Ch.6 Flashcards
Metabolism
- Sum of chemical reactions in a cell
2 parts: - catabolism
- anabolism
Catabolism
Metabolism
- Processes that degrade (break down) compounds to release energy
- Cells capture to make ATP
Anabolism
Metabolism
- Assemble subunits of macromolecules
- build up energy storage
- Use ATP to drive reactions
Energy
- Energy is the capacity to do work
Two types of energy: - Potential
- Kinetic
1st law of thermodynamics
- Energy in universe cannot be created or destroyed, but it can be changed from one form to another
Potential energy
Type of Energy
stored energy (chemical bonds, rock on hill, water behind dam)
Kinetic energy
Type of energy
energy of motion (moving water)
When do exergonic reactions occur? Please define your answer in terms of free energy, reactants and products
- Free energy is energy available to do work
- Energy released when chemical bond is broken
- Exergonic reactions: reactants have more free energy than products
– Energy is released in reaction
– Reactants: A + B + free energy
– Products: AB
What is the usable energy currency of the cell?
- Adenosine triphospate (ATP): energy currency of cell
- Composed of ribose, adenine, three phosphate groups
- Cells use energy to produce ATP by adding Pi to adenosine diphosphate (ADP)
- Energy released by removing Pi from ATP to yield ADP
How do chemoorganotrophs obtain their energy in the 1st place?
obtain energy from organic compounds
Chemoorganotrophs (aka chemoheterotrophs) produce ATP energy in what 2 ways?
- Substrate-level phosphorylation: Energy generated in exergonic reactions
- Oxidative phosphorylation: Energy generated by proton motive force
What does the term “oxidation” mean in both biological beings and in chemistry?
Removing H+
Dehydrogentation
What does the term “reduction” mean in both biological beings and in chemistry?
gaining H+
Hydrogenation
What is the most common starting pathway for the breakdown of sugars (what is the first step of cellular respiration?)
glucose 6C is broken down into two pyruvate molecules, occurring in the cytoplasm
- Generates modest ATP, reducing power, precursors
Why do cells degrade sugars?
to generate ATP
Which molecule serves as the terminal electron acceptor in aerobic respiration?
O2 is terminal electron acceptor
Which molecule serves as the terminal electron acceptor in anerobic respiration?
A molecule OTHER THAN O2 as terminal electron acceptor such as nitrate, nitrite and sulfate
Which process (aerobic, anaerobic, fermentation) produces the greatest amount of energy? Why?
Aerobic because total ATP = 38 ATP
What does fermentation use as the terminal electron acceptor?
organic molecule (pyruvate or a derivative)
How many ATP’s are produced in fermination?
Total ATP: 2
Pyruvate is produced at the end of glycolysis. What are the two major routes in which pyruvate can be further metabolized?
- aerobic respiration= entering the citric acid cycle when oxygen is present
- anaerobic fermentation= converting to lactate in animals or ethanol in yeast when oxygen is absent
Which suffix is used to denote an enzyme?
- Name reflects function
- ends in -ase
How do enzymes speed up reactions?
- Lowers activation energy of reaction
What does the term “induced fit” refer to?
- Active site on surface of enzyme binds substrate(s) weakly
- Causes enzyme shape to change slightly, induced fit
- Resulting enzyme-substrate complex destabilizes existing bond or allows new ones to form
What is another term for Coenzyme?
- A cofactor of minerals or inorganics like magnesium, zinc, copper
- Coenzymes are organic cofactors that help some enzymes transfer certain molecules or electrons from one compound to another
Which Environmental factors affect enzyme activity?
- Temperature, pH, salt concentration
- 10 degrees Celsius increase doubles speed of enzymatic reaction up to maximum
- proteins denature at higher temperatures
- Low salt, neutral pH usually optimal
What is produced in the TCA cycle?
- 2 CO2
- 2 ATP
- 6 NADH
- 2 FADH2
- Precursor metabolites
What is the Proton Motive Force?
energy released promotes movement of protons across membrane
Where does oxygenic photosynthesis obtain electrons and hydrogens from?
water molecules are split to provide a source of electrons for the electron transport chain
Where does anoxygenic photosynthesis obtain electrons and hydrogens from?
inorganic compunds like hydrogen sulfide (H2S) and reduced iron
