the life function that involves the absorption (taking in) and circulation (moving around) of materials throughout an organism.
• the process where digested (broken down) nutrients as well as other dissolved materials enter the cells of an organism• the key organelle that is involved with this life function is the PLASMA (CELL) MEMBRANE
Polar heads Fluid Mosaic love water Model of the & dissolve. cell membrane Non-polar Membrane move tails hide from water. Carbohydrate cell markersProteins
Cell membranes have pores (holes) in it a.Selectively permeable: Allows some molecules in and keeps other molecules out b. The structure helps it be selective! Size (macro or micro), charge (+ or -) and solubility (lipid- soluble or not) affect a molecule’s ability to cross the cell membrane. In general, small noncharged, lipid-soluble molecules easily cross the cell membranes
Remember. it is a double lipid layer with floating proteins... We also can call the plasma membrane the fluid mosaic model. Fluid because the double layermoves around, it never is motionless. A mosaic because that is how it appears--a mosaic is a piece of artthat is made up of lots of little pieces put together.
a. Phosphate head is polar (hydrophilic or water loving)b. Fatty acid tails non-polar (hydrophobic or water fearing)c. Proteins embedded in membrane
• the transport of materials within one cell and/or the transport of materials throughout a multicellular organism• for unicellular organisms, intracellular (inside the cell) circulation is accomplished by the endoplasmic reticulum, Golgi complex, and CYCLOSIS (cytoplasmic streaming).• for multicellular organisms, intercellular (between cells) circulation is accomplished by the diffusion or transport through vascular tissues (like xylem,
(HighLow) * it is called passive transport because NO ENERGY or ATP IS REQUIRED!!! Weeee!!!1. Diffusion2. Facilitated Diffusion high3. Osmosis Tonicity low Water Potential
1. Diffusion2. Facilitated Diffusion – diffusion with the help of transport proteins3. Osmosis – diffusion of water
• *diffusion is where very small particles move from a region of high concentration (a large amount) to a region of lower concentration (a smaller amount).• * molecules move in straight lines in a random direction• * diffusion usually happens until the concentration is the same throughout; this is called EQUILIBRIUM (a balanced state-- HOMEOSTASIS!)• Note: molecules will still move around but stay spread out.
Occurs in liquid or gas mediumDiffusion of a solute within a solvent is affected by several factors: Temperature Pressure Density of the solvent Concentration Gradient Solubility of the solute http://bio.winona.edu/berg/Free.htm
* larger molecules suchas polysaccharides,proteins, and lipidscannot fit, because theyare too big
Passive Transport:2. Facilitated Diffusion2. Facilitated diffusion: diffusion of specific particles through membrane transport proteins to help them move through the cell membrane a. Transport Proteins are specific – they “select” only certain molecules to cross the membrane b. Transports larger or charged molecules c. Concentration gradient required – can’t transport from low to high concentration d. Energy not needed e. Rate of transport reaches a maximum when all membrane transport proteins are used up (saturated) f. Membrane transport proteins are sensitive to inhibitors that can cause them not to function
Passive Transport:2. Facilitated Diffusion A B There are 2 types of membrane transport proteins involved: Channel proteins – contain tunnels/openings that serve as Facilitated passageways of molecules Diffusion diffusion (Lipid Bilayer) (Channel Carrier proteins – undergo Protein) temporary binding to the molecule it carries resulting in conformational change that moves the molecule through the membrane Carrier Protein
the diffusion of water through a semi-permeable membrane
•Water moves freelythrough pores.•Solute (green) to largeto move across.
