Bellringer-December 5, 2014 (Label the letters) Extracellular Fluid Cytoplasm

December 5, 2014 What types of molecules passes easily? What types of molecules does not pass easily and needs assistance?

Answers a-glycoprotein B-glycolipid C-Oligosaccharide chains (attached to glycoprotein) D-nonpolar tails (fatty acid tails) (hydrophobic tails) E-Phosopholipid bilayer F-Polar heads (hydrophilic heads) (phosphate head) G-Peripheral protein H-cholesterol I-Integral Protein J-Cytoskeleton

Cell Movement: PassiveTransport Honors Biology Ms. Kim

Membrane structure LEADS TO selective permeability A cell must exchange materials with its surroundings a process controlled by the selectively permeable plasma membrane

Cell Transport Means moving things INTO and OUT of the cell Cells need to take in Food Get rid of waste products (excretion) Give out such useful substances as hormones and enzymes (secretion).

Permeability and Cell Transport Hydrophobic (non polar) molecules Are lipid soluble (can dissolve) can pass through membrane easily Ex: Hydrocarbons, CO2, O2 Hydrophilic (Polar) molecules Are NOT lipid soluble (can’t dissolve) Lipid INsoluble Do not cross membrane easily Ex: Na+, Cl- , Glucose/ other sugars NOTE: CHARGED molecules need “help” to cross membrane NOTE: LARGE molecules, POLAR molecules need “help”

Types of Cellular Transport high low Weee! Passive Transport cells do NOT use energy Diffusion Facilitated Diffusion Osmosis Active Transport cells DO use energy Protein Pumps Endocytosis Exocytosis high low This is going to be hard!

1) Diffusion Diffusion: Movement of molecules from a high concentration to a lower concentration Does not use energy Can occur in non-living systems (ex: dye) Concentration: Number of molecules of a substance in a given volume Concentration gradient: Difference in concentration of a substance from one location to another

Types of Passive Transport Diffusion is the tendency for a population of molecules (of ANY substance) to spread out evenly into available space A “net” movement Ex: Perfume, a fart , tea, food coloring in water (see demo) http://www.indiana.edu/~phys215/lecture/lecnotes/lecgraphics/diffusion2.gif http://www.biosci.ohiou.edu/introbioslab/Bios170/diffusion/Diffusion.html

DIFFUSION In absence of other forces… Molecules move (diffuse) from area of HIGH [ ] to an area of lower [ ] A.k.a. Molecules move DOWN its OWN concentration gradient No chemical work (ATP energy) is used diffusion is spontaneous!

Substances diffuse down their OWN concentration gradient Figure 7.11 B (b) Net diffusion Equilibrium

copyright cmassengale The Plasma Membrane 4/20/2017 Diffusion of Liquids copyright cmassengale G. Podgorski, Biol. 1010

Factors Affecting Diffusion 1. Temperature Higher temperature  more kinetic energy  molecules move faster 2. Pressure Higher pressure  molecules move faster ExampleTea: Higher temperature and more pressure (twirling/stirring) it around) makes diffusion happen faster.

2) Facilitated Diffusion Molecules move down (not against) a concentration gradient with the aid of special proteins (channel or carrier proteins) Speeds up the process Proteins CAN change SHAPE Does NOT use energy (NO ATP NEEDED) = type of passive transport Moves things from high to low concentrations Moves POLAR molecules  can NOT easily pass through the membrane on it’s own. Example: ions, smaller polar molecules (ex: sugar)

Channel proteins -Provide “tunnels” Channel Proteins animations Channel proteins -Provide “tunnels” Figure 7.15 EXTRACELLULAR FLUID Channel protein Solute CYTOPLASM A channel protein (purple) has a channel through which water molecules or a specific solute can pass. (a)

Carrier proteins -Undergo a subtle change in shape “carry” solute across the membrane

3. Osmosis Osmosis: – diffusion of water across a membrane Water moves across a semi-permeable membrane from an area of high water concentration to an area of low water concentration If water can cross a membrane, but the solute cannot, then… The water moves towards the side with MORE solute to balance the concentrations

Effects of Osmosis on Water Balance The movement of water (water diffusion) across a semipermeable membrane Involves the movement of FREE water molecules down a water [ ] gradient High solute low “free” water [ ] or…. Low solute  high free water [ ]

Osmosis is affected by the concentration gradient of dissolved substances (solutes) Osmosis animation

