CELLS AND CELL THEORY
CELL SCIENTISTS Robert Hooke-1665, observed small cavities in cork which he called cells.
Anton van Leeuwenhoek- late 1600’s, refined the microscope; saw single-celled organisms which he called “animalcules”
Rene Dutrochet-1824, discovered osmosis; concluded that plants and animals are both made of cells.
Robert Brown-1831, First to see and name the nucleus
Felix Dujardin-1835, first to notice cytoplasm
Matthias Schleiden-1839, wrote a paper stating all plants are made of cells
Theodor Schwann-1839, wrote a paper stating all animals are made of cells.
Rudolf Virchow-1855, first to see cell division
CELL THEORY: All living things are made of cells Cells are structurally and functionally similar Cells come from other cells
WHAT IS A CELL? The smallest unit that can perform all life processes.
What is an Organelle? one of several specialized structures, suspended in the cytoplasm of a eukaryotic cell. eukaryoticcell
Prokaryotic Cells: 1. No nucleus 2. No membrane-bound organelles 3. Very small 4. DNA in one loop 5. Only bacteria
Eukaryotic Cells: 1. DNA in long strands (chromatin) in nucleus 2. Large in comparison to bacteria (prokaryotes) 3. Many membrane-bound organelles 4. All other organisms, except bacteria
EUKARYOTIC CELL STRUCTURE: CELL MEMBRANE- Encloses all parts of the cell; Controls what goes in and out
Cell Membrane Structure: Phospholipid bilayer Embedded with proteins: (Marker, Channel, Receptor) Glycolipids Glycoproteins Fluid Mosaic Model
Cell Wall: Found in plants Made of cellulose Surrounds cell membrane Provides rigidity for plant
CELL WALL
Cytoplasm: Jelly-like substance in a cell Surrounds other cell parts Composed of water, salt, & other organic molecules
cytoplasm
Nucleus: Directs & stores instructions for cell functions Encloses DNA (chromatin)
Nuclear Membrane Double membrane that isolates the interior of the nucleus from the cytoplasm Has pores to allow things to be transported into and out of the nucleus. 4 phospholipid layers
Nucleolus: Inside of nucleus Assembles ribosomes May be 1 or more than 1 nucleolus
Chromatin: Long strands of a DNA- protein complex found in nucleus chromatin
Nucleoplasm: A viscous fluid in the nucleus in which the chromatin & nucleolus are suspended.
Ribosomes: Protein factories of cell Line up amino acids in correct order ribosomes
Mitochondria: “Powerhouses” of cell Make ATP Complete breaking down of glucose molecules
Golgi Apparatus: Packages & distributes organic molecules that leave the cell Surround molecules with membrane
Lysosomes: Bags of enzymes that: Digest macromolecules Digest worn out cell parts Destroy invading bacteria
Endoplasmic Reticulum (ER): Membrane system of folded sacs & tunnels Helps maintain homeostasis
Endoplasmic Reticulum (ER): Rough ER has ribosomes & transports proteins Smooth ER has no ribosomes & transports lipid & carbs. Attached to nucleus
Centrioles & Centrosomes: Organizing centers for cell division Found only in animal cells centrosome centrioles
PLASTIDS: A class of organelles found only in plants and in some protists.
Chloroplasts: Site where glucose is made Contain chlorophyll
Leucoplasts: Change glucose to starch Look like grains of rice Starch is stored here leucoplast
Manufacture & store plant pigments Red, orange, purple, yellow Found in fruit, flowers & colorful leaves
Vacuoles: Fluid filled sacs Store enzymes, water, and waste products Large, central vacuole in plants Many small vacuoles in other cells (or none at all)
CYTOSKELETON: Helps cell hold its shape Made of microtubules and microfilaments Animal cell rely on this for maintaining cell structure
Microtubules: Hollow rods of protein Some extend from the cytoplasm to make up cilia and flagella
Microfilaments: Threadlike fibers found below the cell membrane Produce flowing motion in cytoplasm Help circulate organelles; improve cell efficiency
Comparison of Plant Cells to Animal Cells: PLANTANIMAL Cell WallNo Cell Wall PlastidsNo Plastids Large VacuoleSmall vacuoles or none Rely on cell wallRely on for structure cytoskeleton No centriolesCentrioles