IWBAT Describe how molecules pass through a cell
IWBAT: Describe how molecules pass through a cell membrane Do Now: What? HW: Castle learning
Review HW • Demo food coloring in water • Youtube: Food Coloring Diffusion – https: //www. youtube. com/watch? v=STLAJH 7_zk. Y
• Demo raw egg in vinegar • Youtube: Bouncing Rubber Egg - Naked Egg Science Experiment – https: //www. youtube. com/watch? v=f. EYS 5 i 5 P 7 YY • COCA COLA Vs EGG Vs vinegar – Awesome eggs fun life hacks and tricks – https: //www. youtube. com/watch? v=ndt. Ny 3 Z 0 Bk o • The Sci Guys: Science at Home - SE 1 - EP 14: The Naked Egg and Osmosis – https: //www. youtube. com/watch? v=Sr. ON 0 n. EEW mo
• Egg Osmosis (Hypertonic vs. Hypotonic Solution) – https: //www. youtube. com/watch? v=SSS 3 Et. KAz. Yc
Cell membrane or Plasma membrane • Function: Regulates the flow of materials into and out of the cell, thus maintaining homeostasis within the cell • The cell membrane is SEMI-PERMEABLE which means it allows certain substances to pass through
Cell membrane or Plasma membrane • It is made up of a lipids and proteins • Cell membrane has receptors that allow certain materials to pass. This occurs through the proteins
Cell membrane or Plasma membrane • Cell Membrane acts like our “skin” because they can both excrete wastes
Cell membrane or Plasma membrane • Nutrients must get IN • Waste products must get OUT
Cell membrane or Plasma membrane • Has receptors on its surface which allows the cells to recognize hormones and communicate with other cells.
Cell membrane or Plasma membrane • Has receptors on its surface which allows the cells to recognize hormones and communicate with other cells.
Life process: homeostasis: stimulus and response
Cell membrane or Plasma membrane • Cell Membrane does NOT protect you from harmful substances entering your body. This virus attaches to receptors on the cell membrane
Membrane transport animation • https: //www. youtube. com/watch? v=I 1 MZG 65 08 IM • 3: 18
The Amoeba Sisters explain… • Cell membranes and cell transport • https: //www. youtube. com/watch? v=Ptmlvtei 8 hw • 7: 49
• Biology cell transport • https: //www. youtube. com/watch? v=uf. Ci. Gz 75 DAk • 2: 02
transport • The absorption and movement of nutrients through a cell membrane
2 types of transport at a cellular level • Passive transport (Ex: Diffusion or Osmosis) • Active transport
Where is the area of high concentration?
The movement of molecules from an area of higher concentration to lower concentration across the cell membrane.
When there is no net movement of molecules into or out of the cell, it is said to be in equilibrium.
Diffusion is an example of passive transport • When particles move from as area of high concentration to low concentration • Passive transport because NO energy (ATP) is needed. The particles move on their own.
– The goal of both diffusion and osmosis is to reach EQUILIBRIUM within the cell – Equilibrium is when the movement in one direction is equal to the movement in the opposite direction
• Molecules in motion “bounce” off each other and spread out in all directions until there is an equal distribution of molecules in the area.
What materials diffuse into and out of the cell and why? • Materials needed to maintain homeostasis diffuse into and out of the cell. • The size and charge of the material usually determines if the materials will be allowed across the membrane using diffusion. • Ex: Starch is a big molecule and can’t pass through a membrane. Glucose is a small molecule and can pass through a cell membrane
The diagram below represents a laboratory setup used to demonstrate the movement of molecules across a selectively permeable membrane. Before movement
In the diagram below, draw the 5 starch and the 12 glucose molecules to show where they would most likely be located after 15 minutes.
Check
What type of molecules enter and leave the cell? Materials needed for homeostasis ENTER the cell. These include: 1. Oxygen 2. Glucose 3. Digested nutrients (amino acids, fatty acids) Waste materials from the life functions that EXIT the cell include: 1. Carbon dioxide 2. Urea
Passive Transport Animation https: //www. youtube. com/watch? v=JShw. XBW GMy. Y (not necessary)
Key Points: 1. The cell membrane controls what enters and leaves the cell. 2. Passive transport is the movement of materials into or out of the cell which does not require energy (ATP). 3. Diffusion is one type of passive transport in which materials move from higher concentration to lower concentration. 4. Only small materials diffuse easily across the cell membrane.
Osmosis • Passive transport of water
Diffusion of H 2 O Across A Membrane Water molecules moving from an area of higher concentration to an area of lower concentration High H 2 O potential Low solute concentration Low H 2 O potential High solute concentration 37
What happens when cells are placed in various solutions? • When cells are placed in pure (100%) water… water enters the cell by osmosis and causes the cell to swell and eventually burst and is permanently destroyed. • When cells are placed in salt or sugar solutions… water leaves the cell by osmosis and the cell shrinks and gets smaller. This process may be reversed.
