Metabolism and energy Flashcards
(42 cards)
1
Q
What is Anabolism
A
metabolic pathways that build molecules from smaller subunits requires energy.
2
Q
What is Catabolism?
A
Metabolic pathways that breakdown larger molecules into smaller subunits–> release energy.
3
Q
What is the structure of ATP?
A
A nucleotide consists of a sugar molecule (either ribose in RNA or deoxyribose in DNA) attached to a phosphate group and a nitrogen-containing base. The bases used in DNA are adenine (A), cytosine (C), guanine (G) and thymine (T).
and three phosphates.
4
Q
How do we generate energy?
A
- directly from ATP.
- indirectly from NADH and FADH2.
5
Q
How do we indirectly make energy from the previous cofactors?
A
- the electron transport chain.
- takes electrons from NADH and FADH2.
- passes them down a chain of electron carriers with increasing electron affinity.
- eventually passes the electrons to oxygen to make water.
- the energy produced from electron movement is used to pump hydrogen ions into the intermembrane space.
- this creates a hydrogen gradient that is used to drive the production of ATP.
6
Q
What are the 6 anabolic pathways?
A
- gluconeogenesis.
- glycogenesis.
- fatty acid synthesis.
- lipogenesis.
- lipogenesis.
- ketogenesis.
- pentose phosphate shunt.
7
Q
what is gluconeogenesis?
A
- makes glucose from precursor molecules in the mitochondria and cytosol.
8
Q
What is glycogenesis?
A
- makes glycogen to store glucose in the cytosol.
9
Q
what is fatty acid synthesis?
A
- makes fatty acids from acetyl CoA in the cytosol.
10
Q
What is lipogenesis?
A
adds fatty acids to glycerol to make triglyceride lipids in the cytosol.
11
Q
what is ketogenesis?
A
makes ketone bodies from acetyl CoA in the mitochondria.
12
Q
What is the Pentose Phosphate shunt?
A
Shunts glucose into the creation of various 5-carbon sugars and NADPH in the cytosol.
13
Q
What are the 5 catabolic pathways?
A
- glycogenolysis.
- Glycolysis.
- Beta-oxidation.
- Ketolysis.
- Citric acid cycle.
14
Q
What is glycogenolysis?
A
- breakdown of glycogen to release glucose in the cytosol.
- opposite to glycogenesis.
15
Q
What is glycolysis?
A
- breakdown of glucose to pyruvate to produce energy (NADH and ATP) in cytosol
- opposite to gluconeogenesis.
16
Q
What is beta-oxidation?
A
- Breakdown of fatty acids to acetyl CoA to produce energy (NADH, FADH2). Acetyl CoA can enter the CAC to produce more energy in mitochondria.
17
Q
what is ketolysis?
A
- Breakdown of ketone bodies to acetyl CoA. Acetyl CoA can enter the CAC to produce more energy. in mitochondria.
- opposite to ketogenesis.
18
Q
citric acid cycle
A
- Breakdown of citrate (made from acetyl CoA and oxaloacetate) to produce energy (NADH, FADH2, ATP). in the mitochondria.
19
Q
Outline glycolysis;
A
- conversion of glucose into two pyruvate in the cytosol.
- ATP and NADH produced.
- pyruvate can then be converted into acetyl CoA. where we can enter the CAC and make more NADH and can enter the CAC.
20
Q
Why does the conversion of acetyl CoA only happen under aerobic conditions?
A
- because under anaerobic conditions (a lack of oxygen), the conversion of pyruvate to acetyl CoA stops. In the absence of oxygen, electron transport stops. NADH is no longer converted to NAD+, which is needed for the first three stages of cellular respiration.
21
Q
Outline ANaerobic glycolysis;
A
- When there is a lack of oxygen, pyruvate converts to lactate rather than acetyl CoA.
- the purpose of this is to regenerate NAD which can then be oxidized can be reduced to NADH to which helps make ATP in absence of the ETC.
22
Q
Outline gluconeogenesis;
A
- the liver is the main site of GNG.
- helps make glucose to send to tissues when blood glucose is low.
- substrates include certain amino acids , lactate and glycerol.
23
Q
outline glycogenolysis;
A
- breakdown of glycogen for glucose when blood glucose is low.
- the liver and muscle both have glycogen to breakdown.
- liver released glucose to raise blood sugar levels.
- muscles breakdown glycogen for immediate energy source for the working muscle.
24
Q
outline glycogenesis;
A
- this is an anabolic process where we require energy from ATP and UTP
25
What is the pentose phosphate shuttle?
- makes NADPH; used for fatty acid synthesis, antioxidation.
