Lecture 11-Cellular respiration Flashcards
1
Q
What is cellular respiration needed for?
A
DNA replication Protein synthesis Muscle contraction Maintaining body temp Mitosis
2
Q
What are the 3 fates of nutrients?
A
1) Supply energy
2) Serve as building blocks (proteins , hormones, enzymes)
3) Stored for future use (glycogen in liver, triglyceride in adipose tissue)
3
Q
Equation for breakdown of glucose?
A
heat
Glucose + Oxygen –> CO2 + Water
4
Q
1 calories is enough…..
A
to raise 1ml of water by 1 degree Celsius
5
Q
A daily intake of 2250 kCal is enough to ……
A
raise the temp of 70L by 32.C
6
Q
How many enzyme-controlled steps in the breakdown of glucose?
A
19
7
Q
Cell metabolism?
A
The sum total of all chemical reactions that occur inside the cell
8
Q
Catabolism ?
A
Breakdown of larger molecules into smaller ones for the purpose of energy production
9
Q
Anabolism?
A
Production/synthesis of larger molecules for the purpose of making chemical building blocks of the body, usually costing energy
10
Q
What do cells need to do?
A
Efficiently transfer manageable amounts from one molecule to another
11
Q
What is the life-span of ATP?
A
1 minute
12
Q
Is ATP not an energy stores?
A
Yes
13
Q
ATP is used in what and can be used in?
A
In anabolic reactions + can be in catabolic reactions
14
Q
how much % of energy from catabolism is used for cellular function + the rest?
A
40%
60% = lost as heat
15
Q
What do catabolic reactions do?
A
Transfer energy into “high energy” phosphate bonds of ATP
16
Q
Can ATP leave the cell?
A
No , but it can DIFFUSE
17
Q
Oxidation are often what type of reaction + example?
A
Dehydrogenation reactions Lactic acid (-2H+) ---> Pyruvic acid
18
Q
What happens after oxidation of H atoms?
A
Immediately transferred by coenzymes to other compounds
19
Q
NAD
A
a derivative of the B vitamin niacin
20
Q
FAD
A
a derivative of the B vitamin riboflavin
21
Q
NAD+ / NADH what type of agents are they?
A
NAD+ = oxidising agent NADH = reducing agent
22
Q
What can the 2 forms of NAD do?
A
- Carry e- from 1 reaction to another
- Act as a substrate for other enzymes that add/remove chemical groups from proteins
23
Q
What occurs in the cytoplasm?
A
Glycolysis
Pyruvate
*Fermentation
24
Q
What occurs in the mitochondria?
A
Pyruvate Decarboxylation
KREBS cycle
Oxidative Phosphorylation
25
Describe Cardiac Myocyte?
-Rich in glycogen myoglobin + mitochondria
26
How much of a ventricular muscle cell volume is occupied by mitochondria?
~30%
27
What cell is metabolically inactive + no mitochondria?
Erythrocyte
28
Glycolysis I?
1) Splits 6C glucose -> 2x 3C pyruvic acid
2) Consumes 2ATP, makes 4
3) 10 reactions
29
What can convert lactic acid back to pyruvic acid?
Hepatocytes
30
Anaerobic Glycolysis =?
Reduced to lactic acid
31
Aerobic Glycolysis =?
Converted to acetyl coenzyme A
32
What is the key regulator of glycolysis?
Phosphofructokinase
33
During high levels of PFK, what happens?
Elevated ADP levels
34
What happens when ADP is low?
Glucose is shunted away from glycolysis ---> glycogen storage pathway
35
First 5 steps of Glycolysis?
Energy in the form of ATP is invested
| -6C glucose = split ---> 2x 3C of glyceraldehyde 3 phosphate
36
Second 5 steps of Glycolysis?
2 glyceraldehyde molecules ---> 2 pyruvic acid molecules
| -ATP generated
37
Step 6 of Glycolysis?
NADH + H+ is generated
38
What do most cells use the NADH + H+ in step 6 of Glycolysis for?
Generate 4 ATPs in the e- transport chain
39
What is the only energy producing steps of anaerobic respiration?
Glycolysis
40
Example of anaerobic respiration?
Skeletal muscles during exercise
41
Describe the process of anaerobic respiration?
2 Pyruvate molecules reduced by 2H atoms from NADH ---> 2 lactic acid molecules
42
Why is the regeneration of 2NAD+ during anaerobic important?
Used in oxidation of glyceraldehyde 3 phosphate in step 6
43
What does the lactic acid do?
Enter the blood + convert back to pyruvate by hepatocytes
44
What is pyruvate translocase?
A transport protein
45
Pyruvate decarboxylation?
1) Each pyruvic acid ---> 2C acetyl group
- remove 1 molecule of CO2 (waste product)
- loss of 2 H atoms
2) NAD+ reduced ---> NADH + H+
3) Acetyl group attached to coenzyme A ---> acetyl coenzyme A
46
What is the net gain from glycolysis + link reaction?
2 ATP
4 NADH
2 Acetyl coenzyme A
47
What occurs in the matrix of the mitochondria?
Krebs cycles
48
What type of reactions occur in the Krebs cycle?
Redox + decarboxylation reactions
| -Redox = transfer energy to NAD+ and FAD+
49
Krebs Cycle?
