Chapter 5 Flashcards
energy
The capacity to perform work, or to move matter in a direction it would not move if left alone.
kinetic energy
The energy of motion. Includes heat and light.
potential energy
Stored energy. Includes chemical energy.
chemical energy
Arises from the arrangement of atoms and can be released by a chemical reaction. Ex. Oxygen and gas combustion for cars
principle of conservation of energy.
this principle states that energy can neither be created nor destroyed, only converted.
Explain what ATP is and how ATP powers cellular work.
ATP transfers a phosphate group to another molecule, increasing that molecules energy content
Explain how ATP is recycled.
- Cells spend ATP continuously.
- Cellular work spends ATP, which is recycled when ADP and a phosphate are combined, using energy released by cellular respiration.
a. Up to 10 million ATPs are consumed and recycled each second in a working muscle cell.
Explain why enzymes are needed in living organisms and understand the concept of activation energy
the amount of energy that reactants must absorb before a chemical reaction will start. Enzymes enable metabolism to occur by lowering this barrier for reactant molecules
Explain how enzymes are able to speed up specific chemical reactions. Understand what it means to be a catalyst
Enzymes enable metabolism to occur by reducing the amount of activation energy required to break bonds of reactant molecules.
Explain the things that affect the rate of enzyme activity and why they have that effect.
The activity of an Enzyme is affected by its environmental conditions. Changing these alter the rate of reaction caused by the enzyme. In nature, organisms adjust the conditions of their enzymes to produce an Optimum rate of reaction, where necessary, or they may have enzymes which are adapted to function well in extreme conditions where they live.
Increasing temperature increases the Kinetic Energy that molecules possess. In a fluid, this means that there are more random collisions between molecules per unit time.
Any change in pH above or below the Optimum will quickly cause a decrease in the rate of reaction, since more of the enzyme molecules will have Active Sites whose shapes are not (or at least are less) Complementary to the shape of their Substrate.
Changing the Enzyme and Substrate concentrations affect the rate of reaction of an enzyme-catalysed reaction. Controlling these factors in a cell is one way that an organism regulates its enzyme activity and so its Metabolism.
Explain how inhibitors and poisons can affect enzyme activity.
- Certain molecules inhibit a metabolic reaction by
a. binding to an enzyme and
b. disrupting its function. - Some of these enzyme inhibitors are actually substrate imposters that plug up the active site.
- Other inhibitors bind to the enzyme at a site remote from the active site, but the binding changes the enzyme’s shape so that the active site no longer accepts the substrate.
- In each case, an inhibitor disrupts the function of an enzyme by altering its shape.
- In some cases, the binding of an inhibitor is reversible.
- If a cell is producing more of a certain product than it needs, that product may reversibly inhibit an enzyme required for its production, keeping the cell from wasting resources that could be put to better use.
- Many beneficial drugs work by inhibiting enzymes.
a. Penicillin blocks the active site of an enzyme that bacteria use in making cell walls.
b. Ibuprofen inhibits an enzyme involved in sending pain signals.
c. Many cancer drugs inhibit enzymes that promote cell division.
d. Many toxins and poisons also work as inhibitors
Explain what a coenzyme is. What kinds of things act as coenzymes
A substance that enhances the action of an enzyme. (An enzyme is a protein that functions as a catalyst to mediate and speed a chemical reaction).
Coenzymes are small molecules. They cannot by themselves catalyze a reaction but they can help enzymes to do so. In technical terms, coenzymes are organic nonprotein molecules that bind with the protein molecule (apoenzyme) to form the active enzyme (holoenzyme).
A number of the water-soluble vitamins such as vitamins B1, B2 and B6 serve as coenzymes.
Describe the structure of the cell membrane and how the structure allows it to be semi-permeable.
Cellular membranes are composed of a phospholipid bi-layer. The phospholipids are composed of a polar, phosphate based “head” portion attached to a non-polar, hydrocarbon based “tail” portion. Groups of these phospholipids come together as a double thick layer with the hydrophobic tails in the interior and the hydrophilic heads on the exterior. The membrane is described as semi-permeable since only certain kinds of molecules can pass through the cell membrane on their own. Other molecules require help to pass through the membrane. As a result, there are many proteins embedded in the membrane called transport proteins that allow particular substances to pass through the membrane while preventing unwanted materials from passing.
Understand and describe the function of membrane proteins
- Channel Proteins - form small openings for molecules to difuse through
- Carrier Proteins- binding site on protein surface “grabs” certain molecules and pulls them into the cell, (gated channels)
- Receptor Proteins - molecular triggers that set off cell responses (such as release of hormones or opening of channel proteins)
- Cell Recognition Proteins - ID tags, to idenitfy cells to the body’s immune system
- Enzymatic Proteins - carry out metabolic reactions
diffusion versus osmosis
Diffusion is a spontaneous movement of particles from an area of high concentration to an area of low concentration. … Osmosis is the spontaneous net movement of water across a semipermeable membrane from a region of low solute concentration to a more concentrated solution, up a concentration gradient.
