Cellular Transport -movement across the cell membrane

Can you die from drinking too much water? YES. Sadly, a young woman died from participating in a radio contest called “Wee for a Wii”. When you drink excessive amounts of water, the kidneys cannot process it quickly enough to keep the body’s water/salt concentration balanced, so it moves from the bloodstream into cells by the process of OSMOSIS. Animal cells swell as water enters. Most cells have room for this, but not nerve cells that make up the brain. This swelling of brain tissue is what ultimately causes death.

Are my cells alive? Cells are the basic unit of structure and function in living organisms

All living things are made of cells Unicellular organisms are made of one cell –Ex. Bacteria Multicellular organisms are made of many, many, many cells –Ex. YOU!

All life processes occur at a cellular level In a multicellular organism, many of the bodily functions (breathing and eating) are necessary to supply individual cells with things the cell needs

All life processes occur at a cellular level The interactions of all the individual cells in a multicellular create a need for other bodily functions (excreting wastes).

Cells must interact with their environment to maintain homeostasis In order for a cell to gain nutrients, the nutrients must be delivered to the cell (ex. by blood) or taken directly from the environment

Cell membrane Cell membrane is the main structure associated with HOMEOSTASIS in the cell Regulates water concentration and other material –Controls what goes into and out of the cell –Many cells also have CELL WALLS- with large pores, mainly used for support Cell membrane is the main structure associated with HOMEOSTASIS in the cell Regulates water concentration and other material –Controls what goes into and out of the cell –Many cells also have CELL WALLS- with large pores, mainly used for support

Cells must interact with their environment to maintain homeostasis In order for some cells to generate energy, they require oxygen. Therefore, this oxygen must be delivered to the cell (ex. by blood) or taken directly from the environment.

Cells must interact with their environment to maintain homeostasis Cells affect their environment by releasing wastes into their surroundings. Ex. Algae release oxygen into the lake. Cells affect their environment by releasing wastes into their surroundings. Ex. Algae release oxygen into the lake.

How do things get into and out of the cell? All things entering or leaving the cell must pass through the cell membrane

How do things get into and out of the cell? The cell membrane is selectively permeable

Membranes contain structures that allow movement The membrane contains pores (holes) that allow very small molecules that move in and out freely

Membranes contain structures that allow movement The membrane also contains transport proteins that are specifically shaped to allow essential molecules, such as water, into and out of the cell

Fill It In … Two ways that molecules move through the cell membrane: Two ways that molecules move through the cell membrane: 1. 2.

Concentration Gradient MYP Concentration Gradient- amount of material in solution –Measured in g/L –Example: 12g of salt in 6L of water –Example: 12g of salt in 4L of water Which has the higher concentration of solute? Concentration Gradient- amount of material in solution –Measured in g/L –Example: 12g of salt in 6L of water –Example: 12g of salt in 4L of water Which has the higher concentration of solute?

Passive Transport Some types of cell transport DO NOT require energy This is called passive transport Some types of cell transport DO NOT require energy This is called passive transport

Passive Transport Molecules are constantly in motion. The movement of molecules is random. Molecules are constantly in motion. The movement of molecules is random.

Passive Transport Diffusion is the term used to describe the movement of molecules from areas of high concentration to areas of lower concentration due to random movement

Fill It In … Passive transport is movement of molecules from ______ to _____ concentration.

Passive Transport Diffusion can occur in the air, in water, or across a cell membrane –Ex. A drop of red dye spreads throughout the water –Ex. The smell of burnt popcorn spreads through the house Diffusion can occur in the air, in water, or across a cell membrane –Ex. A drop of red dye spreads throughout the water –Ex. The smell of burnt popcorn spreads through the house

Passive Transport Concentration gradient is the term used to describe the difference between higher and lower concentration.

