IB Bio 2 Johnson/Case 8.2 Cellular respiration
In the Mitochondrial electron transport chain, what is the last electron acceptor? a. CO2 b. O2 c. H2O d. NAD
c. H2O
What is the role of NADH + H^+ in aerobic cell respiration? a. To transfer hydrogen to the electron transport chain b. To reduce intermediates in the Krebs Cycle c. To accept electrons from the electron transport chain d. To combine with oxygen to produce water
c. To accept electrons from the electron transport chain
Glycolysis gives a small net gain of ATP without the use of _______
oxygen
______ is needed to bind with the free protons to maintain the hydrogen gradient, resulting in the formation of water
oxygen
Steps for Chemiosmosis:
(1) Energy released as electrons pass along the electron transport chain is used to pump protons across the mitochondrial membrane into the space between the membranes, including space inside cristae. Concentration gradient stores potential energy. (2) ATP Synthase allows the protons to diffuse back across the membrane to the matrix. it uses energy that protons release as they diffuse down the concentration gradient to produce ATP.
Steps in the Krebs cycle
(1)Acetyl CoA links with a 4-Carbon compound to form a 6-carbon compound (2)6-Carbon Compound is oxidized to form a 5-Carbon compound -Carbon is released from the cell as Carbon Dioxide -NAD+ is reduced to NADH2 (3)5-Carbon compound is oxidized and decarboxylated to form a 4-Carbon compound -Carbon is released from the cell as Carbon Dioxid -NAD+ is reduced to NADH
Draw the structure of the mitochondria?
(1)Outer mitochondrial membrane- separates the contents of the mitochondrion from the rest of the cell, creating a compartment with ideal conditions for aerobic respiration (2) Matrix-Fluid inside the mitochondrion containing enzymes fro the krebs cycle and the link reaction. (3)Space between inner and outer-Protons are pumped into this space by the electron transport chain. Because the space is very small, a high proton concentration can easily be formed in chemiosmosis (4) Cristae- Tubular or shelf-like projections of the inner membrane which increase surface area available for oxidative phosphorylation. (5) Inner Mitochondrial membrane- Contains electrons transport chains and ATP synthase, which carry out oxidative phosphorylation
ATP has two key functions within the cell?
(1)it functions as the energy currency of the cell by releasing energy when hydrolysed to ADP (powers cell metabolism) (2)It may transfer the released phosphate group to other organic molecules, rendering them less stable and more reactive
Results of krebs cycle:
-Beginning product is reformed and may be run through the cycle again -2 ATP per glucose molecule -6 molecules of NADH -2 molecules of FADH2 -4 molecules of Carbon dioxide released 36 molecules are produced
Summary of Glycolysis:
-One glucose is converted into two pyruvates -Two ATP molecules are used per glucose but four are produced so there is a net yield of two ATP molecules. This is a small yield of ATP per Glucose, but it can be achieved without use of any oxygen. -Two NADs are converted into two reduced NADs
What do Hydrogen carriers do and why?
-The cristae is the site of the electron transport chain, which uses the energy transferred by the carriers to synthesize ATP -This process requires oxygen to function, and hence only aerobic respiration can generate ATP from hydrogen carriers -This is why aerobic respiration unlocks more of the energy stored in the organic molecules and produces more ATP
The effects of phosphorylation?
-To make the organic molecule less stable and therefore more likely to react in the next stage in a metabolic pathway. -It can turn an endothermic reaction that will only occur at a very slow rate into an exothermic reaction that can proceed rapidly.
Application:Electron tomography used to produce images of active mitochondria
-Used to obtain 3D images of active mitochondria. -The cristae are continuous with the internal mitochondrial membrane -The intermembrane space is of a consistent width thoughout the entire mitochondrion -The relative shape, position and volume of the cristae can change in active mitochondria
What are the four stages of Glycolysis?
1. Phosphorylation 2. Lysis 3. Oxidation 4. ATP Formation
ATP is synthesised from ADP using energy derived from one of two sources?
