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Physiology Exam 2 > Cell Respiration & Metabolism > Flashcards

Cell Respiration & Metabolism Flashcards

1
Q

What is metabolism?

A

All reactions that involve energy transformation

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2
Q

What are the 2 types of metabolism reactions?

A

1) Catabolic: RELEASE energy (breakdown large into smaller molecules)
2) Anabolic: REQUIRE energy (synthesis of large energy-storage molecules)

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3
Q

What is aerobic cellular respiration?

A

The energy releasing metabolic pathways in a cell that oxidize organic molecules such as glucose, fatty acids, and that use oxygen as a final electron acceptor
-oxygen is obtained from the blood

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4
Q

Aerobic cellular respiration is what kind of reaction?

A

Oxidation-reduction

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5
Q

How can a cell make energy without the use of oxygen/mitochondria?

A

Glycolysis (ANAEROBIC)

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6
Q

What is glycolysis and where does it take place?

A

Breakdown of glucose for energy (that does not use oxygen); takes place in the cytoplasm

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7
Q

What is glucose converted to in glycolysis?

A

2 molecules of pyruvic acid (pyruvate)

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8
Q

What does each pyruvic acid contain?

A

3 Carbons, 3 Oxygens, 4 Hydrogens

-4 Hydrogens are removed from intermediates

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9
Q

What is the energy expenditure and gain in glycolysis?

A
  • Makes 4 ATP, uses 2 at the beginning -> NET ATP = 2
  • Makes 2 NADH (each pair of H+ reduces a NAD) and two unbound H+
  • Makes pyruvate
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10
Q

What has to happen to glucose before it enters glycolysis?

A

It has to be activated -> It is first phosphorylated to glucose-6-phosphate because it traps the glucose within the cell (phosphate group is negatively charged which makes it hard for glucose to cross the cell membrane and escape)
-Phosphate is not released but added to intermediate molecules

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11
Q

What is the glycolysis pathway reaction?

A

Glucose + 2 NAD + 2 ADP + 2 Pi -> 2 pyruvic acid + 2 NADH + 2 ATP

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12
Q

Is glycolysis exergonic or endergonic?

A

eXergonic

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13
Q

Where are all the enzymes required for glycolysis located?

A

The cytosol

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14
Q

What is enzyme #1 in glycolysis?

A

HEXOKINASE converts Glucose -> Glucose 6-Phosphate

-rate-limiting step

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15
Q

What is enzyme #3 in glycolysis?

A

PHOSPHOFRUCTOKINASE (PFK) converts Fructose 6-Phosphate -> Fructose 1,6-Biphosphate
-the MOST rate-limiting (by modulating this enzyme you could upregulate or downregulate glycolysis)

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16
Q

What is enzyme #10 in glycolysis?

A

PYRUVATE KINASE converts Phosphoenolpyruvate -> Pyruvate

-rate-limiting step

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17
Q

What happens in the PFK pathway in cancer patients?

A

It incurs mutations at the PFK that make the pathway go much faster
-we can cut off supply of energy to tumor by inhibiting PFK

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18
Q

What happens if a mutation happens such that DHAP cannot be converted to GAP in glycolysis?

A

DHAP is an end enzyme, has to be converted to GAP

  • Not converted -> hemolytic anemia, fatigue
  • RBCs depend only on glycolysis for energy so this mutation causes RBCs to burst
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19
Q

What is the lactic acid pathway?

A

ANAEROBIC metabolic pathway; the formation of lactic acid from glucose. 2 ATP formed per glucose molecule

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20
Q

What is the net gain of the lactic acid pathway?

A

2 ATP

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21
Q

What is the reaction of the lactic acid pathway?

A

NADH + H+ + Pyruvic acid -> Lactic acid + NAD

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22
Q

What enzyme does the lactic acid pathway use?

A

Lactate Dehydrogenase (reversible enzyme)

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23
Q

Why does our body need to convert pyruvate to lactic acid?

