Transcript Cells
Cells Discovery of the Cell We could not have discovered the cell without the invention of the microscope in the 17th century Robert Hooke (1635-1703) 1. Used a microscope to examine cork, trees carrots, and ferns. 2. He saw little boxes that he compared to the rooms that monks live in: cells. Anton van Leeuwenhoek was the first person to observe live cells. The Cell Theory: All living things are composed of one or more cells Cells are the basic unit of structure and function of all living organisms Cells come from other cells Cell Diversity Size A nerve cell can extend all the ways down a giraffe’s leg. Most cells are not visible without a microscope Shape • • cells have a variety of shapes Nerve cells have long extensions, skin cells are flat, and white blood cells can change their shape Internal Organization – Eukaryotic cells contain organelles that can be compared to our organs. – All cells have a cell membrane and genetic information called DNA (called chromosomes when compacted) Prokaryotic vs. Eukaryotic – Prokaryotic cells: have a membrane and DNA only. THEY HAVE NO nucleus or organelles. EXAMPLE: Bacteria – Eukaryotic cells: have a membrane, DNA, and organelles. EXAMPLE: plant, animal, fungi, and protist cells Parts of all cells Cell membrane: surrounds and protects the cell and selectively allows nutrients in and waste out (present in prokaryotes and eukaryotes) Chromosomes Compact DNA present in prokaryotes and eukaryotes Organelles Found in Eukaryotic Cells only! Nucleus Stores hereditary information called DNA. Synthesizes (makes) RNA and ribosomes. Mitochondria Transfers energy from organic compounds to ATP (energy) Muscle cell Tumor cell Ribosomes Organizes the synthesis of proteins found in cytoplasm and on Rough ER Endoplasmic Reticulum prepares proteins for export Rough-packages proteins Smooth-makes steroids Golgi Apparatus Processes and packages substances made by cell. Lysosome digests waste (old molecules, organelles, and foreign substance) Cilia short hair-like structures on the outside of the cell present in large numbers that assist in movement. Example: in respiratory system to keep out foreign particles Flagella long hair-like structures that whip back and forth to propel the cell forward. Example: sperm cell PLANT CELLS ONLY Cell Wall supports and protects (plant cells only) Chloroplast use energy from the sun and convert it into energy. (plant cells only)