Cell Theory & Microscopy PDF

Cell Theory & Microscopy A 2.2 Cell Theory ▶ How do you think these things were discovered and/or supported? Consists of 3 basic principles 1. All organisms are composed of one or more cells ⚫ Unicellular= one cell ⚫ Multicellular= 2 or more cells Cell Theory ▶ ▶ ▶ Light microscope was in...

Cell Theory & Microscopy A 2.2 Cell Theory ▶ How do you think these things were discovered and/or supported? Consists of 3 basic principles 1. All organisms are composed of one or more cells ⚫ Unicellular= one cell ⚫ Multicellular= 2 or more cells Cell Theory ▶ ▶ ▶ Light microscope was invented in 1665 Cells for their name from Anton van Leeuwenhoek, who observed cork and noted that each compartment looked like a tiny animal Botanists and animal scientists confirmed this, noting that animal and plant tissue seemed to be of independent and separate beings Cell Theory 2. How do you think these things were discovered and/or supported? Cells are the smallest units of life ⚫ Organelles within the cell carry out the different life functions Cell Theory ▶ ▶ Components of cell cannot survive independently No one has found a living thing made of less that one cell Cell Theory 3. All cells come from preexisting cells ⚫ Cells multiply through cell division Human embryonic kidney cells dividing How do you think these things were discovered and/or supported? All Cells Come From Pre-Existing Cells... ▶ ▶ Louis Pasteur’s experiments showed that only flasks open to the environment grew bacterial cultures New cells only arise from existing cells Exceptions to the Cell Theory ▶ However, there are some atypical examples… 1. Human skeletal muscle cell - 100x longer than regular cells and contain multiple nuclei Multiple nuclei per cell! Very long in length! Exceptions to the Cell Theory 2. Giant algae - can grow very large (100mm), but are composed of only one cell with one nucleus No individual cell units! Exist as one giant cell (up to several cm long!) Exceptions to the Cell Theory 3. Aseptate fungi - hyphae not divided into sections (cells) but contain many nuclei Very large! Continuous cytoplasm! Multiple nuclei per cell! Functions of life ▶ All cells (unicellular or multicellular) perform the functions of life: 1. 2. 3. 4. 5. 6. 7. Metabolism Response to Stimuli Nutrition Growth Excretion Homeostasis Reproduction Are Viruses Living? ▶ ▶ ▶ No Viruses do not carry out all of the life functions They must use cells to reproduce How do Paramecium Show Characteristics of Life? ▶ ▶ ▶ ▶ Unicellular organism from the kingdom Protista Clusters around food particles Has both food vacuole and contractile vacuole What characteristics of life are demonstrated by studying paramecium? Chlorella ▶ ▶ ▶ Single celled organism with a large chloroplast inside Allows organism to photosynthesize → creating food What would happen if chlorella were stored in dark place? Cells & Cell Sizes ▶ Cells are small! Some are smaller than others, but most require microscopes to see them. Microscopes ▶ ▶ ▶ ▶ Inexpensive Simple to use Specimens may be living or dead Magnifies up to 2000x Light Microscope ▶ ▶ ▶ ▶ ▶ Expensive Complex instructions Specimens must be dead and fixed in plastic Magnifies up to 500,000x MORE detail Electron Microscope Cell Size & Magnification Calculating Magnification Magnification = size of image / actual size (M=I/A) Example: An image measured 60mm is actually 2 μm in size. What is the magnification of the drawing? **Remember, when you solve you need to convert to equal units! Magnification has no units Calculating Cell Size Magnification = size of image / actual size (M = I/A) So… Actual size = size of image / magnification (A = I/M) Example: a sample has been magnified 5000 times and is drawn as 9mm. What is the actual size? ...Remember, you need to convert units so that your numerical answer is a value between 1 and 1000. End of Part 1 Up next on Part 2: Limits to Cells Size, Cell Specialization & Differentiation