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The Microscope. The Art of Looking at Cells. Artists are often inspired by biology and biology depends on art The paintings of Wassily Kandinsky (1866-1944) show the influence of cellular forms. Illustration is an important way to represent what scientists see through microscopes.
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The Art of Looking at Cells • Artists are often inspired by biology and biology depends on art • The paintings of Wassily Kandinsky (1866-1944) show the influence of cellular forms
Illustration is an important way to represent what scientists see through microscopes • The anatomist Santiago Ramón y Cajal (1852-1934) was trained as an artist • He drew these retina nerve cells
INTRODUCTION TO THE WORLD OF THE CELL • The microscope was invented in the 17th century • Using a microscope, Robert Hooke discovered cells in 1665 • All living things are made of cells (cell theory)
The Cell Theory3 Key Observations • All organisms are made up of one or more cells and the products of these cells. • All cells carry on their own life activities. • New cells can only arise from other living cells by the process of cell division.
4.1 Microscopes provide windows to the world of the cell • The light microscope enables us to see the overall shape and structure of a cell Image seen by viewer Eyepiece Ocularlens Objective lens Specimen Condenser lens Light source Figure 4.1A
Electron microscopes were invented in the 1950s • They use a beam of electrons instead of light • The greater resolving power of electron microscopes • allows greater magnification • reveals cellular details
Scanning electron microscope (SEM) • Scanning electron micrograph of cilia • Give a 3-D appearance to the image Figure 4.1B
Transmission electron microscope (TEM) • Transmission electron micrograph of cilia Figure 4.1C
4.2 Cell sizes vary with their function • Below is a list of the most common units of length biologists use (metric) Table 4.2
Cell size and shape relate to function Figure 4.2
4.3 Natural laws limit cell size • At minimum, a cell must be large enough to house the parts it needs to survive and reproduce • The maximum size of a cell is limited by the amount of surface needed to obtain nutrients from the environment and dispose of wastes
A small cell has a greater ratio of surface area to volume than a large cell of the same shape 30 µm 10 µm Surface areaof one large cube= 5,400 µm2 Total surface areaof 27 small cubes= 16,200 µm2 Figure 4.3