BIO 111-14 Chapter 6 Notes
BIO 111-14 Chapter 6 Notes BIOL 111 102
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This 5 page Class Notes was uploaded by Melissa Romano on Wednesday February 17, 2016. The Class Notes belongs to BIOL 111 102 at Camden County College taught by Jill Carroll in Winter 2016. Since its upload, it has received 16 views. For similar materials see Introduction to Modern Biology in Science at Camden County College.
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Date Created: 02/17/16
Chapter 6: The Cell A single cell is too small to see with the naked eye. (This is the purpose of microscopes) Visualizing Cells Magnification: increases apparent size of an image Resolution: the ability to see separate structures when magnified (clarification of object/image) Microscopes Light Microscopes: uses light to assist resolution -Can be used to look at living cells -Don’t have large range of magnification (400x’s max) Electron Microscope: uses beam of electrons to magnify -Need to stain specimen/cells being viewed with heavy metals Kills cells Can’t view living cells Transmission Electron Microscope: used to view interior of specimen/cells Scanning Electron Microscope: used to view surface of specimen/cells Cell Theory 1665 Robert Hooke -First to name the cell after looking at cork under microscope 1838 Schleiden (plants) & Schwann (animals) -Discovered that all living things are made up of cells Theories later expanded to: -Cell is the smallest unit of life -Cells only arise from pre-existing cells (in modern environmental conditions) -All organisms are made up of cells Cell Size Small cell size yields a high surface area (plasma membrane) to volume (cell contents) ratio Volume increases faster than surface area when cell size increases -Cells remain small so membrane can contain/protect cell contents 3 Main Regions of Cells Plasma Membrane: semi-permeable/selectively permeable -Only allows the passage of certain molecules into cell Nucleus: where DNA is located -Called Nucleoid Region in prokaryotic cells with no nucleus -Eukaryotic cells contain a nucleus Cytoplasm: fills all space in cell between the nucleus and the cell membrane -Organelles: structures in a cell with specific functions -Cytosol: fluid structure in a cell (nucleotides, amino acids, etc) in which organelles reside Prokaryotic Cells Cell Wall: all cells have a cell wall and cell membrane Fimbriae: help cells stick to surfaces Flagella: long extensions on exterior of a cell for locomotion (physical movement) -Present in cells that live in a moist environment Nucleoid Region: where DNA molecule(s) is/are located *Single DNA molecule for bacterial cells* -Ribosomes: the site of polypeptide synthesis (Amino Acids) Eukaryotic Cells Large cells Nucleus: -Contains pores to let molecules in/out -Chromatin: made of DNA & proteins Makes up all cells (except bacteria) Histone Proteins (positive charge): regulate/order DNA into structural units called nucleosomes by allowing DNA to wrap around it DNA has negative charge to complement proteins Condenses to form chromosomes during cell division Nucleolus: where formation of ribosomes takes place -Composed of protein and RNA Ribosomes Site of Polypeptide Synthesis Located in cytoplasm (Holds Protein) Attached to membrane (Rough Endoplasmic Reticulum) where proteins get exported Endoplasmic Reticulum Rough ER -Site of polypeptide synthesis -Can pinch off cell and form a transport vesicle Smooth ER -No ribosomes attached -Involved with lipid metabolism -Storage cite for things like Calcium -Involved with breakdown of certain drugs Golgi Aparatus Modifies proteins -Packages it back up in other transport vesicle Lysosomes Animal cells Digestive enzymes (Hydrolytic Enzymes) Vacuoles: membrane bound vesicles Fuse to enzymes while protecting cell Break down other old enzymes Vacuoles Large membrane that takes in old material Central Vacuole: -Plant cells -Takes up most of cell -Mainly holds water -Contains pigment and toxins that protect cell (releases when animals attempt to consume) -Pushes other organelles to outer edges of cell Contractile Vacuoles: -Pump out water -Fill and contract to release water -Protist cells -Only for cells in fresh water Mitochondria: (powerhouse of the cell) where most ATP is made Chloroplasts Plant cells and some Protist cells Only in autotrophs (self feeders) -Where photosynthesis occurs (use sunlight to make food) Cells with chloroplasts also contain mitochondria Only located in green leaves Peroxisomes Use H 2 2o break down substances (Ex: alcohol) Cytoskeleton Microtubules -Made of tubulin -Can change shape Microfilaments -Made of actin -Involved with cell division by pinching cell in half -Involved with locomotion Intermediate Filaments -Permanent structure -Made of Keratin (structural protein) -Surround nucleus -Assist with shape of cell *Micro = can change in shape* Centrioles Pairs at right angles Animal and most protest cells Centrisome = pair of centrioles Flagella and Cilia Animals and Protists Flagella are for locomotion Cilia are shorter and more abundant -Also used for locomotion -Sweeps things along surface of the cell to move (Ex: how mucous is cleared from sinuses) Cell Wall Structural support Plants/Fungi Provides rigidity Extracellular Matrix In tissues Outside of cell Anchors cell in position Ex: Collagen Intercellular Junctions In between two cells Only in multicellular organisms Tight Junctions -Plasma membranes directly connected between two cells -No space between cells -In cells that form sheets Anchoring Junctions -Desmosomes -Allows one cell to move with another without losing structural integrity -Proteins interlock -In tissues that require movement (skin and muscle) Gap Junctions -Communicating junctions -“Tunnels” of two cells that connect -Can open/close -Specific to what molecules are let in (Aquaporens allow water) Plasmodesmata -Connect inside of two cells
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