A

If pyruvate starts building up it can have a negative inhibitor effect (our body wants to keep glycolysis going)

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24
Q

Which tissues are adapted to anaerobic metabolism?

A
  • Skeletal muscle (normal daily occurrence)
  • RBCs (do not contain mitochondria)
  • *ischemia in the heart (if heart is deprived of O2, there will be a build-up of lactic acid)
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25
What happens when you have a buildup of lactic acid?
The liver deals with it | -liver has a lot of LDH that converts lactic acid back to pyruvic acid
26
What is glycogenesis?
Producing glycogen from glucose | -increasing glucose intracellularly would increase the osmotic pressure -> must store carbohydrates as glycogen
27
What happens in glycogenesis? Where does it occur?
Glucose is converted to glucose-6-phosphate by utilizing ATP, it is then converted to its isomer, glucose-1-phosphate, then glycogen synthase removes phosphate groups as it polymerizes glucose to form glycogen; happens in skeletal muscle and liver
28
What is glycogenolysis?
Hydrolysis (breakdown) of glycogen: yields glucose-6-phosphate for glycolysis (in skeletal muscles used for own glycolytic needs), or free glucose that can be secreted into the blood (in liver only)
29
Where is free glucose made?
ONLY in the liver; liver has the enzyme glucose-6-phosphatASE that can remove the phosphate group from glucose-6-phosphate and make free glucose
30
What is the cori cycle?
- Lactate made in the muscle from anaerobic glycolysis goes to the liver where LDH converts lactate to pyruvate - Pyruvate -> glucose-6-phosphate (intermediate for glycolysis) -> free glucose released into blood - Glucose metabolized to lactate again in the liver
31
What is gluconeogenesis?
Production of glucose from noncarbohydrate molecules (through pyruvic acid), including lactic acid and amino acids, primarily in the liver -gluconeogenesis in the liver allows depleted skeletal muscle glycogen to be restored within 48 hours
32
What occurs in the aerobic respiration of glucose?
Pyruvic acid formed by glycolysis, then converted into acetyl coenzyme A (acetyl CoA) -Energy is released in oxidative reactions and is captured as ATP
33
Where does pyruvic acid enter in aerobic respiration?
Inner of mitochondria
34
What is pyruvic acid converted to in aerobic respiration?
Acetyl CoA and 2 CO2
35
What does acetyl CoA serve as?
- Substrate for mitochondrial enzymes | - Intermediate molecule in aerobic cell respiration that, together with oxaloacetic acid, begins the krebs cycle
36
Acetyl CoA combines with oxaloacetic acid to form ___?
Citric acid, which enters the Krebs cycle
37
What is made in the Krebs cycle?
- 1 GTP (can be easily converted to ATP by ADP), 3 NADH and 1 FADH2 - NADH and FADH2 transport electrons to ETC - produces oxaloacetic acid to continue the pathway
38
What enzymes regulate the Krebs cycle?
1) CITRATE SYNTHASE converts Oxaloacetate + Acetyl CoA -> Citrate 2) ACONITASE converts Citrate -> Isocitrate 3) ISOCITRATE DEHYDROGENASE converts Isocitrate -> Alpha-ketoglutarate 4) ALPHA-KETOGLUTARATE DEHYDROGENASE converts Alpha-ketoglutarate -> Succinyl-CoA
39
Where does the Krebs cycle occur?
Inner membrane of mitochondria
40
Where does the electron transport chain occur?
Cristae of the inner mitochondrial membrane
41
What does the electron transport chain consist of?
FMN, Coenzyme Q and cytochromes
42
What happens in the ETC?
- Each cytochrome transfers electron pairs from NADH and FADH2 to next cytochrome - Oxidized NAD and FAD are regenerated and shuttle electrons from the Krebs cycle to the ETC - Cytochrome receives a pair of electrons
43
What happens to iron in the ETC?
Iron is reduced, then oxidized as electrons are transferred
44
