Plasma Membrane
Diffusion/ Osmosis
Transport (proteins)
Energy
Enzymes
100
What is the major molecular component of the plasma membrane?
Phospholipids
100
Describe the concept of diffusion. Provide an example, real or not.
Diffusion refers to the passive (non-energy requiring) movement of molecules down their concentration gradients from an area of high concentration, to an area of lower concentration. Diffusion will persist until there is equilibrium.
100
Describe the differences between Active and Passive transport.
Active- this type of transport requires energy
Passive- this does not require energy
100
Describe the differences between potential and kinetic energy.
Kinetic energy is the energy of an object/molecule in motion, where as potential energy is the energy of an object/molecule that has the potential to move
100
What type of enzymatic reaction breaks down large molecules into smaller molecules?
Catabolic enzyme/reactions
200
Draw a phospholipid bilayer. Describe its hydrophobic/hydrophilic components. Label it with "extracellular fluid" and the "cytosol"
Dr. A will draw!
200
Diffusion question: If the extracellular fluid has 37 molecules of O2, and the cytosol has 15 molecules of O2, which has a higher concentration? Will O2 diffuse, if so which way?
The extracellular fluid has a higher concentration of oxygen, therefore, oxygen will flow into the cytosol until equilibrium is met
200
What are the differences between a transmembrane integral protein and a peripheral protein?
Integral proteins completely pass through the plasma membrane, whereas peripheral proteins are only found on the surface of the plasma membrane, cytosolic and extracelullar surfaces.
200
What is an endergonic reaction?
A reaction that requires energy
200
What type of enzyme builds larger molecules from smaller ones?
Anabolic Enzymes
300
What type of molecules can freely pass through the plasma membrane and why?
Small non-polar molecules, because they are not repelled by the non-polar hydrophobic fatty acid tails within the phospholipid bi-layer of the plasma membrane.
300
List 3 things that affect the rate of diffusion.
-concentration
-temperature
-solubility
-mass of molecule
-surface area
-distance traveled
300
What type of integral proteins are used for facilitated (passive) transport across the plasma membrane?
Channel and Carrier proteins
300
What is an exergonic reaction?
A reaction that releases energy
300
What is the substrate of an enzyme? What is an active site?
The enzymes substrate is the specific molecule/compound that binds the enzyme and gets turned into product.
The active site is where the substrate interacts with the enzyme
400
List the two key components that help to make the plasma membrane "fluid" and how.
Unsaturated fatty acid tails in the phospholipids and cholesterol. Temperature is also important.
400
What is osmosis? What is osmolarity?
Osmosis is the specific diffusion of water. Osmolarity refers to the solute concentration in water. A solution with high solute concentration has a high osmolarity, meaning that water would move towards this solution across a semi-permeable membrane.
400
Describe the differences between a uniporter, symporter, and an antiporter transmembrane protein.
Why would a cell need to use these forms of active transport?
A uniporter moves one molecule in one direction, a symporter moves two molecules in one direction, an antiporter moves two molecules in opposite directions.
Cells need to use active transport (requires energy) to move molecules AGAINST their concentration gradients.
400
What are the two laws of thermodynamics?
1. energy cannot be created or destroyed, but can be transformed
2. Entropy is always increasing, i.e. the transfer of energy is not always efficient, meaning that energy will sometimes be transformed into an unusable form of energy (often heat)
400
Describe how an competitive inhibitor works.
A competitive inhibitor binds directly to the active site of an enzyme, directly preventing the substrate from binding (competes for the active site), thus preventing the enzyme from generating product
500
Why is this depiction of the plasma membrane referred to as the fluid mosaic model?
Fluid- the unsaturated fatty acid tails and the insertion of cholesterol make the membrane flexible. Additionally, components of the membrane are able to float/move around the membrane
Mosaic-the plasma membrane is made up of many different components like a mosaic
500
Osmolarity question: Na+ is a ion, and therefore cannot freely pass through the plasma membrane. There are 42 molecules of Na+ in the cytoplasm and 19 molecules of Na+ in the extracellular matrix. Which side of the cell has the higher osmolarity? Which way will water move? Will this make the cell hypertonic, isotonic or hypotonic?
FUN QUESTION: What type of ion is Na+??
The cytoplasm has the higher osmolarity, therefore water will flow into the cell. This will swell the cell and make it hypotonic.
Fun question: CATion because it is PAWsitive
500
Describe the differences between bulk transport mechanisms of phagocytosis and pinocytosis. What type of eukaryotes heavily rely on endocytosis ?
Phagocytosis is cell eating, and Pinocytosis is cell drinking. Protists, single celled eukaryotes heavily rely on these forms of endocytosis for survival.
500
Provide an example of potential and an example of kinetic energy within a cell. Think of molecules and movement.
Potential energy
-chemical bonds
-concentration gradients
Kinetic energy
-breaking of chemical bonds-molecules moving down their concentration gradients
500
Describe how an allosteric (non-competitive) inhibitor stops enzymes from functioning properly.
The allosteric inhibitor binds to another site of the enzyme (not the active site) and cause a conformational change in the enzyme structure. This change in the enzyme structure prevents the substrate from binding the active site, stopping the enzyme from producing any product