Chapter 3 Cells PDF

Cells Cells are small, but huge from a biological perspective of their importance for us to understand the structure of living organisms!!!!!!!!!!!!!! 1  Cells are… …the smallest unit of life capable of living independentl...

Cells Cells are small, but huge from a biological perspective of their importance for us to understand the structure of living organisms!!!!!!!!!!!!!! 1  Cells are… …the smallest unit of life capable of living independently. Robert Hooke was one of the first people to study cells through his self made microscope. Robert Hooke looked at a wide variety of objects including bee stingers, feathers, fish scales, insects, and cork. Cork consists of dead plant cells, which Robert Hooke coined as “cells”, because they looked like the cubicles where monks would 2  Protists and Bacteria Antony van Leeuwenhoek improved the lenses found in microscopes and managed to look at protists and bacteria for the first time. He called these organisms animalcules. These were new organisms which no one ever knew existed before I am so jealous, because at parties they use to look at A sample of pond organisms under the water under the microscope. My microscope. nerdy self would have been so “cool” 3 in the 17th  Cell Theory Mathias Schleiden and Theodor Schwann proposed the Cell Theory. The Cell theory started off as two components.. Rudolf Virchow added a third component to the cell ) All organisms are made of 1 or more cells theory, that all living cells come from preexisting 2.) the cell is the fundamental unit of life cells. An amoeba. The pointer is Amoebas doing what amoebas pointing at the nucleus. do on a Saturday night, reproducing asexually baby!!! 4  Multicellular organisms cells are a lot like… …Legos. Individual Legos can be put together to build a construct like a…. …castle!!! Cells can …or multicellular, like the exist as …colonial… castle is made of multiple unicellular Legos structures… Rod Woodson is the result of a 40 trillion cells, about the same for each of us.  5  Microscopy… …is the ability to amplify human vision to see the really small by using Light microscopes human technology. And when I say work by really small, I mean REALLY small. streaming light… …(the light source)… …through the object you are The light looking at and microscope can one or more magnify up to lens… 1600 times and resolve objects …which bend that are 200 light so light nanometers will scatter apart. Meaning more widely you can see the increasing the difference of apparent size …(there structures which are two lenses in of the object. are 200 this microscope)… 6 nanometers in  Microscopy improves with…. Transmission electron microscopes (TEM) send a beam of electrons through a thin piece of object. TEM microscopes can magnify objects up to 50 million times their actual size and resolve objects less than 1 angstrom Side note and not apart (10-10 meters). important for test: The most powerful Scanning Electron microscope ever Microscope (SEM) sends called a quantum microscope took the the electrons over a first image of a metal-coated three hydrogen's electron orbit. dimensional specimen. Magnification isn’t as great as TEM, but it can discern textures and crevices on an object. 7  All Cells (whether bacteria, archaebacteria, or eukarya) include these six components… …2.) RNA, which is involved …1.) DNA, the with carrying DNA molecule information to the site of which protein formation. establishes inheritance. …3.) Ribosomes: The site of …5.) Cell Membrane: The structure which protein acts as a barrier formation. …4.) Proteins between the internal and external Note: The environment.cell membrane is also known as the plasma membrane. …and 6.) Cytoplasm which is the liquid interior of the cell. 8  Cells have a… In the picture to the left..minimum size. Their you have a SEM image of mycoplasma bacteria. minimum size is These are the smallest dependent upon their bacteria. They have a cell ability to contain all membrane, a little cytoplasm, a little piece of the cellular structures DNA and RNA, one and to be able to ribosome, and some contain the proteins and other biochemical reactions molecules. necessary for cell …maximum size in their functions. Cell also surface area to volume have a …. ratio. An increase in 3 dimensional size means a more rapid increase in volume to surface area. The picture to the left is of an episode of the 80’s cartoon GI Joe. In this episode a giant bacteria which grew to city size was eating everything. The problem is a single cell of this size does not have enough surface area to diffuse enough food, 9 Three domains of life are characterized by three different types of cells Prokaryotes are the The third simplest and the domain consists most ancient cells. of Eukaryotes. Consist of the two The domain is domains Bacteria and called Eukarya Archaebacteria. Pro = Before Eu = True Karyon = Kernel, refering to the 10 nucleus  Three Domains Domains Nucleus Mebrane Membrane Cell Wall Bound Chemistry Chemistry Organelles Bacteria Absent Absent Fatty Acid Peptidoglcyan Archaebacteria Nonfatty Pseudopeptidoglycan Absent Absent Acid lipids Or protein Usually cellulose ,chitin Eukarya Present Present Fatty Acids or none Bacteria and Archaebacteria are typically 1-10 micrometers in size. Eukaryotes are typically 1-100 micrometers in size 11  Domain Bacteria Bacteria are the most abundant and diverse group of organisms on the face of the earth. The bacteria also have a The nucleoid region is the cell wall which keeps the area where the single circular cell from exploding if it piece of DNA is present takes on too much water which controls the day to day and also maintain the operations of the cell. shape of the bacteria. Some bacteria have And other bacteria have no flagella and some numerous flagella have one flagella Flagella are tail like appendage which allow the bacteria to move through water. 