Exam 3 ( Cellular Respiration) Flashcards
What is the equation for Cellular Respiration?
C6H12O6 + 6O2—> 6CO2+6H2O+ 27-19 ATP + HEAT
What is cellular respiration?
It is a catabolic process in which cells obtain their energy from organic molcules ( mostly glucose)
What are the reactants of Cellular Respiration?
C6H12O6 + 6O2
What are the products of Cellular Respiration?
6CO2 + 6H2O ( metabolic water) + 27-29 ATP
What is being oxidized in Cellular Respiration?
(glucose). C6H12O2—-> 6CO2
What is being reduced in Cellular Respiration?
(oxygen) 6O2—>6H2O
What is respiration at a cellular level?
usage of oxygen by all the cells and the generation of CO2
What kind of reaction is cellular respiration? How do you know?
Exergonic. Energy is being released and the delta G is negative.
what role does blood supply have?
- delivers oxygen and removes CO2
- oxygen and CO2 go between blood and lungs
Can the body use other organic molecules besides glucose? Any exceptions?
Yes, but the brain specifically can only use glucose to function properly.
Why is energy released in a step-wise fashion?
Allows ATP to be produced efficiently.
release energy in small amounts over many redox reactions allows to capture the max E that can be turned into ATP.
What are the enzymes/coenzymes of the REDOX reactions?
NAD+ and FAD are coenzymes
What is the reaction sequence of cellular respiration?
- Glycolsis
- Transition Reaction (pyruvate decarboxylation)
- Citric Acid/ Krebs Cycle
- Electron Transport Chain (Oxidative Phosphorylation )
Where does glycolysis take place?
Cytoplasm
What is the main purpose of oxidative phosphorylation?
the main pathway to produce ATP
What can coenzymes do?
It can be both reduced and oxidized
How does NAD+ oxidize a metabolite?
accepting an e-
How does NAD+ reduce a metabolite?
by giving up e-
What is NAD’s reduced form?
NADH + H+
What is NAD’s oxidized form?
NAD+
What is the oxidized form of FAD?
FAD
What is the reduced form of FAD?
FADH2
What is important about the reduced states of FAD and NAD+?
They can temporarily hold energy within this state.
What happens in glycolysis ( general)?
- occurs in the cytoplasm
- glucose is broken down into 2 molecules of pyruvate
- A net gain of 2 ATP
What is special about glycolysis?
Happens the same way in all cells and indicates that cells have a common ancestry.
What happens in the transition reaction ( general)?
- move into the mitochondria
- both pyruvates are oxidized
- electron energy is stored in NADH+ +H+
- 2 Carbons are released as CO2
What happens in the Citric Acid cycle/ Krebs Cycle ( general)?
- electron energy is stored in the reduced energy carrier ( NADH+ + H_ and FADH2)
- ATP ( GTP) is formed
- 4 Carbons are released as CO2
What happens in the Electron Transport Chain/ Oxidative Phosphorylation ( general)?
- extracts energy from NADH+ +H+ and FADH2 ( reduced energy carriers)
- produces 23-25 ATP
- ETS and ATP synthase
- chemosmosis
- this is when we actually use O2
what does the word glycolysis mean?
break glucose
What are the two stages of Glycolysis?
- Energy Investing Steps
- Energy Harvesting Steps
What are the Energy Investing Steps?
1) 2 ATP are used to activate glucose
2) Glucose splits into 2G3P molecules
How does glucose get activated in glycolysis?
In step 1 glucose is activated by phosphorylation –> adding on phosphates and rearranging the glucose.
What is it called when glucose splits in glycolysis?
cleavage
What are the Energy Harvesting Steps?
- 2 electrons are picked up by two NAD+
- Four ATP and 2 pyruvate produced by substrate-level phosphorylation
What is substrate-level phosphorylation?
Moving the phosphate group from one molecule/substrate and adding to ADP–> ATP
- Occurs in step 4 of glycolysis
What is the net gain of Glycolysis?