Three Relationships of Solutions Which beaker demonstrates the changes of a cell in… Salt water? Fresh water?
Three Relationships of water movement Which RBC’s demonstrates the changes of a cell in… Salt water? Fresh water?
Osmosis in the plant cell: • The plant cell will swell when placed in pure water, but will not burst due to the cell wall. • When placed in salt water, only the inside of the cell and cell membrane will shrink, the cell wall remains the same. Cell membrane Cell wall cytoplasm
When cells are placed in pure water, they will burst; when placed in salt water, they will shrink. Cells in pure water will swell and burst A plant cell will swell but not burst. A cell in salt water gets shrinks! Plant cells have cell wall The inside of cell will shrink, but the cell wall will not.
Osmosis in Onion Cell
Osmosis in Onion Cell In pure water cells swell In salt water cells shrink
A wet-mount slide of red onion cells is studied using a compound light microscope. A drawing of one of the cells as seen under high power is shown below.
In the space below, sketch how the cell would look after the saltwater solution is added to it.
check
• So, answer this question…. Why do “establishments” offer free popcorn, peanuts, and pretzels to their patrons if they are serving beverages? What changes are taking place in the body to initiate the need for more beverages?
9: 27 (not necessary) https: //www. youtube. com/watch? v=Ia. Z 8 Mt. F 3 C 6 M AMOEBA SISTERS EXPLAIN OSMOSIS…
Watching the changes in mass of an egg in hypo/hypertonic solutions (5: 37) https: //www. youtube. com/watch? v=SSS 3 Et. KAz. Yc Oxygen Transport from Lungs to Cells (2: 14) https: //www. youtube. com/watch? v=5 Lj. LFrm. KTSA
Active transport • Moves particles from a low concentration to a high concentration • Requires energy (ATP) to push particles into a concentrated level through a cell membrane. • Proteins in the cell membrane help this process
Active transport • Moves particles from a low concentration to a high concentration • Requires energy (ATP) to push particles into a concentrated level through a cell membrane. • Proteins in the cell membrane help this process
Active Transport • Phagocytosis: cytoplasm of cell surrounds and engulfs particle (ex: white blood cells ingest germs!) • “Cell eating”
Active Transport • Phagocytosis: cytoplasm of cell surrounds and engulfs particle (ex: white blood cells ingest germs!) • “Cell eating”
Sci. Show Video • https: //www. youtube. com/watch? v=d. PKv. Hr. D 1 e. S 4 • 11: 44 Not necessary
Diffusion or active transport?
Review • Diffusion – the movement of molecules across the cell membrane (high to low); requires no energy (ATP). • Osmosis – the movement of water across the cell membrane; requires no energy (ATP). • In pure water, cells swell and burst • In salt and sugar solutions cells shrink and get smaller • Active Transport – uses energy (ATP) to move large molecules across membrane, or to go against normal flow of molecules (low to high).
Summary questions: 1. What is the name of the cell function which involves the movement of materials into/out of cell? 2. Which materials will diffuse into/out of the cell? 3. Why is no energy required for these materials to cross the cell membrane? 4. What happens to cells when placed in pure water and salt water? 5. Why do animal cells burst when they swell, but plant cells do not? 6. What is the process called when only water crosses the cell membrane? 7. State one possible reason a certain substance can not pass across a cell membrane. 8. Describe what will happen to red onion cells in a wet-mount slide when a saltwater solution is added to them.
Summary questions: 1. What is the name of the cell function which involves the movement of materials into/out of cell? diffusion 2. Which materials will diffuse into/out of the cell? Water, glucose, H 2 O, CO 2, waste 3. Why is no energy required for these materials to cross the cell membrane? The particles need to reach equilibrium 4. What happens to cells when placed in pure water and salt water? A cell in pure water swells; a cell in salt water shrinks
Summary questions: 5. Why do animal cells burst when they swell, but plant cells do not? Plant cells have a cell wall 6. What is the process called when only water crosses the cell membrane? Osmosis 7. State one possible reason a certain substance can not pass across a cell membrane. The molecules are too big 8. Describe what will happen to red onion cells in a wet-mount slide when a saltwater solution is added to them. The cell membrane will shrink
Membrane Transport and Diffusion mc
Living Environment workbook read p 7 -8 • Answer q 20 -35 p 9 -10
Summary questions: 1. What is the name of the cell function which involves the movement of materials into/out of cell? 2. Which materials will diffuse into/out of the cell? 3. Why is no energy required for these materials to cross the cell membrane? 4. What happens to cells when placed in pure water and salt water? 5. Why do animal cells burst when they swell, but plant cells do not? 6. What is the process called when only water crosses the cell membrane? 7. Why does the cell expend (use) energy to bring some materials into or out of the cell? 8. Give at least one example of when cells use active transport.
- Slides: 67