Something extra … There are two types of diffusion: –(Simple) diffusion Movement through the pores –Facilitated diffusion Movement through the transport proteins There are two types of diffusion: –(Simple) diffusion Movement through the pores –Facilitated diffusion Movement through the transport proteins

Passive Transport Osmosis is the term used to specifically describe the movement of water across a membrane due to diffusion

Fill It In … Differentiate between the terms “diffusion” and “osmosis”: Diffusion - Osmosis - Differentiate between the terms “diffusion” and “osmosis”: Diffusion - Osmosis -

The principles of diffusion (and osmosis) can be used to predictthe response of cells in different environments ….

Diffusion Demo BEFORE: Dialysis bag is “selectively permeable” Starch (large molecule) inside bag Iodine (small molecule) in beaker AFTER: Starch (large molecule) still inside bag; did NOT diffuse out Iodine (small molecule) diffused INTO bag – evidence is color change

An example of diffusion: A cell has a conc. of 8.0% carbon dioxide gas and 0.4% oxygen gas. The blood surrounding the cell has an oxygen concentration of 1.2% and a carbon dioxide concentration of 0.1%. What will the cell lose? What will the cell gain? Oxygen 0.4% Carbon dioxide 0.8% Oxygen 1.2% Carbon dioxide 0.1% Oxygen 1.2% Carbon dioxide 0.1%

An example of diffusion: Answer: Oxygen will diffuse into the cell and carbon dioxide will diffuse out of the cell. This is called gas exchange Oxygen 0.4% Carbon dioxide 0.8% Oxygen 1.2% Carbon dioxide 0.1% Oxygen 1.2% Carbon dioxide 0.1%

Fill It In … Explain WHY the oxygen and carbon dioxide move as they do …

Examples of osmosis: more water A blood cell has the same conc. of water and salt as saline solution. A doctor who failed high school biology and did not listen to the attending nurse used an injection full of distilled water (100% water). What will happen to the blood cells surrounded by the distilled water? less water

Examples of osmosis: more water Answer: Water will move into the cell through the porcess of osmosis, causing the cell to swell and possibly burst less water

Examples of osmosis: You go to the pet store and purchase a fresh water fish. When you get home and place the fish in a salt water aquarium, the fish dies and you cry out “why?” less water (more salt) x Fish Cell more water

Examples of osmosis: Answer: water in the fish’s cells left the cell due to osmosis. The loss of water in the gill cells caused the death. Answer: water in the fish’s cells left the cell due to osmosis. The loss of water in the gill cells caused the death. less water (more salt) x Fish Cell more water

The point at which the molecules are evenly dispersed is called equilibrium

Fill It In … Equilibrium means …

Several factors affect the speed at which equilibrium is reached. These factors include temperature (higher temp speeds up the rate of diffusion) and concentration gradient (steeper gradients speed diffusion)

At equilibrium, molecules continue to move but there is no net change in the concentration (distribution) of molecules.

Ameoba Sisters- Osmosis

Osmotic Pressure MYP Pressure of water acting on the cell membrane –Animal cell might burst –Plant Damage to the cell wall may occur Pressure of water acting on the cell membrane –Animal cell might burst –Plant Damage to the cell wall may occur

Example: Penicillin Penicillin works by inhibiting the enzyme used in bacteria that produces a chemical cross-link in their cell wall (damaging the cell wall Bacteria can build a resistance to this by making β-lactamase, which defends the bacterial walls by assaulting the β-lactam ring Penicillin works by inhibiting the enzyme used in bacteria that produces a chemical cross-link in their cell wall (damaging the cell wall Bacteria can build a resistance to this by making β-lactamase, which defends the bacterial walls by assaulting the β-lactam ring

Some types of transport DO require energy. This is called active transport. Active transport moves molecules against the concentration gradient (from low conc to high conc) This is called active transport. Active transport moves molecules against the concentration gradient (from low conc to high conc)

Active Transport MYP Change protein shape- role in acting as a pump –Used to keep the cell alive –Move Ca +2 K + and Na +2 Change protein shape- role in acting as a pump –Used to keep the cell alive –Move Ca +2 K + and Na +2

Fill It In … Active transport is movement of molecules from ______ to ______ concentration

Some types of transport DO require energy. Active transport also moves large molecules into and out of the cell that could not normally cross the cell membrane.

