Lipids 3

1. 1Recap: Triacylglycerols
   - made of 3 [blank_start]fatty[blank_end] acids esterfied ([blank_start]ester[blank_end] linked) to a [blank_start]glycerol[blank_end] molecule
   - they are neutral molecules (contain [blank_start]no[blank_end] charged groups)
   - sometimes called [blank_start]neutral[blank_end] lipids
   - form in which lipid energy stores are deposited in [blank_start]adipose[blank_end] tissues of animals (as fats) and in seed of oilseed [blank_start]plants[blank_end] (as oils)
   - fats and [blank_start]oils[blank_end] from different sources has a characteristic distribution of [blank_start]fatty[blank_end] acids

   1. Afatty
   2. Bester
   3. Cglycerol
   4. Dneutral
   5. Eno
   6. Fadipose
   7. Gplants
   8. Hoils
   9. Ifatty
2. 2Phospholipids can be split into 2 types
   - [blank_start]phosphoacylglycerols[blank_end] also called phospholipids
   - [blank_start]sphingolipids[blank_end]

   1. Aphosphoacylglycerols
   2. Bsphingolipids
3. 3Phosphoacylglycerol
   - a.k.a. [blank_start]phospholipid[blank_end]
   - 2 fatty acids [blank_start]ester[blank_end] linked to glycerol
   - also contain a [blank_start]phosphate[blank_end] group and other specific groups
   - the phosphate group replaces the fatty acid on C number 3 of a triacylglycerol molecule
   
   The 3rd carbon is a [blank_start]phosphodiester[blank_end] linked to a phosphate and an 'x' group

   1. Aphospholipid
   2. Bester
   3. Cphosphate
   4. Dphosphodiester
4. 4X groups
   - in phosphoacylglycerol on the 3rd carbon on glycerol a [blank_start]phosphate[blank_end] group and an X group is phosphodiester linked
   
   X groups are very [blank_start]polar[blank_end] molecules and are often charged, examples to know include:
   - [blank_start]ethanolamine[blank_end] (ethanol + charged amine group)
   - [blank_start]serine[blank_end] (NCC, with methanol as side chain)
   - [blank_start]choline[blank_end]
   - inositol (has a [blank_start]ring[blank_end] structure; not charged)
   
   When choline is part of phosphoacylglycerols it is called [blank_start]phosphatidyl[blank_end] choline
   - this is the same format for all X groups
   
   Phosphatidyl serine, phosphatidyl inositol

   1. Aphosphate
   2. Bpolar
   3. Cethanolamine
   4. Dserine
   5. Echoline
   6. Fring
   7. Gphosphatidyl
5. 5Characteristics of Phosphoacylglycerols ([blank_start]phospholipids[blank_end])
   - They are [blank_start]amphipathic[blank_end] (amphiphiles) > the molecule has one polar end ([blank_start]head[blank_end]) and one non-polar end (tail)
   - this property allows them to carry out their [blank_start]biological[blank_end] functions
   - fatty acid (acyl groups) are really [blank_start]non[blank_end]-polar therefore hydrophobic and point away from the [blank_start]polar[blank_end] phosphate group
   - the polar phosphate group and the non polar fatty acids point in opposite [blank_start]directions[blank_end]
   - phosphate is [blank_start]negatively[blank_end] charged
   
   In phosphoacylglycerols the X group and the phosphate group are as far away as possible from the fatty acid/[blank_start]acyl[blank_end] chains (hydrophobic)
   
   

   1. Aphospholipids
   2. Bamphipathic
   3. Chead
   4. Dbiological
   5. Enon
   6. Fpolar
   7. Gdirections
   8. Hnegatively
   9. Iacyl
6. 6Arrangement of Phosphoacylglycerols (phospholipids)
   - [blank_start]amphipathic[blank_end] (amphiphiles) molecules spontaneously form a number of specific structures including:
   - [blank_start]monolayers[blank_end] > hydrophilic heads point down towards the liquid and [blank_start]hydrophobic[blank_end] tails point up towards the air (at a liquid-air interface) e.g. [blank_start]oil[blank_end] sitting on top of water
   
   - [blank_start]micelles[blank_end] > hydrophobic tails all point inwards in a sphere
   
   - bilayer > 2 [blank_start]monolayers[blank_end] put together, aqueous solutions on either side, very [blank_start]non[blank_end]-polar in the centre of the bilayer
   
   

   1. Aamphipathic
   2. Bmonolayers
   3. Chydrophobic
   4. Doil
   5. Emicelles
   6. Fmonolayers
   7. Gnon
7. 7Biological Membranes
   - The phosphoacylglycerol or phospholipid [blank_start]bilayer[blank_end] is the basis of the biological membrane structure
   - [blank_start]polar[blank_end] heads interact with the solution around the outside (the solvent)
   - [blank_start]non[blank_end]-polar tails exclude water
   - 2 [blank_start]monolayers[blank_end] squished together with polar heads at either side with non-polar tails in the middle
   