1.Solar energy 2.Oxidative processes
Using ideal ATP production numbers, how many ATPS would an individual generate if he or she consumed only pyruvate and carried one pyruvate molecule through cellular respiration?
12 ATPs are generated by the Krebs cycle and the electron transport chain. A further 3 ATPs are generated from the NADH formed in the link reaction. So a total of 15 ATPs would be produced (not 18 because there is no glycolysis reaction to consider in this question)
Substrate-level phospharylation?
ATP is produced directly in one of reactions.
If ATP synthase was not present in the Cristae of the mitochondrion, what would be the effect?
ATP synthase allows a faster reaction bringing about phosphorylation of ADP. If this enzyme did not exist, the process of ATP production would be extremely slow.
In chemiosmosis protons diffuse through ______ ______
ATP synthase to generate ATP
the complete breakdown of organic molecules for a larger yield of ATP (oxygen is required)
Aerobic respiration
The synthesis of more complex molecules from simpler ones -Photosynthesis
Anabolic Pathways
the incomplete breakdown of organic molecules for a small yield of ATP (no oxygen required)
Anaerobic respiration
What is the link reaction in aerobic respiration? -a. Pyruvate is carboxylated, acetyl reacts with coenzyme A, reducing NADH + H^+ -b. Pyruvate is decarboxylated, acetyl reacts with coenzyme A, forming NADH + H^+ -c. Pyruvate reacts with coenzyme A, forming NADH + H^+ -d. Pyruvate is decarboxylated, reacting with coenzyme A, reducing NADH + H^+
B. Pyruvate is decarboxylated, acetyl reacts with coenzyme A, forming NADH + H^+
What are discrete steps for linked reactions via breakdown of molecules?
By staggering the breakdown, the energy requirements are reduced (activation energy can be divided across several steps) The released energy is not lost - it is transferred to activated carrier molecules via redox reactions (oxidation / reduction)
Which two are the most linked in the actions they carry out? A.Cytochromes-ribulose biphosphate B.Catabolic reactions-photosynthesis C.Thylakoids- cristae D.ATP synthase- Calvin cycle
C.Thylakoids- cristae
The breakdown of complex molecules into smaller ones -Cellular respiration
Catabolic Pathways
-The process of forming ADP to ATP through phosphorylation and energy -Involves the movement of protons to provide energy
Chemiosmosis
Energy released by oxidation reactions is carried to the _____ of the mitochondria by reduced NAD and FAD
Cristae
Tubular or shelf-like projections of the inner membrane which increase surface area available for oxidative phosphorylation.
Cristae
In Glycolysis, glucose is converted to pyruvate in the __________
Cytoplasm
The pathway is catalysed by enzymes in the____
Cytoplasm
CO2 is removed in two of the reactions. The CO2 is a waste product and is excreted together with the CO2 from the link reaction.
Deoxycarbolations of the krebs cycle
-where most of the ATP from glucose is produced -First stages where oxygen is needed -Occurs on the inner mitochondrial membrane and on the membranes of the cristae -Energy gradient allows electron carries to pass electron from one another -Electrons are passed due to a difference in electronegativity -FADH2 has a lower energy than NADH and produces less ATPs -At end of chain de-energized electrons combine with available oxygen -Oxygen accepts the last electron because of its high electronegativity -Greater number of electron carriers allow for less energy to be lost when electrons are transferred
Electron Transport Chain
If glucose is the substrate, the 1st stage of cell respiration is a metabolic pathway called
Glycolysis
Arrange the following options into the correct order: Krebs Cycle Glycolysis Electron Transport Chain Link Reaction
Glycolysis, Link Reaction, Krebs Cycle, Electron Transport Chain
In the krebs cycle, the oxidation of acetyl groups is coupled to the reduction of ________ _______, liberating CO2
Hydrogen carriers
Contains electrons transport chains and ATP synthase, which carry out oxidative phosphorylation
Inner Mitochondrial membrane
Occurs in the Matrix Cyclical pathway Cycle will run twice for every glucose molecule that passes through it
Krebs Cycle
phosphorylation of molecules makes them _________
Less stable
In aerobic cell respiration pyruvate is decarboxylated and oxidized, and converted into acetyl compound and attached to coenzyme A to form acetyl coenzyme A in the _______
Link Reaction
-If oxygen is present pyruvate enters the matrix via active transport -Pyruvate is decarboxylated -Acetyl group is oxidized with the formation of reduced NADH -Acetyl group combines with coenzyme A to from acetyl CoA -Controlled by a system of Enzymes -If ATP levels are low, acetyl CoA enter the KRebs cycle Links reaction
Links reaction
The hexose biphosphate is split to form two molecules of triose phosphate
Lysis
Fluid inside the mitochondrion containing enzymes fro the krebs cycle and the link reaction.
