1.4 Syllabus
U1. Particles move across membranes by simple diffusion, facilitated diffusion, osmosis and active transport.
Passive Transport: Movement of molecules from an area of higher concentration to an area of lower concentration
(Down the concentration gradient)
→Simple diffusion: Passive transport of molecules through a membrane, without the need of protein channels
(Use any part of a membrane/ oxygen diffusion)
→Facilitated diffusion: Passive transport of molecules facilitated by channel proteins
(Use Channels in the membrane/ Sodium or calcium transport)
→Osmosis: Passive transport that is the movement of water from the area of low solute concentration to the area of high solution concentration. ex) Water from soil to root
Related Question:
Q. Outline the role of proteins in active and passive transport of molecules through membranes
Answer: Membranes are permeable that allows diffusion. Diffusion is passive movement of particles from high to low concentration. No ATP is involved due to random motion of molecules. Diffusion continues until concentration are equal across the membrane.
(Down the concentration gradient)
→Simple diffusion: Passive transport of molecules through a membrane, without the need of protein channels
(Use any part of a membrane/ oxygen diffusion)
→Facilitated diffusion: Passive transport of molecules facilitated by channel proteins
(Use Channels in the membrane/ Sodium or calcium transport)
→Osmosis: Passive transport that is the movement of water from the area of low solute concentration to the area of high solution concentration. ex) Water from soil to root
Related Question:
Q. Outline the role of proteins in active and passive transport of molecules through membranes
Answer: Membranes are permeable that allows diffusion. Diffusion is passive movement of particles from high to low concentration. No ATP is involved due to random motion of molecules. Diffusion continues until concentration are equal across the membrane.
SIMPLE DIFFUSION VS FACILITATED DIFFUSION
Active Transport: Movement of molecules from an area of lower concentration to an area of higher concentration, with the use of energy ATP. (Against the concentration gradient)
Related Question:
Q. Outline the role of proteins in active and passive transport of molecules through membranes
Answer: Channel proteins allow diffusion/osmosis/passive transport. Large polar molecules cannot cross the hydrophobic membrane freely. Facilitated diffusion involves moving molecules through proteins down their concentration without requiring ATP. Aquaporins (specific integral membrane proteins) facilitate the movement of water molecules which is the osmosis. Some proteins for facilitated diffusion are specific to molecules. Active transport involves moving molecules through proteins against their concentration gradient requiring ATP. Some proteins in membrane are pumps which perform active transport (sodium potassium pump)
PASSIVE TRANSPORT VS ACTIVE TRANSPORT
U2. The fluidity of membranes allows materials to be taken into cells by endocytosis or released by exocytosis. Vesicles move materials within cells.
Exocytosis: Transport of molecules from the golgi apparatus to the cell membrane, using a vesicle made of phospholipids which upon contact with the plasma membrane fuses with it and releases the content.
Related Question:
Q. Outline the process of exocytosis
Answer: Vesicles carry material to plasma membrane. Vesicles fuses with membrane by joining or phospholipid bilayers aided by the fluidity of the membrane. Materials are released from the cell and membrane flattens. ex) Exocytosis of neurotransmitter
Endocytosis: Transport of molecules into the cell through invagination of the plasma membrane and formation of the phospholipid vesicle containing the molecule.
Related Question:
Q. Outline the process of endocytosis
Answer: Endocytosis occurs when a membrane encloses a target particle. Fludity of membrane permits movement of membrane. Membrane sinks inwardly to enclose particle. Membrane seals back on itself. 2 phospholipid layers enclose particle moving vesicle. Inner phospholipid layer of original membrane becomes outer phospholipid layer of vesicle membrane. Outer phospholipid layer of vesicle membrane. Outer phospholipid layer of membrane becomes inner phospholipid layer of vesicle membrane. Vesicle breaks away from membrane and moves into cytoplasm. Changes in membrane shape require energy. ex) pinocytosis
Related Question:
Q. Outline the process of exocytosis
Answer: Vesicles carry material to plasma membrane. Vesicles fuses with membrane by joining or phospholipid bilayers aided by the fluidity of the membrane. Materials are released from the cell and membrane flattens. ex) Exocytosis of neurotransmitter
Endocytosis: Transport of molecules into the cell through invagination of the plasma membrane and formation of the phospholipid vesicle containing the molecule.
Related Question:
Q. Outline the process of endocytosis
Answer: Endocytosis occurs when a membrane encloses a target particle. Fludity of membrane permits movement of membrane. Membrane sinks inwardly to enclose particle. Membrane seals back on itself. 2 phospholipid layers enclose particle moving vesicle. Inner phospholipid layer of original membrane becomes outer phospholipid layer of vesicle membrane. Outer phospholipid layer of vesicle membrane. Outer phospholipid layer of membrane becomes inner phospholipid layer of vesicle membrane. Vesicle breaks away from membrane and moves into cytoplasm. Changes in membrane shape require energy. ex) pinocytosis
A1. Structure and function of the sodium-potassium pumps for active transport and potassium channels for facilitated diffusion in axons.
Osmolarity: Measurement of solute concentration of a sodium,
-Hypotonic: Solute concentration inside the cell is higher/ Water goes in/ Plant cell: Turgid/ Animal cell: Lysed (Burst)
It has relatively lower osmolarity
-Hypertonic: Solute concentration outside the cell is lower/ Water goes out/ Plant cell: Shrink/ Animal cell: Shrivel
It has relatively higher osmolarity
Related Question:
Q. Outline the effects of putting plant tissue in a hypertonic solution
Answer: Hypertonic solution has higher solute concentration than the cells. Water moves out of the cells by osmosis into the hypertonic solution. Water moves from lower solute concentration to higher solute concentration. Cell becomes plasmolysed. Cell is no longer turgid.
-Hypotonic: Solute concentration inside the cell is higher/ Water goes in/ Plant cell: Turgid/ Animal cell: Lysed (Burst)
It has relatively lower osmolarity
-Hypertonic: Solute concentration outside the cell is lower/ Water goes out/ Plant cell: Shrink/ Animal cell: Shrivel
It has relatively higher osmolarity
Related Question:
Q. Outline the effects of putting plant tissue in a hypertonic solution
Answer: Hypertonic solution has higher solute concentration than the cells. Water moves out of the cells by osmosis into the hypertonic solution. Water moves from lower solute concentration to higher solute concentration. Cell becomes plasmolysed. Cell is no longer turgid.
A2. Tissues or organs to be used in medical procedures must be bathed in a solution with the same osmolarity as the cytoplasm to prevent osmosis.
-The importance of osmotic control is preventing damage to cells and tissues.
-Common medical procedures in which an isotonic saline solution is useful:
• fluids introduction to a patient’s blood system via an intravenous drip, e.g for rehydration
• used to rinse wounds, skin abrasions etc.
• keep areas of damaged skin moist before applying skin grafts
• eye drops/wash
• frozen and used pack donor organs for transportation
=in order to keep the cells "fresh" and like ready to be placed into someones body they want to be put in an ISOTONIC solution before they're used
-Common medical procedures in which an isotonic saline solution is useful:
• fluids introduction to a patient’s blood system via an intravenous drip, e.g for rehydration
• used to rinse wounds, skin abrasions etc.
• keep areas of damaged skin moist before applying skin grafts
• eye drops/wash
• frozen and used pack donor organs for transportation
=in order to keep the cells "fresh" and like ready to be placed into someones body they want to be put in an ISOTONIC solution before they're used