Cell Structure

Cell Structure History of the Cell - Scientist were aware of cells only after the discovery of microscopes “Guys” who contributed to cell theory: •Hooke (1665) – coined term ‘cell’ •Van Leeuwenhoek – viewed first living cells •Schleiden (1838) – plants are composed of cells •Schwann (1839) – animals are composed of cells •Virchow (1858) – cells come from cells Cell theory which states: All living things are composed of one or more cells In organisms, cells are the basic units of structure and function Cells are produced only from existing cells ALL cells share certain structural characteristics: Cell or Plasma membrane Cytoplasm Genetic Material Cell or plasma membrane – •Composed of lipid bilayer and proteins •Separates the cell contents from materials outside the cell •Regulates what enters and leaves the cell, maintaining homeostasis; called selectively permeable Cell Membrane Cytoplasm – gel-like substance that suspends organelles and contains sugars, amino acids, and proteins •Contains Organelles – membranebound internal compartments that carry out specific functions •Contains free-floating ribosomes Site of protein synthesis (where proteins are made) Not considered organelles because they have no membranes surrounding them Ribosomes: the little black dots! Genetic material: •Composed of DNA •Controls reproduction of cell, contains hereditary information, and carries out the day-to-day cellular activities •In eukaryotic cells, DNA surrounded by a double membrane (nuclear membrane) is the Nucleus •Nuclear membrane is passageway for RNA and ribosome subunits •Nucleus contains chromosomes (DNA superwound around histone proteins into highly condensed form) •Nucleolus – where ribosome subunits are made DNA: chromatin Nuclear membrane and pores Plant nucleus Nucleolus The Interior of a Cell: Internal Membranes (double layer of lipids): Endoplasmic reticulum (ER) • Series of channels that weave through the cell transporting substances made by the cell • Isolated spaces of ER forming sacs are called vesicles a Rough ER – ER that contains ribosomes on the outside and carry proteins b Smooth ER – ER with no ribosomes on the outside and carry lipids Rough ER Sorry, no pictures of smooth ER Vesicles Golgi apparatus (bodies) – collect, package, and distribute molecules made in the cell Golgi bodies Powerhouses: Mitochondria • Contains folded membranes called cristae (increases surface area) • Generate energy for the cell through cellular respiration 2 Chloroplast: • Consist of stacks of membranes called grana surrounded by liquid called stroma • Sites of photosynthesis (make food in form of sugar) in plants and algae Chloroplasts Grana Stroma Central Vacuole Biochemical factories - membrane-bound spheres Peroxisomes: • Some contain enzymes that convert fats to carbohydrates • Some alter harmful molecules to harmless molecules Lysosomes • Contain digestive enzymes to breakdown proteins, nucleic acids, lipids, and carbohydrates • Digest and recycle the cell’s used component Lysosome Internal framework A Microtubules - hollow protein fibers that makeup: Cytoskeleton: support shape of cell and anchor organelles Cytoskeleton Flagella – long, whip-like tail used for locomotion Cilia – shorter, more numerous hairs cell Centrioles – associated with microtubules that move chromosomes during cell division  ... of cells •Schwann (1839) – animals are composed of cells •Virchow (1858) – cells come from cells Cell theory which states: All living things are composed of one or more cells In organisms, cells... basic units of structure and function Cells are produced only from existing cells ALL cells share certain structural characteristics: Cell or Plasma membrane Cytoplasm Genetic Material Cell or plasma... Cell - Scientist were aware of cells only after the discovery of microscopes “Guys” who contributed to cell theory: •Hooke (1665) – coined term ? ?cell? ?? •Van Leeuwenhoek – viewed first living cells