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Download Anton van Leeuenhoek (1674) Robert Brown (1820)
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2/19/2015 OVERVIEW OF THE CELL: ANIMAL CELLS Biology 11 Anton van Leeuenhoek (1674) Described living blood cells, bacteria, and single-celled organisms in a drop of water. Robert Brown (1820) Described the appearance of a tiny sphere in plant cells, which he called the nucleus. Nuclei were soon discovered in animal cells. cells 1 2/19/2015 1838 German scientists Schleiden and Schwaan discovered that plant and animal tissue was composed of cells. 1858 – Rudolph Virchow Theorized that all cells come from pre-existing cells. Review: Cell Theory 1. 2. 3. 3 main ideas: All living things are composed of one or more cells. The cell is the smallest, basic functional unit of all life and retains the properties of life. New cells arise only from cells that already exist. 2 2/19/2015 Two Types of Cells Two Fundamentally Different Cell Architectures: 1) A prokaryotic cell 2) A eukaryotic cell 1. Prokaryotic cells have no nucleus or organelles enclosed within membranes. All species in the domains Archaea and Eubacteria have prokaryotic cells. 2. Eukaryotic cells (main focus) have a nucleus and organelles that are surrounded by membranes. Usually described as being “round” and irregular in shape. shape Each organelle does a specific cell function. All species in the Eukaryota domain (protists, fungi, plants, and animals) have eukaryotic cells. Individual protists have only one cell, while plants and animals can have trillions of cells. 3 2/19/2015 Eukaryotic – Plant and Animal Both plant and animal cells have aspects in common: 1. Cell Membrane – a.k.a. Plasma membrane Forms the outer boundary of the cell. made of proteins and a double lipid bilayer G Gives cellll its shape h selectively permeable 2. Protoplasm – all material inside the cell (includes nucleus). 3. Cytoplasm – the fluid that contains all cellular parts enclosed inside the plasma membrane, excluding the nucleus; cyclosis 70% water, 30% material 4. Nucleus – largest organelle; near center of protoplasm; control center of cell; carries hereditary info; bound by a double membrane. 5. Nucleolus – small, spherical structure found inside the nucleus; may be associated with RNA; involved in making a genetic material called rRNA - possibly directs ribosomes? The nuclear envelope/membrane is a double lipid bilayer that surrounds the nucleolus/contains genetic info and separates cytoplasm from nucleoplasm. Centrioles Small bodies Made of proteins (microtubules). These separate chromosomes during cell division. 4 2/19/2015 Chromatin complex of macromolecules found in cells, consisting of DNA, protein and RNA (chromosomes). Basic Structure: Eukaryotic Cell Animal Cells: Organelles an organelle is a specialized sub-unit within a cell that has a specific function. Only found in Eukaryotic cells Some will call them cell compartments: a component that is closed. The cell, and its organelles, are usually compared to a factory, with the cell acting as the building and each organelle acting as a component. 5 2/19/2015 1. Mitochondria (mitochondrion) Oval-shaped The power plant of the cell. Each provides the cell with stored energy (through cellular respiration); they do not make it. it Made of 2 membranes: a smooth outer and folder outer. The inner contain cristae that are covered with enzymes. 2. Ribosomes Smallest organelle Proteins are synthesized here. Make up the greatest portion of the cytoplasm Helps to make more proteins faster 6 2/19/2015 3. Endoplasmic Reticulum (ER) A network of interconnected canals that carry material throughout the cytoplasm. Composed of parallel membranes Membranes appear either rough (RER) or smooth (SER) The RER gets its name because it has many ribosomes attached to it. SER has no ribosomes and is the area where lipids (fats) are made. 4. Golgi Apparatus (body) Stores, modifies, and packages proteins from the RER. Looks like stack of flattened balloons – actually membranous sacs. Secretes mucous These pinch off at both ends to produce smaller protein-filled sacs called vesicles/vacuoles. 7 2/19/2015 Golgi Apparatus continued… Vesicles move toward plasma membrane and empty contents. Exocytosis Endocytosis Vacuoles Not found in all animals Differ from vesicles in that they contain only water and help in pressure changes (osmoregulation) 8 2/19/2015 5. Lysosomes Only found in animal cells Bound by single membrane Formed by Golgi apparatus. C t i a variety Contain i t off enzymes tto break b k down d large l molecules and cell parts within the cytoplasm. E.g. any food particles E.g. white blood cells/bacteria/pus E.g. old cells Microtubules & Microfilaments Microtubules – tube-like fibres that transport materials throughout the cytoplasm. Microfilaments – pipe-like structures in cytoplasm to help give shape and movement for cells. Eg. muscles 9 2/19/2015 10