Matrix
The sum of all the chemical reactions carried out by an organism has two reaction: Catabolic and Anabolic pathways
Metabolism
the structure of the ________ is adapted to the function it performs
Mitochondrion
If both NAD and FAD are reduced, which would allow the greater production of ATPs via the electron transport chain and chemiosmosis?
NAD allows production of more ATP because it enters the electron transport chain at an earlier point than FAD.
separates the contents of the mitochondrion from the rest of the cell, creating a compartment with ideal conditions for aerobic respiration
Outer mitochondrial membrane
-Addition of O2 atoms to a substance -removal of H+ from a substance -loss of electrons from substance -Results in many C-O bonds -Results in a compound with lower potential energy
Oxidation
Two atoms of hydrogen are removed from each triose phosphate molecule. This is an oxidation. The energy released by oxidation of each triose phosphate molecule is used to convert two ADP molecules to ATP. The end product is pyruvate
Oxidation
H+ is removed in four of the reactions. H+ is accepted by hydrogen carriers, which become reduced. In three of the oxidations the hydrogen is accepted by NAD. In other oxidation, FAD accepts it. These oxidation release energy, most of it stored by carriers when they accept hydrogen. This energy is later released by electron transport chain and used to make ATP
Oxidations of Krebs cycle
cell respiration breaks down organic molecules to release chemical energy that is stored as ATP
Oxidative processes
Two phosphates groups are added to a molecule of glucose to form Hexose bi phosphate. Two ATP molecules provide the phosphate groups. The energy level of Hexose is raised by phosphorylation, so it is less stable and the subsequent reactions are possible
Phosphorylation
Arrange the following events in photosynthesis from first to last . Chemiosmosis Photolysis Calvin cycle Formation of triose phosphate
Photolysis, chemiosmosis, calvin cycle, formation of triose phosphate
Transfer of electrons between carriers in the electron transport chain in the membrane of the cristae is coupled to _________
Proton pumping
-Removal of O2 from substance -Addition of H+ to a substance -Addition of electrons to a substance -Results in many C-H bonds -Results in a compound with higher potential energy
Reduction
photosynthesis converts light energy into chemical energy that is stored as ATP
Solar energy
Protons are pumped into this space by the electron transport chain. Because the space is very small, a high proton concentration can easily be formed in chemiosmosis
Space between inner and outer
Striated or voluntary muscles that occur in humans generally have a larger number of mitochondria than other cell types. Why is this important?
Striated muscle cells are very active. They allow all voluntary motion. It takes large amounts of ATP to allow the movements muscles have the function of providing.
If an individual took a chemical that increased the ability of hydrogen ions to move through the phospholipid bilayer of the mitochondrial membranes, what would the effect be on ATP production?
The result would be fewer ATPs produced because the hydrogen ions would not be forced to move through the channels of ATP synthase. It is the movement of hydrogen ions through these channels that allows the phosphorylation of ADP.
Cell respiration involves the oxidation and reduction of ______________
electron carriers
