Unit C: Cellular Respiration Flashcards
What is Cellular respiration?
Takes place in the mitochondria of animals.
This process uses glucose from plants to synthesize ATP. Carbon dioxide is a byproduct of cellular respiration, which can take place either with or without oxygen.
What is the equation of cellular respiration?
Glucose + oxygen gas –> carbon dioxide + water + energy
C6H12O6 + O2 –> 6CO2 + 6H2O + ATPs
What does aerobic respiration mean?
With oxygen
What does anaerobic respiration mean?
Without oxygen
What are the main steps of aerobic cellular respiration?
1) Glycolysis
2) Kreb’s Cycle
3) Electron Transport Chain
Where do each of the processes of aerobic respiration take place (4 cycles)
- Glycolysis
◼in cytoplasm - Pyruvate Oxidation
◼ In mitochondria - Kreb’s cycle
◼in matrix of mitochondria - Electron Transport Chain and Chemiosmosis
◼inner membrane of mitochondria
What is glycolysis and its purpose?
Glycolysis is the first step of cellular respiration. It’s main purpose is to split the glucose obtained from food into two molecules of pyruvate through a series of reactions. This process takes place without oxygen, and occurs outside the mitochondria in the cytoplasm of the cell.
What are the OTHER PRODUCTS OF GLYCOLYSIS
- Glucose is oxidized
- NAD+ is reduced
- NADH molecules are also produced
WHAT HAPPENS TO THE PRODUCTS OF GLYCOLYSIS?
⦿ Pyruvate enters the next phase of cellular
respiration (pyruvate oxidation)
⦿ NADH is used in chemiosmosis and electron
transport
⦿ ATP is used by the cell
What are the 3 steps of glycolysis?
- 2 molecules of ATP are required to initiate the
reactions. This causes glucose to be broken down into
two molecules of G3P. - G3P then reduces NAD+ in the cytoplasm to NADH.
NADH will later be used for the Krebs cycle.
Reduction of NAD+ also leads to the generation of 2
molecules of ATP by each G3P (so 4 ATP produced in
total, resulting in a net gain of 2 ATP throughout
the entire process of glycolysis) - Via the process of reduction described above, G3P
becomes pyruvate, a high energy three-carbon
compound which is required for the next stage of
cellular respiration (Krebs cycle)
What is the Pre-Kreb’s cycle/Pyruvate Oxidation?
If oxygen is present, cells will then move Pyruvate into the Matrix following
glycolysis. By reacting Pyruvate with Co-Enzyme A, electrons are collected as CO2
is
removed from pyruvate. The purpose is to modify pyruvate to produce Acetyl CoA.
➢ Before pyruvate can enter the Krebs Cycle, it
must lose one carbon atom in the form of carbon
dioxide. The remaining two carbon atoms then
bond to a molecule called Coenzyme A (CoA) to
become Acetyl Coenzyme A (acetyl CoA).
➢ This reaction also causes another molecule of
NAD+ to be reduced to NADH.
➢ Acetyl CoA then enters the mitochondria to
initiate the Krebs Cycle
What is the Krebs cycle? (step 2)
The main purpose of the Krebs Cycle is to produce even more high-energy compounds (NADH & FADH2) for use in step 3…
➢ Once acetyl CoA enters the mitochondria, it
undergoes a series of reactions to generate three molecules of NADH from NAD+, one molecule of ATP from ADP, and one molecule of FADH2 from FAD. (multiply by two for an entire glucose molecule)
➢ CO2 is also released as a by-product
What happens in the Electron Transport Chain in step 3
The majority of ATP is produced by the electron transport chain. This takes place across the inner
membrane of the mitochondria, and involves the passing of high-energy electrons (NADH & FADH2) from carrier to carrier.
1. As electrons are passed down the chain, energy is
released. This energy is used to pump hydrogen
ions across the membrane from the matrix to the
intermembrane space.
2. The building concentration gradient (high
concentration of hydrogen in the intermembrane
space, low concentration in the matrix) forces
hydrogen ions through membrane-embedded
protein ATP synthase, generating ATP via the
reduction of ADP.
3. Oxygen is the final electron acceptor in the chain.
It accepts both electrons and hydrogen ions,
resulting in a molecule of water which will be
released as a by-product.
What happens in anaerobic cellular respiration?
(where it occurs, organisms and similar steps)
In environments where oxygen is in short supply, some organisms have evolved to obtain energy from food in a different way; these organisms are mostly prokaryotic (bacteria and archaea).
➢ Anaerobic respiration involves a similar set
of steps as aerobic respiration (electron
transport system and concentration gradient to generate ATP), but instead of using oxygen as the final electron acceptor, a different chemical must be utilized.
➢ Depending on the type of organism, this may be sulfate, nitrate, or carbon dioxide
What is fermentation?
When cells of aerobic organisms must go short periods without oxygen, many are able to utilize
fermentation to release energy from food. Fermentation is much less efficient than aerobic cellular respiration, as it produces less ATP than aerobic respiration. It also often leads to the build-up of harmful by-products.
Where does fermentation take place and where does it occur
➢ In fermentation, glycolysis proceeds as usual. However, once pyruvate is formed, it undergoes a different series of reactions that do not require
oxygen to occur. These reactions vary depending on the type of organism.
Fermentation takes place in the cytoplasm of the cell.
➢ Lactate fermentation is used by single-celled organisms such as those found in yogurt. The by-product of this form of fermentation is lactic acid. This is also the form of fermentation our muscles use when they have limited access to oxygen; the buildup of lactic acid is what causes muscle cramps.
➢ Ethanol fermentation is used by a number of different types of bacteria. The by-product of this form of fermentation is alcohol. This process is used to manufacture products such as wine and beer.
Cellular respiration location:
occurs in mitochondria
CR formula (energy too): C6H12O6 + 6O2 – 6CO2 + 6H2O / chemical potential E (glucose)- ATP
CR energy facts:
CR releases E (exothermic)
C6H12O6 is oxidized (loses e) to CO2
Final product of CR:
ATP
Aerobic steps:
- process of glycolysis
- krebs prep
- krebs cycle
- electron transport chain and chemiosmosis
anaerobic steps:
- process of glycolysis
- fermentation
a) lactic acid (animals)
b) ethyl alcohol (plants)
Aerobic respiration facts:
-O2 present
-mitochondria
-glycolysis
- krebs prep
- krebs cycle
- ETS and chemiosmosis
-slow process
-produces 36 ATP molecules
anaerobic facts:
-no O2
-cytoplasm
-glycolysis
-fermentation
-FAST process
-net gain of only 2 ATP
