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Biology I 10/18/12 HW: Cell Theory – Write & Restate Take out 7.1 Reading Guide CHAPTER 7 CELL STRUCTURE & FUNCTION Objectives Explain what the cell theory is. Describe how researchers explore the living cell. Distinguish between eukaryotes and prokaryotes. 7.1 Life is Cellular Cells are the basic structural and functional units of life. They differ in structure and complexity This idea is relatively new Microscopes were first used around mid-1600’s The invention of microscopes made the discovery of the cell possible Robert Hooke In 1665, Robert Hooke used an early compound microscope to look at cork Observed that cork was made up of 1000’s of hollow chambers Dubbed them cells since they looked like the monastery’s tiny rooms called “cellula”. Anton van Leeuwenhoek Late 1600’s- Dutch textile salesman Created different types of microscopes Observed pondwater and found living organisms Discovered over 5,000 types of microscopic life Lenses were able to magnify up to 300X The Cell Theory A fundamental concept: a summary of confirmed discoveries Cells are the most basic unit and structure of life All living things are made up of cells New cells are produced from existing cells More Discoveries 1839 – German biologists Matthias Schleidan & Theodor Schwann proposed that all organisms are made of cells. 1855 – German physician Rudolf Virchow Proposed that all cells produce more cells through time Exploring The Cell Three major types of microscopes 1. Light Microscope Magnifies 40-1,000 times Used to magnify objects that light can pass through Uses slides 2. Electron Microscopes - Uses electrons to illuminate objects Magnifies from 30,000 to 9 million times Two types Transmission – Beam of e- pass through thin slice Images are 2-D Useful to study internal cell structures, large proteins Scanning – beam of e- scan over surface 3-D images Useful to study external structure Can only be used to look at dead specimens 3. Scanning Probe Microscopes Traces surface of sample with a probe View single atoms, DNA, protein molecules Can view living things Cells Cells come in a variety of shapes Range in size from microscopic bacteria to giant amoeba Mycoplasma pneumoniae Chaos carolinensis – Giant amoeba, approximately 1mm in length All cells have a cell membrane – outer flexible barrier All cells have (or had) DNA Cells Cell membrane Nucleuscontaining DNA 2 Main categories of cells Eukaryotes- have cells that enclose their DNA in a nucleus Prokaryotes- cells that do not enclose their DNA in a nucleus Nucleus: large, membrane-bound structure that contains the cell’s genetic material in the form of DNA Prokaryotes Are generally smaller than eukaryotic cells Have no nucleus Carry out all of life’s processes Ex: bacteria Bacillus anthracis Eukaryotes Are generally larger and more complex than prokaryotes Contain dozens of membrane bound structures that are specialized Nucleus separates DNA from rest of cell Come in a variety of shapes and sizes Ex: protists, fungi, plant, and animal cells HW: Cell Theory: Write & Restate 1. 2. 3. 4. Write the 1st part of the cell theory Restate the sentence in your own words Draw a picture to describe the statement Repeat steps 1-3 for 2nd and 3rd sentences. Example: Write: Each day the temperature is below 32 degrees. Restate: It’s freezing everyday! SunDraw: Mon Tue Wed Thur Fri Sat