Chap3 - Chapter 3: The Cell Chapter Anatomy of the Cell...

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Unformatted text preview: Chapter 3: The Cell Chapter Anatomy of the Cell Anatomy Cells are not all the same All cells share general structures Cells are organized into three main Cells regions regions – Nucleus – Cytoplasm – Plasma membrane Figure 3.1a Cells: The Simplest Unit of Life Cells: Cells: Must do all of life’s functions: Therefore an ORGANELLE or STRUCTURE in or on Cell must be present for each of the 7 “life functions” We are studying animal cells which are EUKARYOTIC cells. Function: Organelle Function: All of the basic functions are covered: Reproduction and Growth: Nucleus Digestion: Lysosomes Metabolism: Mitochondria Excretion: Plasma Membrane Maintaining Boundaries: Plasma Maintaining Membrane Membrane . Nucleoli Nucleoli Nucleus contains one or more nucleoli Sites of ribosome production – Ribosomes then migrate to the cytoplasm Ribosomes through nuclear pores through Mitochondria Mitochondria – “Powerhouses” of the cell – Change shape continuously – Carry out reactions where oxygen is used to Carry break down food break – Provides ATP for cellular energy Lysosomes Lysosomes – Contain enzymes that digest nonusable Contain materials within the cell materials Peroxisomes – Membranous sacs of oxidase enzymes Detoxify harmful substances Break down free radicals Break (highly reactive chemicals) (highly – Replicate by pinching in half The Plasma Membrane The MAJOR FUNCTIONS : Serves as a barrier, while maintaining Serves integrity of cell contents, integrity 2. Allows for selective transport of molecules Allows selective across it…into and out of cell for purpose of ingestion and excretion and allowing important electrolytes in and out. important 3. Play a major role in cell to cell Play communication as receptors are bound communication externally here on hormones and specialized white blood cells etc. 1. Phospholipids:Role in Membrane Phospholipids:Role Head- Polar “charged” water loving, Headtherefore this side lies inward toward cell contents. contents. Tail-NONPOLAR “not-charged” repels Tail-NONPOLAR water. This side lies outward. NOW cell is WATERPROOF…won’t dissolve. Lipids found in Plasma Membrane Membrane Composition of Membrane Composition Fluid Mosiac “Sandwich” of: Phospholipids Cholesterol Glycoproteins Glycolipids Plasma Memebrane Plasma What are the functions of the PROTEINS found on the Plasma membrane? membrane? Transmembrane Proteins- allow Transmembrane substances to pass through membrane substances Receptors- for hormones, chemical messengers like neurotransmitters etc. messengers Binding sites Glycoproteins-these are receptors for Glycoproteins-these viruses and bacteria; play a role in cell to cell interaction to The LDL ( Bad Cholesterol) receptor is a glycoprotein glycoprotein Solutions and Transport Solutions Solution – homogeneous mixture of two or more components or – Solvent – dissolving medium – Solutes – components in smaller quantities Solutes within a solution within Intracellular fluid – nucleoplasm and cytosol cytosol Interstitial fluid – fluid on the exterior of the Interstitial cell cell What Permeates the Membrane Easily? Easily? Simple Diffusion Simple Particles will collide Particles and be even distributed as the concentration gradient goes ‘downhill”. goes Equilibrium is Equilibrium established in the second container. Simple Diffusion (Passive) Simple Molecules move with Molecules conc. Gradient until in equilibrium. in 1) They are small 1) enough to pass through membrane through 2) They are lipid-soluble Facilitated Diffusion Facilitated A type of passive transport involving type facilitator--- a protein membrane facilitator--channel. channel. NO ATP required however Required for lipid-insoluble or large Required molecules. A Channel or transporter is involved Channel Diffusion through the Plasma Membrane Membrane Figure 3.10 Membrane Junctions Membrane Gap Junctions- These spaces allow chemicals,ions to pass through thereby allowing cell to cell communication. CONNEXONS are the tubes which are seen between gap junctions. Desmosomes- Anchoring junctions; prevent Desmosomes Anchoring cells from being pulled apart. Tight Junctions- Impermeable Junctions. Tight While cells are bound together they are leakproof at these junctions. Plasma Membrane Specializations Specializations Membrane junctions – Tight junctions – Desmosomes – Gap junctions Figure 3.3 Adenosine Triphosphate (ATP) Adenosine Figure 2.19a How ATP Drives Cellular Work How Figure 2.20 Active Transport Processes Active Transport substances that are unable to pass by Transport diffusion diffusion – They may be too large – They may not be able to dissolve in the fat core They of the membrane of – They may have to move against a They