Biology Chapter 6 BOOK notes highlighted
Biology Chapter 6 BOOK notes highlighted BSC 2010
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This 5 page Class Notes was uploaded by Marla Notetaker on Saturday October 8, 2016. The Class Notes belongs to BSC 2010 at University of South Florida taught by Dr Daniel in Summer 2015. Since its upload, it has received 59 views. For similar materials see Cellular processes in Biology at University of South Florida.
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Date Created: 10/08/16
Chapter 6 – A Tour of the Cell Yellow: Vocabulary GREE: Key concepts Concept 6.1 I. Microscopy Light microscope: “visible light is passed through the specimen and then though glass lenses. 3 Components of microscopes: Magnification: ratio of an object’s image size to its real size Resolution: measure of the clarity of the image – minimum distance 2 points can be separated and still be distinguished as separated points. Contrast: difference in brightness between the light and dark areas in image. Organelles: the membraneenclosed structures within eukaryotic cells. Electron Microscopy: focuses a beam of electrons through the specimen or onto its surface Scanning electron microscope (SEM): used for detailed study of the topography of a specimen Transmission Electron Microscope (TEM): II. Cell Fractionation Takes cells apart and separates major organelles and other subcellular structures from one another – use of centrifuge… it spins and the large components settle at the bottom with lower speed….. if it is increased therefore the smaller parts would settle down then. Concept 6.2 Cells: the basic structural and functional units of every organism Eukaryote: protists (unicellular eukaryotes), fungi, and animals Prokaryotes: Bacteria and Archaea I. Comparing Eukaryotic and Prokaryotic Cells Basic Features of a EVERY: Plasma membrane: cell is bounded by this phospholipid bilayer Cytosol: “jellylike” fluid inside the cell that “suspends” all the subcellular components Chromosomes: carry genes in form of DNA Ribosomes: in charge of protein synthesis DNA location In Eukaryotes: in the nucleus, which is bonded by a double membrane In Prokaryotes: in nucleoid, a space inside the cell that has no membrane Meaning of the word: Eukaryote: “true nucleus” – Greek eu, true, and karyon, the nucleus Prokaryote: “before nucleus” – Greek pro, before Cytoplasm Eukaryotes: area between the nucleus and the plasma membrane with organelles membrane bounded Prokaryotes: Do not have membrane bounded organelles Concept 6.3 I. The Nucleus: Information Central Nucleus: hold most of the genetic material of the cell Has 2 membranes (envelope) Pores: holes from the inside of the nucleus to the cytoplasm o Pore complex: proteins that surround the opening of the pores which determines what goes in and out of the nucleus Nuclear lamina: protein filaments within the envelope of the nucleus that maintains its shape Nuclear Matrix: More protein fibers INSIDE the nucleus also providing shape. DNA Chromosomes: X shaped genetic arrangement. o 46 chromosomes regular human cells o 23 chromosomes sex cells (ovule and sperm) Chromatin: ALL the chromosomes Nucleolus: where ribosomal RNA is synthesized II. Ribosomes: Protein Factories Formed by ribosomal RNA and Protein Function: Synthesize protein Are not classified “organelles” because they do not have membranes Location of protein synthesis: Free ribosomes: “suspended in the cytosol” (p.104) Bound ribosomes: anchored in the outside of the endoplasmic reticulum Concept 6.4 Endomembrane system: system of membranes in the cell. Nuclear envelope Lysosomes Golgi Apparatus Endoplasmic Reticulum Vesicles Vacuoles Plasma Membrane I. The Endoplasmic Reticulum (ER) Is about half (1/2) of the totally membrane (mass) of the cell Cisternae: tubules and sacs that conform the ER ER Lumen (cavity): the space INSIDE the membranes of the ER Smooth ER It does NOT have ribosomes The one further away from the nucleus Functions: o Synthesis of lipids Oil Phospholipids Steroids Sex hormones (animal) Some other hormones of the adrenal glands Sex organs (testicles and ovaries) have large amounts of Smooth ER o Metabolism of Carbohydrates o Detoxification of drugs and poison Usually needs to add –OH to solubilize Tolerance: usually, in order to process the drugs and detoxify the body, the cell creates more Smooth ER with more detoxifying enzymes, which results and better “handling” of the toxin, meaning that next time more of that toxin has to be used. Smooth ER can also decrease the effect of the drug o Storage of Calcium ions In muscle cells Calcium in the cytosol is sent to the inside of the smooth ER In order to contract the muscle the ER lumen releases the calcium back to the cytosol. Rough ER Functions: o Synthesis of protein o Creates membranes II. Golgi Apparatus (GA) Here is where everything is packed and sent somewhere else Flattened cisternae It has an orientation o Cis face: receives the products… (cis…on the same side – as the ER) o Trans face: “ships” the products (trans… the opposite side) “Removes some sugar monomers” Cisternal maturation model: the Golgi apparatus moves ITSELF from cis to trans III. Lysosomes A sac formed of membranes with “hydrolytic enzymes” Used to break down molecules. These “hydrolytic enzymes” are synthesized in the rough ER and sent to the GA Phagocytosis: eating (engulfing) of other organisms o Macrophages: present in the human body, part of the WBC Autophagy: when the cell “recycles its own material. o Tin – Sachs disease: because there is an absence or inhibition of an enzyme that digests lipids the brain has too much fat and stops working. IV. Vacuole: Diverse Maintenance Compartments “Derived from the ER and he GA” Types: o Food vacuole: stored excess material in the cell o