Cells were beyond our limit 4 1 Introduction

Cells were beyond our limit 4. 1 Introduction to until the invention of the Cell pp. 69 -72 microscope. What would these • Hooke witnessed dead scientists have plant cells in cork (patterns) noticed? • Leeuwenhoek witnessed live cells (patterns)

Cell Theory 4. 1 Introduction to 1. All living things are the Cell pp. 69 -72 composed of cells (1 or What kind of cells are more) in you? 2. Cells are the basic units of structure and function of organisms 3. Cells come from the reproduction of existing cells: cells make cells

Cell diversity 4. 1 Introduction to • Cells have different sizes the Cell pp. 69 -72 and shapes to fit their function Crazy numbers: – Humans have over 200 kinds of cells – Humans have a total of about 50 trillion cells (50000000) – Humans have 500 to 1000 different species of bacteria in the gut – There at least 500 trillion cells in you, that aren’t you

Cell shape: 4. 1 Introduction to • Function determines shape the Cell • Shape ↔ Function • Nerve cells are long like telephone lines

Cell size: 4. 1 Introduction to • Most cells are microscopic the Cell pp. 69 -72 (10 μm or 0. 01 mm) • Can be larger: • Chicken egg • Nerve cells up to 2 m long • Small size means high surface area to volume ratio so materials can enter fast • Important in physical contact

• 4. 1 Introduction to the Cell pp. 69 -72

• 4. 1 Introduction to the Cell pp. 69 -72 S. A. = (3 mm x 3 mm) x 6 S. A. = 54 mm 2 V=3 mm x 3 mm V= 27 mm 3

• 4. 1 Introduction to the Cell pp. 69 -72 OUT: SHOW YOUR WORK

10 m Human height Length of some nerve and muscle cells 0. 1 m Chicken egg 1 cm 100 µm 10 µm Most plant and animal cells Nucleus Most bacteria 1 µm 100 nm 1 nm 0. 1 nm Mitochondrion Smallest bacteria Viruses Ribosomes Proteins Lipids Small molecules Atoms Electron microscope 1 mm Frog egg Light microscope 1 m Unaided eye Fig. 6 -2

Fig. 6 -8 Surface area increases while total volume remains constant 5 1 1 Total surface area [Sum of the surface areas (height width) of all boxes sides number of boxes] Total volume [height width length number of boxes] Surface-to-volume (S-to-V) ratio [surface area ÷ volume] 6 150 750 1 125 6 1. 2 6