Respiration - Chapter 12 Flashcards
What are the 4 stages in respiration ?
- Glycolysis
- The Link reaction
- The Krebs cycle
- Oxidative phosphorylation
What is glycolysis ?
The splitting of glucose
What does respiration produce?
ATP
Where does glycolysis occur?
In the cytoplasm
Describe the process of glycolysis.
- phosphorylation of glucose using ATP, making triose phosphate
- Oxidation of triose phosphate to pyruvate (removal of hydrogen from triose phosphate for oxidation)
- net gain of ATP (2 ATP)
- NAD goes to reduced NAD
The process of glycolysis (detailed version)
-phosphorylating glucose to glucose phosphate using ATP
(The inorganic phosphates come from the hydrolysis of 2 molecules of ATP)
- each glucose molecule is split into 2 molecules of a 3 carbon compound : triose phosphate
- oxidation of triose phosphate to produce pyruvate
-hydrogen is removed from each triose phosphate molecule and transferred to NAD forming reduced NAD (NADH)
- a series of enzyme controlled reactions convert TP molecules to 3 Pyruvate molecules regenerating 2 ATP molecules from ADP
What are the products of glycolysis?
2x pyruvate (used in the link reaction)
Net gain of 2 ATP ( although there is 4, 2 had to be used for glucose phosphate)
2x NADH (will be used in oxidative phosphorylation)
What type of process is glycolysis ?
It is an aerobic process (occurs in both aerobic and anaerobic processes)
Where does the link reaction take place
In the mitochondrial matrix
What type of process is the link reaction ?
An aerobic process
In the absence of oxygen, anaerobic respiration takes place in the _____
If oxygen is present, then the cell carries out aerobic respiration in ________
Cytoplasm
Mitochondria
What is the reaction in the link reaction ?
Pyruvate + coenzyme A ~~~~~~~~~~~~~~~~> acetyl coenzyme A + CO2
NAD~> reduced NAD
Link reaction doesn’t require oxygen
Explain the link reaction ?
-pyruvate and NADH are diffuse from the cytoplasm into the mitochondrial matrix
- the pyruvate made in glycolysis is oxidised to acetate
-acetate combines with coenzyme A to produce acetyl coenzyme A
-the remaining one carbon part of the pyruvate (see diagram) leaves as a molecule of carbon dioxide
-at the same time,an oxidation reaction takes place NAD + H ~>reduced NAD (NADH)
-during a link reaction, a molecule of CO2 is released from the pyruvate. When CO2 is removed from the molecule, it’s called decarboxylation reaction
Because we have an oxidation + decarboxylation reaction, this is called oxidative decarboxylation
When is there a decarboxylation reaction in the link reaction, and then is there an oxidation reaction ?
During a link reaction, a molecule of CO2 is released from the pyruvate. When CO2 is removed from a molecule, it’s called a decarboxylation reaction.
Oxidation reaction - NAD + H ~> reduced NAD (NADH)
How many times does the link reaction take place for each molecule of glucose entering respiration and why ?
Glycolysis produces 2 pyruvate molecules for each molecule of glucose.
So the link reaction takes place twice for each molecule of glucose entering respiration ( as it only uses 1 pyruvate molecule in the reaction).
What are the products from the 2 link reactions and where do they go ?
2 acetyl coenzyme A - goes to the Krebs cycle
2 carbon dioxide - released as a waste product
2 reduced NAD - to oxidative phosphorylation
Name 2 substances for which there would be a net movement into the mitochondrion
Oxygen, pyruvate
The mitochondria in muscles contain many cristae. Explain the advantage of this.
Large surface area for electron carrier system.
Provides ATP for contraction.
Where does the Krebs cycle take place?
In the mitochondrial matrix
What type of process is the Krebs cycle?
An aerobic process
Explain the Krebs cycle (detailed)
- The acetyl coenzyme A reacts with a 4C molecule called oxaloacetate. (The 2C part of acetyl Coda moves onto the 4C molecule, creating the 6C molecule : citrate)
At the same time, the coenzyme A is released, back into the link reaction - A whole series of chemical reactions takes place:
1st a decarboxylation reaction of citrate releases one molecule of CO2.
A dehydrogenation reaction produces a molecule of reduced NAD.
We now have a 5 Carbon molecule. - Another dehydrogenation reaction takes place producing one molecule of reduced NAD.
Another decarboxylation reaction takes place releasing one molecule of CO2.
One molecule of ATP is also produced, by substrate - level phosphorylation (where a phosphate is removed and used to generate a molecule of ATP). - Finally, we have 2 more dehydrogenation reactions, which produce one molecule of reduced FAD and one molecule of reduced NAD.
- During these reactions, we regenerate our starting molecule, the 4C oxaloacetate, which allows the Krebs cycle to continue again.
Need to know how to draw glycolysis diagram and the krebs cycle diagram !
What are the products of the Krebs cycle and where do they go?
(For each glucose molecule that enters respiration, the Krebs cycle operates twice)
2x ATP
6x reduced NAD, to the ETC
2x reduced FAD, to the ETC
4x CO2 released, as a waste product
Where does oxidative phosphorylation take place?
In the mitochondrial inner membrane - cristae
