Cell Membrane Transport Notes PDF

Cell Membrane Transport.notebook December 09, 2015 Do Now Problems: 1. Compare and contrast the lysosome with the vacuole. 2. Draw the Lewis dot diagram for CaCl2...

Cell Membrane Transport.notebook December 09, 2015 Do Now Problems: 1. Compare and contrast the lysosome with the vacuole. 2. Draw the Lewis dot diagram for CaCl2 May 15­7:49 AM Transport Across Cell Membranes Recall that only certain substances are allowed to cross the membrane (selective transport) May 16­8:46 AM 1 Cell Membrane Transport.notebook December 09, 2015 Concentration gradient: all matter is made up of particles which are in constant, random motion (BROWNIAN MOTION) http://www.youtube.com/watch?v=6VdMp46ZIL8 This random motion results in a net movement toward areas where the concentration of particles is lower. o E.g.: tea, Kool­Aid The difference in concentration between the two areas: concentration gradient. o Particles will always move “down” a concentration gradient o High concentration à low concentration Once particles are evenly distributed = equilibrium Recall: solute = that which is dissolved Solvent = that which does the dissolving May 16­8:53 AM Passive Transport Brownian motion and concentration gradient help move materials across membranes. (From high concentration to low concentration) this does not require additional energy May 16­8:56 AM 2 Cell Membrane Transport.notebook December 09, 2015 1) Diffusion Particles (small) move across the membrane from high concentration to low concentration o E.g.: O2 needed for cellular respiration o (There is always a high concentration on the outside so O2 constantly diffuses into the cell. o E.g.: CO2 diffuses out from high concentration to low concentration May 16­8:59 AM 2) Osmosis Diffusion of water across cell membrane from high concentration to low concentration 3 situations: a) Hypotonic solution o [water] high outside of the cell o Water will flow into the cell o Solution outside cell is hypotonic to inside b) Hypertonic solution o [water] high inside the cell o Water will flow out of the cell o Solution outside cell is hypertonic to inside c) Isotonic solution o Equal concentration = In equilibrium o An equal amount of flow in and out of cell. cells must maintain water balance as too much or too little can kill the cell (burst or shrivel up) plants can withstand increased water in the cells (with the help of the cell wall) = turgor pressure (keeps the cells firm) May 16­9:04 AM 3 Cell Membrane Transport.notebook December 09, 2015 May 16­9:06 AM May 16­9:06 AM 4 Cell Membrane Transport.notebook December 09, 2015 3) Facilitated diffusion A way for large and charged particles to enter/leave the cell Transport proteins aid the diffusion across the membrane Still move from [high] à [low] therefore passive transport Two types of transport proteins: Carrier proteins o E.g.: glucose o Fits into protein, which changes shape and releases glucose on the other side of the membrane (see Figure b below) Channel proteins o Acts like a tunnel to allow movement (see next Figure) May 16­9:06 AM May 16­9:07 AM 5 Cell Membrane Transport.notebook December 09, 2015 http://www.youtube.com/watch?v=9QCxTf0QfTo Diffusion and Osmosis http://www.youtube.com/watch?v=SSS3EtKAzYc Egg in hypo & hypertonic solution https://authoring.concord.org/activities/1066/single_page/21e52caa­f476­4c94­a992­9d407eb7e92b May 23­7:28 PM Active transport When you must move molecules against the concentration gradient o [low] à [high] = moving against the concentration gradient o Requires energy aka active Proteins use energy to transport particles. o E.g.: minerals from soil into already mineral rich roots. May 16­9:07 AM 6 Cell Membrane Transport.notebook December 09, 2015 Other: Endocytosis and Exocytosis ­ see page 305 Some molecules cannot be transported across the membrane Endocytosis (aka phagocytosis (solid) and pinocytosis (liquid)) bringing into cell cell membrane forms a pocket around the molecule encloses the molecule and pinches off to form a vesicle May 16­9:14 AM Exocytosis taking out of a cell reverse of endocytosis May 16­9:15 AM 7 Cell Membrane Transport.notebook December 09, 2015 http://www.youtube.com/watch?v=kfy92hdaAH0 After 3 minutes phagocytes May 23­7:45 PM Read pg 297­307 CYU # 1­5, 7 May 16­9:16 AM 8 Cell Membrane Transport.notebook December 09, 2015 Cell Size and Function May 25­7:30 AM Once a particle is inside a cell, diffusion carries it around the cytoplasm and, eventually, to where it can be used. This takes time because the concentration gradient disappears once inside the cell See Figure 8.21 for an example of diffusions limitations. May 25­7:35 AM 9 Cell Membrane Transport.notebook December 09, 2015 The important ratio for a cell s size is its surface area to volume ratio. Volume increases faster than surface area as a cell grows. The smaller the ratio, the harder it is for a cell to obtain what it needs and to move it around inside the cell. May 25­7:37 AM Read pages 308 to 314 and answer questions 1 ­ 5 on page 314. May 25­7:39 AM 10 Cell Membrane Transport.notebook December 09, 2015 To study for your quiz tomorrow: ­Read pgs. 297­314 in textbook ­Pg. 307 #1­5, 7 ­Pg 314 #1­5 ­Topic 1­2 Practice questions (handout) Dec 9­7:37 AM 11