12  Domain Archaea Archaea (Archaebacteria) are superficially like that of bacteria. Both lack a nucleus and membrane bound organelles. Have simple structural components. Have a more diverse array of metabolism and environments they can survive in than that of eukaryotes. Archaeabacteria were the first extremophiles discovered. Extremophiles are organisms which can live in extreme environments In the picture above boiling Extreme heat, cold, salinity, acidity, or water from a geyser contain alkalinity to name a few thermophiles, which are Later discovered a lot of Bacteria are also organisms which thrive in extreme heat. These extremophiles as well. organisms are capable of Expanded how we hypothesize life maybe surviving boiling water!!!! 13 on other planets.  Ribosomes Ribosomes are structures found in both prokaryotes and eukaryotes. Prokaryotic ribosomes are smaller than eukaryotic ribosomes. Ribosome are the site where protein formation (translation) takes place. They consist of a small unit and a large unit which come together when protein synthesis occurs. 14  Domain Eukarya (this includes us!!!! ) The domain eukarya includes unicellular organisms (a lot of the protists and a few fungi) and the multicellular organisms (plants, fungi, animals, and a few algae). This domain includes the most complex The picture above is a cells. paramecium taken through a You can see structures of the cell light microscope. Notice that you can make out structures Thisunder domain a light microscope.bound has membrane The first within the cell. structure observed was the The picture below is organelles. an artist impression of nucleus These are structures within the the structures. cell which have a membrane, like the plasma membrane, surrounding the structure. Includes the nucleus (protects the DNA), vacuoles, lysosomes, and the endomembrane system, too name a few. 15  Membranes Membranes separate surroundings. Cell membranes separates the external and internal environments of the cell Organelle membranes separate the volume of the organelle from the cytoplasm Membranes consist of a phospholipid bi- layer Two layers of phospholipid Each phospholipid consist of a negatively charged phosphate head and a hydrophobic tail The bi-layer consists of two layers of phospholipids with the tails of each phospholipid facing each other and the negatively charged heads facing outwards and inwards towards the 16  Fluid Mosaic Model The fluid mosaic model is a model used to describe the structure of the cell membrane. The “fluid” component of the model is a description of the fluid nature of the cell membrane. The individual molecules found within the cell membrane and make up the structure of the membrane are not solidified in place and can move around the membrane in a fluid like nature. The “mosaic” component of the model is a description of the components of a cell membrane. The phospholipids make up the general structure of the membrane. Proteins create the other functions for the membrane Sterols, including cholesterol, are involved with keeping the membrane in a fluid structure. 17  Membrane Proteins include…..Transport proteins which allow matter to enter and exit the cell. Certain transport proteins allow certain molecules to enter and/or …Enzymes: facilitate exit. chemical reactions along the membrane. …Receptor proteins take chemical signals and use it for information to trigger a reaction within the cell. …Recognition proteins serve as …Adhesion proteins nametags to allow for a cell to be able allow for cells to stick to identify another cell as part of the together. same structure (organ) or a part of the same organism. Recognition proteins often couple with a carbohydrate. 18  Division of Labor Organelles found within the eukaryotic cell allow the cell to divide the labor. Organelles come in a variety of different types which do different functions within the cell. The rest of the power point will be about structures in the cell. 19  Endomembranous System Endomembranous system consists of… the endoplasmic reticulum… …Golgi aparatus… …cell membrane… …the nuclear envelope…..Lysosomes are found in animals, while different kinds of vacuoles are found in plants and protists. The endomebranous system helps to differentiate labor out in the cell. 20  The Nucleus One of the most prominent organelles is the nucleus. You can see it under a light microscope. The nuclear envelope acts as the “cell membrane” of the nucleus separating the nucleoplasm from the cytoplasm. Nuclear pores allow for mRNA molecules to leave the nucleus carrying the information to build new proteins. The nucleolus appears as a darker area within the nucleus and is the site of Fig. 3.14 construction of ribosome subunits 21  Endoplasmic Reticulum There are two types of endoplasmic reticulum… Rough Endoplasmic Reticulum is a site of protein manufacturing. Proteins made here will be secreted out of the cell. Proteins kept in the cell are manufactured by ribosomes in the cytoplasm. Smooth Endoplasmic Reticulum synthesizes lipids. Enzymes which detoxify poisons and drugs are found here. Smooth ER is found in high abundance Fig. 3.15 in liver cells. Special Smooth ER in muscle cells store and release Calcium ions, which are necessary for muscle contraction;. 