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carbs+lipid, transport types, anabolic --> condensation --> build up…

- - - - polar head + 2 tail form lipid bilayer amphoteric bc both hydrophic/phillic, arrange in phospholipid
  - - - fats
        
        straight chains, more tightly packed, more efficient energy storage, causes high IMF hence high MP so stays solid untill 25deg
        
        needed for energy storage
    - - trans
        
        hydrogen on diffrent side, doesnt cause kink
      - cis
        
        hydrogen on same side, cause kink
      - kinks loosen packing, less IMF, liquid exist as oils
- - - - polysaccaride (large molecule
        
        found in plants
        
        starch
        
        function: storage in plant
        
        formed: produced from glucose in photosynthesis
        
        amylose
        
        A1-4 unbranched helical
        
        amylopectin
        
        A1-4 + A1-6 (more 1-6) so branched
        
        cellulose
        
        very strong (prenents cell from bursting)
        
        formed: B1-4 glucose
        
        every other glucose flips upside-down to fit
        
        found in animals
        
        glycogen
        
        Animals do not store carbohydrate as starch but as glycogen.
        
        Glycogen has a similar structure to amylopectin, containing many alpha 1–6 glycosidic bonds that produce an even more branched structure.
        
        Glycogen is stored as small granules, particularly in muscles and liver.
        
        Glycogen is less dense and more soluble than starch, and is broken down more rapidly. This indicates the higher metabolic requirements of animals compared with plants.
      - formed by glycosidic bond between hydroxyl group 1-4 bond by connecting 1-4 carbons
        
        maltose (glucose glucose) malt
        
        sucrose (glucose+fructose) table sugar
        
        lactose (glucose galactose) milk
    - - energy source, soluble
      - 6 carbons=hexose
      - tranport for carb
      - alpha (OH bottom
      - beta (OH top)
    - - pentose 5 Carbon
      - ribose DNA
      - deoxyribose RNA
- - - - net movement of water molecules across a semi-permeable membrane from a region of low solute concentration to a region of high solute concentration (until equilibrium is reached)
        
        While water is moving to a more concentrated solution, osmosis is still a passive process as there are less free water molecules when solute levels are higher (so water is still moving along the water gradient)
        
        Osmolarity is a measure of solute concentration, as defined by the number of osmoles of a solute per litre of solution (osmol/L), and The osmolarity of a tissue may be interpolated by bathing the sample in solutions with established solute concentrations
        
        The tissue will lose water when placed in hypertonic solutions and gain water when placed in hypotonic solutions
        
        Water loss or gain may be determined by weighing the sample before and after bathing in solution
        
        Tissue osmolarity may be inferred by identifying the concentration of solution at which there is no weight change (i.e. isotonic)
        
        cells that lack cell wall uncontrolled osmosis will have negative effects with regards to cell viability
        
        In hypertonic solutions, water will leave the cell causing it to shrivel (crenation)
        
        In hypotonic solutions, water will enter the cell causing it to swell and potentially burst (lysis)
        
        In multicellular organisms, it is therefore important that tissue fluid remains isotonic to prevent harmful changes
        
        In plants and fungi, the effects of uncontrolled osmosis are moderated by the presence of an inflexible cell wall
        
        In hypertonic solutions, the cytoplasm will shrink (plasmolysis) but the cell wall will maintain a structured shape
        
        In hypotonic solutions, the cytoplasm will expand but be unable to rupture within the constraints of the cell wall (turgor)
        
        Excess water may be stored in a large, central vacuole that has its own membrane called the tonoplast
      - Solutions may be loosely categorised according to their relative solute concentrations
        
        Solutions with relatively higher solute concentrations are categorised as hypertonic (high solute ⇒ gains water)
        
        Solutions with relatively lower solute concentrations are categorised as hypotonic (low solute ⇒ loses water)
        
        Solutions that have equivalent solute concentrations are categorised as isotonic (same solute ⇒ no net water flow)
        
        medical applications:
        
        Tissues or organs to be used in medical procedures must be kept in solution to prevent cellular dessication
        
        This solution must share the same osmolarity as the tissue / organ (i.e. isotonic) in order to prevent osmosis from occurring
        
        Isotonic solutions can also be delivered intravenously to restore fluid levels to patients with hypovolemia
        
