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Transcript
Cell Theory Cell Size Function of Organelles Cell Theory All organisms are composed of one or more cells Cells are the basic living unit of structure and function in organisms All cells come only from other cells Cell Size • Surface Area to Volume Ratio Surface area affects the ability of nutrients to get into the cell and wastes to get out Large cells need more nutrients and produce more wastes than small cells Small cells have more surface area per volume than large cells Eukaryotic Organelles • What defines a eukaryotic cell? Has a nucleus • How do plant cells differ from animal cells? Cell wall Primary cell wall Cellulose = strength Secondary cell wall Lignin = even stronger Chloroplasts Chlorophyll Photosynthesis The Outer Boundaries • Plasma membrane Composition: Phospholipid bilayer with embedded proteins Function: Defines cell boundary Regulates entrance and exit of molecules • Cytoplasm – Semifluid medium that contains organelles – Surrounds the nucleus inside the cell membrane The Nucleus Composition: Nuclear envelope (Double membrane with pores) Nucleoplasm Chromatin (DNA and proteins) Nucleoli (Nucleolus) o Composition: Concentrated area of chromatin, RNA and proteins o Function: Ribosomal subunit formation Function: Storage of genetic information Synthesis of DNA and RNA View Fig 3.4, p. 52 in your textbook Composition: Ribosomes Protein and rRNA Two subunits (large and small) Very small organelles Occur in the cytoplasm: - Singly - Groups (polyribosomes) Attached to the Endoplasmic reticulum Function: Protein synthesis The Endomembrane System Consists of: Nuclear envelope Endoplasmic Reticulum Golgi Apparatus Lysosomes Transport Vesicles The Endoplasmic Reticulum Composition: Membranous, flattened channels, tubular canals Function: Synthesis and/or modification of proteins + other substances Distribution via vesicle formation The Rough ER Composition: studded with ribosomes Function: protein synthesis The Smooth ER Composition: having no ribosomes Function: lipid synthesis and forms vesicles for transport The Golgi Apparatus Composition: Stack of membranous saccules Function: Processing Packaging Secretion Distribution of proteins and lipids Formation of lysosomes Lysosomes Composition: Membranous vesicle produced by Golgi apparatus Contains hydrolytic digestive enzymes Function: Intracellular digestion Macromolecules Bacteria Cell contents Vacuoles Composition: Large membranous sac (vacuoles are larger than vesicles) Both animals and plant have them, but much bigger in plants (in plants: large, central, filled with water, sugar, salt, pigments, toxins support, color and protection) Function: Store substances Peroxisomes Composition: Membranous vesicles Contain specific enzymes Function: Various metabolic tasks Result in the production of hydrogen peroxide molecules Catalase breaks into water and oxygen Energy-Related Organelles ATP CO2 + H2O Useable energy for cells Carbohydrate Mitochondria Cellular Respiration: carbohydrate + oxygen Solar energy + carbon dioxide +water Chloroplast Photosynthesis: Solar energy + carbon dioxide +water carbohydrate + oxygen Chloroplasts (only in plant cells) Composition: Membranous grana bounded by two membranes Stroma (fluid filled space with DNA, ribosomes, enzymes) Thylakoids (flattened sacs) stacked = grana contains chlorophyll Function: Photosynthesis Mitochondria Composition: Double membrane Inner membrane folded= Cristae Increases surface area for ATP production Inner fluid filled space = Matrix Contains DNA, ribosomes, enzymes to break down carbohydrates Function: Cellular Respiration (produce ATP) Composition: Microtubules The Cytoskeleton Help evenly distribute chromosomes during cell division Maintain shape and help organelles move around Intermediate filaments Help support nuclear envelope and plasma membrane Lends mechanical strength Actin filaments Structural role Formation of Pseudopods Movement of cells and organelles (Myosin) Function: Shape of the cell Movement of cell parts Centrioles (only in animal cells) Composition: 9+0 pattern of microtubule triplets Function: Formation of basal bodies organization of cilia + flagella Microtubule formation Composition: Cilia and Flagella 9+2 pattern of microtubule doublets, around 2 central microtubules Membrane bounded cylinders enclosing a matrix Cilia are much shorter than flagella Functions: Movement of the cell Q U E S T I O N S ?