22  Golgi Apparatus The Golgi Apparatus: A structure of pancake like… Vesicles which have..I said detached from the ER. pancake like!!! Now I am hungry!! …That’s better!! …structures which accept vessicles which break off of the ER. They take proteins (made in the rough ER) and lipids (made in the smooth ER) and complete their construction. It also sorts and packages their products to have them moved to the proper place. Finalized improvements on proteins can include lipid or carbohydrate attachment and final folding of the shape of the 23 protein. The NUCLEUS…. …The Endoplasmic Reticulum… …The Golgi Apparatus Are a part of a endomembranous system which secretes materials out of the cell. The role of the nucleus though is more to protect the DNA from molecular oxygen and other hazards. I am coming to get your DNA!! Oxygen our friend and our enemy. We need for ATP production, but is also a carcinogen. Want to avoid cancer, stop 24  Cellular Digestion Heterotroph s consume food!!! Autotrophs harness raw energy and produce Cellular digestion is the ability food. of cells to break down organic molecules into smaller molecules so they can be reused. The next set of slides are going to be about parts of the cell involved with cellular 25 digestion.  Legos (yes once again) Legos can be... …and rebuilt....taken apart… The same as a starch grain… …and then built into..gets broken down into (found in corn) glycogen in animals. glucose… 26  Lysosomes Fig. 3.17 Lysosomes are organelles which contain digestive enzymes. Look it is a cute Break down food, capture bacteria, “baby” lysosome!! old organelles, and debris/waste Can be used in the destruction of the cell. Enzymes are produced in the Rough Endoplasmic Reticulum Golgi bodies recognize the enzymes by a particular sugar molecule Golgi body absorbs the protein and construct a lysosome with the enzymes Lysosomes produced by a have thelower pH than the rest of the cell. endoplasmic pH 4.8 versusreticulum. a general pH of 7 in the rest of the cell. The lower pH allows the lysosome to break down molecular structures When a cell needs to be terminated all of their lysosomes will burst 27 releasing their digestive enzymes.  Vacuoles It’s a picture of Plant cells generally lack lysosomes, but our plant cell often have a large central vacuole. model!! Contains enzymes which helps the plant digest molecules and organelles. Vacuoles have a low pH (acidic) which helps it to digest molecules. Plant cells grow with the growth of their central vacuole. Growth stimulated by Someincreases protists in water have a different kindpressure (turgor of vacuole called a pressure). contractile vacuole. Helps pump out excessive water. 28  Peroxisomes Fig. 3.18 All eukaryotic cells contain peroxisomes. Contain enzymes which break down toxic Peroxisomes substances. originate in the endoplasmic reticulum. Peroxisomes protect the cell from toxic byproducts. Some chemical reactions within the cell produce hydrogen peroxide (H2O2) Liver and kidney cells have peroxisomes that help break down toxins found in blood. Peroxisomes also break down fatty acids to produce cholesterols 29  Photosynthesis produces food. Fig. 3.19 Chloroplasts are the site of photosynthesis in eukaryotes. Chloroplasts consist of two outer membranes. They have a liquid interior called the stroma. They have a third type of internal membrane (within the stroma) which are called thylakoids. Thylakoids are stacked in structures called grana. Photosynthetic pigments are found embedded in the Chloroplasts are a type of plastid. Plastids come in a variety of types thylakoids. which synthesize different substances. Plastids are different from most other organelles because they contain their own DNA and ribosomes. 30  Mitochondria extract energy from food (fig. 3.20) Mitochondria are organelles which break down molecules to extract energy which is used to produce ATP. Glucose molecules are already broken down in the cytoplasm. The remnant of the glucose molecules left over are further broken down in mitochondria Mitochondria have two membranes, with the inner membrane creating folds called cristae. The chemical reactions which occur in mitochondria use oxygen. This process not only helps produce more ATP, but also helps protect us from molecular oxygen found in the atmosphere. Mitochondria, like plastids/chloroplasts, have their own DNA and ribosomes. Mitochondria and plastids are theorized to be living organisms which 31 have become a part of the eukaryotic cell in the past.  Cytoskeleton System Cytoskeleton is a structural framework for the cell to maintain the shape of the cell. The flagella cytoskeleto n system is also a part The cytoskeleton system provides transportation of cell of internal components of the cell and also division and provides a framework flagella, and cilia, and motion for pseudopods. the motion of chromosom es. Cilia pseudopod 32  Three general types of Cytoskeletal structures Fig. 3.23 Microfilament Allow cells to survives stretching and compression actions Help cells anchor to each other Intermediate filaments Smallest of the three Form an internal scaffolding for the cell. Also play a part in binding cells together. Microtububule Composed of a protein called tubule. This Pull DNA apart during cell division. Giardia Form a “rail system” for organelles to sp. has move along. multiple Think of like a rail road track flagella. Centrosomes are important components in animal cells for the creation of flagella and cilia. 33 Fig. 3.24  Cell walls Cell walls provide structural support for the cell. Plant cells have Fungi have cellulose as a chitin in their major part of their cell wall. cell walls. Bacteria have peptidoglycan in their cell wall. Animal cells have no cell walls. Animals have what I call “cell wall envy”. 34  Cell Junctions Multi-cellular and colonial organisms have to have structures which hold the cells together. Tight Junctions are junctions which create impermeable barriers between cells. Create barriers between the blood and the brain; the digestive Anchoring tract; junction thecells hold kidney tubules. together like the skin cells. Gap junctions Gap Junction allow for exchange of chemicals between cells. Animal cells Plasmodesmata provide channels between plant cells. 35 Table 3.3 p. 66 Table 3.23 p. 66 provides a brief summary of the structures of a eukaryotic cell. Just wanted to mention that.  36