O S M I

Diffusion of H2O Across A Membrane The Plasma Membrane 4/20/2017 Diffusion of H2O Across A Membrane High H2O potential Low solute concentration Low H2O potential High solute concentration copyright cmassengale G. Podgorski, Biol. 1010

Osmoregulation Osmoregulation – control of water balance Turgor pressure – pressure inside a cell Tonicity – tendency of a cell to lose or gain water based on the solution it is in 3 Types of solutions: Isotonic Hypotonic Hypertonic

3 Different Types of Solutions Recall: SOLUTION = a uniform mixture of 2 or more substances ** compare solutions OUTSIDE cell to inside cell 1. ISOTONIC-Solution has same concentration of dissolved particles as the cell (same amount of solute outside and inside the cell) Water moves into and out of cell at equal rates and cell size remains constant Cell does not change shape There will be NO net movement of water

ISOTONIC SOLUTION Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium)

2. If a solution is hypertonic Solution has a higher concentration of dissolved particles than the cell (more solute outside of the cell than it is inside the cell) Water flows OUT of the cell The cell shrivels up and turgor pressure decreases “hyper” means more (high [solute]) Ex: when salinity increases in lake, fish can die! NaCl The water will move out of the fish towards the area with MORE solutes (ocean) to balance the concentrations! Poor fish…

HYPERTONIC SOLUTION Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis)!

3. If a solution is hypotonic Solution has a lower concentration of dissolved particles than the cell (less solute outside of the cell than it is inside the cell) Water flows INTO the cell The cell swells/gets big! Ex. Happens with distilled water Animals: Cytolysis (when a cell BURSTS!) “hypo” means “less” (low [solute]) Think: Hypo- sounds like hippo…hippos are big & round; cells in hypotonic solutions get big & round Also, think “hypo” is “low” meaning “low” solutes SURROUNDING cell “Hypo” is LOW!!!

HYP0TONIC SOLUTION Result: Water moves from the solution to inside the cell): Cell Swells and bursts open (cytolysis)!

Cell in ___________ Solution The Plasma Membrane 4/20/2017 Cell in ___________ Solution 10% NaCL 90% H2O ENVIRONMENT CELL NO NET MOVEMENT 10% NaCL 90% H2O What is the direction of water movement? Dynamic equilibrium The cell is at ____________________. G. Podgorski, Biol. 1010

Cell in ____________ Solution The Plasma Membrane 4/20/2017 Cell in ____________ Solution 10% NaCL 90% H2O ENVIRONMENT CELL 20% NaCL 80% H2O What is the direction of water movement? copyright cmassengale G. Podgorski, Biol. 1010

Cell in ___________ Solution The Plasma Membrane 4/20/2017 Cell in ___________ Solution 15% NaCL 85% H2O ENVIRONMENT CELL 5% NaCL 95% H2O What is the direction of water movement? copyright cmassengale G. Podgorski, Biol. 1010

Osmosis Animations for isotonic, hypertonic, and hypotonic solutions http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm

Real life examples

Water Balance of Cells with Walls Cell walls Help maintain water balance Cell walls are in: Plants Prokaryotes Fungi Some protists

Plant Cells & Solutions Isotonic (Flaccid) Plant cells at isotonic solutions are flaccid (can also be in hypertonic solution) Cells are limp Hypotonic (Turgid) Plant cells prefer hypotonic solutions because the cell wall provides more support and plant cells are less likely to lyse (burst) Turgor pressure increases (vacuole fills with water) It is very firm A healthy state in most plants Plasmolysis Video - http://teachertube.com/viewVideo.php?video_id=135394 Hypertonic (Plasmolysis) Plants wilt, undergo plasmolysis The cytoplasm and plasma membrane begin to pull away from the cell wall Causes cell with walls to wilt & can be lethal.

Water balance in cells with walls Plant cell. Plant cells are turgid (firm) and generally healthiest in a hypotonic environment, where the uptake of water is eventually balanced by the elastic wall pushing back on the cell. (b) H2O Turgid (normal) Flaccid Plasmolyzed Figure 7.13

Types of Cellular Transport #1 Passive Transport DOES NOT require chemical energy (ATP) #2 Active Transport DOES require chemical energy (ATP)

Exit Slip-December 5, 2014 Draw 3 cells in the following solutions AND draw water direction the water is moving (draw dots to represent the SOLUTE): Hypertonic solution Hypotonic solution Isotonic solution