What is the final electron acceptor in the ETC?
OXYGEN oxidizes cytochrome a3 and accepts 2 electrons | -O2 + 4e- + 4H+ -> 2 H2O
45
What kind of reactions occurs in the ETC?
Oxidative phosphorylation | -energy derived is used to phosphorylate ADP to ATP
46
What is chemiosmotic theory?
The ETC powered by transport of electrons pumps H+ from the mitochondria matrix into space between inner and outer mitochondrial membranes -coupling ETC to ATP
47
What does NADH-coenzyme Q reductase complex transport?
4 H+ for every pair of electrons
48
What does Cytochrome C reductase complex transport?
4 H+ for every pair of electrons
49
What does Cytochrome C oxidase complex transport?
2H+ for every pair of electrons
50
What happens to the higher [H+] in intermembrane space?
Repiratory assemblies: permit the passage of H+ | -phosphorylation is coupled to oxidation when H+ diffuse through the respiratory assemblies
51
What are uncoupling proteins?
No ATP made, just heat; protons find a bypass to return to the inner mitochondrial membrane **clinical manifestation: in weight loss the more you energize heat without making ATP your body will start burning fat to make energy
52
How much ATP is produced in glycolysis?
2 ATP
53
How much ATP is produced in oxidative phosphorylation?
2.5 ATP for each pair of electrons NADH donates 1.5 ATP for each pair of electrons FADH2 donates 36 ATP total
54
What happens when more energy is taken in than consumed?
Glycolysis is inhibited ; glucose is converted into glycogen and fat
55
What is lipogenesis?
The formation of fat ; occurs mainly in adipose tissue and liver - Acetic acid subunits from acetyl-CoA are converted into various lipids - Fat stored in adipose cells serves as the major form of energy storage in the body
56
What 2 ways does our body get cholesterol?
1) Endogenous - made by the body | 2) Exogenous - by what we eat
57
What is lipolysis?
The breakdown of fat (in times of starvation) ; lipase breaks triglycerides down into glycerol and fatty acids
58
What do free fatty acids serve as?
Blood-borne energy carriers
59
What happens in beta-oxidation of fatty acids?
Enzymes remove 2-carbon acetic acid molecules from the acid end of fatty acids -> forms acetyl-CoA and enters the Krebs cycle
60
What is a popular fatty acid
Palmitic acid
61
What would happen in beta-oxidation of a fatty acid with a negative amount of carbons, like C-13?
5 (2) = 10 acetyl CoA and 3 carbons left
62
NItrogen is ingested primarily as _____. And excess niitrogen must be _____.
Protein; excreted
63
What is nitrogen balance?
Amount of nitrogen ingested minus amount excreted - (+) N balance -> more ingested than excreted (if this happens it becomes cytotoxic) - (-) N balance -> more excreted than ingested
64
What is transamination?
``` Amino group (NH2) transferred from one amino acid to form another to obtain a new amino acid -adequate amino acids are required for growth and repair ```
65
What is oxidative deamination?
Process by which excess amino acids are eliminated
66
What is urea and where is it made/excreted?
Amine group from glutamic acid removed -> ammonia and excreted as urea ; made in the liver but excreted by the kidneys
67
How does NH3 exist in our bodies?
NH3 + H2O -> NH4+ + OH- (this ammonia ion is the reason why too much nitrogen can get cytotoxic -> buildup of ammonia -> water will follow -> lysis in brain cells) -doesn't exist at NH3 because it is a gas
68
What is deamination?
Energy conversion - amino acid is deaminated - ketoacid can enter the Krebs cycle
69
What is an anapleurotic reaction?
Chemical reactions that form intermediates of a metabolic pathway -when deaminated, amino acids can enter the pathways of glycolysis as pyruvate, acetyl CoA, etc.

Physiology Exam 2 (4 decks)

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