the importance of membranes of different types of cells Flashcards
importance of membranes in photosynthesis
-chlorophyll molecules absorb light energy from photons of sunlight
-this excites electrons to a higher energy level which causes them to be released from the chlorophyll
-two excited electrons enter the electron transport chain which is a series of carrier proteins embedded in the membrane that allows electrons to be transferred down the chain through a series of redox reactions which releases energy.
-this energy is coupled to the active transport of hydrogen ions from the stroma into the thylakoid space creating an electrochemical gradient for the hydrogen ions
-in chemiosmosis the hydrogen ions move down the electrochemical gradient into the stroma via ATP synthase.
-energy is used to join ADP and an inorganic phosphate to from ATP
-NADP is reduced by electrons and protons
-the NADP and ATP is required to reduce glycerate 3 phosphate to make triose phosphate which is converted to glucose necessary for cellular respiration
importance of membranes in microvilli
-sodium ion are actively transported out the small intestine epithelium cells into the bloodstream which occurs on a carrier protein embedded in the membrane
-this maintains a concentration gradient by maintaining a higher concentration of sodium ions in the small intestine lumen than the epithelial cells
-this causes sodium ions to move down their conc gradient into the epithelium cells by facilitated diffusion
-glucose is cotransported with the sodium ions via a sodium-glucose co- transporter protein embedded in the membrane
-these epithelial membranes are important in the absorption of digested products like glucose which required transportation into the blood to be used in respiration. this is necessary for ATP production which is used for metabolic processes such as muscle contraction
importance of membranes in synapses
-an action potential arrives at the synaptic knob of the presynaptic membrane
-this stimulates voltage gated calcium channels to open so calcium ions diffuse into the synaptic knob
-the influx of calcium ions causes the synaptic vesicles to fuse with the presynaptic membrane
-the vesicles releases neurotransmitters into the synaptic cleft
-the neurotransmitter diffuses across the synaptic cleft and binds to specific receptors on the postsynaptic membrane
-sodium ion channels open and sodium ions diffuse into the postsynaptic neuron causing depolarisation of the membrane
-if the threshold is reached it enables an action potential to be generated which allows an organisms to respond to stimulus in order to increase their chances of survival
importance of membranes in immune response
-when a pathogen enters the body the phagocyte detects the pathogen due to it’s foreign antigens on its membrane
-the phagocyte’s cytoplasm moves around the pathogen, engulfing it and packaging it into a phagocytic vacuole in the cytoplasm to form a phagosome
-lysosomes then fuse to the vacuole and release hydrolytic enzymes called lysozymes which hydrolyse the pathogen
-the phagocyte absorbs the soluble contents from the pathogen hydrolysis
-the phagocyte displays the antigen from the pathogen on its cell surface membrane to become an antigen presenting cell
-this is important as it activates the humoral response to activate long term immunity