Movement into the cell = endocytosis Movement out of the cell = exocytosis Movement into the cell = endocytosis Movement out of the cell = exocytosis

Some types of transport DO require energy. The cell uses a special kind of energy for this transport. The chemical the cell uses is called ATP. The cell uses a special kind of energy for this transport. The chemical the cell uses is called ATP.

Check Yourself! 1. Why must some multicellular organisms breathe and eat? 2. Why do cells interact with their environment? 3. What structure do molecules pass through when entering or leaving the cell? 4. What type of transport requires no energy and includes diffusion and osmosis? 5. What is a concentration gradient? 6. What term is used to describe the diffusion of water across a membrane? 7. What type of transport moves molecules against the concentration gradient? 1. Why must some multicellular organisms breathe and eat? 2. Why do cells interact with their environment? 3. What structure do molecules pass through when entering or leaving the cell? 4. What type of transport requires no energy and includes diffusion and osmosis? 5. What is a concentration gradient? 6. What term is used to describe the diffusion of water across a membrane? 7. What type of transport moves molecules against the concentration gradient?

Check Yourself! 1. Why must some multicellular organisms breathe and eat? TO SUPPLY INDIVIDUAL CELLS WITH THE THINGS THEY NEED 1. Why must some multicellular organisms breathe and eat? TO SUPPLY INDIVIDUAL CELLS WITH THE THINGS THEY NEED

Check Yourself! 2. Why do cells interact with their environment? TO MAINTAIN HOMEOSTASIS 2. Why do cells interact with their environment? TO MAINTAIN HOMEOSTASIS

Check Yourself! 3. What structure do molecules pass through when entering or leaving the cell? CELL MEMBRANE 3. What structure do molecules pass through when entering or leaving the cell? CELL MEMBRANE

Check Yourself! 4. What type of transport requires no energy and includes diffusion and osmosis? PASSIVE TRANSPORT 4. What type of transport requires no energy and includes diffusion and osmosis? PASSIVE TRANSPORT

Check Yourself! 5. What is a concentration gradient? THE DIFFERENCE BETWEEN HIGHER AND LOWER CONCENTRATIONS 5. What is a concentration gradient? THE DIFFERENCE BETWEEN HIGHER AND LOWER CONCENTRATIONS

Check Yourself! 6. What term is used to describe the diffusion of water across a membrane? OSMOSIS 6. What term is used to describe the diffusion of water across a membrane? OSMOSIS

Check Yourself! 7. What type of transport moves molecules against the concentration gradient? ACTIVE TRANSPORT 7. What type of transport moves molecules against the concentration gradient? ACTIVE TRANSPORT

Check Yourself! 8. What term is used to describe an equal distribution of molecules between a cell and its environment? EQUILIBRIUM 8. What term is used to describe an equal distribution of molecules between a cell and its environment? EQUILIBRIUM

Types of Cell Transport Passive Cell TransportActive cell transport Does NOT require energyRequires energy Movement DOWN the concentration gradient Movement AGAINST the concentration gradient High  LowLow  High

Diffusion is a type of Passive Transport Lets food in for NUTRITION Lets oxygen in for RESPIRATION Lets waste out for EXCRETION Diffusion Movement of molecules from a high to low concentration Example: Oxygen is moved from a high concentration in the lungs, to a low concentration in the blood Molecules move until they reach EQUILIBRIUM: An equal concentration on both sides of the membrane

Osmosis is a type of diffusion (a type of passive transport) Osmosis Movement of WATER molecules from a high to low concentration Example: In salt water, there is more WATER in the cell than in the surrounding environment, so water leaves the cells and they shrivel Molecules move until they reach EQUILIBRIUM: An equal concentration on both sides of the membrane