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31 Cards in this Set

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What is respiration?
Utilization of oxygen by an organism
What is external respiration?
Entrance of air into lungs and gas exchange between alveoli and blood
What is internal respiration?
Gas exchange between blood and cells and the intracellular processes of respiration
What is the fundamental reason for photosynthesis?
Converts energy of the sun in chemical energy in compounds such as glucose
What are the favored fuels in living cells?
Fats and Carbohydrates
What bond is of importance in respiration?
As hydrogen is removed, bond energy is made available.

The C-H bond is energy rich, capable of releasing the largest amount of energy per mole.

CO2 is energy exhausted, end product of respiration
What is dehydrogenation?
High energy hydrogen atoms are removed from organic reactions via oxidation reaction

The subsequent acceptance of the hydrogen atom by hydrogen acceptor is the redox reaction

Energy released by reduction step is used to form high energy phoshpate bond in ATP

Initial oxidation step requires energy input, final reduction step releases energy
Why do small reductions occur several times rather than one large one and what is it called?
The energy can not be efficiently harnessed if it were release in one giant step

Electron transport chain
What steps does degradative oxidation of glucuse occur in?
Glycolysis

Cellular Respiration
What are the basics of Glycolysis?
Oxidative breakdown of glucose into two molecules of pyruvate

Production of ATP

Reduction of NAD+ into NADH

All reactions occur in cytoplasm regulated by specific enzymes
What is alcohol fermentation?
Commonly occurs only in yeast and some bacteria

Pyruvate produced in glycolysis is converted to ethanol, in this way, NAD+ is regenerated and glycolysis can continue
What is lactic acid fermentation?
Occurs in certain fungi and bacteria, and in human cells during strenuous activity

When oxygen supply to muscle cells lags behind the rate of glucose metabolism, pyruvate is reduced to lactic acid

NAD+ used is regenerated when pyruvate is reduced
What is cellular respiration?
Most efficient catabolic pathway used by organisms to harvest the energy stored in glucose.

Where glycolysis yields only 2 ATP per molecule of glucose,
Cellular respiration yields 36-28 ATP

Oxygen acts as the final stage of glucose oxidation

Metabolic reactions of cell respiration occur in the eukaryotic mitochondrion and are catalyzed by specific enzymes
What three stages can cellular respiration be divided into?
Pyruvate decarboxylation
Citric acid cycle
Electron transport chain
What is pyruvate decarboxylation?
Pyruvate formed during glycolysis is transported from the cytoplasm into the mitochondrial matrix where it is decarboxylated (loses CO2) and the acetyl group that remains is transferred to coenzyme A to form acetyl CoA

In the process, NAD+ is reduced to NADH
What is the citric acid cycle?
AKA: Krebs Cycle

Begins when the two-carbon acetyl group from acetyl CoA combines with oxaloacetate, a four-carbon molecule, to form the six-carbon citrate.

2 CO2 are released, oxaloacetate is regenerated for another turn of the cycle
What is produce by each turn of the citric acid cycle?
1 ATP is produced by substrate level posphorylation via a GTP intermediate

Electrons are transferred to NAD+ and FAD, generating NADH and FADH2

These coenzymes then transfer electrons to the electron transport chain, where more ATP is produced
What is the Electron Transport Chain?
Complex carrier mechanism located on the inside of the inner mitochondrial membrane

Sequential redox reactions occur as electrons are transferred from one carrier to the next

Each carrier is reduced as it accepts an electron, and is then oxidized when it passes it on to the next carrier

Final electron accepter is O2, picks up 2 Hydrogens from environment and forms H2O

2H+ + 2e- + O2 = H2O
What are most of the molecules in the Electron Transport Chain?
Cytochromes, resemble hemoglobin in the structure of their active site
What are other energy sources when glucose supplies run slow?
In preferrential order:
Other carbohydrates, fats, proteins

First converted to glucose or glucose intermediates, which can then enter the glycolyic pathway and citric acid pathway
How are carbohydrates used as energy sources?
Disaccharides are hydrolyzed into monosaccharides, most of which can be converted into glucose or glycolytic intermediates

Glycogen stored in the liver can be converted, when needed, into a glycolytic intermediate
How are fats used as energy sources?
Fat molecules are stored in adipose tissue in the form of triglyceride

When needed, hydrolyzed by lipases to fatty acids and glycerol and carried to body via blood

Glycerol can be converted into PGAL
What is the process of converting fat into a usable form of energy?
A fatty acid must first be "activated" in the cytoplasm

This requires 2 ATP

Once activated, fatty acid is transported into the mitochondrion and taken through a series of beta-oxidation cycles that convert it into two-carbon fragments, which are then converted into acetyl CoA.

Acetyl CoA then enters the TCA cycle.

Each round of beta-oxidation of saturated fatty acid, 1 NADH and 1 FADH2 is generated
What energy source yields the greatest ATP per gram and is the most efficient in energy storage?
Fat
How are proteins used as energy sources?
Body degrades protein only when there is not enough carbohydrates or fat available

Undergo transamination reaction in which the lose an amino group to form an alpha-keto acid.

Carbon atoms of most amino acids are converted into acetyl CoA, pyruvate, or one of the intermediates of the citric acid cycle.

These intermediates can enter their respective metabolic pathway
How does respiration occur in unicellular and simple multicellular organisms?
Simple diffusion through the cell membrane
How does respiration occur in annelids?
Mucus secred by cells on the external surface of the earthworm's body provides a moist surface for gaseous exchange by diffusion

Circulatory system brings O2 to the cells and waste products such as CO2 back to the skin for excretion
How does respiration occur in arthropod phylum?
Respiratory system of grasshoppers consists of a series of respiratory tubules called trachae whose branches reach almost every cell.

Tubes open to surface in openings called spiracles

Thus, allows exchange via diffusion
What are bronchi?
Two branches that lead to lungs after trachea
What are alveoli?
Thin walled sacs in lungs that permit gas exchange
What controls ventilation?
Regulated by neurons (respiratory centers) located in the medulla oblongata

When CO2 levels rise, medulla oblongata stimulates an increase in the rate of ventilation