)  content: ~80% water, with organic and inorganic compounds  other organelles of the cell are embedded  a place for many important chemical reactions https://tmrwedition.files.wordpress.com/2017/04/cells-in-the-human-body-5.jpg Prepared by SWT 2024 email: [email protected] 8  Organelles – endoplasmic reticulum (ER)  Endoplasmic reticulum (ER) 內質網  elongated sacs, membranous canals filled with fluid  transportation system of the cell  Rough ER – involved in production, folding, quality control and dispatch of proteins  Smooth ER – associated with the production of lipids and steroids, and responsible for detoxifying the cell https://tmrwedition.files.wordpress.com/2017/04/cells-in-the-human-body-5.jpg Prepared by SWT 2024 email: [email protected] 9 Smooth ER – associated Rough ER – involved in production, folding, with the production of lipids quality control and dispatch of proteins and steroids, and responsible for detoxifying the cell Prepared by SWT 2024 email: [email protected] 10  Organelles – mitochondria  Mitochondrion 線粒體  pl. mitochondria  number of mitochondria per cell varies widely  contains a set of DNA different from nucleus  “powerhouse” of the cell  site of cellular respiration  turns energy from the food  produces ATP  tissues with high demand for ATP have many mitochondria  Play a role in calcium storage and cell death https://tmrwedition.files.wordpress.com/2017/04/cells-in-the-human-body-5.jpg (apoptosis) Prepared by SWT 2024 email: [email protected] 11 Prepared by SWT 2024 email: [email protected] 12  Organelles – Golgi apparatus  Golgi apparatus 高爾基體  “post office” of the cell  plays a role in processing & packaging secretory proteins, and synthesizing complex polysaccharides  once processed by the Golgi complex, materials to be exported from the cell are packaged into secretory vesicles  plays a role in modification of macromolecules through glycosylation and phosphorylation https://tmrwedition.files.wordpress.com/2017/04/cells-in-the-human-body-5.jpg Prepared by SWT 2024 email: [email protected] 13 Prepared by SWT 2024 email: [email protected] 14  Organelles – ribosomes  Ribosomes 核醣體  “factories” where proteins are synthesized based on mRNA  some float freely in the cytoplasm; others are attached to the ER  consists of two subunits that are different in size, shape and composition  large subunit in human cells: 60s  small subunit in human cells: 40s https://tmrwedition.files.wordpress.com/2017/04/cells-in-the-human-body-5.jpg Prepared by SWT 2024 email: [email protected] 15 Prepared by SWT 2024 email: [email protected] 16  Organelles – lysosomes  Lysosomes 溶酶體  storage containers for enzymes that digest specific biological molecules  help in the digestion and removes wastes  digest dead and damaged cells https://tmrwedition.files.wordpress.com/2017/04/cells-in-the-human-body-5.jpg Prepared by SWT 2024 email: [email protected] 17  Prepared by SWT 2024 email: [email protected] 18  Organelles – centrioles & vacuoles  Centrioles 中心粒  found in all animal cells and some plant cells  cylindrical cell structures that are composed of groupings of microtubules 微管  organize the assembly of microtubules during cell division  Vacuoles 液泡  remove and store wastes or harmful foreign products  store water and nutrients such as lipids, https://tmrwedition.files.wordpress.com/2017/04/cells-in-the-human-body-5.jpg proteins and carbohydrates Prepared by SWT 2024 email: [email protected] 19  Organelles – microvilli  Microvillus 微絨毛  pl. microvilli  tiny finger-like protrusions, formed as cell extensions from the plasma membrane surface  the primary surface of nutrient absorption; increase the surface area of the region https://tmrwedition.files.wordpress.com/2017/04/cells-in-the-human-body-5.jpg Prepared by SWT 2024 email: [email protected] 20  Organelles – cell wall  Cell wall 細胞壁  lies outside the cell membrane  found in plant cells, some bacterial cells, some fungal cells…  provides mechanical strength and structural support  provides a physical barrier (i.e., protection) and withstands turgor pressure  controls the direction of cell growth and regulates cell cycle Prepared by SWT 2024 email: [email protected] 21 Organelles – chloroplasts  Chloroplasts 葉綠體  found in plant cells, some bacterial / fungal / algal cells…  site of photosynthesis in plants and algae (depend directly on solar energy)  produce chlorophyll  can be quite numerous in the cells of green plants Prepared by SWT 2024 email: [email protected] 22 Prepared by SWT 2024 email: [email protected] 23 Organelles – large vacuole  Large Vacuole 液泡  a storage area for the cell  holds food and water for later use  holds waster for removal  maintains the turgor pressure that keeps the plant from wilting Prepared by SWT 2024 email: [email protected] 24 Prepared by SWT 2024 email: [email protected] 25 Organelles of locomotion  Flagellum (pl. flagella)  Cilium (pl. cilia)  hairlike structure  locate outside the cytoplasm  aid the cell in locomotion  Flagella and cilia can be found in eukaryotic cells  Prokaryotes have flagella, but no cilia Prepared by SWT 2024 email: [email protected] 26  Cell differentiation 細胞分化  Cells are membrane-bound groups of organelles that work together to allow it to function  When cells express specific genes that characterize a certain type of cell, we say that a cell has become differentiated  Once a cell becomes differentiated it only expresses the genes that produce the proteins characteristic for that type of cell  Differentiated cells are important in a multicellular organism because they are able to perform a specialized function in the body Prepared by SWT 2024 email: [email protected] 27  Stem cells  Multicellular organisms must therefore retain some unspecialized cells that can replenish cells when needed  Cells that are in the undifferentiated state are known as stem cells 幹細胞  The stems cells are described as totipotent 全能 differentiation-Attaincom-Global-Ventures.jpg https://atgventure.com/wp-content/uploads/2018/12/Cell- Prepared by SWT 2024 email: [email protected] 28  Basics of Cells https://kahoot.it/solo/?quizId=0e577749-3510-47c7-83e4- Kahoot! Game f01b805c3925 Prepared by SWT 2024 email: [email protected] 29