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Transcript
Chapter 4 Notes BIOLOGY “The Cell” 4-1 CELLS Science is not static World is flat Planets revolve around the Earth Only things that we can see, exist 1665 Robert Hooke- England: looked at a thin slice of cork Where does cork come from? He saw chambers, and called them “cells” Why were the chambers empty? 1665… Anton Von Leewenhoek Used a single lens microscope to observe pond water He probably saw paramecium, euglena, and amoebas Paramecium Euglena Amoeba Metaboly movements of Euglena. Cells are the basic units of life Cell Theory has 3 parts that are accepted by all scientists…. 1. All living things are made up of cells 1838 Matthias Schleiden – all plants are made of cells 1839 Theodor Schwann- all animals are made of cells 2. New cells only come from other cells 1855 Rudolf Virchow said this … 3. Cells are the basic unit of structure and function of all living things. Atoms are the smallest part that can exist alone Cells are the smallest part that can exist alone and be considered “alive” Technology: define each on yr own Fluorescent Labels Confocal Light microscope Hi Resolution Video Electron Microscope TEM SEM Scanning Probe microscope Cells: have a cell membrane, and have DNA at some point in their lives Prokaryotes/ Eukaryotes Prokaryotes -No nucleus -Smaller -Have free floating DNA -Bacteria -Can swim/ glide Eukaryotes -Have nucleus -Larger/complex -Specialized -Some fd uni-cellular org -Some fd multi cellular org 4-2 Eukaryotic Cell Structure Organelles; the mini organs of the cell In the NUCLEUS Nucleus- sends out instructions for making proteins “the brain” Nuclear envelope- separates the nucleus from rest of cell Nucleolus – dense region of the nucleus where manufacturing of proteins begin Chromatin- DNA + protein Chromosomes- thickened chromatin that are visible during cell division in nucleus In the CYTOPLASM Ribosomes- where proteins are assembled ER- where lipid parts needed for cell membrane are made, also some proteins Rough ER- is involved in making proteins, ribosomes are found on its surface Proteins made on these ribosomes, go into the rough er and are modified Most proteins that are made here will be exported out of the cell Smooth ER- contains collections of enzymes, ready for action These enzymes perform specialized tasks like detoxification of drugs Liver cells contain a lot of smooth ER ? Tylenol, alcohol CYTOPLASM… Lysosomes: clean up crew Filled with enzymes, that help digest proteins, lipids, carbs- “get the junk out of the cell”. Tay Sachs Disease: these don’t function properly Vacuoles Storage place for water, salts, proteins, carbs In plants, it is VERY LARGE, and holds water and is under pressure – Making it possible for the plant to support structures like leaves and flowers Paramecium has a contractile vacuole to pump out excess water CYTOPLASM… Golgi Apparatus: (discovered by Camillo Golgi) modifies, sorts and packages proteins, from the ER for storage or secretion outside the cell Customization, finishing touches are put on the proteins- then they are packed and leave the factory Mitochondria- “powerhouse” of the cell, converts chemical energy in food, to a compound the cell can actually use Mitochondria has its own simple circular DNA In humans, Mitochondrial DNA is inherited from your mom Your heart cells many mitochondria in each cell Chloroplasts w/ chlorophyll Capture energy from sunlight, and convert it into chemical energy Contain the pigment chlorophyll Cytoskeleton: protein filaments that help maintain cell’s shape- also involved in movement Centrioles- help to organize cell division (stars) in animals cells only Microtubules and filaments: help maintain cell shape- help amoeba move Flagellum/ Cilia For movement or sweeping – respiratory tract Sperm cells Cell membrane- both animals and plants Regulates what enters and leaves Provides some protection and support Cell wall Present in plants, algae, fungi, and most prokaryotes Porous enough to allow water, oxygen and carbon dioxide among other substances through Fiber- and bowel movement Strong supporting layer made of cellulose a tough carbohydrate fiber Why don’t cells just grow bigger? Adults don’t have bigger cells than kids… they just have MORE of them The world's tallest man in 2007 7’9”, Bao Xishun and his 5’6” wife… most people with acromegalic gigantism eventually die because of complications from heart problems. "Keeping the blood going round such an enormous circulation becomes a huge strain for the heart," Why don’t cells just grow bigger? DNA overload….DNA would need extra copies to handle “information demand” Too difficult to get enough nutrients and oxygen IN and waste products OUT What would happen? Calculate ratio of surface area to volume L * W * # of sides= surface area L * W * H= Volume Practice problem: if cell was a cube and its sides were 1cm each ….figure SA? Figure V… What if the cell were 3cm? SA? V? What is the ratio? Volume increases faster than surface area 1*1*6=6 SA 1*1*1=1 V Ratio 6:1 3*3*6=54 SA 3*3*3=27 V Ratio 54:27 reduce… 2:1 The decrease in ratio of SA to V- makes it harder for the cell to move needed products in and out.