biology – lecture 44
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Biology – Lecture 44 . Cell Homeostasis and Transport. Cell Homeostasis. Cells must maintain a constant internal environment and must be able to reproduce themselves when needed by the body. Why do Cells Need Homeostasis?. to function properly and stay alive keeps the cell stable - PowerPoint PPT PresentationTRANSCRIPT
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Biology – Lecture 44
Cell Homeostasis and Transport
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Cell Homeostasis
• Cells must maintain a constant internal environment and must be able to reproduce themselves when needed by the body.
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Why do Cells Need Homeostasis?
• to function properly and stay alive• keeps the cell stable • help the organism function properly• the organism to remain healthy
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How do cells maintain homeostasis?
• The waste is being transported away from the cell while it receives the nutrients it needs to continue to function.
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What cell organelles help with cell homeostasis?
• Different parts of the cell work to constantly maintain homeostasis in the cell.
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What main cell organelle helps with homeostasis?
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The Main Homeostasis Organelle
• The cell membrane - the outer wall between the cell and the outside world.
• It protects the cell from outside stimuli that could disrupt a cell's homeostasis.
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Cell Membrane’s Job
• Acts as the gatekeeper to what goes into and leaves the cell.
• It is made up of mostly fats (lipids) and protein and is selectively permeable, meaning it only lets certain molecules pass through the membrane
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How does it decide what passes?
• When there is too much of a certain molecule inside the cell, the cell membrane allows some of the molecules to permeate the membrane and leave the cell.
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What Else can pass?
• When there is too much of a molecule outside the cell and not enough inside the cell, the cell membrane will allow enough of the molecule to permeate inside to maintain homeostasis.
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What cannot pass on its own?
• Charged molecules and large molecules cannot pass through the cell membrane, while small and uncharged molecules can.
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Types of Cell Transport
• Passive Transport– Diffusion– Osmosis– Filtration– Facilitated Diffusion
• Active Transport
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Passive Transport
• Passive forms of transport move molecules such as water and substrates across the cell membrane with no energy on the cell's part.
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Diffusion
• Diffusion is the movement of material from an area of high concentration to an area with lower concentration.
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The Concentration Gradient
• The difference of concentration between the two areas
• Diffusion will continue until this gradient has been eliminated.
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Diffusion
• The movement of solutes down the concentration gradient.
• It moves the extra molecules from the area in which they have the highest concentration and spread them out.
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How Does Diffusion Work?
• When there is too much of a certain molecule within the cell, the cell uses diffusion to transport some of those molecules into the environment.
• When there is not enough of a molecule within the cell, the cell uses diffusion to transport molecules from the environment into the cell.
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Example of Diffusion
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Osmosis
• The process of allowing water or other solvents to permeate the cell membrane.
• It is the diffusion of water molecules.
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Example of Osmosis
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Example of Osmosis
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Hypertonic Solution
• No enough water in the cell• Too many molecules outside the cell• Causes the cell to shrink up
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Isotonic Solution
• The right amount of water in the cell.• The right amount of molecules outside the
cell.• These are healthy cells.
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Hypotonic Solution
• Too much water in the cell• Too much water outside the cell.• The cell swells and can burst open.
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The Goal of Diffusion and Osmosis
• Maintain homeostasis in the cell by transporting molecules to create equilibrium between the inside of the cell and its environment.