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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
Q

What happens when you have a buildup of lactic acid?

A

The liver deals with it

-liver has a lot of LDH that converts lactic acid back to pyruvic acid

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26
Q

What is glycogenesis?

A

Producing glycogen from glucose

-increasing glucose intracellularly would increase the osmotic pressure -> must store carbohydrates as glycogen

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27
Q

What happens in glycogenesis? Where does it occur?

A

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

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28
Q

What is glycogenolysis?

A

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
Q

Where is free glucose made?

A

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
Q

What is the cori cycle?

A
  • 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
Q

What is gluconeogenesis?

A

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
Q

What occurs in the aerobic respiration of glucose?

A

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
Q

Where does pyruvic acid enter in aerobic respiration?

A

Inner of mitochondria

34
Q

What is pyruvic acid converted to in aerobic respiration?

A

Acetyl CoA and 2 CO2

35
Q

What does acetyl CoA serve as?

A
  • Substrate for mitochondrial enzymes

- Intermediate molecule in aerobic cell respiration that, together with oxaloacetic acid, begins the krebs cycle

36
Q

Acetyl CoA combines with oxaloacetic acid to form ___?

A

Citric acid, which enters the Krebs cycle

37
Q

What is made in the Krebs cycle?

A
  • 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
Q

What enzymes regulate the Krebs cycle?

A

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
Q

Where does the Krebs cycle occur?

A

Inner membrane of mitochondria

40
Q

Where does the electron transport chain occur?

A

Cristae of the inner mitochondrial membrane

41
Q

What does the electron transport chain consist of?

A

FMN, Coenzyme Q and cytochromes

42
Q

What happens in the ETC?

A
  • 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
Q

What happens to iron in the ETC?

A

Iron is reduced, then oxidized as electrons are transferred

44
Q

What is the final electron acceptor in the ETC?

A

OXYGEN oxidizes cytochrome a3 and accepts 2 electrons

-O2 + 4e- + 4H+ -> 2 H2O

45
Q

What kind of reactions occurs in the ETC?

A

Oxidative phosphorylation

-energy derived is used to phosphorylate ADP to ATP

46
Q

What is chemiosmotic theory?

A

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
Q

What does NADH-coenzyme Q reductase complex transport?

A

4 H+ for every pair of electrons

48
Q

What does Cytochrome C reductase complex transport?

A

4 H+ for every pair of electrons

49
Q

What does Cytochrome C oxidase complex transport?

A

2H+ for every pair of electrons

50
Q

What happens to the higher [H+] in intermembrane space?

A

Repiratory assemblies: permit the passage of H+

-phosphorylation is coupled to oxidation when H+ diffuse through the respiratory assemblies

51
Q

What are uncoupling proteins?

A

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
Q

How much ATP is produced in glycolysis?

A

2 ATP

53
Q

How much ATP is produced in oxidative phosphorylation?

A

2.5 ATP for each pair of electrons NADH donates
1.5 ATP for each pair of electrons FADH2 donates
36 ATP total

54
Q

What happens when more energy is taken in than consumed?

A

Glycolysis is inhibited ; glucose is converted into glycogen and fat

55
Q

What is lipogenesis?

A

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
Q

What 2 ways does our body get cholesterol?

A

1) Endogenous - made by the body

2) Exogenous - by what we eat

57
Q

What is lipolysis?

A

The breakdown of fat (in times of starvation) ; lipase breaks triglycerides down into glycerol and fatty acids

58
Q

What do free fatty acids serve as?

A

Blood-borne energy carriers

59
Q

What happens in beta-oxidation of fatty acids?

A

Enzymes remove 2-carbon acetic acid molecules from the acid end of fatty acids -> forms acetyl-CoA and enters the Krebs cycle

60
Q

What is a popular fatty acid

A

Palmitic acid

61
Q

What would happen in beta-oxidation of a fatty acid with a negative amount of carbons, like C-13?

A

5 (2) = 10 acetyl CoA and 3 carbons left

62
Q

NItrogen is ingested primarily as _____. And excess niitrogen must be _____.

A

Protein; excreted

63
Q

What is nitrogen balance?

A

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
Q

What is transamination?

A 
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
Q

What is oxidative deamination?

A

Process by which excess amino acids are eliminated

66
Q

What is urea and where is it made/excreted?

A

Amine group from glutamic acid removed -> ammonia and excreted as urea ; made in the liver but excreted by the kidneys

67
Q

How does NH3 exist in our bodies?

A

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
Q

What is deamination?

A

Energy conversion

  • amino acid is deaminated
  • ketoacid can enter the Krebs cycle
69
Q

What is an anapleurotic reaction?

A

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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