Water Potential – term for movement of water molecules as it undergoes osmosis - The measure of the difference between the “force” that pushes water molecules and the “force” exerted by the membraneWater solution with less solute (more diluted solution because of more water) = higher water potentialWater solution with more solute (more concentrated solution) = lower water potentialWater Potential Gradient - when 2 solutions of different water potentials are separated by a semipermeable membrane, thus allowing osmosis to occurOsmotic Pressure – “force” that moves water molecules through a semi- permeable membrane
If the concentration of solute (salt) is equal on both sides, the water willmove back in forth but it wont have any result on the overall amount ofwater on either side."ISO" means the same
"HYPO" means less In this case there are less solute (salt) molecules outside the cell, since salt sucks, water will move into the cell, causing it to swell. The cell will gain water and grow larger. As osmosis continues, osmotic pressure builds up inside the cell causing cell lysis.In plant cells, the vacuoles will fill and the plant becomes stiff and rigid.The pressure exerted by the water molecule is called TURGORPRESSURE, and the phenomenon TURGIDITY. The turgor pressure inplants will not result in cell lysis as the cell wall keeps the plant frombursting.TURGIDITY is important in maintaining the firm and erect position of aplant.
• Osmosis Animations for isotonic, hypertonic, and hypotonic solutionsHypotonic: The solution has a lower concentration ofsolutes and a higher concentration of water thaninside the cell. (Low solute; High water)Result: Water moves from the solution to inside thecell): Cell Swells and bursts open (cytolysis)!
"HYPER" means moreIn this case there are more solute (salt) molecules outside the cell, whichcauses the water to be sucked in that direction.Causes cells to shrink and lose shape because of water loss.In plant cells, the central vacuole loses water and the cells shrink, causingwilting (plasmolysis). In animal cells, the cells also shrink.In both cases, the cell may die.
• Osmosis Animations for isotonic, hypertonic, and hypotonic solutionsHypertonic: The solution has a higher concentrationof solutes and a lower concentration of water thaninside the cell. (High solute; Low water) shrinksResult: Water moves from inside the cell into thesolution: Cell shrinks (Plasmolysis)!
Passive Transport:3. OsmosisTonicity – strengthof a solution inrelation to osmosis3 Types:IsotonicHypotonicHypertonic Remember: Salt is a solute, when it is concentrated inside or outside the cell, it will draw the water in its direction. This is also why you get thirsty after eating something salty.
What type of solution are these cells in ? A B C Hypertonic Isotonic Hypotonic
•Bacteria and plants have cell walls that prevent themfrom over-expanding. In plants the pressure exerted onthe cell wall is called tugor pressure.•A protist like paramecium has contractile vacuoles thatcollect water flowing in and pump it out to prevent themfrom over-expanding.•Salt water fish pump salt out of their specialized gills sothey do not dehydrate.•Animal cells are bathed in blood. Kidneys keep theblood isotonic by remove excess salt and water.
* a process where a cell USES ENERGY or ATP to move molecules from a region of low concentration to a region of high concentration * special proteins called carrier proteins This is often called pumps are used to move gonna be hard molecules from one side of the membrane work!! high to the other low
Example: Sodium-Potassium Pumpsare important in nerveresponses. Theytransfer Na and Kions in and out of thenerve and musclecells. Protein changes shape to move molecules: this requires energy!
EXOCYTOSIS – going out of the cell ENDOCYTOSIS - going inside the cell Pinocytosis: * a process where very large (too big to go through the plasma membrane) particles are "sucked in" to a cell, forming a vacuole. * "cell drinking"--uses energy (active transport)
1. Endocytosis: taking bulky material that can’t use transport proteins (like macromolecules) into a cell • Uses energy • Cell membrane in-folds around the macromolecule to be transported • 3 Types: Phagocytosis Pinocytosis Receptor-mediated Endocytosis
ENDOCYTOSIS - going inside the cell Phagocytosis: * a process where a cell engulfs large undissolved particles, forming a vacuole * "cell eating"--uses energy (active transport)
Receptor-mediated Endocytosis – “cell drinking”- Compared to pinocytosis, is very specific. The plasma membrane becomes indented and forms a pit. The pit lined with receptor proteins picks specific molecules from its surroundings. The pit will close and pinch off to form a vesicle which will carry the molecules inside the cytoplasm.
2. Exocytosis: Forces material out of cell in bulk • membrane surrounding the material fuses with cell membrane • Cell changes shape – requires energy • EX: Hormones or wastes released from cell