2 ATP
What is being oxidized/reduced in glycolysis?
oxidized: substrate /G3P
reduced: carrier NAD+
What does hexokinase do?
Used to first phosphorylate glucose ( with ATP) into glucose 6 phosphate
- irreversible
What is PFK?
Phosphofructokinase
What does PFK do?
Used to phosphorylate glucose a 3rd time and turn it into fructose-1-6 bisphosphate
- regulatory step
How does PFK regulate ATP production?
If ATP is sufficient
- ATP will bind to PFK ( step 3)
- Feedback Inhibition
How does feedback inhibition work with PFK?
End result feeds back to earlier steps, the ATP hinders PFK until ATP is needed again
If oxygen is available what happens at the end of glycolysis?
You go into the Krebs Cycle
Summary of Glycolysis?
C6H12O6 + 2NAD+ + 2ATP + NADHP + 4Pi
——————————————>
2 pyrvate + 2(NADH+H+) + 4ATP + 2ADP
What is the summary of the transition Reaction?
2 pyruvate + 2CO- A —-> 2 acetyl- CO-A + 2CO2
What is step 1 of the transition reaction?
Pyruvate enters the mitochondrial matrix
How does step 1 work for the transition reaction?
To move pyruvate in step 1 –> use H/pyruvate pump
is the H/pyruvate pump secondary or primary active transport?
secondary, it is using a H ion gradient set up by primary active transport
what does decarboxylate mean?
to remove CO2
What is step 2 of the transition reaction?
Pyruvate is decarboxylated to make acetyl —> attached to COA ( Coenzyme A)
What is step 3 of the transition reaction?
Electron is picked up ( w/hydrogen atom) by NAD+
What happens to the CO2 that comes from step 2 of the transition reaction?
It is released and transported out of mitochondria and into the cytoplasm
What is being oxidized/reduced in the transition reaction?
oxidized: pyruvate/substrate
reduced: electron, Energy, and proton from carbon-based molecule to make 2NADH + H+
Where does the Krebs/Citric Cycle happen?
Matrix of mitochondria
- series of redox reactions
- runs twice for every glucose molecule ( 2 acetyl to move through the cycle)
What is step 1 of the Citric Cycle?
- COA delivers the acetyl and then goes back to the transition reaction
Acetyl-COA ( from the transition reaction) combines with Ocoaloacetate to make Citrate.
How does carbon change in step 2 of the citric cycle?
acetyl ( C2) + ocxaloacetate ( C4) = Citrate ( C6)
What is step 2 of the Citric Cycle?
Citrates are oxidized; NAD+ is reduced to NADH+ + H+
C6 –> C5–> C4
- decarboxylated
CO2 is released
What is Step 3 of the Citric Cycle?
2 ATP are produced through substrate-level phosphorylation
Why is the Citric Cycle a cycle?
It is a cycle because you start with Oxaloacetate and end with Oxaloacetate
What is step 4 of the Citric Cycle?
Succinate ( a C4 molecule) oxidized to Fumarate (a C4 molecule)
What is step 5 of the Citric Cycle?
Fumarate (C4) oxidized to Oxaloacetate ( C4)
- NAD+ is reduced to NADH+ + H+
How is the Citric Cycle Regulated?
- competitive inhibition
oxaloacetate competes w/ succinate on succinate dehydrogenase
- if there is a lot of oxaloacetate then it binds to the enzyme first and will slow the Kreb cycle
- if their succinate wins then the Kreb cycle continues.
What is the summary of the Kreb cycle?
2 Oxaloacetate + 2Acetyl CoA + 6NAD+ + 2ADP + 2FAD ————————->
2 Oxaloacetate + 2CoA + 6NADH + H+ + 2ATP + 2FADH2 + 4CO2
Where does Oxidative Phosphorylation happen?
Eukaryotes: cristae of mitochondria
Aerobic prokaryotes: plasma membrane
what goes on in the electron transport system?
