Metabolism Flashcards
Which two fundamental tasks must cells accomplish in order to grow?
- Synthesize new components
~ Need carbon, oxygen, hydrogen, nitrogen, sulfur, phosphorus, etc. - Harvest energy
What is metabolism?
The sum total of chemical reactions of biosynthesis and energy-harvesting
What are the 3 central metabolic pathways?
- Glycolysis
- Pentose phosphate pathway
- Tricarboxcylic acid cycle
What are the 3 things that central pathways provide?
- Energy in the form of ATP
- Reducing power (electrons bound to carriers)
- Precursor metabolites
What is glycolysis?
The oxidizing of glucose to two molecules of pyruvate
Which 3 tasks does the Pentose phosphate pathway accomplish?
- Breaks down glucose
- Produces molecules for biosynthesis
- Works in conjunction with glucose degrading pathways
How many times does the TCA cycle turn for each molecule of Glucose that enters glycolysis?
Twice
When does pyruvate enter a transition step?
Between glycolysis and the TCA cycle.
What are the 3 electron carriers used in respiration?
- Nicotinamide adenine dinucleotide - NAD+
- Flavin adenine dinucleotide - FAD+
- Nicotinamide adenine dinucleotide phosphate - NADP+
When are Electron carriers reduced?
when they pick up electrons
Reduced electron carriers bonds contain a form of what?
Usable energy
What does NAD+ carry?
2 electrons and a proton
NAD+ + 2e- + 2H+ ↔ NADH + H+
What does FAD+ carry?
2 electrons and 2 protons
FAD+ + 2e- + 2H+ ↔ FADH2
What does NADP+ carry?
2 electrons and a proton
NADP+ + 2e- + 2H+ ↔ NADPH + H+
If glucose was oxidized all at once, what would be the form of the released energy?
Heat and light
Why are electrons passed from carrier to carrier through the Electrom Transport Chain?
To release the energy gradually, so that energy can be used to make ATP.
What is the Electron Transport Chain?
A group of membrane-embedded electron carriers that accept electrons and pump protons across (cytoplasmic) membrane.
How is a proton motive force created?
Some carriers accept electrons only and some accept electrons and protons, so protons are effectively pumped out of the membrane, creating a concentration gradient.
How does a cell utilize proton motive force?
to synthesize ATP, actively transport substances, or rotate a flagella
What is the “Final Destination” of the electrons in aerobic respiration?
oxygen– making water
Waht are the end products of fermentation?
- Lactic acid
~ if pyruvate itself serves as the final destination of the electrons - Other acids or alcohols
~ if pyruvate is first converted to another chemical
~ ex. propionic acid and CO2
~ ex. Ethyl alcohol and CO2
What can the end products of fermentation be used for in the lab?
identification of microorganisms
Name 3 anaerobic terminal electron acceptors.
- nitrate (NO2-)
- from glucose to sulfate
~ sulfate reducers (Obligate anaerobes) - from hydrogen gas to carbon dioxide
~ methanogens
Which releases more energy: aerobic respiration or anaerobic respiration?
Aerobic
What does anaerobic respiration use as the terminal electron acceptor in the electron transport chain?
An inorganic chemical other than oxygen
What does aerobic respiration use as the terminal electron acceptor?
Oxygen
What does fermentation use as the terminal electron acceptor?
An organic compound
What do Photosynthetic organisms harvest energy from?
Sunlight
What are “light capturing pigments”?
Chlorophyll or similar molecules
What are the steps of photosynthesis?
- Electrons are stripped from water
- Added to chlorophyll
- Raised in energy by light energy
~ Redox reaction is thus oxidation of (excited) chlorophyll and reduction of chlorophyll.
What is the production of Oxygen in photosynthesis called?
Oxygenic photosynthesis
Where do electrons come from in anoxygenic photosynthesis?
hydrogen gas, hydrogen sulfide, or organic compounds
Can photosynthesis electrons generate a proton motive force similar to how the electron transport chain does?
Yes.
Which color of bacteria are Anoxygenic Phototrophs, and where do they live?
Purple and Green bacteria often inhabit bogs and upper layers of mud
What is the earliest Oxygenic Phototrophs and where do they live?
Cyanobacteria thought to be earliest, and they inhabit a wide range of environments (aquatic to terrestrial)
What is the most common pathway of carbon fixation?
The Calvin Cycle
How is carbon dioxide converted to organic carbon? How much energy does it consume?
Through carbon fixation, which consumes a great deal of energy
