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

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

4.1 Introduction to the Cell pp. 69-72 Cell diversity Cells have different sizes and shapes to fit their function Humans have over 200 kinds of cells Humans have a total of about 50 trillion cells (50000000000000) Humans have 500 to 1000 different species of bacteria in the gut There are at least 500 trillion cells in you, that aren’t you Crazy numbers:

4.1 Introduction to the Cell Cell shape: Function determines shape Shape ↔ Function Nerve cells are long like telephone lines

4.1 Introduction to the Cell pp. 69-72 Cell size: Most cells are microscopic (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 Cell size matters: Calculate the surface area to volume ratio of a cube: Area = (length x width) x6 side = 3mm Volume= length x width x height 𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎 𝑣𝑜𝑙𝑢𝑚𝑒 =

4.1 Introduction to the Cell pp. 69-72 Cell size matters: Calculate the surface area to volume ratio of a cube: Area = (length x width) x6 side = 3mm S.A. = 54 mm2 Volume= length x width x height volume = 27 mm3 𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎 𝑣𝑜𝑙𝑢𝑚𝑒 = 54 mm2 27 mm3 = 2 1 𝑚𝑚 S.A.= (3mm x 3mm) x6 S.A. = 54 mm2 V=3mm x 3mm x 3mm V= 27 mm3

4.1 Introduction to the Cell pp. 69-72 OUT : Calculate the surface area to volume ratio of a cube: Area = (length x width) x6 side = 8mm Volume= length x width x height 𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎 𝑣𝑜𝑙𝑢𝑚𝑒 = OUT: SHOW YOUR WORK

10 m 1 m 0.1 m 1 cm 1 mm 100 µm 10 µm 1 µm 100 nm 10 nm 1 nm 0.1 nm Fig. 6-2 10 m Human height 1 m Length of some nerve and muscle cells 0.1 m Unaided eye Chicken egg 1 cm Frog egg 1 mm 100 µm Most plant and animal cells Light microscope 10 µm Nucleus Most bacteria 1 µm Mitochondrion 100 nm Smallest bacteria Electron microscope Viruses Ribosomes 10 nm Proteins Lipids 1 nm Small molecules 0.1 nm Atoms

Surface area increases while total volume remains constant 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] 6 150 750 Total volume [height  width  length  number of boxes] 1 125 125 Surface-to-volume (S-to-V) ratio [surface area ÷ volume] 6 1.2 6