Transcript Document
Cells 1. Theory and Structure 2. Animal Cells 1 Cell Theory 1.All organisms are composed of one or more cells 2.The cell is the basic unit of organization (structure and function) of organisms 3.All cells come from pre-existing cells 2 Exceptions to the Cell Theory • Electron microscope reveals that mitochondria and chloroplasts can reproduce themselves • Not all living things are composed of cytoplasm and a nucleus surrounded by a cell membrane(Examples: skeletal tissue, slime mold) • Virus particles can reproduce 3 4 Cell Organelles • Membrane-bound cell structures that perform one or more functions 5 Cytoplasm • Fluid protoplasm (living matter) that fills the cell and contains the organelles 6 Cytoskeleton • Network of thin, hollow • • • • tubes and fibers Provides support and shape Composed of microtubules (thin, hollow cylinders composed of protein) and microfilaments (thin protein fibers) Microtubules – support Microfilaments – aid in cell movement 7 Nucleus • EUKARYOTES • Control center • Contains genetic material (DNA) • Pores in the nuclear membrane permit passage of certain chemicals into cytoplasm • Contains chromosomes (contain code that guides all cell activities) • Chromatin threads (DNA tangles) form the chromosomes 8 Nucleolus • Found in nucleus • Produces ribosomes 9 Plasma Membrane • Boundary between cell and external environment that • • • • controls movement of what goes into and out of the cell ( Oxygen and nutrients in; waste products and excess water out) Functions to identify the cell Functions in communication between cells “Selectively permeable” (semi permeable) Lipid bilayer in which large protein molecules float (Cholesterol is a component) 10 Pinocytic Vesicles • Sac-like enfolding of the plasma membrane • Small particles that cannot pass through the plasma membrane may be taken into the cell • Pinocytosis- “to drink” • Phagocytosis- “to eat” ( a protective mechanism) 11 Endoplasmic Reticulum • Assembly and transport of • • • • proteins Folded membrane with a network of interconnected departments Connects nuclear membrane with plasma membrane Rough ER – attached ribosomes Smooth ER – no ribosomes, makes new membranes for the cell 12 Ribosomes • “Protein factories” (Site of protein synthesis) • Has a subunit made of RNA • Free in cytoplasm or attached to endoplasmic reticulum 13 Golgi Apparatus • Closely stacked flattened sacs • Synthesizes, packages, and secretes cell products • “Carbohydrate producing and packaging factory” (Makes mucus) • Produces lysosomes • Packages and ships proteins made by the cell either out of the cell or to another part of the cell 14 Lysosomes • Round organelles that contain digestive enzymes • Digests excess or worn-out cell parts, food particles, invading viruses/bacteria • “Suicide-sacs” – sometimes digest cells that contain lysosomes 15 Mitochondria • Outer membrane and an inner membrane • • • • with long, narrow folds called cristae “Powerhouse of the cell” “Survival of the cell” Respiration: food molecules are broken down to release energy Mitochondria-energy-ATP 16 Cilia and Flagella • Movement • Cilia- short hair-like projection of plasma membrane that have beating motion (found in lining of wind pipe) • Flagella- long, whip-like projections that lash back and forth ( found in sperm cells ) 17 Chromatin and Chromosomes • Chromatin granules in the nucleus are thread-like structures made of DNA • Chromosomes are tightly coiled DNA molecules (This happens during cell division.) 18 Centrioles/Centrosomes • Most animal cells have centrioles, cylinders containing tiny tubules, that appear to play an important role in mitosis (cell division for growth and repair) • Centrosomes also play a role in cell division 19