        Hypovolemia (low blood plasma levels) can occur due to dehydration or trauma (excessive blood loss)
    - - Facilitated diffusion is the passive movement of molecules across the cell membrane via the aid of a membrane protein, used by large polar molecules and ions
        
        2 types of transport proteins
        
        channel
        
        contain hydrophobic per which oons cross one side of a mambeane to another
        
        are ion-selective and may be gated to regulate the passage of ions in response to certain stimuli
        
        only move molecules along a concentration gradient
        
        have a much faster rate of transport than carrier proteins
        
        carrier
        
        Integral glycoproteins which bind a solute and undergo a conformational change to translocate the solute across the membrane
        
        Carrier proteins will only bind a specific molecule via an attachment similar to an enzyme-substrate interaction
        
        When a carrier protein moves material against the gradient (using ATP hydrolysis) it is called a protein pump
        
        Carrier proteins have a much slower rate of transport than channel proteins (by an order of ~1,000 molecules per second)
      - ion channels
        
        are integral membrane proteins which contain a hydrophilic inner pore through which ions may pass
        
        This allows ions to either enter or exit a cell according to the concentration gradient (facilitated diffusion)
        
        The channel proteins may be ion-selective (only allows passage to specific ions) and may be gated (can control the timing of ion movement)
        
        Ion channels are essential to the operation of nerve cells as they are used to establish charge differentials across a membrane (membrane potentials)
        
        2 types
        
        voltage gated
        
        Voltage-gated ion channels cycle between an open and closed conformation according to the transmembrane voltage
        
        In neurons, voltage-gated sodium channels are used to transport sodium ions into the neuron during depolarisation
        
        Conversely, voltage-gated potassium channels will transport potassium ions out of the neuron during repolarisation
        
        ligand gated
        
        Ligand-gated channels change their conformation in response to the binding of a specific chemical (ligand)
        
        In neurons, acetylcholine is a neurotransmitter released from the nerve cells to stimulate adjacent cells
        
        Muscles contain nicotinic acetylcholine receptors that will trigger the opening of an ion channel when activated
        
        Binding of acetylcholine to these receptors results in the influx of ions into the muscle, triggering a cascade that results in muscular contraction
    - - movement of small or lipophilic molecules that can freely cross the bilayer, movement will continue untill evenly dispersed (equilibrium), occurs when small lipophilic molecules pas between phopsolipids to freely cross bilayer
        
        rate is effected by
        
        molecule size (bigger=more resistance)
        
        temp (high=faster)
        
        steepness of gradient
        
        Small, non-polar gases and lipophilic molecules (such as oxygen and carbon dioxide)(non polar steroids like testosterome and oestradiol) will cross the plasma membrane via simple diffusion
        
        large charged molecules cant cross
- - - - A specific solute will bind to the protein pump on one side of the membrane
      - The hydrolysis of ATP (to ADP + Pi) causes a conformational change in the protein pump
      - The solute molecule is consequently translocated across the membrane (against the gradient) and released
    - - A molecule is moved against its gradient coupled to another molecule moving down an electrochemical gradient, which is indirectly coupling transport with another molecule that is moving along its gradient
        
        Cotransporters link the movement of an ion along its concentration gradient to the movement of a solute against its concentration gradient
        
        This is a form of secondary active transport, as the electrochemical gradient is used as an energy source (instead of ATP hydrolysis)
        
        An example of cotransport is the absorption of glucose in the kidneys and small intestine (contransported with sodium ions)
        
        antiports
        
        Antitransporters move two molecules in opposite directions across the membrane
        
        An example of antiport is the translocation of sodium and potassium ions by the sodium-potassium pump
        
        This pump is used by nerve cells (neurons) to establish an electrochemical gradient across the membrane (resting potential)
        
        Three sodium ions bind to intracellular sites on the sodium-potassium pump
        
        A phosphate group is transferred to the pump via the hydrolysis of ATP
        
        The pump undergoes a conformational change, translocating sodium across the membrane
        
        The conformational change exposes two potassium binding sites on the extracellular surface of the pump
        
        The phosphate group is released which causes the pump to return to its original conformation
        
        This translocates the potassium across the membrane, completing the ion exchange