1 ALL LIFE PROCESSES ARE CARRIED OUT BY CELLS WHETHER THE ORGANISM HAS ONLY ONE CELL OR MANY CELLS. UNIT 2 PART 1: THE CELL

2 THE CELL THEORY All organisms are made of one or more cells and the products of those cells. All cells carry on life activities. New cells only come from other living cells by the process of cell division.

3 Organization Organisms can have only one cell (unicellular) or many cells (multicellular). In multicellular organisms the cells are specialized and can not live on their own. Each cell carries out only some of the necessary life functions and depends on all the other types of cells. This requires organization and energy. ORGANIZATION

4 Biosphere Ecosystem Community Population Organism Organ systems Organs Tissues Cells Molecules Atoms Levels of Organization

5 Parts of a Cell: CELL (PLASMA) MEMBRANE NUCLEAR MEMBRANE NUCLEUS NUCLEOLUS CYTOPLASM ENDOPLASMIC RETICULUM RIBOSOME GOLGI BODY VACUOLE MITOCHONDRIA MICROTUBULES MICROFILAMENTS CILIA AND FLAGELLA THESE ARE ONLY IN ANIMAL CELLS: - LYSOSOME -CENTRIOLES THESE ARE ONLY IN PLANT CELLS AND SOME BACTERIA: -PLASTIDS (CHLOROPLAST) -CELL WALL

6 Plasma (cell) Membrane The plasma membrane separates the cell from its environment. It regulates movement of materials in and out of the cell. Maintains homeostasis Homeostasis – maintaining a constant internal environment.

7 A fluid-mosaic of phospholipids and proteins. Phospholipids form a thin, double layer that is a barrier to many other molecules. Proteins float within the lipid bilayer & perform a variety of jobs: a.Transport channels b.Enzymes c.Receptors d.Identity markers e.Adhesives f.Cytoskeleton Cell Membrane Structure

8 Diffusion The movement of molecules from a region of high concentration to a region of low. The difference between the high and low concentrations is called the concentration gradient. Diffusion is a type of passive transport: it does not cost the cell any energy. –Ex: perfume Some molecules get help across: facilitated diffusion

9 Osmosis Osmosis is the diffusion of water across a membrane

10 Active Transport Active transport uses energy (ATP) to move molecules against the concentration gradient from low to high

11 Nucleus & Nucleolus The nucleus is surrounded by a nuclear membrane. The nucleus controls all activities of the cell. The nucleus contains chromosomes that are made of DNA. The nucleolus makes RNA and ribosomes needed for protein synthesis.

12 Nuclear Membrane The nucleus is encased by a double membrane. The nuclear membrane is full of pores that let RNA and ribosomes pass through it. The membrane forms the ER, lysosomes & golgi body.

13 Cytoplasm The jellylike stuff inside the cell It acts as a solvent Many biochemical reactions take place here

14 Endoplasmic Reticulum Membrane bound, fluid-filled canals that form a continuous network with one extremely large enclosed space Manufactures, processes, and transports molecules used in and out of the cell Rough ER has ribosomes on it Smooth ER has no ribosomes

15 Ribosomes Site of protein synthesis Made of RNA from nucleolus May be on Rough ER or free in cytoplasm Not surrounded by a membrane

16 Golgi Bodies Form from bubbles off of the ER (like a lava lamp) Bubbles join into flattened sacs, making a ‘stack of sacs’ Synthesize, package & secrete cellular products for use in the cell or export

17 Lysosomes Formed from the Golgi body, this membrane bound sack contains digestive enzymes, like a stomach. Food Vacuole

18 Vacuole Membrane bound space that contains –Food –Water –Waste Contractile vacuole pumps water out of the cell V V CV

19 Mitochondria Site of aerobic cellular respiration –Provides energy for the cell to use –Converts energy stored in food to ATP Double membrane bound organelle –Outer smooth –Inner folded Bacteria-like structure

20 MICROTUBULES AND MICROFILAMENTS MICROTUBULES –Long, hollow cylindrical structures –Cell skeleton –Found in centrioles, cilia, flagella MICROFILAMENTS –Threadlike strands –Cytoplasmic streaming

21 Centrioles Two found in animal cell cytoplasm near the nucleus Function in cell division Make spindle fibers Cylinder of 9 triplets of microtubules

22 Cilia & Flagella Used in locomotion & feeding –Flagella: 1 long whip –Cilia: Many small hairs Similar in structure to centrioles

23 Chloroplast Site of photosynthesis –Captures light energy –Makes food (sugar) Double membrane bound organelle similar to mitochondria –Inner membranes are arranged into stacks called grana –Grana contain Chlorophyll Bacteria-like structure

24 CELL WALL FOUND ONLY IN PLANTS AND BACTERIA FOR SUPPORT AND PROTECTION