Chapter 3: Cells: Living Units – Flashcards

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cells
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the basic unit which make up all living organisms, over 200 different types found in the body
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3 parts of basic cell
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1. plasma membrane 2. cytoplasm 3. nucleus
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The ______ ______ acts as a boundary between the intracellular fluid and extracellular fluid.
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plasma membrane
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Describe the composition of the plasma membrane.
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bilayer of phospholipids with proteins embedded in it
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fluid mosaic model
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model of the plasma membrane
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What part do proteins play in the "fluid mosaic model"?
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mosaic pattern
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What part do phospholipids play in the "fluid mosaic model"?
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fluidity
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2 major components of plasma membrane
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1. phospholipid 2. protein
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Phospholipid
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has polar "head" region which is hydrophilic has nonpolar "tail" region of 2 fatty acid chains which is hydrophobic
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Protein
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gives stability to the membrane found throughout the membrane - providing an everchanging mosaic pattern
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2 types of membrane proteins
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1. integral 2. peripheral
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____ proteins are inserted into the membrane - most span entire width of the membrane.
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integral
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____ proteins are attached to integral proteins.
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peripheral
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What component makes up 20% of the membrane lipids and provides stability to the membrane?
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cholesterol
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What is the function of the glycocalyx?
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bio markers > cells recognize each other so body doesn't attack the cells
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3 types of membrane junctions that help to bind cells together
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1. tight junctions 2. desmosomes 3. gap junctions
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tight junctions
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this type of junction is formed by the fusing of protein molecules of adjacent cells, thereby producing an impermeable junction.
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desmosomes
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this type of junction is formed by anchoring junctions that bind adjacent cells together by the use of protein filaments that extend out from plaques.
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gap junctions
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this type of junction is formed by channels between cells which allow chemical substances to pass between the cells.
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The plasma membrane plays a part in membrane transport - it is said to be a _____ barrier, letting some substances through while not allowing others.
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selective
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2 ways substances pass through the plasma membrane
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1. passive 2. active
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passive transport
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processes occur without the input of energy
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active transport
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transport requires the input of energy in the form of ATP
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Diffusion
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- passive process - the movement of molecules from areas of their higher concentration to areas of their lower concentration (so molecules are said to move down their concentration gradient)
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3 types of diffusion
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1. simple diffusion 2. facilitated diffusion 3. osmosis
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simple diffusion
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-occurs when nonpolar and lipid-soluble substances move through the membrane
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examples of nonpolar and lipid-soluble substances
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oxygen carbon dioxide fat-soluble vitamins alcohol
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facilitated diffusion
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occurs when substances move through the membrane by protein carriers or water-filled protein channels - so this is a highly selective process
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osmosis
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the diffusion of water through the selectively permeable membrane
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tonicity
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deals with solutions which change the shape of cells
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isotonic
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solution has the same concentration of nonpenetrating solutes as the cell - so the cell will retain its same shape in this type of solution
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hypertonic
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solution has a higher concentration of nonpenetrating solutes than the cell - so cell will lose water and shrink aka CRENATE
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hypotonic
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solution has lower concentration of nonpenetrating solutes than the cell - so cell will gain water and swell and possibly burst aka LYSE (LYSIS)
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Active transport is similar to facilitated diffusion in that it uses carrier proteins - but in active transport, _____ _____ are used to move substances against their concentration gradient.
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solute pumps
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2 types of active transport determined by their source of energy
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1. primary active 2. secondary active
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primary active transport
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- energy comes from ATP - example is the sodium-potassium pump where Na+ and K+ leak slowly through channels along their concentration gradient - if these 2 ions are left alone they would eventually balance themselves on both sides of the membrane, but the body pumps 2 K+ in and pumps 3 Na+ out during the action of the sodium-potassium pump. - this ionic concentration difference is essential for excitable cells like muscle and nerve cells to function
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secondary active transport
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- energy indirectly comes from primary active transport pumps , like Na+ - K+ pump. - all these systems are coupled which means they move more than one molecule at a time - after Na is pumped out by the Na+ - K+ pump, as NA moves back into the cell by facilitated diffusion it drags other substances with it like glucose
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vesicular transport
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- type of active transport that moves large particles and fluids across the membrane in membranous sacs called vesicles with the use of energy - exocytosis & endocytosis
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exocytosis
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moves substances out of the cell - a substance is first enclosed in a vesicle which moves to the membrane, fuses with it and then releases the substance out of the cell
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endocytosis
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moves substances inside the cell - Clathrin-coated vesicles are the major way how this occurs - substance is first enclosed by infolding of the membrane which leaves a clathrin coat produced by the cytoplasm side of the membrane forming then a vesicle - 3 types
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3 types of endocytosis
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1. phagocytosis 2. pinocytosis 3. receptor-mediated endocytosis
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phagocytosis
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"cell eating" occurs when substance is engulfed by the cell - vesicle formed is called a phagosome and fuses with lysosome to allow digestion of the contents
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pinocytosis
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"cell drinking" occurs when membrane infolds forming a vesicle to take in fluid
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receptor-mediated endocytosis
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most common of all 3 types of endocytosis selective type of endocytosis because there are specific receptors on the membrane for only certain substances to bind to
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3 structures that compose the cytoplasm
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1. cytosol 2. organelles 3. inclusions
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cytosol
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the fluid in which organelles and such are found
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organelles in cytoplasm
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mitochondria ribosomes endoplasmic reticulum (rough & smooth) golgi apparatus lysosomes peroxisomes cytoskeleton centrioles cellular extensions
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