Biological membranes
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- Created by: Esme.B
- Created on: 31-01-18 14:47
What are the membranes at the surface of cells called?
Plasma membranes
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x3 functions of plasma membranes. (membranes at the surface of cells)
1) Barrier between cell + it's environment:controlling substances leaving+entering cell. Partially permeable (substances move across by diffusion, osmosis +active transport) 2). allow cell recognition by other cells. 3) Allow cell communication.
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What is meant by 'partially permeable'?
Let some molecules through but not others.
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What's 'Cell communication' sometimes also called?
Cell signalling
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x2 functions of the membranes within cells?
1). Membranes around organelles divide cell into different compartments.- act as barrier between organelles + cytoplasm(makes functions more efficient (i.e-respiration) 2). Can form vesicles to transport substances between different areas of the cell
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x3 functions of the membranes within cells?
1) control substances entering+leaving organelle (partially permeable) 2). membranes within organelles- act as barriers between membrane, contents +rest of organelle. 3). membranes =site of chemical reactions.
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Give an example of how a barrier between the organelle + cytoplasm makes a function for efficient?
Substances needed for respiration (i.e-enzymes) are kept together inside mitochondria.
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Lis an example of a membrane within a cell being the site of chemical reactions?
inner membrane of mitochondria contains enzymes needed for respiration
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What structure of the arrangement of molecules in a cell membrane referred to as?
The 'Fluid Mosaic' model
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'Bilayer'?
phospholipid molecules form a continuous double layer.
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Why is the 'bilayer' referred to as 'fluid'?
Phospholipids are constantly moving.
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Where is 'Cholesterol' present?
within the bilayer
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Where are protein molecules located in the cell membrane?
scattered through the bilayer.
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'Glycoproteins'?
proteins that have polysaccharide (carbohydrates) chains attached.
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'Glycolipids'?
Lipids that have polysaccharide chains attached.
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Primary role of 'phospholipids'?
Form a Barrier to dissolved substances.
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Role of 'phospholipids'? (x3 main points)
1). Head=hydrophilic +Tail=hydrophobic 2). Arranged in bilayer-heads face out towards water. 3) centre bilayer=hydrophobic(doesn't let water-soluble substances(ions)through- acts as barrier)fat-soluble substances can dissolve through bilayer+membrane
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Primary role of 'Cholesterol'?
Gives the membrane stability
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Where are the 'Cholesterol' molecules located?
Fit between the phospholipids.
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Role of 'Cholesterol'? (x3 main points)
1) type of lipid 2). present in all cell membranes 3). Provides membrane stability 4). Bind to hydrophobic tails of phospholipids, causing them to pack more closely making membrane less fluid+more rigid.
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Primary role of 'proteins'?
controls what enters + leaves the cell
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Role of 'proteins'? (x3 main points)
1). some proteins form channels in membrane-allow small/charged particles through 2). carrier proteins=transport molecules+ions across membrane via active transport +facilitated diffusion 3) Act as receptors for molecules in cell signalling.
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What occurs when a molecules binds to a protein?
Chemical reaction is triggered inside the cell.
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Primary role of 'Glycolipids' and 'Glycoproteins''?
Act as Receptors for messenger molecules.
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Role of 'Glycolipids' and 'Glycoproteins'? (x4 main points)
1) Stabilise the membrane by forming hydrogen bonds with surrounding water molecules 2). Sites where drugs, hormones+antibodies bind 3). act as receptors for cell signalling 4). They are antigens cell surface molecules involved in the immune response
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List the x3 steps of how 'Cell signalling' works?
1). x1 cell releases messenger molecule (i.e-hormone). 2). This molecule travels (i.e in the blood) to another cell. 3). messenger molecule detected by the cell because it binds to receptor on its cell membrane.
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List x4 main reasons of how cell membrane 'receptors' play an important role in 'Cell signalling'?
1) proteins in cell membrane act as receptors, called: 'membrane-bound receptors' 2). receptor proteins= specific shapes:messenger molecules have to be complementary shaped in bind 3). Different cells=Different types of receptors
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What is a 'Target cell'?
A cell that responds to a particular messenger molecules.
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Give x1 example of how 'Cell signalling' works?
1). Glucagon is a hormone that is released when there's not enough glucose in the blood. 2). Glucagon binds to receptors in liver cells. 3) This causes the liver cells to break down stores of glycogen to glucose.
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What x2 effects can there be when drugs bind to cell membrane receptors?
1) trigger a response in cell 2). block receptor + prevent it from working
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Give x1 example of a drug that binds to a cell membrane receptor?
1)Cell damage causes the release of Histamine 2).Histamine binds to receptors on surface of other cells which cause inflammation 3).Antihistamines block histamine receptors on cell surface 4).prevents histamine from binding to cell+stops inflammation
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Other cards in this set
Card 2
Front
x3 functions of plasma membranes. (membranes at the surface of cells)
Back
1) Barrier between cell + it's environment:controlling substances leaving+entering cell. Partially permeable (substances move across by diffusion, osmosis +active transport) 2). allow cell recognition by other cells. 3) Allow cell communication.
Card 3
Front
What is meant by 'partially permeable'?
Back
Card 4
Front
What's 'Cell communication' sometimes also called?
Back
Card 5
Front
x2 functions of the membranes within cells?
Back
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