Cell Membranes - Parts and Roles II
- Created by: Vikki4
- Created on: 08-03-15 15:50
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- Cell Membranes
- Phospholipids
- Short chain fatty acids increase fluidity
- Fluid barrier
- Unsaturated fatty acids also increase membrane fluidity (especially cis)
- Does not allow water soluble or polar molecules through easily due to its hydrophobic core
- Allow fluidity
- Membrane fusion
- Vesicle formation
- Glycolipids
- Have high specificity
- Involved in cell cell recognition
- Cholesterol
- Steroid
- Mechanically stabilises the membrane
- Reduces leakage of polar molecules
- Regulates membrane fluidity
- Roles of the structures
- Allow membrane to be partially permeable
- Proteins and glycoproteins
- Receptors for hormones and neurotransmitters
- Involved in cell cell recognition
- Are enzymes (microvilli)
- Channels and carrier proteins
- Involved in energy tranfser reatcions in respiration and photosynthesis
- Have high specificities
- Proteins and glycoproteins
- Allow fluidity
- Membrane fusion
- Vesicle formation
- Selective cell cell recognition
- Glycolipids
- Have high specificity
- Involved in cell cell recognition
- Proteins and glycoproteins
- Receptors for hormones and neurotransmitters
- Involved in cell cell recognition
- Are enzymes (microvilli)
- Channels and carrier proteins
- Involved in energy tranfser reatcions in respiration and photosynthesis
- Have high specificities
- Glycolipids
- Separate cell contents and allow compartmentalisation
- Allow membrane to be partially permeable
- Membrane fludidty
- Classic experiment to prove
- Cell with plasma membrane proteins green fluorescence
- Shocked cells to fuse
- Expected half green half red if proteins rigid
- Actually got random mixtures of proteins, proving they could move and membranes are fluid
- Shocked cells to fuse
- Cell with plasma membrane proteins red fluorescence
- Shocked cells to fuse
- Expected half green half red if proteins rigid
- Actually got random mixtures of proteins, proving they could move and membranes are fluid
- Shocked cells to fuse
- Cell with plasma membrane proteins green fluorescence
- Effect of changing tempreature
- Increased movement of phospholipids makes membranes leak
- Increased temperature gives molecules more kinetic energy
- For beetroot this means the betalain will diffuse more quickly
- Denaturation of proteins makes membranes leak
- At high temperatures, denatured proteins can reblock gaps in the membrane
- Extremophiles have different membrane compositions (cholesterol and different fatty acid chain lengths)
- Classic experiment to prove
- Roles in cell signalling
- Communication and coordination between cells
- Specific substance released by one cell and binding to specific receptor on another cell to create a response
- Signal and receptor are complementary
- Drugs work by having same shapes as signalling molecules
- Examples
- Neurotransmitters
- Hormoes released into the blood
- Adrenaline binds to liver cells to stimulate breakdown of glycogen
- Made by endocrine glands
- Diffuse from blood to target cell receptors or cytoplasm
- Local cell mediators (short distances)
- Cytokines in immune response
- Only in immediate environment
- Taken up by cells or rapidly destroyed
- Phospholipids
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