Chapter 3 Cell Processes Learning Target l I can. l 1)Explain the difference between diffusion and osmosis. l 2)Predict the movement of particles into and out of a cell. 1
Section 3.2 MOVING CELLULAR MATERIAL All cells must obtain and use materials for energy.. Copyright Cmassengale 2
ATP " Stands for Adenosine triphosphate " Also known as energy. " It s the fuel for cells. " How do cells get energy?... " Cells break down sugar and fats to help release energy. " This energy is transferred to ATP which the cell can use. " The energy must be transferred to ATP before the cells can use it. 5 Quickcheck: l Which organelle in a cell is responsible for the production of ATP? l MITOCHONDRIA Copyright Cmassengale 3
Remember me: The Cell Membrane 7 Cell Membrane The cell membrane is made of 2 layers of phospholipids called the lipid bilayer 8 4
Close that window!!! l There are many reasons we open and shut the windows in our house. l Do you want to let all of the bugs and leaves in? l A window screen provides the protection to keep unwanted things outside. But it also allows some things to pass into and out of the room like air, unpleasant odors, or smoke. l How does the cell membrane carry out similar functions to that of a window screen? The cell membrane l A cell membrane, like a screen, will let some things through more easily than others. l Ex: Air gets through a screen, but insects are kept out. l A cell s membrane is selectively permeable. In other words it allows some things to enter or leave the cell while keeping other things outside or inside of the cell. 5
l Materials that are soluble in lipids can pass through the cell membrane easily Solubility 11 What determines how particles move in and out of the cell? l Which way particles moves depends on the l a) size of the molecule or particle, l B) the path taken through the membrane, c) whether or not energy is used. Copyright Cmassengale 6
Semipermeable Membrane Small molecules move through the cell membrane very easily. e.g. (O 2, CO 2, H 2 O) 13 Semipermeable Membrane Molecules larger than water (such as proteins) do not move through the membrane on their own. 14 7
Types of Transport Across Cell Membranes 15 Moving things without energy l The movement of substances through the cell membrane without using energy is called passive transport. l The cell membrane can move things into and out of the cell without using energy either by: l Simple Diffusion l Osmosis 8
Diffusion Simple Diffusion v Doesn t require energy v Moves materials from high to low concentration v Example: Oxygen and/ or water diffusing into a cell and carbon dioxide diffusing out. 17 Simple Diffusion l In other words l Molecules move from crowded to less crowded areas of concentration. l This can occur in solids, liquids, and gases. 18 9
Diffusion in action.. l You might smell perfume when you sit near or walk past someone wearing it. This is because the perfume molecules are randomly moving throughout the air. l The molecules are going from an areas that is crowded (such as inside the bottle) to a less crowded l l area (such as the air itself). There s more space for the molecules to spread out and move in the air. l Diffusion stops once there is an equal number of molecules in both areas. l The molecules are in equilibrium. Diffusion is a PASSIVE process which means no energy is used to make the molecules move, they have a natural KINETIC ENERGY DIFFUSION 20 10
Diffusion of Liquids 21 Diffusion through a Membrane Cell membrane Solute moves DOWN concentration gradient (HIGH to LOW) 22 11
Remember there are three factors that determine how particles move in and out of the cell: l Which way particles moves depends on the l a) size of the molecule or particle, l B) the path taken through the membrane, c) whether or not energy is used. Copyright Cmassengale Diffusion Simple Diffusion v Doesn t require energy v Moves materials from high to low concentration v Example: Oxygen and/ or water diffusing into a cell and carbon dioxide diffusing out. 24 12
Diffusion Because they are so small, molecules such as Oxygen, water, and carbon dioxide diffuse in and out of a cell at any point of entry. 25 Osmosis l Diffusion of water across a membrane l Moves from HIGH water potential (low solute) to LOW water potential (high solute) Diffusion across a membrane sem-i-permeable membrane 26 13
Molecules that are not so small. Such as Glucose (sugar) or amino acids (--a chain of proteins) Find transport proteins to provide doorways to help move material from high to low concentration 27 This is an example of how it works Molecules will spontaneously move through the pores of the cell membrane with the help of Channel Proteins that provide a doorway 28 14
Another example of how larger molecules can get across the cell membrane l Carrier proteins do not extend through the membrane. l They bond and drag molecules through the lipid bilayer and release them on the opposite side. 29 Sample problem. 10% NaCL 90% H 2 O ENVIRONMENT CELL 10% NaCL 90% H 2 O No net movement What is the direction of water movement? The cell is at. equilibrium 30 15
Practice:Sample 1 10% NaCL 90% H 2 O CELL 20% NaCL 80% H 2 O What is the direction of water movement? 31 Practice: sample 2 15% NaCL 85% H 2 O ENVIRONMENT CELL 5% NaCL 95% H 2 O What is the direction of water movement? 32 16
Practice 3 40% NaCl 60% H 2 O ENVIRONMENT CELL 20% NaCl 80% H 2 O What is the direction of salt (NaCl) movement? Practice 4 20% NaCl 80% H 2 O ENVIRONMENT CELL 90% NaCl 10% H 2 O What is the direction of salt (NaCl) movement? 17