concentration gradient concentration Two common forms of active transport – Solute pumping – Bulk transport Active Transport Processes Active Solute pumping – Amino acids, some sugars and Amino ions are transported by solute pumps pumps – ATP energizes protein carriers, ATP and in most cases, moves substances against concentration gradients concentration PRESS TO PLAY ACTIVE TRANSPORT ANIMATION Sodium –Potassium Pump Sodium Figure 3.11 Active Transport Processes Active Bulk transport – Exocytosis Moves materials out of the cell Material is carried in a Material membranous vesicle membranous Vesicle migrates to plasma Vesicle membrane membrane Vesicle combines with plasma Vesicle membrane membrane Material is emptied to the Material outside outside Active Transport Active Any transport that involve the use of energy is Any called ACTIVE TRANSPORT. If a substance is needed in the cell ..or out of the cell..but is in lower conc. (against its conc. Gradient) OR Gradient) IF too large to pass through membrane and has no IF special carrier or channel.. special Examples: BULK tranfer and SODIUM PUMPS Sodium-Potassium Pump Sodium-Potassium Na-K Pump: How it Works Na-K A type of active transport. type 3 sodium ions move out of cell sodium 2 potassium ions move into cell. ATP is needed as each of these ions are moving ATP against their conc. gradient. against Mostly used in cardiac muscle and nervous Mostly tissue. Maintains Na+K gradient concentration. Huge amount of ATP goes into this NaK pumps! pumps! Exocytosis Exocytosis Endocytosis: Phagocytosis Endocytosis: Selective Permeability Selective The plasma membrane allows The some materials to pass while excluding others excluding This permeability includes This movement into and out of the cell movement Active Transport Processes Active Bulk transport – Endocytosis Extracellular substances are engulfed Extracellular by being enclosed in a membranous vescicle vescicle – Types of endocytosis Phagocytosis – cell eating Pinocytosis – cell drinking Osmosis Osmosis Deals with water across a membrane Osmosis is the term used for diffusion of Osmosis water across a membrane. water Special pores called aquaporins created Special aquaporins by proteins for this Tonicity Tonicity Is related to OSMOTIC PRESSUREIsotonic, Hypotonic and Hypertonic Isotonic, Solutions Solutions H e r e is h o w o s m o s is wo r ks : O s m o s is illus t r at e d : T wo s o lut io ns s e par at e d b y a s e m i ­ pe r m e ab le m e m b r ane . W h ic h is h y pe r t o nic ? W h ic h d ir e c t io n d o e s wat e r t r ave l? W h at h appe ns wh e n y o u plac e a r e d b lo o d c e ll in d if f e r ing s o lut io ns ? T h is is a plant c e ll in a h y pe r t o nic s o lut io n. • Remember, a plant cell has a r igid wall. • Wat er is drawn out , and t he membrane shrinks. – Pulled f rom cell wall. – This is called “plasmolysis” versus crenat ion in animal cells. i W h at ab o ut c e lls plac e d int o h y po t o nic s o lut io ns ? A nim al Ce lls Plant c e lls No t ic e t h at all o f t h e s e c e lls s we ll, b e c aus e wat e r r us h e s int o t h e m . A nim al c e lls c an b ur s t ( h e m o ly s is ) , b ut plant c e lls ( t ur g o r pr e s s ur e ) c an’t . Receptor-Mediated Endocytosis Receptor-Mediated VERY SPECIFIC or SELECTIVE VERY SELECTIVE Receptors for target molecules are Receptors internalized in a vesicles internalized Flu and cold viruses enter your cells via RM endocytosis. Cytoplasmic Organelles Cytoplasmic Ribosomes – Made of protein and RNA – Sites of protein synthesis – Found at two locations Free in the cytoplasm Attached to rough endoplasmic reticulum reticulum Transcription and Translation Transcription Transcription – Transfer of information from DNA’s base Transfer sequence to the complimentary base sequence of mRNA sequence Translation – Base sequence of nucleic acid is translated to Base an amino acid sequence an – Amino acids are the building blocks of Amino proteins proteins Role of RNA Role Transfer RNA (tRNA) – Transfers appropriate amino acids Transfers to the ribosome for building the protein protein Ribosomal RNA (rRNA) – Helps form the ribosomes where Helps proteins are built proteins Messenger RNA – Carries the instructions for Carries building a protein from the nucleus building to the ribosome to RIBOSOME in ACTION RIBOSOME The ribosome has a The Large subunit and a Large Smaller subunit The nucleic acid The strand is in the middle ( with a code for a protein) protein) The beads are a The nascent polypeptide nascent Protein Synthesis Protein Figure 3.16 ...
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This note was uploaded on 12/08/2011 for the course AMY 10 taught by Professor Dianeolin during the Winter '09 term at Riverside Community College.

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