Flashcards in Respiration Deck (40)
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1
Why does respiration occur?
To produce ATP for energy
Required in metabolic processes and for the organism to survive
2
Give examples of biological processes where ATP is required
Active Transport
Endocytosis
Exocytosis
Protein synthesis
DNA Replication
Cell division
Movement
Anabolic and Catabolic reactions
3
Describe the structure of ATP
Pentose sugar (Ribose)
Adenine base
3 phosphates joined to sugar by phosphodiester bond
4
Describe the process of Glycolysis
Phosphorylation of Glucose to Hexose biphosphate
Lysis of Hexose biphosphate to Triose phosphate
Oxidation of Triose phosphate to Pyruvate
5
What are the 4 stages of aerobic respiration?
Glycolysis
Link Reaction
Krebs Cycle
Oxidative Phosphorylation
6
What are the products of Glycolysis?
2 ATP (4 were made by 2 were used at start)
2 reduced NAD (NADH)
2 Pyruvate
7
In What organelle does respiration occur?
Mitochondrion
8
Outline the key structures in the mitochondria
Double membrane (inter-membrane space)
Matrix
Cristae
ATP Synthase channels
9
What does the matrix contain?
Enzymes
NAD and FAD molecules
Oxaloacetate
mitochondrial DNA
mitochondrial ribosomes
10
Why is the inner membrane folded into cristae?
To provide a large surface area for the electron carriers and ATP synthase enzymes
11
Where does the link reaction occur?
Mitochondrial matrix
12
What enzyme catalyses the link reaction?
Pyruvate dehydrogenase
13
What is the main products of the link reaction?
Acetyl CoA and NADH
14
What is the bi-product of the Link reaction
CO2
15
How many molecules of each product are formed per 1 molecule of pyruvate in the link reaction?
1 Acetyl CoA
1 NADH
1 CO2
16
Where does the Krebs cycle occur?
Mitochondrial matrix
17
What is substrate-level phosphorylation?
the formation of ATP from ADP by donation of a phosphate from a substrate.
Low yield of ATP
18
Outline the main stages of the Krebs cycle
Acetyl (2C) group released from Acetyl CoA and combines with Oxaloacetate (4C) to form Citrate (6C)
2 stages of oxidative (aka dehydrogenation) decarboxylation occur forming a 4C compound releasing 2CO2 and 2 NADH
4C compound further dehydrogenated releasing FADH
4C compound is rearranged by isomerase enzymes and dehydrogenated (releasing NADH) to form oxaloacetate
19
What is the Krebs cycle designed to make lots of?
NADH (reduced NAD)
20
Outline the process by which energy is produced from the ETC
NADH releases a H atom, this then splits into H+ and e-
H+ accumulate in the matrix
e- picked up by a carrier protein which causes it to become reduced and pass it on to the next carrier protein in the chain (series of redox reactions)
at the end of the chain:
4H+ + 4e- + O2 = 2H2O
21
How is the energy released from the ETC used to create ATP?
the energy released is used to actively transport the H+ from the matrix into the inter-membrane (IM) space
H+ accumulate in IM space (as the membrane is impermeable to H+) forming an electrochemical gradient.
H+ move back through protein channels coupled to ATP Synthase enzymes
Causes a conformational change in ATP Synthase driving the production of ATP
22
Where does oxidative phosphorylation occur?
Cristae
23
Why will the process of oxidative phosphorylation not occur in anaerobic conditions?
No O2 as final acceptor of ETC
Build up of e- in the matrix
Electrochemical gradient doesn't form
ATP Synthase isn't activated
No ATP produced
24
Why must NADH be reoxidised for respiration to continue?
Because it is needed for the link reaction and Krebs cycle to occur
25
What are the 2 anaerobic pathways to reoxidise NADH?
Ethanol fermentation
Lactate fermentation
26
What organisms use alcohol fermentation?
Fungi such as yeast
27
What organisms use lactate fermentaion?
Mammals
28
Outline the stages of ethanol fermentation?
Pyruvate is decarboxylated to form Ethanal + CO2
Ethanal accepts H+ from NADH which reduces it to Ethanol + NAD
This means the NADH has been reoxidised allowing glycolysis to continue.
29
What enzyme catalyses Pyruvate to Ethanal?
Pyruvate Decarboxylase
30
What enzyme catalyses Ethanal to Ethanol?
Ethanol Dehydrogenase
31
Outline the Lactate fermentation pathway
Pyruvate accepts H+ from NADH, reducing it to lactate
This means the NADH has been reoxidised allowing glycolysis to continue.
32
What happens to the lactate molecules when they are produced?
Transported to the liver
When more O2 becomes available it is:
Converted back to pyruvate
Recycled into glucose and glycogen
33
Describe the yield of ATP from anaerobic respiration compared to aerobic respiration
Neither ethanol nor lactate fermentation produce any ATP
However, they allow glycolysis to continue which means a small amount of ATP per molecule is still made
Glycolysis happens a lot more frequently in anaerobic respiration than aerobic respiration so the yield of ATP is still high.
34
How are different carbohydrates converted to glucose for respiration?
Disaccharides are hydrolysed into monosaccharides
Monosaccharides such as fructose and galactose are rearranged by isomerase enzymes
35
Why do lipids have a higher energy value than other respiratory substrates?
Because the long fatty acid chains contain lots of hydrogens that can be snipped off at any length.
The are broken down into Acetate (2C) which combines with CoA in the link reaction
more h+ = more energy
36
What is the name of the process where excess amino acids are converted to pyruvate?
Deamniation
37
Where does Deamination occur?
Kidneys
38
What is the equation for respiratory quotient?
RQ = CO2 produced / O2 consumed
39
What are the RQ values for the different respiratory substrates?
Glucose = 1
Fatty acid = 0.7
Amino acid= 0.8 - 0.9
40