- each carrier is more electronegative than the last
- carrier molecules are oxidized and reduced over and over
- shuttle electrons along
- as the electrons pass, energy is extracted
- energy is used to pump H
- movement of H = ATP
What are cytochromes?
respiratory enzymes
- use O2 —> generate CO2
Where does the oxidative phosphorylation get its energy from?
made to receive electrons from reduced energy carriers
- NADH+ + H+/ FADH2
= ATP
What is the definition of oxidative phosphorylation?
the process in which ATP is formed as a result of the transfer of electrons from NADH + H+ or FADH2 to O2 by a series of electron carriers
How does H move in the ETC?
- H and electrons from reduced energy carriers are sent into the electron transport system
- H is going to ultimately go to combine with oxygen to make metabolic water
- NADH+ + H+ delivers enough energy to make 2.3 ATP
- FADH2 delivers enough energy to make 1.38 ATP
Why is oxygen so important in the electron transport chain?
- oxygen is the final electron and proton acceptor
What is the main purpose of the electron transport chain?
mobilize energy in a step-wise fashion, ultimately regenerating the NAD and FAD to keep running previous cycles
How are coenzymes recycled in the ETC?
- once NADH+ + H+ delivers H it turns back into NAD
- H must be combined with oxygen to make water
- If oxygen is not present, NADH+ + H+ cannot release H
- no longer recycled back into NAD+
Can the Kreb or Electric Transport Chain occur without oxygen?
No
What is the summary of Oxidative phosphorylation?
1/2 O2 + 2H+ + 2e- —-> H2O
- does not account for the process that actually goes on
What is chemiosmosis? Where does it occur?
the process of moving ions (e.g. protons) to the other side of a biological membrane, and as a result, an electrochemical gradient is generated. This can then be used to drive ATP synthesis.
- ETC
What are respiratory poisons?
Will at some point block cellular respiration.
What are the three kinds of respiratory poisons?
- Block ETS
- Respiratory Poisons
- Uncouplers
How do Block ETS poisons work?
binds with electron carrier in the first protein complex
- blocks passage of e- to oxygen
- no production of ATP
What are some examples of Block ETS poisons?
Rotenone: used to kill pests, fish, insects
Cyanide
Carbon Monoxide
How do respiratory poisons work?
Inhibit ATP synthase
- blocks the passage of H+ through ATP Synthase
-ETS works normally
What are some examples of respiratory poisons?
Oligomycin - an antibiotic used to treat fungal infections on the skin.
Malachite green
How do Uncouplers work?
-ETS and ATP synthase are fine
- The mitochondrial membrane is weak/leaky, allowing H+ to come through.
- weak electrochemical gradient/ not as much ATP
What is an example of an Uncoupler?
DNP- Dinitrophenol, rapidly burns up fat stores boosting metabolism
- lose weight very fast
- die of fever
What is the metabolic pool?
Use of carbs, fats, and proteins in cellular respiration, also provides our cells with building blocks for homeostasis
How do other macromolecules enter into cellular respiration?
Breakdown products ( of proteins and fats) enter into respiratory pathways as intermediates, at different points of celllular respiration
How do proteins enter into cellular respiration?
Enter through amino acids (aa)
- some aa used to make each other
What are essental aa?
necessary in our bodies
- we do not produce them ,
- brought in through diet
How is Nitrogen from excess aa deaminated?
how do we get rid of nitrogenous waste ?
- ammonia ( NH3) processed in liver into urea
-urea expelled in urine, blood, sweat , bile, and milk
What is uric acid?
another form of nitogenous waste
ex. expelled in bird poop
What is the Urea cycle?
how to get rid of urea
- backwards citric cycle
What is glycogensis
production of glycogen ( glucose storage)
What is glycogenolysis?
breakdown of glycogen ( get that glucose out)
lipogensis?
production of lipids ( excess glucose=fats)
lipolysis?
breakdown of lipids
gluconeogenesis?
production of glucose from non-carbohydrate sources (fats+ proteins turn into glucose)
Are fermentation and anaerobic respiration the same?