Contractile vacuole: extract the unnecessary water out of the cell o Central Vacuole: hold water in Cell plants and ion concentrations Concept 6.5 Mitochondria: as people say “lungs of the cell” where most cell respiration happens o C6H 12 6 6O 2 6CO + 62 O + 2nergy (ATP) Chloroplasts: photosynthesis o 6CO 2 6H O2+ energy (from light) > C H 6 12 6O 2 I. The Evolutionary Origins of Mitochondria and Chloroplasts Endosymbiont theory: some organism engulfed another, which consumed oxygen and because the larger one functioned better with the smaller one they created the symbiotic relationship… this is what chloroplasts and mitochondria have 2 membranes Evidence supporting this theory: o The 2 membranes ^ o Mitochondria and Chloroplasts have both its own DNA and Ribosomes o These 2 can reproduce themselves II. Mitochondria: Chemical Energy Conversion Usually cells that are very active have more mitochondria Outer membrane is smooth Inner membrane: folded cristae, which adds more surface area Intermembrane space: as the name suggests, is the space between the membranes. Mitochondrial Matrix: space enclosed by the SECOND (2 ) membrane. III. Chloroplasts Thylakoids: each “disk” inside the chloroplasts Granum: stack of thylakoids Stroma: liquid inside the chloroplasts and outside the thylakoid Plastids: special organelles in plants o Amyloplast: “colorless organelle that stores starch (amylose) Roots and Tubers Potatoes o Chromoplast: gives the color of yellow and orange IV. Peroxisomes Add Hydrogen atoms to Oxygen (O ) mole2ules to produce Peroxide (H O ) 2 2 This H O 2s 2 xic for the cell, however Peroxisomes also can make water from this Glyoxysomes: present in “fatstoring tissues of plant seeds.” Before the plant grows these special peroxisomes covert the fatty acids of this tissue into sugar so the plant can get energy until it grows and can do photosynthesis They can enlarge by adding to their shape proteins and lipids from the ER They can divide themselves when they get too big Concept 6.6 Cytoskeleton: fibers that compose the cytoplasm Compoents: o Microtubules (tubulin polymers, thickest) o Microfilaments (actin filaments, thinnest) o Intermediate Filaments I. Role of cytoskeleton: support and mobility “give mechanical support to the cell and maintain its shape Motility = mobility Motor proteins: proteins that carry vesicles along the cytoskeleton It can bend the plasma membrane to create food vacuoles a. Microtubules Dimer: αtubulin AND βtubulin The amount of Dimer is what determines the length of the Microtubule Microtubule are the “rails” of the motor proteins Play part in the separation of chromosomes in cell division Centrosomes and centrioles: o Centrosome: composed of 2 centrioles placed at 90* angle from each other near the nucleus. o Centrioles: 9 triplets (groups of 3) arranged in a “circular”, “star” o Some eukaryotic cells lack centrosomes Cilia and Flagella o Elements that extend to outside of the cell for movement or transport of the cell o Flagella are longer than Cilia and while Cilia are probably multiple per cells Flagella normally is just 1 extension o Primary Cilium: Interesting enough the Cilia of most cells do not move o “9+2” pattern: the structure of the flagellum and cilium ITSELF consisting of 9 groups of duplets (2 microtubules) arranged around 3 central tubules o “9+0” pattern: basal body, which is the “anchor” of the flagellum/cilium TO the cell. It looks like centriole o Dynein: motor protein bends the flagella/cilium to move them b. Microfilaments (Actin Filaments) “Solid rods” made of double stand of actin intertwined Function: “bear tension” Cortical microfilaments: supports the shape of the cell Cortex: “outer cytoplasmic layer of a cell” Myosin: thicker than actin filaments Pseudopodia: fake feet, mostly in amoeba Cytoplasmic streaming: the circulation inside the cell c. Intermediate Filaments Are more persistent, absorb impact, elastic, persistent to tension Even if the cell dies they sometimes stay Some research believes that they anchor certain organelles Concept 6.7 I. Cell Walls of Plants Extracellular structure present in plants Functions: o Protect plant o Maintain shape of the plant o Does not allow the plant to take TOO MUCH water *Some special cells of the wall keeps the plant standing up* Thicker than the plasma membrane Structure: o Cellulose microfibrils Cellulose synthase creates ^ to send it to the outside of the cell (extracellular space) to bind with other proteins and saccharides o Primary cell wall: first “relatively thin” cell wall created by baby plants o Middle Lamella: “a thin layer rich in pectin (“sticky saccharide”) which “glues adjacent cells together.” o Secondary cell wall: between primary cell wall and plasma membrane produced when the plant gets older in order to tough up the cell wall II. The Extracellular Matrix (ECM) of Animal Cells Main components of the ECM o Glycoproteins – “covalently bonded carbohydrates” Collagen: most abundant glycoprotein in animal cells (40% of protein in human body) o “Carbohydratecontaining molecules” o Proteoglycans: some protein as a base with a lot of carbohydrates covalently bonded… this is what holds collagen o Integrins: “cell surface receptor proteins” Can communicate ECM and cytoskeleton “ECM can regulate cell’s behavior – coordination o Fibronectin: proteins in the ECM that binds it to the Integrins III. Cell Junctions a. Plasmodesmata in Plant Cells This is the general tame to call cell junctions Types of junctions: o Tight Junction: Proteins tight the 2 cells together by proteins (like stitches) o Desmosomes: keratin (Inter. Fils) form patches tightening the cells together. o Gap junction: Proteins surrounds pores I the cytoplasm and creates a tunnel to the other cell.
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