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1 Link Between Our Knowledge and Technology As in all fields of science, or any other field of study our knowledge increases as technology improves Result of the fact that new technologies provide new perspective and allow observations that were not possible before A clear example of this in Biology is the development of the Microscope http://www.youtube.com/watch?v=BTicXXxzQA 4&feature=related 2 Microscope Development First developed in the mid-1600s With the development allowed a once invisible world to now be visible Called the structures cells because they reminded him of the cells inhabited by monks living in a monastery The World of Cells This world of cells was first described by Robert Hooke Hooke used his primitive microscope to view cork and the structures he saw, he called “cells” 3 Cell History Continued Next came Anton van Leeuwenhook Made his own more advanced microscopes Used his microscopes to be the first to observe drop of pond water and various bacteria samples His findings were confirmed and Anton became a worldwide celebrity soon after People were skeptical of his findings so Robert Hooke sent to confirm his findings 4 Cell History Continued The real importance of cells not recognized until the 1830s 1838-1839 Matthias Schleiden and Theodor Schwann work with cells made the first two tenets of the cell theory The final tenet of the cell theory came in 1855 from the work of Rudolf Virchow 5 Cell Theory Made of the following three tenets: 1. All organisms are composed of 1 or more cells 2. The cell is the structural unit of life 3. Cells can arise only by division from a preexisting cell 6 Basic Properties of Cells Cells are highly complex and organized Cells possess a genetic program and a means to use it Cells are capable of producing more of themselves Cells acquire and utilize energy Cells carry out a variety of chemical reactions Sum total of the reactions in a cell represent the cell’s metabolism Cells engage in numerous mechanical activities Cells are able to respond to stimuli Cells are capable of self regulation Cells evolve 7 The Cell Classes Prokaryotic Cells Considered to be structurally simpler Findings suggest started to exist approximately 2.7 billion years ago Eukaryotic Cells Considered to be structurally more complex Findings suggest started approximately 2 billion years ago Cell Parts and Functions Cell is composed of many structures and parts with various functions The functions a cell must carry out include: Intake of nutrients Movement These functional parts of Growth cells are called organelles Response to stimuli Exchange of gases These functions allow Waste removal cells to survive in Reproduction unicellular (single- celled) and multicellular organisms 9 Plant Cell 10 Animal Cell 11 Organelles Common to Both Plant and Animal Cells Cell Membrane Cytoplasm Nucleus Vacuoles and Vesicles Mitochondria Lysosomes Golgi Apparatus Cytoskeleton Ribosomes Endoplasmic Reticulum (ER) Smooth Endoplasmic Reticulum Rough Endoplasmic Reticulum Common Organelles Cell Membrane Forms a protective barrier around the cell Made of a double layer of lipids Lipid is a fat-like molecule that does not dissolve in water Cell Membrane Diffusion relies on the amount of Designed to allow movement of certain dissolved particles present, the concentration, to occur substances Particles will diffuse, or move, One form of movement across the membrane from area of is called diffusion high concentration of that substance to areas of low concentration of that substance. 14 Common Organelles Cytoplasm Jelly-like substance that fills the cell and surrounds the organelles Contains the nutrients to allow the cell to carry out its life processes Allows things to move within the cell Common Organelles Nucleus Control centre organelle of the cell Controls everything (e.g. growth and reproduction) Surrounded by a nuclear envelope Movement across this occurs through nuclear pores Most have a small dense area called the nucleolus Contains all the cell’s DNA DNA= Deoxyribonucleic Acid Common Organelles Vacuoles Membrane bound organelle Help with storage of nutrients, wastes and other substances used by cells Important in plants as often have central vacuole Mainly stores water, causing cells to swell, making the plant become firm Vesicles Membrane bound organelle Also helps with storage Bigger role in the transport of the stored substances throughout the cell Common Organelles Mitochondria Provides the supply of energy for the cell Does this by converting chemical energy in sugars into usable for the cell, ATP ATP=Adenosine Triphosphate Powerhouses of the cell Common Organelles Lysosomes Organelles where digestion takes place Are small organelles packed with enzymes Enzymes are proteins that speed up chemical reactions in a cell Also help break down invading bacteria and damaged organelles Work as the clean up system In the image the purple structures are lysosomes Common Organelles Golgi Apparatus Receives proteins from endoplasmic reticulum Function is to modify, sort, and package these proteins for delivery throughout the cell or outside the cell Looks like a stack of flattened membranes Resembles stack of pancakes Common Organelles Cytoskeleton Internal network of fibres Made of protein filaments Helps maintain cell’s shape Ribosomes Small, dense-looking organelles Either free floating in cytoplasm or attached to the rough endoplasmic reticulum Site of protein assembly Common Organelles Endoplasmic Reticulum Organelle made of series of interconnected small tubes that carry materials through the cell Found in 2 forms: 1. Smooth Endoplasmic Reticulum Associated with the production of fats and oils 2. Rough Endoplasmic Reticulum Associated with making proteins Considered rough due to presence of ribosomes 23 Plant vs Animal Cells Organelles that are only found in Plant cells Cell Wall Chloroplasts Organelles that are only found in Animal cells Centrioles Plant Cells Chloroplasts Contains chlorophyll Chlorophyll uses energy from the Sun to convert carbon dioxide and water into sugar and oxygen through photosynthesis Made of little sacs called thylakoids Stack in fashion that resembles a coin stack A stack of thylakoids is called a granum Chloroplasts have many grana Stack of thylakoids surrounded by thick fluid called stroma Thylakoids are “solar collectors” Plant Cells Cell Wall Rigid frame around the cell that provides: Strength Protection Support Animal Cells Centrioles Paired structure Involved in cell division Other Differences Between Plant and Animal Cells Compounds / Chemical Plants cells have specialized chemical compound called chlorophyll, a pigment that allows photosynthesis Animal cell have some specialized compounds like hemoglobin in red blood cells Vacuoles Plant cells have large central vacuole Animal cells vacuoles tend to be small Energy storage Plants cells store energy in the form of starch or oils Animal cells store energy in the form of glycogen (a carbohydrate) or as lipids in the form of fats 28 29