No, fermentation is an anaerobic pathway but DOES NOT involve ETS; anaerobic respiration DOES use ETS
What happens when oxygen is not present at the end of ETS?
NAD and FAD are not regenerated and instead form free radicals
- glycolysis stops
What are two things organisms do when oxygen is not present?
1) anaerobic respiration
2) Fermentation
Can all organisms do anaerobic respiration?
No, only prokaryotes
How does anaerobic respiration work for prokaryotes?
They donate to a different electron acceptor at the end of oxidative phosphorylation
How does fermentation work?
- provides NAD+ for glycolysis to continue
- a rapid burst of ATP
- NADH+ + H+ combines with pyruvate to yield NAD+
What is Zymology?
Science of fermentation.
Where can you find Prokaryotes that perform Anaerobic Respiration?
Smelly marshes, coastal area
Even though we cannot perform anaerobic respiration why is it important to us?
Anaerobic respiration plays a major role in:
- global nitrogen cycles
- global sulfur cycles
- global oxygen cycles
Is anaerobic respiration efficient?
It is not as efficient as aerobic respiration but it doesn’t need to be
- prokaryotes don’t need as much
What are the two types of fermentation?
- Lactic Acid Fermentation
- Alcoholic Fermentation
What process happens in our cells when oxygen is not present?
Lactic Acid Fermentation
How does Lactic Acid Fermentation work?
- pyruvate at the end of glycolysis when in the presence of lactate dehydrogenase is REDUCED into lactic acid.
- Pyruvate REDUCED by NADH + H–> NADH+H is OXIDIZED into NAD
- glycolysis can continue
What is the issue with Lactic Acid buildup?
Can result in PH change
Do lactic acid molecules cause fatigue?
No, the buildup of phosphate and O2 debt causes fatigue
How does the body deal with built-up lactic acid?
It is sent to the liver to be converted into ATP
- Cori cycle
What molecule goes through Alcoholic Fermentation?
yeast ( single-celled fungi)
How does alcoholic fermentation work?
- the pyruvate at the end of glycolysis in the presence of pyruvate dehydrogenase turns into acetaldehydes
- pyruvate decarboxylated –> CO2 released - acetaldehydes REDUCED into ethanols—> NADH + H OXIDIZED back into NAD
- Glycolysis continues
What is primary metabolism?
breakdown of nutrients to give us building blocks and produce ATP
What is secondary metabolism?
Synthesis of molecules that are not essential for cell structure or growth
What roles do second metabolites have?
roles in defense, attraction, protection, and competition
What are the 4 categories of Second metabolites?
- Phenolics
- Alkaloids
- Terpenoids
- Polyketides
What are Phenolics? What is important about them?
Antioxidants with intense flavor and smell
- stabilize free radicals
What are some examples of Phenolics?
- super fruits, acai berries, vanilla, flowers
- called flavinoids
What are the phenolics that could upset the GI tract?
Tannins: animal hides
Lignins: wood
What are Alkaloids?
bitter-tasting molecules for defense
What are some examples of Alkaloids?
Cocaine
Caffeine
Codeine - morphine
Capeisin- chilli peppers
What are some of the side effects of consuming alkaloids?
- upset stomach
- unpleasant order
- burning sensation
- feel nauseous
- accelerated heart rate
- get sick and die
What are Terpenoids? Why do we need them?
intense smells and colors; used to attract or repel
- biggest group of secondary metabolites
- high variation
- beta- beta-carotene for our photoreceptors
What are examples of terpenoids>
Carotenoids, steroid hormones, cinnamon, fennel, clove, cumin, mint
What are Polyketides?
chemical weapons ( lots of variety)
- defence; highly toxic
What are some examples of Polyketides?
- blue-ringed octopus, pufferfish, salamanders, cone snail