1) Entry of acetyl group ---> citrate + regeneration of CoA
2) Isomerisation ---> isocitric acid
3) Oxidative decarboxylation = remove CO2 + formation of NADH + alpha ketoglutarate
4) Oxidative decarboxylation = addition of CoA ---> succinlyCoA + NADH
5) Substrate level phosphorylation = CoA is displaced for a phosphate group which is transferred to GDP + donated to ATP ---> succinate
6) Dehydration = succinate is oxidised ---> fumarate by FADH2 formation
7) Hydration = fumarate is converted ---> malate by addition of H2O
8) Dehydrogenation ---> oxaloacetate + formation of NADH
50
What is formed in Krebs Cycle?
3 NADH
1 FADH2
Contain the energy originally stored in glucose
1 ATP made by SUBSTRATE LEVEL PHOSPHORYLATION
51
What is the e- transport chain?
Series of e- carriers
| -integral membrane proteins in the inner mitochondrial membrane
52
How is the e- transport chain formed?
From a series of proteins in the inner mitochondrial membrane
53
What does the cristae do?
It maximise the SA ---> greater ATP production
54
What happens as e- pass through the chain?
Exergonic reactions release energy used to form ATP
| -Chemiosmosis
55
What is the final e- acceptor in the e- transport chain?
Oxygen for water
56
What does the e- transport chain perform?
Oxidative phosphorylation
57
Complex I?
NADH dehydrogenase
-NADH produced during the KREBS cycle = oxidised
produces ---> H+ , NAD+ , 2E-(bind to the complex) + 4H+ are TRANSLOCATED into the intermembrane space
58
Complex II?
Succinate dehydrogenase
- E- delivered ---> guinine pool from succinate via FAD
- Parallel to complex I
- Doesn't transport any H+ into the intermembrane space (so lower energy production than complex I)
59
Complex III?
CoQH2 cytochrome c reductase
- Receives 2 e- from coenzyme Q that passed ---> cytochrome c
- 2 other e- also passes to reduce quinone section of cytochrome c ---> quinol
- Quinol = oxidised producing 4H+ that are transferred to the intermembrane space
60
Complex IV?
Cytochrome c oxidase
- 4 e- removed from 4x cytochrome c
- transferred to O2 which binds with H+ ions in the matrix ---> 2 H20
- 4H+ ions = translocated into the intermembrane space (total = 4 removed from matrix)
61
Summary of e- transport chain?
1) Complex I accepts e- from Krebs cycle NADH
2) passes them to coenzyme Q
3) also receives e- from complex II
4) Q passes e- to complex III
5) which passes them ---> cytochrome c
6) Cyt c passes e- ---> Complex IV , which uses the e- + H ions to reduce oxygen to water
62
E- transport chain coupled with oxidative phosphorylation?
- Inner mitochondrial membrane = impermeable to H+ ions
- Generating conc gradient
- The H= ions move down their conc gradient via Complex V (ATP Synthase)
- For every H+ ion, ATP synthase phosphorylates 1 ADP molecule (producing ATP)
63
Chemiosmosis?
The use of chemical gradient to produce ATP via ATP synthase
64
How many molecules of ATP are generated from each molecule of glucose by the ETC?
32 / 34 ATP molecules
65
How many ATP molecules are generated from the 10 molecules of NADH + H+ + 2FADH2?
28/30 ATP molecules
66
What happens when NADH made in glycolysis cannot enter the mitochondria?
- Donate e- to either malate / glycerol phosphate shuttle
- Liver, kidneys + the heart use the malate shuttle = 3ATP molecules result
- The rest of the body uses the glycerol phosphate shuttle , 2ATP molecules result
67
How many ATP molecules are made in total from each glucose molecules/
36 /38 ATP molecules
68
GLUT2?
Liver, beta cells, hypothalamus
High capacity
High Km (low affinity)
69
GLUT3?
```
Neurons
Placenta
Testes
Low Km 1mM
High capacity
```
70
GLUT4?
Skeletal + cardiac muscle , fat
Activated by insulin
Km = 5mM
71
Apical vs Basolateral
```
Apical = Na- + glucose
Basolateral = Na+ + K+
```
72
How does glucose in the Gi pass through the Plasma Membrane?
Secondary active transport
- Facilitated diffusion via GluT molecules
- High insulin levels = increase expression of GluT4
- Glucose = phosphorylated upon entering cell + can't with GluT
73
What do the hepatocytes in the GI do?
Convert most of the fructose + all of galactose --> glucose
74
How is some fructose is converted to glucose in the Gi?
Intestinal epithelial cells
75
How much glucose % is digested in the GI?
80%
76
How is glycogenesis stimulated?
By insulin in hepatocytes + muscle cells
77
How does hepatocytes produce the ATP it is needed?
Hepatocytes release glucose by glycogeneolysis
78
Are the 2 reactions of gluconeogenesis simple reversals?
No
79
What is needed to breakdown from branched chain in glycogenesis?
Phosphorylation
80
How is Glycogen Phosphorylase activated?
Hormones glucagon + adrenaline
81
How much glucose in the blood?
90mg/100ml (2-3g)
82
What is glucose a part of?
- ATP production (glucose is oxidised)
- AA synthesis (protein synthesis)
- Glycogen synthesis(hepatocytes + muscle cell, 500g)
- Triglyceride synthesis (when glycogen storage is saturated glycerol + FFAs are made)
83
Fructose transport?
GLUT5 -small intestine