   NOTE: acylglycerols [blank_start]cannot[blank_end] form bilayers for they are not amphipathic; fatty acid soaps are [blank_start]amphipathic[blank_end] for ester salts have a polar and non-polar region

   1. Abilayer
   2. Bpolar
   3. Cnon
   4. Dmonolayers
   5. Ecannot
   6. Famphipathic
8. 8[blank_start]Sterols[blank_end] are also found in membranes due to their amphipathic nature
   e.g. cholesterol and [blank_start]stigmasterol[blank_end]
   
   - its not only phospholipids found in biological [blank_start]membranes[blank_end]
   - cholesterol has [blank_start]polar[blank_end] and non-polar regions (amphipathic) > polar regions interact with [blank_start]hydrophilic[blank_end] (water loving) heads and non-polar regions interact with [blank_start]hydrophobic[blank_end] (water hating) tails
   - cholesterol is often found in [blank_start]animal[blank_end] membranes
   - Stigmasterol is found in [blank_start]plant[blank_end] membranes and is also amphipathic

   1. Astigmasterol
   2. BSterols
   3. Cmembranes
   4. Dpolar
   5. Ehydrophilic
   6. Fhydrophobic
   7. Ganimal
   8. Hplant
9. 9Membrane Structure cont.
   - membranes can also have [blank_start]carbohydrates[blank_end] associated with them
   - membrane structure is [blank_start]not[blank_end] rigid > fluid [blank_start]mosaic[blank_end] structure
   - proteins and carbohydrates can move within the [blank_start]plane[blank_end] of the membrane
   
   [blank_start]integral[blank_end] proteins = proteins which span the membrane, may be made of multiple trans membrane segments or partly immersed in lipid layer
   
   [blank_start]peripheral[blank_end] proteins = are loosely attached: [blank_start]electrostatic[blank_end] interaction, bonding to integral protein, hydrophobic anchor, bonding to phosphoacylglycerols via carbohydrate chain BUT normally electrostatic interactions or [blank_start]hydrogen[blank_end] bonding between polar heads but overall [blank_start]loosely[blank_end] attached

   1. Anot
   2. Bcarbohydrates
   3. Cmosaic
   4. Dplane
   5. Eintegral
   6. Fperipheral
   7. Gloosely
   8. Helectrostatic
   9. Ihydrogen
10. 10Why do we have proteins and carbohydrates in the membrane?
    - cell [blank_start]recognition[blank_end] > to recognise specific cells
    - extracellular [blank_start]enzyme[blank_end] activities; for reactions
    - transport of compounds across the [blank_start]membrane[blank_end]

    1. Arecognition
    2. Benzyme
    3. Cmembrane

11. 11There are 3 types of diffusion of compounds across a membrane
    - [blank_start]diffusion[blank_end]
    - [blank_start]passive[blank_end] transport (facilitated diffusion)
    - [blank_start]active[blank_end] transport

    1. Adiffusion
    2. Bpassive
    3. Cactive
12. 12[blank_start]Diffusion[blank_end] = the [blank_start]net[blank_end] movement of molecules in the direction of lower concentration
    - solute passes across membrane from an area of higher concentration to an area of [blank_start]lower[blank_end] concentration
    - driven by a [blank_start]concentration[blank_end] gradient
    - [blank_start]small[blank_end] polar molecules diffuse through small gaps in the hydrophobic environment (the [blank_start]acyl[blank_end]/fattyacid chains)
    - large [blank_start]polar[blank_end] molecules cannot (particularly if charged) diffuse
    - uncharged, [blank_start]lipophilic[blank_end] (lipid loving) molecules can diffuse readily

    1. ADiffusion
    2. Bnet
    3. Clower
    4. Dconcentration
    5. Esmall
    6. Facyl
    7. Gpolar
    8. Hlipophilic
13. 13Passive transport a.k.a [blank_start]facilitated[blank_end] diffusion
    - depends on the presence of specific [blank_start]proteins[blank_end] which transport the molecule from one side of the membrane to the other
    - still requires [blank_start]no[blank_end] energy
    - driven by the concentration [blank_start]gradient[blank_end]: moves from high --> low
    - moves until an [blank_start]equilibrium[blank_end] is reached
    - The [blank_start]activation[blank_end] energy is very high for diffusion of hydrophilic molecule through a bilayer > doesn't happen readily
    - the activation [blank_start]energy[blank_end] of this diffusion of a hydrophilic molecule through the bilayer is lowered through the use of a transported [blank_start]protein[blank_end]

