Membranes
- Created by: abbie2030
- Created on: 02-02-20 18:07
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- Membranes
- Structure
- Phospholipids
- Hydrophobic tails
- go on the inside away from the water
- Hydrophilic tails
- go on the outside to be in the water
- Hydrophobic tails
- cholesterol
- flexibility and stability
- glycolipids
- receptor of toxic
- glcoproteins
- recognition site for hormones and chemicals
- intrinsic proteins
- embedded through both layers of the membrane
- channel proteins
- allow a hydrophobic pathway for passive transport
- polar molecules can get through because the charges are different
- allow a hydrophobic pathway for passive transport
- carrier proteins
- active transport and diffusion
- Extrinsic proteins
- sit on the surface
- Phospholipids
- factors affecting membrane structure
- Temperature
- as temperature increases the kinetic energy also increases
- this creates bigger gaps in the bilayer
- makes it more permeable
- this creates bigger gaps in the bilayer
- as temperature increases the kinetic energy also increases
- solvents
- water is a polar molecule and is important in the structure
- non-polar or less polar molecules disrupt the bilayer creating gaps making it more permeable
- Temperature
- Diffusion
- lipid-soluble molecules, non-polar molecules and very small polar molecules can pass straight through a bilayer
- facilitated
- ions and large polar molecules
- channel proteins
- pores which can be gated
- allow diffusion of ions
- carrier proteins
- have shapes that allow only the passage of specific molecules or ions
- factors affecting diffusion rate
- steeper concetration gradient , the bigger the gradient the bigger the rate
- shorter diffusion pathway
- greater surface area
- greater concentration of carrier proteins
- Active Transport
- moving against a concentration gradient with the use of ATP
- carrier proteins (pumps) eg for glucose. low outside the cell
- a) carrier proteins take up molecules from outside the plasma membrane
- b) glucose molecules bind to the carrier protein and ATP attatches to the extrinsic protein inside the cekk
- c) the binding of the glucose molecule causes the protein to change shape to let the glucose into the cell
- bulk transport
- movement of large molecules
- endocytosis
- bulk transport into cells using vesicles
- pinocytosis
- engluf liquid and small dissolved particles
- phagocytosis
- engulf large solid material
- exocytosis
- movement out of cells using vesicles formed by the golgi apparatus that go to the cell membrane to release their content
- osmosis
- net movement of water particles from a high to low concentration
- water potential
- "how watery the water is"
- osmosis goes from high water potential (more watery water) to a low water potential
- measured in KiloPacals
- pure water has a water potential of 0
- effect of osmosis on plant and animal cells
- higher water potential enters the cell
- animal cell will swell and burst (lysis)
- plant cell with become turgid
- equal concentrations of water on both sides of the membran
- no change
- lower water potential leaves cell
- aminal cell shrinks
- plant cell goes through plasmolysis where the membran pulls away from the wall
- higher water potential enters the cell
- Structure
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