Module 7: Cellular Respiration Flashcards
What is cellular respiration?
A series of metabolic pathways that convert glucose into ATP.
What are redox reactions?
A combination of:
1. Oxidation reactions. Takes away an electron.
2. Reduction reactions. Gains an electron.
What is NAD?
An electron carrier derived from vitamin B. Easily oxidised or reduced.
NAD+ is the oxidised form (less electrons).
NADH is the reduced form (added 2 electrons and a proton).
What does NAD stand for?
Nicotinamide Adenine Dinucleotide.
vitamin B, which NAD is derived from, is also known as B3 or niacin
What is the reduction equation for NAD+?
RH + (NAD+) → NADH + R
Where RH is reducing agent.
And R is oxidised.
What is a reducing agent?
A compound that reduces (gives electrons to) another compound.
What is FAD+?
Flavin adenine dinucleotide.
Derived from vitamin B2, riboflavin.
Its reduced form is FADH2.
What is NADP?
A second variation of NAD, containing an extra phosphate group.
Why can’t living cells store significantly amounts of free energy?
Excess free energy would increase heat in the cell, resulting in excess thermal motion that could damage and destroy the cell.
What is ribose?
A five-carbon sugar found in RNA.
What is the order of creation of ATP?
AMP + 1 phosphate group → ADP + 1 phosphate group → ATP
What is AMP?
Adenosine monophosphate.
Composed of an adenine molecule bonded to a ribose molecule and a single phosphate group.
AMP is one of the nucleotides in RNA.
What is dephosphorylation?
The removal of a phosphate group/s by hydrolysis.
Releases energy.
What is the standard chemical equation of hydrolysis?
AB + H2O → AH + BOH
How is water affected by hydrolysis of ATP?
Water is broken down into a hydrogen atom (H+) and a hydroxyl group (OH-), which is added to a larger molecule.
Water is reformed when the third phosphate is added to ADP, forming ATP.
What are the 2 methods of phosphorylation?
- Substrate phosphorylation. A phosphate group connected to other molecule transfers to ADP to form ATP.
- Oxidate phosphorylation/chemiomosis. Occurs in the mitochondria (eukaryotic) or in the plasma membrane (prokaryotic).
What is glycolysis?
The first step of cellular respiration.
Converts glucose into pyruvate.
Anaerobic.
What are the 3 steps of aerobic cellular respiration?
- Glycolysis.
- Krebs Cycle/citric acid cycle.
- Electron Transport Chain
How does glucose enter heterotophic cells?
- Through active secondary transport against the glucose concentration gradient.
- Through a group of integral protein transporters called GLUT proteins.
What is the net production from 1 glucose molecule in glycolysis?
2 pyruvate molecules.
2 NADH.
2 ATP.
What is pyruvate?
The conjugate base of pyruvic acid.
Three carbon molecules composed of a ketone functional group and a carboxyl group.
C3H3O3.
Where does glucolysis take place?
In the cytosol of the cell.
What do the first 5 steps of glycolysis do?
The preparation phase.
Converts a 6-carbon sugar (glucose) into two 3-carbon sugars (glyceraldehyde-3-phosphate).
ATP is consumed in the 1st and 3rd steps. Both these reactions are irreversible.
What do the last 5 steps of glycolysis do?
The Pay-Off Phase.
Produces energy.
In steps 7 and 10, 1 ATP is made per glyceraldehyde-3-phosphate.
Step 7 is reversible, step 10 is not.
How many steps are in glycolysis?
10 steps.
What is the total production of ATP and NADH in glycolysis?
4 ATP and 2 NADH.
Because 2 ATP are used in glycolysis, the net total is:
2 ATP and 2 NADH.
When is NADH formed in glycolysis?
In the 6th step, by an enzyme called dehydrogenase.
How many pyruvate molecules are produced through glycolysis?
2 pyruvate molecules.
How is pyruvate changed during pyrvate oxidation?
Pyruvate → acetyl CoA
This occurs in the mitochondria.
What are the steps of pyruvate oxidation?
- Carboxyl group removed from pyrvate, releasing CO2. This creates a 2 carbon hydroxyethyl group bound to the enzyme (pyruvate dehydrogenase).
- The hydroxyethyl group is oxidised to an acetyl group and the electrons picked up by NAD+, forming NADH.
- The enzyme-bound acetyl group is transferred to CoA, producing a molecule of acetyl CoA.
What is CoA?
Coenzyme A.
A carrier compound derived from vitamin B5.
What happens to acetyl CoA in the first step of the citric acid cycle?
Acetyl CoA → Citrate
It loses its acetyl group (2 Carbons) to a 4-carbon molecule, oxaloaceate, to form citrate.
What is citrate?
A 6-carbon molecule with 3 carboxyl groups.
What is the overall equation for cellular respiration?
C6H12O6+ 6O2→ 6CO2+ 6H2O + ATP
glucose + oxygen → carbon dioxide + water + ATP
How is the citric acid cycle different from the linear glycolysis?
The citric acid cycle is a closed loop.
The last part of the pathway regenerates the compound used in the first step.
What are the outputs of the citric acid cycle?
Per 1 glucose molecule (2 pyruvate):
4 carbon dioxide.
2 ATP
6 NADH.
2 FADH2.
What are the inputs of the citric acid cycle?
Per 1 glucose molecule (2 pyruvate):
2 Acetyl CoA
2 Oxaloacetate
What are the outputs of pyruvate oxidation?
Per 1 glucose molecule (2 pyruvate)
2 acetyl CoA
2 Carbon Dioxide
2 NADH
What is the chemical transformation of acetyl CoA in the citric acid cycle?
Acetyl CoA + Oxaloacetate → Citrate → Succinate → Oxaloacetate
What is the electron transport chain?
A series of protein complexes embedded in the mitochondrial membrane that transfer electrons to form a hydrogen ion gradient.
What are the structures in the electron transport chain?
Complex I
Complex II
Q - ubiquinone B
Complex III
Complex IV
ATP Synthase
How is ATP generated using ATP synthase?
- H+ ions flow down their electrochemical gradient into ATP synthase.
- These H+ ions turn the rotors of the ATP synthase.
- ATP synthase facilitates the addition of a phosphate to ADP, forming ATP, using this energy.
- The hydrogen ions are accepted by oxygen, forming water as an end product.
What is the final electron acceptor in the electron transport chain?
Oxygen.