- 5-C sugars such as ribose 5-P for nucleotide synthesis.
- can feed sugars back into glycolysis (shunt) if needed to.
26
outline lipolysis;
- release fatty acids from triglycerides.
- compared to glycogen TG's take up less space. based on their structures which is why they can store more energt
27
Outline ketogenesis;
- the liver can make ketone bodies from acetyl CoA.
- these ketone bodies can then be used by other tissues (such as cardiac muscle, smooth muscle and the brain) when energy is needed.
28
outline Ketolysis;
- the breakdown of ketone bodies to release acetyl CoA.
- acetyl CoA can then go to the citric acid cycle.
- any cycle that can lead to the production of acetyl CoA can feed into the CAC to make more energy.
29
Outline gluconeogenesis;
- gluconeogenesis is the synthesis of glucose de novo, from non carbohydrate precursors.
- gluconeogenesis occurs in the liver and kidney.
- provides a source of glucose for other tissues in the body, particularly important in times of fasting.
30
is gluconeogenesis simply the reversal of glycolysis?
- no glycolysis has 3 reactions that are irreversible.
- step one 3 and 10 .
- these 3 steps therefore need bypass reactions for these steps.
31
What is PEPCK deficiency?
- PEPCK deficiency is an extremely rare disorder characterized by episodes of low blood sugar (hypoglycemia). It is a disorder of carbohydrate metabolism caused by a deficiency in the enzyme called phosphoenolpyruvate carboxykinase or PEPCK.
32
outline Glucose-6-phosphatase deficiency
- G6PD deficiency is an inherited condition. It is when the body doesn't have enough of an enzyme called G6PD (glucose-6-phosphate dehydrogenase). This enzyme helps red blood cells work properly. A lack of this enzyme can cause hemolytic anemia. This is when the red blood cells break down faster than they are made.
33
outline pyruvate carboxylase deficiency;
- Pyruvate carboxylase deficiency (PC deficiency) is a rare genetic disorder present at birth characterized by failure to thrive, developmental delay, recurrent seizures and a failure of the body to produce the necessary fuels for energy and neurotransmitters important for brain function.
34
outline fructose 1,6 bisphosphatase deficiency;
Fructose-1,6-bisphosphatase deficiency is an inherited metabolic disorder in which the body cannot properly make glucose. Glucose is the main type of sugar in the blood and a primary source of energy for the body's cells.
35
What are some available substrates for gluconeogenesis?
- pyruvate.
- glycerol.
- glucogenic amino acids like alanine.
36
outline lactate as a substrate for gluconeogenesis;
- lactate is a product of anaerobic glycolysis.
- lactate travels to the liver via the blood.
- once in the liver it is converted back to pyruvate by lactate dehydrogenase (NAD--> NADH + H+) known as the cori cycle.
37
Outline glycerol as a substrate for gluconeogenesis;
- glycerol can enter gluconeogenesis pathway by being converted into DHAP.
- glycerol is first converted to glycerol 3-phosphate by glycerol kinase with the use of ATP. this is then converted to DHAP by glycerol 3 phosphate dehydrogenase while oxidizing NAD.
38
outline gluconeogenic amino acids as substrates for gluconeogenesis;
- all amino acids except for leucine and lysine are gluconeogenic.
- these amino acids can either be converted into pyruvate or citric acid cycle intermediates.
- the citric acid cycle intermediates eventually can make there way into oxaloacetate and can therefore serve as a substrate for gluconeogenesis.
- alanine and glutamine are of main importance.
39
outline alanine as a substrate for gluconeogenesis;
- alanine can be converted into pyruvate by alanine transaminase but requires PLP as a coenzyme.
- alpha-ketoglutarate is converted to glutamate at the same time.
40
outline the shuttle systems;
- gluconeogenesis begins in the mitochondria.
- alanine is converted into pyruvate inside the mitochondria.
- lactate is converted into pyruvate in the cytosol and pyruvate is shuttled into the mitochondria (pyruvate carboxylase is situated in both mitochondria and the cytosol).
- however when converted to oxaloacetate it needs to be shuttled back to the cytosol because it can not cross the inner mitochondrial membrane.
41
outline the malate (malate-aspartate shuttle)
- used when the starting substrate is alanine.
- oxaloacetate is converted into malate , malate can cross the inner mitochondrial membrane with the help of a antiporter.
- once in the membrane malate is converted back to oxaloacetate which can then continue gluconeogenesis.
42
outline the lactate shuttle;
- lactate is converted to pyruvate in the cytosol.
- lactate is then converted to oxaloacetate in the mitochondria which is then converted to PEP, PEP is shuttles out of the mitochondria and can then continue gluconeogenesis.
