Respiration (5) Flashcards
What are the four stages in aerobic respiration?
- Glycolysis
- Link reaction
- Krebs cycle
- Oxidative phosphorylation
Where do each of the stages of aerobic respiration happen?
Glycolysis happens in the cytoplasm of cells while the rest happens in the mitochondria
What are the first unit of respiration?
It is usually glucose but organisms can also break down other complex organic molecules to respire like fatty acids and amino acids
What is the process of glycolysis?
Glycolysis occurs in the cytoplasm of the cells and involves splitting one molecule of glucose into two smaller molecules of pyruvate. This reaction does not require oxygen.
What are the structures that make up a mitochondrion?
- outer mitochondrial membrane
- inner mitochondrial membrane
- cristae
- mitochondrial DNA
- ribosomes
- mitochondrial matrix
What are the stages in glycolysis? (Phosphorylation and Oxidation)
- glucose is phosphorylated into hexose biphosphate
- hexose biphosphate is split into 2 x triose phosphate
- Triose phosphate is oxidized to form two molecules of pyruvate
What are the products of glycolysis?
- 2x pyruvate
- 2 reduced NAD
- net gain of 2 ATP
What are the steps in the link reaction?
- Pyruvate is decarboxylated- removed CO2
- NAD becomes reduced by collecting hydrogen from the pyruvate to form acetate
- Acetate combines with coenzyme A to form acetyl-coA
(NO ATP is produced)
How does pyruvate enter the matrix of the mitochondria before the link reaction?
They are actively transported into the mitochondria
What are the steps in the Krebs Cycle?
- Acetyl-coA enters the krebs cycle and loses coA to become an acetyl group
- The acetyl group combines with oxoacetate to from citrate
- Citrate is converted to a 5 carbon compound through dehydrogenation (NADH) and decarboxylation (CO2)
- This 5 carbon compound also undergoes dehydrogenation (NADx2 and FADH2) and decarboxylation (CO2) and substrate level phosphorylation (ATP)
- The formed oxaloacetate then combines with another acetyl group and the cycle is repeated
What enzyme catalyzes the reaction between an acetyl group and oxaloacetate?
Citrate synthase
What is oxidative phosphorylation in relation to respiration?
This is the process where the energy carried by electrons, from reduced coenzymes is used to make ATP. This process happens in the inner mitochondrial membrane and produces a lot of ATP.
What are the steps in oxidative phosphorylation?
- hydrogen atoms are released from the reduced coenzymes and then split into H+ ions and electrons 2. The electrons move along the electron transport chain- losing energy at each carrier
- The energy provided by the electrons is used to pump H+ ions from the matrix into the intermembrane space
- As the concentration of H+ ions is higher in the intermembrane space than the matrix it form an electrochemical gradient
- H+ ions move down this gradient back into the matrix through channels/ATP Synthesase which causes phosphorylation of ADP into ATP
- At the end in the matrix the H+, O2 and electrons combine to form water
What is the electron transport chain?
The electron transport chain happens in the inner mitochondrial membrane. It is where electrons lose energy as they are passed between carriers.
Why is the inner mitochondrial membrane folded into cristae?
This increases the membrane’s surface area to maximize respiration.
What is chemiosmosis?
Chemiosmosis is the process when H+ ions move down the electrochemical gradient through ATP synthesase which produces ATP
What is oxygen referred to in the stage of oxidative phosphorylation?
It is referred to as the final electron acceptor
How much ATP can one cell make from one molecule of glucose?
32 ATP
What is different about anaerobic respiration and aerobic respiration?
Anaerobic respiration doesn’t involve the link reaction, the Krebs cycle or oxidative phosphorylation as it does not require oxygen
What are the two types of anaerobic respiration?
Alcoholic fermentation and lactate fermentation
How are aerobic and anaerobic respiration similar?
They both start with glycolysis and take place in the cytoplasm
What is different between anaerobic and aerobic respiration?
They differ in which organisms they occur in and what happens to the pyruvate
What is lactate fermentation?
Reduced NAD transfers hydrogen to pyruvate to form lactate and NAD. The NAD can then be reused in glycolysis
Why can glycolysis continue when there isn’t much oxygen around?
The production of lactate regenerates NAD and glycolysis needs NAD to take place.
