7.1 Introduction to Cells I. The Discovery of Cells A. microscope led to the discovery of the basic units of life B. Robert Hooke 1. English scientist, used crude 30 power microscope on cork cells 2. Hooke saw “little boxes” he called cells. a. later saw cells in roots & stems of plants C. Van Leeuwenhoek 1. Dutch scientist, used microscope that could magnify to 300 times 2. discovered living creatures in pond water.

D. Schleiden (German Botanist,1838) 1. concluded cells make up every part of plants E. Schwann (German Zoologist,1839) 1. concluded that animals are made up of cells F. Virchow (German physician,1858) 1. proposed cells come from existing cells G. Cell Theory 1. All living things are made up of one or more cells 2. Cells are the basic unit of structure and function in organisms 3. All cells arise from existing cells

II. Looking at Cells A. Cells vary greatly in size & shape B. Cell’s shape reflects its function 1. Can be branched, flat, round, or rectangular C. Humans are made up of 100 trillion cells III. Cell Features A. Cell membrane 1. acts as a barrier to outside environment B. Cytosol 1. the fluid inside a cell C. Cytoplasm 1. includes the fluid and structures D. Ribosome 1. makes proteins

IV. Prokaryotes A. No nucleus, only single loop of DNA B. only life on Earth for millions of years V. Eukaryotes A. complex organization 1. carry out specialized functions B. Contains a nucleus with DNA C. Contains organelles 1. structures that carry out specific functions.