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600 PT - A&P > Metabolism 1 > Flashcards

Metabolism 1 Flashcards

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1
Q

REVIEW: Metabolism
Metabolism

A

is all chemical reaction occurring in body

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2
Q

REVIEW: Metabolism
* Catabolism

A
  • break down complex molecules into simpler ones
  • Exergonic: reactions release energy stored in the molecules
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3
Q

REVIEW: Metabolism
Anabolism

A
  • combine simple molecules into complex ones
  • Endergonic: requires energy
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4
Q

Metabolism
* Cellular catabolism or aerobic metabolism or cellular respiration

A
  • Requires oxygen
  • Occurs in the mitochondria
  • 40 percent of energy is captured
  • Used to convert adenosine diphosphate (ADP) to
    adenosine triphosphate (ATP)
  • ATP is used for anabolism and other cellular functions
  • 60 percent of energy escapes as heat
  • Warms the interior of the cell and the surrounding
    tissue
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5
Q

REVIEW: ATP
* Adenosine Triphosphate (ATP)

A
  • “energy currency” of the body
  • The energy stored in this molecule is found within the bonds between each phosphate group
  • ATP is created in exergonic reactions and used in endergonic reactions
  • ADP + P + energy ↔ ATP
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6
Q

Role of ATP in Linking Anabolic & Catabolic
Reactions

A
  • Catabolic reactions created ATP:
  • Example: glycolysis
  • Anabolic reactions require energy:
  • Example: glycogenesis
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7
Q

Metabolism
* Nutrient pool

A
  • Source for organic substrates (molecules) for
    both catabolism and anabolism
  • Anabolism in the cell required for:
  • Replacing membranes, organelles, enzymes, and
    structural proteins
  • Catabolism in the cell required for:
  • Converting substrates to a 2-carbon molecule
  • Utilized by mitochondria to produce A T P
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8
Q

Metabolism
* Utilization of nutrients

A
  • Comes from the diet and from reserves
  • Reserves are mobilized when absorption across the digestive tract is insufficient to
    maintain normal nutrient levels
  • Liver cells break down triglycerides and glycogen
  • Fatty acids and glucose can be released
  • Adipocytes break down triglycerides
  • Fatty acids can be released
  • Skeletal muscle cells break down contractile proteins
  • Amino acids can be released
  • We can use all of these reserves to create ATP
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9
Q

Metabolism
Restoration of nutrient reserves

A
  • Reserves are stocked when absorption by the digestive tract is greater than immediate nutrient needs
  • Liver cells store triglycerides and glycogen
  • Adipocytes convert excess fatty acids to triglycerides
  • Skeletal muscles build glycogen reserves and use amino acids to increase numbers of myofibrils
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10
Q

Metabolism
* Utilization of resources

A
  • Cells in most tissues continuously absorb and catabolize glucose
  • Nervous tissue must have a continuous supply of glucose
  • During starvation, other tissues can shift to fatty acid or amino acid catabolism
  • Conserves body’s glucose for nervous tissue
  • Can also uses ketones (more later)
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11
Q

REVIEW: REDOX Reactions
Oxidation

Oxidation and reduction always paired

A

= removal of electrons from a molecule
* Decrease in potential energy
* Typically involves a loss of hydrogen atoms, also called dehydrogenation reactions

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12
Q

REVIEW: REDOX Reactions
* Reduction

Oxidation and reduction always paired

A

= addition of electrons to a molecule
* Increase in potential energy

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13
Q

REVIEW: REDOX Reactions
* So when a molecule is oxidized, it often loses electrons (in the form of hydrogen
atoms)

A
  • These liberated hydrogen atoms have to go somewhere (something must be
    reduced)
  • 2 common coenzymes used are:
  • Nicotinamide adenine dinucleotide (NAD)
  • NAD+ is reduced to NADH + H+
  • Flavin adenine dinucleotide (FAD)
  • FAD is reduced to FADH2
  • When we start talking about glucose metabolism, the process involves the oxidation of glucose
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14
Q

REVIEW: REDOX Reactions
* Glucose is C6H12O6

A
  • During glycolysis it is split into 2 pyruvate molecules
  • Pyruvate is C3H4O3 (reminder: there are two of these molecules)
  • Therefore, we have lost 4 hydrogen atoms
  • Where do they go? They are accepted by NAD+ which becomes NADH/H
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15
Q

REVIEW: REDOX Reactions
* LEO the lion says GER
* OIL RIG

A
  • Loss of Electrons = Oxidation
  • Gain of Electrons = Reduction
  • Oxidation is Loss
  • Reduction is Gain
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16
Q

Mechanisms of ATP Generation

A
  1. Substrate-level phosphorylation
  2. Oxidative phosphorylation
  3. Photophosphorylation
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17
Q

Mechanisms of ATP Generation
1. Substrate-level phosphorylation

A
  • Transferring of a high-energy phosphate group from an intermediate directly to ADP
  • Examples: Glycolysis, citric acid cycle, and phosphocreatine
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18
Q

Mechanisms of ATP Generation
Oxidative phosphorylation

A
  • Remove electrons and pass them through electron transport chain to oxygen
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19
Q

Mechanisms of ATP Generation
Photophosphorylation

A
  • Only in chlorophyll-containing plant cells - not going to be discussed here!
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20
Q

Carbohydrate Metabolism

A
  • Remember glucose? Breakdown product of carbohydrates that is absorbed in the small intestine
  • Glucose is the preferred source of energy, most other saccharides are converted to glucose
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21
Q

Carbohydrate Metabolism
* Why is glucose preferred?

A
  • Glucose is a small, soluble molecule that is easily distributed through body fluids
  • Glucose can provide A T P anaerobically (without oxygen) through glycolysis
  • Glucose can be stored as glycogen, which forms compact, insoluble granules
  • Glucose can be easily mobilized because the breakdown of glycogen (glycogenolysis)
    occurs very quickly
  • Mobilization of other intracellular reserves involves much more complex pathways and takes
    considerably more time.
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22
Q

Carbohydrate Metabolism
* GluT transporters

A
  • bring glucose into the cell via facilitated diffusion
  • Insulin causes expression of more of these
    transporters in the plasma membrane, increasing
    rate of entry into cells
  • Glucose is trapped in cells after being
    phosphorylated
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23
Q

Carbohydrate Metabolism
* Fate of glucose depends on needs of body cells

A
  1. ATP production
  2. Glycogen synthesis
  3. Synthesis of amino acids
  4. Triglyceride synthesis
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24
Q

Carbohydrate Metabolism
* Fate of glucose depends on needs of body cells
1. ATP production

Study These Flashcards
A
  • if energy is needed immediately
25
Carbohydrate Metabolism * Fate of glucose depends on needs of body cells Glycogen synthesis
* combining hundreds to thousands of glucose molecules to form glycogen (stored form of glucose)
26
Carbohydrate Metabolism * Fate of glucose depends on needs of body cells Synthesis of amino acids
* used to form proteins
27
Carbohydrate Metabolism * Fate of glucose depends on needs of body cells Triglyceride synthesis
* when other body stores are full, the remaining glucose is converted to fats
28
Carbohydrate Metabolism * Cellular Respiration * There are 4 steps in the complete utilization of a glucose molecule (glucose catabolism)
1. Glycolysis 2. Formation of acetyl coenzyme A 3. Citric Acid Cycle reactions (Kreb’s Cycle) 4. Electron transport chain reactions
29
Carbohydrate Metabolism * Cellular Respiration 1. Glycolysis
* Anaerobic respiration: does not require oxygen * Substrate-level phosphorylation
30
Carbohydrate Metabolism * Cellular Respiration Formation of acetyl coenzyme A
* Aerobic respiration: requires oxygen
31
Carbohydrate Metabolism * Cellular Respiration Electron transport chain reactions
* Aerobic respiration: requires oxygen * “oxidative phosphorylation”
32
Glycolysis * Overview
* Cellular respiration begins with glycolysis * Splits 6-carbon glucose into two 3-carbon molecules of pyruvic acid * Occurs in the cytosol * 10 reactions * Consumes 2 ATP but generates 4 🡪 NET GAIN of 2 ATP * First 5 steps uses the ATP and increases the potential energy in the molecules * Steps 6-10 is where 4 ATP are generated
33
Glycolysis * Important Reactions: Reaction 1
* First step is always phosphorylation * Addition of phosphate group to glucose * Uses the enzyme **hexokinase** in most cells (**glucokinase** in the liver) *** REQUIRES 1 ATP** * Benefit: phosphorylation of glucose to keep it in the cell * GluT transporters do not recognize G-6-P
34
Glycolysis * Important Reactions: Reaction 3
* Another phosphorylation reaction * Addition of phosphate group to F-6-P * Uses the enzyme **phosphofructokinase** *** REQUIRES 1 ATP** * Rate-limiting step * **The rate limiting step** is the slowest (irreversible) step in a pathway * determines how fast the whole pathway can be carried out
35
Glycolysis * Important Reactions: Reaction 4
* One 6-carbon molecule is split into two 3-carbon molecules (G-3-P)
36
Glycolysis * Important Reactions: Reaction 6
* Redox Reaction * G-3-P is oxidized, NADH is reduced * **GENERATES 2 NADH**(one from each 3-carbon molecule) * Also, each G-3-P is phosphorylated * Does not require ATP (exergonic reaction, uses energy to add Pi) * Now we have added 4 phosphate groups total
37
Glycolysis * Important Reactions: Reaction 7
* 1 phosphate group from each 3-carbon molecule is removed * **GENERATES 2 ATP** (1 from each 3-carbon molecule)
38
Glycolysis * Important Reactions: Reaction 10
* 1 more phosphate group from each 3-carbon molecule is removed * **GENERATES 2 ATP** (1 from each 3-carbon molecule) * Final product is pyruvate
39
Glycolysis * End Products from one glucose molecule
* 2 pyruvate molecules * 4 ATP molecules (net 2 ATP) * 2 NADH * If oxygen is available, will go to ETC to create more ATP
40
What Happens to Pyruvate? * Fate of pyruvic acid depends on oxygen availability
* If oxygen is scarce (anaerobic), it is reduced to lactic acid * If oxygen is plentiful (aerobic), pyruvic acid is converted to acetyl coenzyme A and it enters the Citric Acid Cycle
41
Formation of Acetyl coenzyme A * The second step in cellular respiration
* Transitional step between glycolysis and Krebs cycle * Each pyruvic acid is converted to 2-carbon acetyl group * Remove one molecule of CO2 as a waste product * **Pyruvic acid enters the mitochondria** first and then is converted to acetyl coenzyme A * Each pyruvic acid also loses 2 hydrogen atoms * NAD+ reduced to NADH/H+
42
Formation of Acetyl coenzyme A * Occurs in
* Occurs in mitochondrial matrix * End products per glucose molecule: * 2 CO2 (waste product) * 2 NADH * will go to ETC to create more ATP
43
What Happens to Pyruvate?
* If oxygen is scarce (anaerobic), it is reduced to lactic acid * 2 pyruvic acid + 2NADH + 2H+ 🡪 2 lactic acid and 2 NAD+
44
What Happens to Pyruvate? * Cori Cycle:
* Once lactic acid is produced, it quickly diffuses out of the cell and enters the blood * Hepatocytes can convert lactic acid to glucose * Other oxygenated tissue can reduce the lactic acid back into pyruvate, where it will then be used
45
The Citric Acid Cycle (CAC)
* Also known as Kreb’s Cycle or TCA Cycle (Tricarboxylic Acid Cycle) * The third step of cellular respiration * Requires oxygen (aerobic respiration) * Occurs in matrix of mitochondria * Series of redox reactions that transfer energy to coenzymes * Overall function is to remove hydrogen atoms from specific organic molecules and transfer them to coenzymes
46
The Citric Acid Cycle (CAC) * 2 decarboxylation reactions release CO2
* CO2 will diffuse out of cell and will be carried to the lungs * Reduced coenzymes (NADH and FADH2) are the most important outcome * For every ONE acetyl CoA that enters the Krebs cycle, 3 NADH + 3H+, and 1 FADH2 is produced * **One molecule of ATP generated by substrate-level phosphorylation**
47
The Citric Acid Cycle (CAC) * End products of the CAC
* Per acetyl CoA molecule (per glucose molecule in brackets) 1. 2 CO2 (4 CO2 per glucose molecule) * Waste product 2. 3 NADH (6 NADH per glucose molecule) * will go to ETC to create more ATP 3. 1 FADH2 (2 FADH2 per glucose molecule) * will go to ETC to create more ATP 4. 1 ATP (2 ATP per glucose molecule)
48
Electron Transport Chain (ETC)
* Series of electron carriers called cytochromes in **inner mitochondrial membrane** * Receive electrons from NADH and FADH2 * Each electron carrier is reduced or oxidized as it passes along electrons down the chain * O2 is the final electron acceptor * The site of **oxidative phosphorylation**
49
Electron Transport Chain (ETC) * Oxidative Phosphorylation Overview
* Each electron carrier has an increased infinity for electrons as we move down the chain * As electrons are passed from one carrier to another, energy is released * Energy is used to pump H+ ions into intermembrane space * Energy stored in electrochemical gradient is used to create ATP *** Final electron acceptor is O2 and water is formed** *** Produces more than 90% of ATP used in the body**
50
Electron Transport Chain (ETC) * Oxidative Phosphorylation Overview * Lack of oxygen stops the ETC
* Blocking cytochromes also stops the ETC * Example: poisons such as cyanide * With no functioning ETC, the citric acid cycle stops * Cells die from lack of ATP
51
Electron Transport Chain (ETC) * Steps in Oxidative Phosphorylation
1. NADH/FADH2 deliver hydrogen atoms from the citric acid cycle to the ETC 2. Cytochromes pass electrons sequentially down the chain of electron carriers 3. Released energy is used to pump hydrogen ions into the intermembrane space creating an electrochemical gradient * Stored energy is called proton-motive force 4, Hydrogen ions can diffuse downelectrochemical gradient back into the matrix only through specific hydrogen ion channels 5, O2 is the final electron acceptor
52
Electron Transport Chain (ETC) * Yield from the ETC
* Each NADH will yield 2.5 ATP * Each FADH2 will yield 1.5 ATP
53
# Electron Transport Chain (ETC) Steps in Oxidative Phosphorylation 1. NADH/FADH2 deliver hydrogen atoms from the citric acid cycle to the ETC
* The hydrogen atom is composed of: * A high-energy electron (e-) * Given to the ETC * A hydrogen ion or proton (H+) * Released into the mitochondrial matrix
54
Electron Transport Chain (ETC) * Steps in Oxidative Phosphorylation Hydrogen ions can diffuse down electrochemical gradient back into the matrix only through specific hydrogen ion channels
Hydrogen ions can diffuse down electrochemical gradient back into the matrix only through specific hydrogen ion channels
55
ATP Produced By One Molecule of Glucose
10 NADH x 2.5 ATP/NADH = 25 ATP * 2 FADH2 x 1.5 ATP/FADH2 = 3 ATP * 4 ATP * 32 ATP per glucose molecule
56
Glucose Metabolism * Glucose storage: glycogenesis
* Polysaccharide that is the only stored carbohydrate in humans * If glucose is not needed, many glucose molecules will combine to form glycogen * Insulin stimulates hepatocytes and skeletal muscle cells to synthesize glycogen * The body can store about 500g of glycogen (75% of that is in skeletal muscle)
57
Glucose Metabolism * Glucose release: glycogenolysis
* Glycogen stored in hepatocytes is broken down into glucose and released into blood * Glycogen stored in muscle will be converted to glucose-6-phosphate and then will enter glycolysis * Skeletal muscle lacks the enzyme to cleave the final phosphate * Stimulated by glucagon and epinephrine
58
Glucose Metabolism * Gluconeogenesis
* Glucose formed from noncarbohydrate sources * Substances that can be used: * Glycerol part of triglycerides * lactic acid * most amino acids * Occurs in the liver * Stimulated by cortisol and glucagon

600 PT - A&P (8 decks)

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