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Energy
What are some types of energy we use everyday?
Living things require chemical energy stored within their food to function.
Cellular Respiration
Cells break down food into energy *some as heat *some as chemical energy
Occurs in multiple steps called a biochemical pathway
Each step is regulated by enzymes and involves the transfer of electrons
Energy
Energy derived from food is not given off in a great burst…how come?
Our cells would die!!!
Small packets of energy are stored in high energy bonds of ATP
Bond, Phosphate Bond
ATP = adenosine triphosphate -stores chemical energy
ATP is made of:
1) 1 Adenine2) 1 Ribose3) 3 Phosphates
Phosphorylation: ATP transfers a phosphate group (releases energy) it becomes ADP (adenosine diphosphate)
ADP
Energy transfer…
Electrons carry energyEnergy is transferred to carriers
If an atom is oxidized, it loses energy
If an atom is reduced, it gains energy
Electron Carriers…
Two types in cellular respiration:
NAD+ and FAD
Each of these can accept a pair of electrons and H atoms…
Respiration Types
Aerobic respiration requires O2
Anaerobic resp. does not require O2
Aerobic resp. produces much more energy
Who does what?
Only the unicellular organisms (bacteria mostly) rely solely on anaerobic resp.
Everything else can do both anaerobic and aerobic resp.
Glycolysis
*First step of all respiration*Takes place in the cytoplasm*Does not require oxygen
*Glycolysis= splitting of glucose Lysis - to split Glyco- refers to glucose
*Requires energy from ATP
Glycolysis
2 ATP molecules split glucose4 ATP molecules are created when pyruvic acid is formed.
How much net ATP is made through glycolysis?
2 NET ATP
Anaerobic Respiration
ATP is only made during glycolysis.
Therefore how much ATP do anaerobic organisms make?
2ATP
Fermentation…
*2 types:
1) Lactic acid fermentation
2) Alcoholic fermentation
*Any reaction that occurs after glycolysis in an anaerobic organism
Lactic Acid Fermentation
Pyruvic acid is converted to lactic acid.
Any athletes who have felt muscle burn after a strenuous workout are feeling lactic acid buildup.
Alcoholic Fermentation
Some organisms (yeast) have enzymes that break pyruvic acid into ethyl alcohol and carbon dioxide.
Alcoholic fermentation is important in the process of… breadmaking!!!!
(CO2 makes bread rise)
Alcohol again…
Alcoholic fermentation also gives rise to alcohol…
Glucose Source Beverage
Barley Beer
Potato Vodka
Grapes Wine
Rice Sake
Aerobic respiration continued…
In order for pyruvic acid to be broken down, yielding further energy, 2 things are required:
1) Oxygen (O2)
2) Mitochondria
Breaking pyruvic acid…*Pyruvic acid enters the mitochondrion*Broken into a 2 carbon molecule*Forms acetyl CoA*Enters the Krebs Cycle
Each molecule of pyruvic acid yields 1 CO2 and 1 NADH
Interesting tidbits…For every turn of the Kreb’s cycle, only 1 ATP is produced!!!CO2 is given off
Where does the rest of the ATP come from?
Electron Transport Chain
Energy stored in NADH and FADH2 is released in steps
Electrons passed from carrier to carrier, until O2 accepts the last 2 electrons.
Ahhh, big words…
As e- pass energy passes
Some of that energy is used to convert ADP to ATP (by means of a H+ pump)
The last step…
*O2 is the final electron acceptor*Combines with 4 H, to form…
WATER!!!
2 NET ATP from glycolysis2 ATP from the Kreb’s32 from the ETC 36 ATP gained!!!
Recap:
Why aerobic respiration instead of anaerobic?
Aerobic respiration yields 18 times more energy!!! (36:2)
What if we don’t have oxygen?
Aerobic respiration can’t occur without it.
Without oxygen, the Kreb’s cycle will stop, leaving a buildup of pyruvic acid…
The fate of pyruvic acid.
Without oxygen, what are 2 things that could happen to pyruvic acid?
Alcoholic or lactic fermentation!
What happens to us?
Lactic acid fermentation!
Oxygen Debt
Anytime your muscles get starved for oxygen, and lactic acid fermentation begins, you experience oxygen debt.
Oxygen debt is the amount of oxygen your body requires to get rid of lactic acid.
Atkins Heaven
Glucose is the main source of energy for ATP, but proteins and fats may be used as well.
Fat produces twice as much energy as glucose does, but you must be twice as active to burn a gram of fat…
Proteins may be used as an energy source as well, though there is much controversy as to whether this is good for the body or not…and it is terribly inefficient.
Ramifications? Kidney problems
Man vs. Machine
Another interesting tidbit:
Roughly 45% of the available energy of a glucose molecule is stored as ATP following aerobic respiration.
In comparison only 20% of the energy of gasoline is used by cars.