3.1,2,3,4 Contd: Cells And Energy Flashcards
Living cells have a constant flow of _____ in an out of the cell membranes, meaning that they are not at _____.
- materials
- equilibrium
What are the three types of work that cells perform?
Mechanical, transport and chemical
What is mechanical work?
Movement ( such as beating cilia, movement of chromosomes, contraction of muscle cells)
What is transport work?
Pumping substances across membranes against spontaneous movement
What is chemical work?
Synthesis of molecules (ex, building polymers from monomer)
What is ATP?
Molecules that organisms use as a source of energy to perform work
How exactly does ATP power cellular work?
- ATP couples exergonic rxn to endergonic rxn to power cellular work
- Exergonic process then drives the endergonic process
- Then organisms get energy by breaking the bond between the 2 and 3 phosphate in a hydrolysis reaction
What occurs in phosphorylation?
The released phosphate moves to another molecule to give energy
Ex. ATP to ADP
This was not in the notes, but why is cellular respiration exergonic, even though you need energy from the exergonic process to produce ATP?
- synthesis of ATP is endergonic, but cellular respiration as a whole is exergonic because more energy is released
The Law of thermodynamics tells us a reaction is ____, but it does not describe what?
- spontaneous
- rate of reaction
Some spontaneous reactions move slow that it would be impossible for cells to utilize them efficiently. An example is the hydrolysis of sucrose to glucose, which would take 1000 years. What speeds up these reactions, and why?
- enzymes are macromolecules that catalyzes reactions by lowering activation energy
Are enzymes consumed by reactions?
No, they can be reused over and over
Enzymes are a type of ___ that usually end in___.
- protein
- ase
What is an enzyme’s reactant called?
Substrate
What is an active site?
Area on enzyme for substrate to bind
Substrates are held in active site by ____ interactions.
Weak
What is an induced fit?
- enzymes will change shape of their active site to allow the substrate to bind better
What is enzyme catabolism?
Enzyme helps breakdown complex molecules
Enzyme anabolism
Enzyme helps build complex molecules
Since enzymea are proteins, their 3D shape is affected by different factors. What is their efficientcy affecfes by?
- temperature
- pH
- Chemicals
THUS A CHANGE IN SHAPE INDICATES A CHANGE IN FUNCTION
What are optimal conditions?
- the condition (Temp and pH) that allow enzymes to function optimally (at their best)
The rate of enzyme activity ____ with temperature (due to collision) up to a certain point. What happens after this?
- increases
After a certain point, enzyme will DENATURE
What happens if an enzyme is out of their normal pH range?
- cause weak hydrogen bonds in the enzyme to break, changing the shape of the enzyme
What are enzyme cofactors? (3)
- non-protein molecules that assist enzyme function
- inorganic cofactors consist of metals
- can be bound loosely or tightly
What is a holoenzyme?
Enzyme with the cofactor attached
What are coenzymes?
Organic factors, such as vitamins
What are enzyme inhibitors?
Reduce the activity of specific enzymes
How can inhibition be permanent?
- inhibitor binds with covalent bonds
Ex. Toxins or poisons
How can inhibition be reversible?
Inhibitor binds with weak interactions
What do competitive inhibitors do? How can inhibition be reversed?
- they reduce the enzyme activity by blocking substrates from binding to the active site
- inhibition can be reversed with increased substrate concentration
What do noncompetitive inhibitors do? What type of inhibition is this?
- bind to an area other than the active site (allosteric site) which changes shape of active site, preventinf substrates from binding
- type of allosteric inhibition
How does a cell regulate its metabolic pathways? (2)
- Control where and when enzymes are active
- switch genes that code for enzymes on or off
