From ffeaee957ad571d6809b1573615e3761c1c87233 Mon Sep 17 00:00:00 2001 From: johnruina Date: Mon, 17 Aug 2026 13:28:29 -0400 Subject: [PATCH] 2026-08-17 13:28:28: Tonicity and Osmoregulation --- .obsidian/graph.json | 2 +- .obsidian/workspace.json | 59 +++++++++++++----- .../Pasted image 20260817123835.png | Bin .../Facilitated Diffusion.md | 22 +++++++ .../Membrane Transport.md | 2 +- .../Tonicity and Osmoregulation.md | 54 ++++++++++++++++ 6 files changed, 121 insertions(+), 18 deletions(-) rename Pasted image 20260817123835.png => Assets/Pasted image 20260817123835.png (100%) create mode 100644 biology/Cell Structure and Function/Facilitated Diffusion.md create mode 100644 biology/Cell Structure and Function/Tonicity and Osmoregulation.md diff --git a/.obsidian/graph.json b/.obsidian/graph.json index 65021a9..60f31e2 100644 --- a/.obsidian/graph.json +++ b/.obsidian/graph.json @@ -17,6 +17,6 @@ "repelStrength": 18.5634118967452, "linkStrength": 1, "linkDistance": 52, - "scale": 0.44236331897771103, + "scale": 0.6201858078102251, "close": true } \ No newline at end of file diff --git a/.obsidian/workspace.json b/.obsidian/workspace.json index e55c8c2..dd521bd 100644 --- a/.obsidian/workspace.json +++ b/.obsidian/workspace.json @@ -181,16 +181,44 @@ "state": { "type": "markdown", "state": { - 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Requires no energy. + +# Summary +* Aquaporins are channel proteins that move large quantities of water across the membrane. +* Facilitated diffusion uses transport and channel proteins to move molecules that can't cross the hydrophobic core on their own across the membrane. (More info in Membrane Transport) +* Movement of ions across membrane can polarize it, creating an uneven charge distribution + +**How molecular structure decides the route:** +- Small and nonpolar: passes directly through the bilayer. +- Large and polar (like glucose): needs a transport protein. +- Charged ion (like Na⁺ or K⁺): needs a channel protein. + +Water can cross the membrane on their own but it's slow, aquaporins transport large quantities. + +| Transport Type | Energy Required? | Direction | Examples | +| --------------------- | ---------------- | ----------- | --------------------------------------- | +| Simple Diffusion | No | High to Low | O₂, CO₂ | +| Facilitated Diffusion | No | High to Low | Glucose, ions, water through aquaporins | +| Active Transport | Yes (ATP) | Low to High | Na⁺/K⁺ pump, calcium pumps | +Key difference between simple and facilitated is the protein. \ No newline at end of file diff --git a/biology/Cell Structure and Function/Membrane Transport.md b/biology/Cell Structure and Function/Membrane Transport.md index 6352da3..0efb80e 100644 --- a/biology/Cell Structure and Function/Membrane Transport.md +++ b/biology/Cell Structure and Function/Membrane Transport.md @@ -53,7 +53,7 @@ Requires direct input of energy (usually ATP). |Simple Diffusion|No|High to Low|O₂, CO₂| |Facilitated Diffusion|No|High to Low|Glucose, amino acids| |Active Transport|Yes (ATP)|Low to High|Na⁺/K⁺ pump, calcium pumps| -1. Selective permability creates control +1. Selective permeability creates control 2. Active transport allows for creating concentration gradients 3. Passive transport allows for equilibrium 4. Maintaining water and solute levels is vital to an organism diff --git a/biology/Cell Structure and Function/Tonicity and Osmoregulation.md b/biology/Cell Structure and Function/Tonicity and Osmoregulation.md new file mode 100644 index 0000000..9eddeb3 --- /dev/null +++ b/biology/Cell Structure and Function/Tonicity and Osmoregulation.md @@ -0,0 +1,54 @@ +[[Cell Structure and Function]] + +Tonicity compares solute concentrations in and out of a cell, telling you which direction the water will move. Cells and organisms use osmoregulation to keep water and solutes balanced. + +Tonicity is essentially comparing solute concentration inside and outside a cell. + +Osmoregulation is how cells handle water balance and solute concentration. + +# Summary: +* Tonicity compares solute concentration inside and outside a cell. +* Osmosis moves water from high water potential to low water potential +* Water potential: $\psi=\psi_s+\psi_p$ +* Adding solute lowers water potential, pressure raises it. +* Solute potential: $\psi=-iCRT$ +* As solute concentration rises, $\psi$ becomes more negative. + +# Tonicity +Tonicity compares solute concentration inside and outside a cell. +* Hypertonic is when a cells solute concentration is higher than its environment, causing the water inside to leave by osmosis and making animal cells crenate and plant cells undergo plasmolysis. +* Hypotonic is when a cells solute concentration is lower than the environment so the surrounding water flows in, making animal cells lyse and plant cells turgid. +* Isotonic is when solute concentrations match, so the cell keeps its shape. + +# Osmosis +Passive movement of water across a selectively permeable membrane. Water moves from hypotonic (low solute concentrations) to hypertonic (higher) (equivalent to moving from high water potential to low). Water is polar, so it moves through aquaporins, which provide an hydrophilic path. Aquaporins are important in plant cells, red blood cells, etc. + +# Water Potential +$$\psi=\psi_s+\psi_p$$ +$\psi$ is total water potential, $\psi_s$ is solute potential, $\psi_p$ is pressure potential. Adding solute lowers solute potential, pressure potential is physics pressure on solution. + +In an open container, pressure potential is zero, in a plant cell turgor pressure increases pressure potential. + +# Solute Potential +$$\psi=-iCRT$$ +$i$ is ionization constant (number of molecules a particle makes in a solution) +$C$ is molar concentration +$R$ is pressure constant ($R=0.0831 L*bars/mol*K$) +$T$ is temperature in Kelvin + +Solute potential is always zero or negative. +Solute concentration has a negative relation with solute potential, drawing more water to the region. + +# Osmoregulation and Homeostasis +Organisms must regulate water potential and solute composition to maintain homeostasis. +* Contractile vacuoles in freshwater protists: freshwater environments are hypotonic to protist's cytoplasm, so they constantly pump this water out. +* Central vacuole in plant cell: Large central vacuole stores water and dissolved substances, making the plasma membrane push against cell wall and making the cell rigid and strong. +# How Water and Solutes Cross Membranes +Channel Proteins: +Provides a hydrophilic passage through the membrane for certain ions and molecules. Aquaporins are a channel protein for water. Movement of these ions can charge the membrane. + +Carrier Proteins: +Change shape to shuttle molecules across the membrane. Transport rate is slower than channel proteins. They let large polar molecules move down concentration gradient. + +Active Transport (Related Context): +Transport above is passive because it moves along the gradient. Active transport requires ATP and moves against gradient. \ No newline at end of file