Life is Cellular Section 7.1

Objectives Understand Cell theory Distinguish between prokaryotes and eukaryotes Understand different types of microscopy, and how they work in more detail

What is a Cell The smallest part of a living organism that can be considered alive Pre 1500s nobody cared about cells – if you couldn’t see it it didn’t matter! In 1665, in Britain cork was analyzed under a microscope, first cells discovered Bacteria first identified in Holland around the same time Anton Van Leeuwenhoek

1838, decided that all plants are made of cells After Van Leeuwenhoek’s discovery, it became clear that cells are the basic units of life 1838, decided that all plants are made of cells Mattias Schleiden 1839 – all animals made of cells as well Theodor Schwann 1855 – Shown that cells can reproduce Rudolf Virchow

Cell Theory All living things are made of cells Cells are the basic units of structure and function in living things New cells are produced from existing cells

Staining microscope slide Many living cells are transparent Stains allow us to see a number of features Can use stains that only pick out specific structures

Electron microscopes Two types – scanning and transmission

Prokaryotes vs Eukaryotes No Nucleus Nucleus – separates genetic material from the rest of the cell Small and simple Often contain dozens of structures and internal membranes Although simple, fulfil al criteria to be alive Large amount of variety Example - Bacteria Protists live as unicellular organisms Can form multicellular organisms – plants, animals and fungi Both come in a range of shapes and sizes Eurkaryotes tend to be more complex