    1. Afacilitated
    2. Bproteins
    3. Cno
    4. Dgradient
    5. Eequilibrium
    6. Factivation
    7. Genergy
    8. Hprotein
14. 14Transporter proteins in facilitated diffusion/passive transport
    - transporter proteins [blank_start]lower[blank_end] the activation energy of diffusion of hydrophilic molecules through the membrane
    - transporter proteins make non-[blank_start]covalent[blank_end] interactions that replace [blank_start]hydrogen[blank_end] bonding, allowing molecules to pass through the bilayer
    - large polar charged molecules are very hydrated (lots of hydrogen bonds with [blank_start]water[blank_end]) > we need to strip this hydration [blank_start]shell[blank_end] but this normally requires a lot of energy = high activation energy
    - but transporter proteins lower this [blank_start]activation[blank_end] energy
    

    1. Alower
    2. Bcovalent
    3. Chydrogen
    4. Dwater
    5. Eshell
    6. Factivation
15. 15[blank_start]Active[blank_end] Transport
    - also depends on the presence of specific transport [blank_start]proteins[blank_end]
    - transport requires [blank_start]energy[blank_end]
    - can be [blank_start]against[blank_end] a concentration gradient
    

    1. AActive
    2. Bproteins
    3. Cenergy
    4. Dagainst
16. 16[blank_start]Primary[blank_end] Active Transport e.g. sodium-[blank_start]potassium[blank_end] pumps in animal cells
    - the cell wants high [blank_start]potassium[blank_end] concentration inside the cell and low [blank_start]sodium[blank_end]
    - outside the cell is high sodium and low potassium
    - so you would expect the ions to diffuse down their concentration [blank_start]gradient[blank_end] therefore increase sodium inside and decreasing potassium
    - however a protein called the [blank_start]sodium[blank_end]-potassium pump keeps the ion gradients intact
    - the ions are [blank_start]actively[blank_end] pumped [blank_start]against[blank_end] their concentration gradient
    - primary active transport involves the direct [blank_start]hydrolysis[blank_end] of ATP which provides the [blank_start]energy[blank_end] required for the transport
    
    1. [blank_start]3[blank_end] sodium ions and 1 [blank_start]ATP[blank_end] bind to the pump > ATP phosphorylates the pump and causes it to change [blank_start]shape[blank_end] and deliver the sodium ions to the outside
    2. at the same time ion binding sites open up on the extracellular face of the pump and picks up 2 [blank_start]potassium[blank_end] ions
    3. as potassium binds the pump releases its inorganic [blank_start]phosphate[blank_end] > the release causes the pump to change [blank_start]shape[blank_end] and deliver the potassium ions to the inside of the cell

    1. APrimary
    2. Bpotassium
    3. Cpotassium
    4. Dsodium
    5. Egradient
    6. Fsodium
    7. Gactively
    8. Hagainst
    9. Ihydrolysis
    10. Jenergy
    11. K3
    12. LATP
    13. Mshape
    14. Npotassium
    15. Ophosphate
    16. Pshape
17. 17[blank_start]Secondary[blank_end] active transport
    - a substance such a glucose is pumped from a region of lower concentration to a region of [blank_start]higher[blank_end] concentration
    - requires [blank_start]energy[blank_end]
    - but energy does not come [blank_start]directly[blank_end] from ATP
    - it comes from the energy stored in a sodium ion [blank_start]gradient[blank_end] (which was initially created by ATP)
    - because ATP does not fuel the pump directly this process is called [blank_start]secondary[blank_end] active transport
    - to pump glucose [blank_start]against[blank_end] its concentration gradient, the pump takes up both [blank_start]sodium[blank_end] and glucose from the outside of the cell and then changes [blank_start]shape[blank_end], depositing both inside the cell
    
    a pump that transports 2 substances in the same direction is called a [blank_start]symport[blank_end] protein
    - the sodium ions that enter the cell are later returned to the outside by the sodium-[blank_start]potassium[blank_end] pump

    1. ASecondary
    2. Bhigher
    3. Cenergy
    4. Ddirectly
    5. Egradient
    6. Fsecondary
    7. Gagainst
    8. Hsodium
    9. Ishape
    10. Jsymport
    11. Kpotassium
18. 18[blank_start]Osmosis[blank_end] = the process by a which a solvent passes across a semi-[blank_start]permeable[blank_end] membrane from a solution with a low osmotic pressure to one which a [blank_start]high[blank_end] osmotic pressure
    - a semi-permeable membrane is one that allows the passage of [blank_start]solvent[blank_end] but not solute

    1. AOsmosis
    2. Bpermeable
    3. Chigh
    4. Dsolvent
19. 19Tonicity
    - biological membranes are [blank_start]selectively[blank_end] permeable not semi-permeable
    - allow free passage of [blank_start]solvents[blank_end] and some solutes but not all
    - [blank_start]tonicity[blank_end] = due to the osmotic pressure exerted only by the solutes which [blank_start]cannot[blank_end] pass across the selectively permeable membranes
    - the state of a solution in respect to [blank_start]osmotic[blank_end] pressure

    1. Aselectively
    2. Bsolvents
    3. Ctonicity
    4. Dcannot
    5. Eosmotic

Description

Biochemistry Quiz on Lipids 3, created by sophie waddington on 03/05/2018.

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