Just a little more practice Draw the illustration 25% NaCl 65% H 2 O Outside Environment CELL 35% NaCl 35% H 2 O What is the direction of water movement? What is the direction of the salt (NaCl)? Explain your answers. Answer 25% NaCl 65% H 2 O Outside Environment CELL 35% NaCl 35% H 2 O What is the direction of water movement? What is the direction of the salt (NaCl)? Out of the cell Explain your answer. Into the cell Molecules move from areas of high concentration to lower concentration 18
A simple rule to remember is: salt sucks 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! 30% salt 70% water container 100% water 0% salt Flower The addition of salt in the container lowers the concentration of water. The water concentration is higher in the cells of the flower. What happens when you put salt on a snail? l They will shrivel up!!! l Why? l The bodies of snails and slugs contain much water in them. Due to the process of osmosis, in the scenario of salt and snails, the snails act as the area with high water concentration. On the other hand, the salt that you add to the snails has a low water concentration. l The snails really do not melt when we add salt. They dry up because too much water in their bodies is sucked out of them and into the salt. The poor snails shrivel up and die as a result. 19
What do you think? A fish that is accustomed to living in salt water is placed in fresh water. What do you predict might happen to the cells of the fish? A. They might shrink up and cause the fish to die. B. They would become healthier because the water is so fresh. C. They might swell and burst and cause the fish to die. The process of osmosis would explain the net movement of water into a cell if the percentage of A. water was 90% inside the cell and 95% outside the cell B. water was 95% inside the cell and 90% outside the cell C. protein was 30% inside the cell and 35% outside the cell D. water and protein was equal inside and outside the cell 20
Active Transport v DOES Require energy (ATP) v Moves materials from LOW to HIGH concentration. It goes v AGAINST the concentration gradient 41 Types of Active Transport Some transport proteins require energy to do work These Protein Pumps change shape to move molecules: this requires energy! Sodium Potassium Pumps (Active Transport using proteins) 21
2 Ways to Move the Big Stuff 1) Large molecules move materials into the cell by endocytosis. 43 Endocytosis. It takes in dissolved molecules as a vesicle is being formed. This is sometimes called Cell eating. 44 22
Now Watch it Work! J Endocytosis: taking bulky material into a cell Uses energy Cell membrane surrounds the food particle Called cell eating because it forms a food vacuole & digests food This is how white blood cells eat bacteria! Another Way to Move the Big Stuff 2) Exocytosismoving large things out. Large molecules are moved out of the cell by vesicles that fuse with the cell membrane through exocytosis. Exocytosis is how many hormones are secreted and how nerve cells communicate with one another. 46 23
Now Watch it work! J Exocytosis: a process that forces material out of cell in bulk Membrane surrounds the material and fuses with the cell membrane Cell changes shape requires energy EX: Hormones or wastes released from cell Endocytosis & Exocytosis animations Active vs Passive transport l Is similar to riding a bike It takes no energy to ride the bike and carry things downhill (passive transport) l But it takes energy to ride a bike to carry you uphill (active transport) 24
Types of Cellular Transport Animations of Active Transport & Passive Transport Passive Transport cell doesn t use energy 1. Diffusion 2. Facilitated Diffusion 3. Osmosis Active Transport cell does use energy 1. Protein Pumps 2. Endocytosis 3. Exocytosis high high Weeee!!! low low This is gonna be hard work!! SECTION 3.3 CELL ENERGY 50 25
Here are your Target Goals: l I can: l ---describe photosynthesis and cellular respiration. It Begins with Sunlight! 52 26
The sun s energy! Mostly all the earth s energy comes from the sun. Plants and some other types of organisms that contain chlorophyll are able to use the light energy from the sun to produce food. 53 Photosynthesis l Involves the Use Of Light Energy to convert Water (H 2 0) and Carbon Dioxide (CO 2 ) into Oxygen (O 2 ) and High Energy Sugar(C 6 H 12 O 6 or Glucose). 54 27
The Photosynthesis Equation 55 Pigments In addition to water, carbon dioxide, and light energy, photosynthesis requires pigments. Chlorophyll is the primary pigment that traps the sunlight and it is found inside the organelle called chloroplasts. 56 28
All organisms need energy. Animals and other organisms can not make their own food. l Instead they consume plants and other organisms as their source of food. l The food you eat has to be broken down so that the energy it contains can be converted into a form your cells can use. l Do you remember what that form of energy is? 57 How do we get our energy??.. l organisms break down food and release energy. through a process called l Cellular respiration --- it involves the use of oxygen.. It is also called aerobic respiration. 58 29
Chemical Equation for Cellular Respiration l Study this and tell me How is it similar to the equation for photosynthesis? Cellular respiration In most Eukaryotes l Cellular respiration takes place in the mitochondria of plants and animals. 60 30
Releasing Energy From ATP l Energy is released in your body in the form of ATP. It is constantly being used and remade by cells. l ATP provides all of the energy for cell activities. l Most of the energy released is in the form of heat (which your body uses to maintain body temperature). 61 A little senseless humor Copyright Cmassengale 31