Essential Question How does a cell both protect

Essential Question: How does a cell both protect itself from hazards in its environment and allow resources from that environment in to carry out lifesustaining functions? INB Pg. 35

A. The cell membrane undergoes SELECTIVE PERMEABILITY - Allowing only certain substances in & out of the cell. (due to molecule size & polarity)

B. Cell Membrane structure 1. comprised of a lipid bilayer (2 layers) a. lipids (fats) are compounds that are insoluble in water. b. lipids have two ends: 1). Polar Head end, “loves water” (hydrophilic) 2). Nonpolar 2 tail ends, “fear water” (hydrophobic) c. bilayer arrangement: (lets draw it)

C. How does nutrients get in & waste get out… 1. Simple diffusion: small/nonpolar molecules pass through the cell membrane using a concentration gradient. a. Concentration gradient= one side of the membrane contains an area with a higher # of particles & the other side has a lower # of particles. b. particles move from an area of higher concentration to an area of low concentration = HOMEOSTASIS (balance)

2. Osmosis: simple diffusion of WATER across a cell membrane Big Idea: large molecules cannot diffuse (fit) across the membrane, so water moves to achieve homeostasis http: //highered. mheducation. com/sites/00724958 55/student_view 0/chapter 2/animation__how_osm osis_works. html Let’s go back to our Cell Transport Model

HW: Analysis Questions -Answer these questions directly under your cell transport notes. 1. Why does this arrangement allow for molecules with one hydrophobic end and one hydrophilic end to exist in an environment that has water on both sides? 2. Explain the science behind this the slug cartoon. Include a labeled drawing in your explanation.

a. Osmotic Solutions 1. Hypotonic- contains low amount of solute compared to the solution on the other side of the membrane. *cell placed in a hypotonic solution = swelling & bursting. Plant cells don’t burst because of cell wall. Don’t put me in a lake!!

a. Osmotic Solutions 2. Hypertonic- contains a high amount of solute compared to the solution on the other side of the membrane. *cell placed in hypertonic solution = shriveling

a. Osmotic Solutions 3. Isotonic- concentration of solutes is equal on both sides. *water moves in & out at even rate.

3. Facilitated diffusion- larger molecules (sugar) that cannot fit through the membrane use a Protein channel.

4. Active Transport- moving substances AGAINST the concentration gradient (from low to high) a. Protein Pumps- proteins across the membrane send molecules from low to high concentration. Ex: Body cells must pump carbon dioxide out into the surrounding blood vessels to be carried to the lungs for exhale. Blood vessels are high in carbon dioxide compared to the cells, so energy is required to move the carbon dioxide across the cell membrane from LOW to HIGH concentration.

b. Endocytosis- moving bulk material INTO the cell through fusing with the cell membrane. c. Exocytosis- moving bulk materials OUT of the cell

Types of Cellular Transport • Passive Transport cell doesn’t use energy 1. Diffusion 2. Facilitated Diffusion 3. Osmosis • Weeee!!! high low Active Transport cell does use energy 1. Protein Pumps 2. Endocytosis 3. Exocytosis This is gonna be hard work!! high https: //www. youtube. com/watch? v=Ptmlvtei 8 hw low

Processing Point -Complete this task directly under your notes on Pg. 36 or 37 5 word Summaries: -Use ONLY five words to describe the following cell transport terms. *Diffusion *Osmosis *Facilitated diffusion *Endocytosis *Exocytosis *Protein pumps