Cell Theory
Discovery of the Cell Robert Hooke (1635-1703) – invented the term cell; studied dead plant cells such as cork. Anton van Leeuwenhoek (1632-1723) - 1st to observe living cells.
Invented the microscope van Leevheohoek Invented the microscope
Came up with the name “cells” Robert Hooke Came up with the name “cells”
Discovery of the Cell Matthias Schleidan (1804-1881) – concluded that all plants are composed of cells. Theodor Schwann (1810-1882) - concluded all animals were composed of cells. Rudolf Virchow (1821 – 1902) - reasoned that cell come only from other cells.
“All plants are made up of cells” Schleiden “All plants are made up of cells”
All animals are made up of cells Schwann All animals are made up of cells
All cells come from pre-existing cells Virchow All cells come from pre-existing cells
1) All living things are made of cells CELL THEORY 1) All living things are made of cells
CELL THEORY 2) Cells are the basic unit of structure and function for all living things
3) Cells come from pre-existing cells CELL THEORY 3) Cells come from pre-existing cells
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 Ocular lens Objective lens Specimen Condenser lens Red blood cells teaching.path.cam.ac.uk/partIB_pract/NHP1/ Light source Figure 4.1A Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings
websemserver.materials.ox.ac.uk/cybersem/getf... Electron microscopes 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 websemserver.materials.ox.ac.uk/cybersem/getf...
Scanning electron microscope (SEM) Used to see detailed structure of cell surface Red blood cells http://commons.wikimedia.org/wiki/Image:SEM_blood_cells.jpg Figure 4.1B Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings
Transmission electron microscope (TEM) Used to examine the internal structures of a cell Red blood cell in capillary commons.wikimedia.org/wiki/Image:A_red_blood_... Figure 4.1C Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings
Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings Cell size and shape relate to function Figure 4.2 Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings
Different kinds of animal cells white blood cell red blood cell cheek cells sperm nerve cell muscle cell Amoeba Paramecium
Levels of organization Cells are grouped together and work as a whole to perform special functions
Tissue A group of similar cells to perform a particular function Animals : epithelial tissue, muscular tissue Plants : vascular tissue, mesophyll
Organ Different tissues group together to carry out specialized functions Heart : consists of muscles, nervous tissue and blood vessels Leaf : consists of epidermis, mesophyll and vascular tissue
The Structures of a Leaf (Plant Organ) Chloroplast Palisade Mesophyll Cell Spongy Mesophyll Cell Air Space Stoma
The Structures of a Heart (Animal Organ)
System Several organs and tissues work together to carry out a particular set of functions in a co-ordinated way Human : digestive, respiratory, excretory, circulatory and reproductive systems Plant : root and shoot systems
Levels of Organization CELLS (muscle cells,nerve cells) TISSUES (muscle, epithelium) ORGANS (heart, lungs, stomach) SYSTEMS (circulatory system) ORGANISM (human)
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 Surface area of one large cube = 5,400 µm2 Total surface area of 27 small cubes = 16,200 µm2 Figure 4.3 Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings