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DAT > SNS Biology - Respiration > Flashcards

SNS Biology - Respiration Flashcards

1
Q

Glycolysis

A

Occurs in cytoplasm

  1. Glucose + ATP > glucose-6-phosphate + ADP
  2. > fructose-6-phosphate
  3. +ATP > fructose-1,6-diphosphate
  4. > glyceraldehype-3-phosphate (PGAL) + dihydroxyacetone phosphate
  5. dihydroxyacetone + NAD+ > PGAL + NADH
  6. 2 x PGAL > 2 x 1, 3-diphosphoglycerate
    • 2 x ADP > 2 x 3-phosphoglycerate + 2 x ATP
  8. > 2 x 2-phosphoglycerate
  9. > 2 x phosphoenolpyruvate
    • 2 x ADP > 2 x pyruvate + 2 x ATP
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2
Q

Glycolysis

Net Reaction

A

One molecule glucose used, two molecules pyruvate formed

Two ATP used, 4 generated - net production of two ATP per glucose

Two NADH per glucose

Glucose + 2ADP + 2Pi + 2NAD+ > 2Pyruvate + 2ATP + 2NADH + 2H+ + 2H2O

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3
Q

Glycolysis

Substrate Level Phosphorylation

A

ATP synthesis directly coupled to degradation of glucose without participation of an intermediate molecule such as NAD+

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4
Q

Glycolysis

Fermentation

A

For glycolysis to continue in the absence of oxygen, NAD+ must be regenerated, accomplished by reducing pyruvate into ethanol or lactic acid

Fermentation therefore produces only 2ATP per glucose

  1. Ethanol - yeast, some bacteria. Pyruvate converted into ethanol regenerating NAD+
  2. Lactic acid - fungi, bacteria, human muscle during strenous activity. Pyruvate reduced to lactic acid regenerating NAD+
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5
Q

Cellular Respiration

A

Aerobic

  1. Pyruvate decarboxylation
  2. Citric acid cycle
  3. Electron transport chain
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6
Q

Cellular Respiration

Pyruvate Decarboxylation

A
  • Transported from the cytoplasm into the mitochondrial matrix
  • Is decarboxylated (loses CO2) and remaining acetyl group is transferred to coenzyme A to form acetyl CoA
  • In the process NAD+ is reduced to NADH
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7
Q

Cellular Respiration

Citric Acid Cycle

A
  • Begins when 2C acetyl group from acetyl-CoA combines with 4C oxaloacetate to form 6C citrate
  • Via complex series of reactions, 2CO2 are released and oxaloacetate regenerated
  • For each cycle, 1ATP produced by substrate level phosphorylation via GTP intermediate.
  • Additionally electrons are transferred to FAD and NAD+ to form FADH2 and NADH. These conenzymes transport the electrons to the electron transport chain
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8
Q

Cellular Respiration

Citric Acid Cycle

Net Reaction

A

For each molecule of glucose, 2 pyruvates enter the cycle, so 6 NADH, 2FADH2, 2ATP formed.

2 Acetyl CoA + 6NAD+ + 2FAD +2GDP + 2Pi +4H2O > 4CO2 + 6NADH + 2FADH + 2GTP(ATP) +4H+ + 2CoA

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9
Q

Cellular Respiration
Electron Transport Chain

A
  • Electrons transferred from NADH to FADH2 to oxygen via series carrier molecules located on the inner mitochondrial membrane, most of which are cytochromes
  • Functional unit of the cytochrome consists of central iron atom, capable of undergoing reversible redox reaction
  • Final electron acceptor is O2 which also picks up 2H+ to form water
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10
Q

Anaerobic and Cellular Respiration
Total Energy Produced per Glucose

A
  1. Anaerobic (substrate level phosphorylation) = 2ATP
  2. Citric Acid Cycle = 2ATP
  3. Oxidative Phosphorylation = 32 ATP

Sum = 36 ATP

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11
Q

Cellular Respiration
Electron Transport Chain
Net Reaction

A

• Each glucose molecule produces 2NADH via glycolysis, 2NADH via pyruvate decarboxylation and 6NADH and 2FADH2 via the TCA cycle.
• Each FADH2 generates 2ATP
• Each NADH generates 3ATP, except the two of glycolysis which generate 2ATP
32ATP total therefore produced via the electron transport chain

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12
Q

Alternative Energy Sources

A

• In order of preference:

  1. Carbohydrates
  2. Fats
  3. Proteins
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13
Q

Alternative Energy Sources

A
  • Disaccharides are hydrolysed to monosaccharides most of which can be converted into glucose or glycolytic intermediates.
  • Glycogen stored in liver can be converted when needed to a glycolytic intermediate
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14
Q

Alternative Energy Sources
Fats

A
  • Fat molecules stored in adipose tissue as triglycerides. When needed, converted by lipases to Fas and glycerol - Carried by blood to other tissues for oxidation
  • Glycerol can be converted to PGAL, a glycolytic intermediate
  • Fas must first be activated in the cytoplasm, requiring 2ATP, before transport into mitochondria and taken through cycles of beta oxidation to form 2C fragments which are converted to Acetyl-CoA. This then enters the TCA cycle.
  • With each cycle of beta oxidation of a saturated FA, 1NADH and 1FADH2 produced
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15
Q

Alternative Energy Sources
Proteins

A
  • Only degraded when insufficient carbs and fat available
  • Most AAs undergo transamination
  • Carbon atoms of most AAs converted to acetyl-CoA, pyruvate or another of the intermediates of the TCA cycle
  • Alternatively, AAs may be converted to keto acids via oxidative deamination
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16
Q

Alternative Energy Sources
Proteins
Transamination

A

• Amino group of an AA exchanged for a ketone group of another acid to form an alpha-keto acid

17
Q

Alternative Energy Sources
Proteins
Oxidative Deamination

A
  • Removes an ammonia molecule from an AA directly
  • Ammonia is toxic to vertebrates – fish can excrete it, insects and birds convert it to uric acid for excretion, and mammals to urea
18
Q

Photosynthesis
Net Reaction

A

6CO2 + 12H2O + light energy > C6H12O6 + 6O2 + 6H2O

19
Q

Photosynthesis
Reactions

A
  1. Light reaction – photolysis. Convert solar energy to chemical energy (ATP and NADP).
  2. Dark reaction – or reduction synthesis – carbs produced by reducing CO2. Coupled to the light reactions. Incorporate CO2 into organic molecules by carbon fixation
20
Q

Photosynthesis
Reactions
Light Reactions

A
  1. Cyclic
  2. Non-cyclic – key pathway
21
Q

Photosynthesis
Reactions
Light Reactions
Cyclic

A
  1. Photon of light is absorbed by chlorophyll a P700,
  2. Electrons excited to a higher energy level
  3. Move along a series of carriers and a series of redox reactions take place which ultimately return them to P700 whilst cyclic phosphorylation occurs to generate ATP
22
Q

Photosynthesis
Reactions
Light Reactions
Non-Cyclic

A
  1. Photon of light is absorbed by chlorophyll a P700,
  2. Electrons excited to a higher energy level
  3. Transferred to NADP+ to form NADPH instead of returning to P700 along electron transport chain
  4. When light strikes P680, excited electrons travel down same electron carrier chain as for cyclic reaction until reach P700 where replace lost electrons, producing ATP by noncyclic phosphorylation
  5. P680 is strong enough oxidising agent to oxidise water to replace lost electrons, producing 2H+, 2e- and O2
23
Q

Photosynthesis
Reactions
Dark Reactions

A
  • Use NADPH and ATP generated by light reactions to reduce CO2 to carbohydrates
  • CO2 is the source of carbon for carb production by the Calvin cycle
24
Q

Photosynthesis
Reactions
Dark Reactions
Calvin Cycle

A
  1. CO2 fixed to 5C ribulose bisphosphate (RBP)
  2. Resulting 6C molecule splits to form 2 x 3C phosphoglyceric acid (PGA)
  3. PGA phosphorylated and reduced by ATP and NADPH to PGAL
  4. Most PGAL recycled to RBP via complex series of reactions
  5. PGAL considered prime end product
25
Q

Photosynthesis
Reactions
Dark Reactions
PGAL

A

Used as:

  1. Intermediate food nutrient
  2. Combined and rearranged to form monosaccharides such as glucose
26
Q

Photosynthesis
Reactions
Dark Reactions
Calvin Cycle
Net Reaction

A

• In 6 turns, 12 PGAL former from 6CO2 and 6 RBPThe 12 PGAL combine to form 6 RBP and 1 molecule glucose (end product)

27
Q

Respiration
Invertebrates
Protozoa and Hydra

A
  • Every cell in contact with external environment
  • Respiratory gases can be exchanged by simple diffusion across the cell membrane
28
Q

Respiration
Invertebrates
Annelids

A
  • Mucous secreted by cells on the external surface provides a moist surface for gaseous exchange by diffusion
  • The circulatory system brings O2 to the cells and returns waste products to the skin for excretion
  • Vascularity of the skin makes cutaneous respiration very efficient
  • Aquatic annelids use branchial respiration via gills or parapodia for gas exchange
29
Q

Respiration
Invertebrates

Arthropods

A
  • Respiratory system of the grasshopper consists of series of respiratory tubules – tracheae – whose branches reach to almost every cell
  • Access the surface by spiracles (openings)
  • Permits intake, distribution and removal of respiratory gases by diffusion
  • No O2 carrier needed and its efficiency allows insects to have relatively effortless open circulatory system
30
Q

Respiration
Humans
Alveoli number and surface area

A
  • ~3 million
  • 100m2 surface
31
Q

Ventilation

A

• Process by which air is inhaled and exhaled from the lungs

  1. Muscular diaphragm contracts and flattens
  2. External intercostal muscles contract pushing the rib cage and chest wall up and out
  3. Thoracic cavity increases in volume, reducing pressure in the lungs
  4. Lungs expand and fill
32
Q

Ventilation
Exhalation

A

• Generally a passive process - Lungs and chest wall are highly elastic and tend to recoil to original positions

  1. Diaphragm and intercostal muscles relax
  2. Chest wall moves inward
  3. Decrease in thoracic volume, increase in pressure
  4. Lungs deflate
33
Q

Ventilation
Control

A
  • Regulated by collections of neurons – respiratory centres – located in the medulla oblongata
  • Rhythmic discharges from the medulla stimulate the intercostal muscles and/or diaphragm to contract
  • When partial pressure CO2 rises, medulla stimulates increase in rate of ventilation
34
Q

Ventilation
Pulmonary Surfactant

A
  • Water molecules coat the walls of the alveoli
  • Pulmonary surfactant is secreted by alveolar cells in order to prevent surface tension between water molecules from causing collapse of alveoli
  • Coats alveolar walls reducing surface tension, permitting easier gas exchange and better pulmonary compliance 9lung elasticity)
35
Q

Respiration In Plants

A
  • Plants undergo aerobic respiration similar to animals
  • Glycolysis produces 2ATP and pyruvic acids, 36ATP per glucose
  • Anaerobic respiration takes place in simple plants in a similar manner to animals

DAT (53 decks)

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