CELLS!!!
Cell Scientists Robert Hooke Anton van Leeuwenhoek Looked at cork under a microscope 1st to use the term “cell” Anton van Leeuwenhoek Looked at pond water 1st to see living cells Schleiden, Schwann, and Virchow Came up with cell theory
Cell Theory All living things are composed of one or more cells Cells are the basic unit of structure and function in all organisms Cells come only from the reproduction of pre-existing cells
Prokaryotes Appeared 3.5 bya Primitive Small in size No membrane-bound organelles Smaller ribosomes Single, circular DNA Ex: bacteria
Eukaryotes Appeared 1.5 bya Complex Contain membrane-bound organelles Larger ribosomes Paired, linear chromosomes NUCLEUS!
Parts of a Eukaryotic Cell
Plasma Membrane Also called the cell membrane Separates cell from its environment
Plasma Membrane Semi-permeable allows only certain molecules to enter or exit
Plasma Membrane Phospholipid bilayer Fluid-mosaic model Embedded with proteins Fluid-mosaic model
Nucleus “Brain” of the cell Controls cellular activities Contains DNA (chromosomes)
Nucleus Nuclear membrane Nucleolus Surrounds nucleus Double membrane Contains nuclear pores (holes) Nucleolus Produces ribosomes Ribosomes leave through nuclear pores
Cytoplasm Cytosol Organelles Fluid portion Membrane-bound compartments that carry out specific functions
Mitochondria Breaks down glucose to CREATE ENERGY (ATP) Have own DNA Active cells (muscle)= hundreds of mitochondria Inactive cells (fat)= few mitochondria Have own DNA Have a double membrane
Ribosomes Create proteins Composed of 2 interlocking subunits Some float free in cytosol Some attach to ER
Endoplasmic Reticulum (ER) Intracellular highway 2 types Rough ER Smooth ER
Rough ER Covered in ribosomes Produces phospholipids and proteins
Smooth ER Lacks ribosomes Produces lipids, estrogen, and testosterone Helps detoxify drugs and poisons Increased use = increased smooth ER Possibly linked to increased tolerance
Endoplasmic Reticulum
Golgi Apparatus Transport (FedEx of the cell) Receive vesicles from ER Can modify packages en route
Vesicles Lysosomes Contain digestive enzymes Digest organic molecules, worn organelles or living cells
Vesicles Peroxisomes Neutralize free radicals (oxygen ions) Detoxify alcohol and drugs Breakdown fatty acids
Cilia/Flagella Cilia Flagella Hair-like Short and numerous Tail-like Long and less numerous
Plant Cell Vs. Animal Cell
Animal Cells Only! Cytoskeleton Network of microtubules & filaments Gives the cell shape Holds organelles in place
Animal Cells Only Centrioles Used during cell division
Plant Cells Only! Cell wall Rigid layer surrounding plasma membrane Made of cellulose Pores allow water, ions, and other molecules to pass Bacteria, some protists and fungi also have cell walls
Plant Cells Only! Chloroplast Contain chlorophyll Site of photosynthesis Energy (sunlight) -> food Contain own DNA Have a double membrane
Plant Cells Only! Central vacuole Large, fluid-filled organelle Stores water, ions, enzymes, and waste Can be up to 90% of cell’s volume Animal cells have small vacuoles