Download I. Cellular Respiration

RESPIRATION
(has two meanings...)
* the life function which involves the transfer of potential (stored) chemical energy
into a form that an organism can use--CELLULAR RESPIRATION
* the exchange of gases (namely CO2 and O2) between the organism and the
environment--ORGANISMAL RESPIRATION
I. Cellular Respiration
* energy is released from glucose (a carbohydrate...a monosaccharide)
* this energy is converted by enzymes (a protein...a polypeptide) to a more usable
form called ATP
ATP = adenosine triphosphate
* all cells carry out cellular respiration
* all cells use ATP
triphospate= 3 phosphates
* ATP = ENERGY!!! the bonds between the phosphates are high energy bonds
* when these bonds are broken (that is, when ATP is hydrolyzed) lots of energy is
released that can be used by the organism
THE REACTION... ATP + H2O <====> ADP + P +
* ATP (adenosine triphosphate) is hydrolyzed (split with water) to form ADP
(adenosine diphosphate) and energy
diphosphate--2 phosphates
THE ATP-ADP CYCLE
* ATP and ADP are constantly converting back and forth with the help of the
the ATP/ADP
cycle is
described here
enzyme ATP-ase
ATP ---> ADP releases energy
ADP ---> ATP needs energy
okay...back to cellular respiration
Respiration
* cellular respiration (releasing the chemical energy of glucose to form ATP
which is used for energy) can happen with or without oxygen (O2)
ANAEROBIC RESPIRATION--does not use O2
AEROBIC RESPIRATION--uses O2; most organisms carry out aerobic
respiration
A) Anaerobic Respiration (Fermentation)
* the breakdown of glucose without oxygen
* some organisms like bacteria (KINGDOM--Monera) and yeast (KINGDOM-Fungi) do not have the necessary enzymes to use oxygen
* other cells use anaerobic respiration (fermentation) when no O2 is present
* the enzymes for anaerobic respiration (fermentation) are found in the
cytoplasm
* during anaerobic respiration (fermentation) glucose is broken down to
either lactic acid or alcohol/CO2 depending on the organism
LACTIC ACID--muscle fatigue in animals; also produced by bacteria; used
to make cheese, buttermilk and yogurt
ALCOHOL and CO2--produced by yeast; used in baking and brewing
The reaction of anaerobic respiration (fermentation)...
* it takes 2 ATP molecules of energy to break down glucose, which gives off
4 ATP...this means there is a NET GAIN of 2 ATP for anaerobic respiration
(fermentation)
glucose ------> 2 lactic acid
both sets of end products
can be used to get more energy)
glucose ------> 2 alcohol + 2 CO2
The process of breaking down glucose to start cellular respirstion is called...
watch the basics of
glycolysis
GLYCOLYSIS
So, glycolysis (the breakdown of glucose) results in the formation of 2
pyruvic acid and a net gain of 2 ATP. The pyruvic acid is then converted to
either lactic acid or alcohol and carbon dioxide without the production of any
more ATP.
B) Aerobic Respiration
Respiration
* the breakdown of glucose with oxygen
* the energy from glucose is released gradually in a series of enzyme controlled
steps (the electron transport chain)
* the enzymes for aerobic respiration are found in the mitochondria
THE OVERALL PICTURE...
glucose + oxygen -----> water + carbon dioxide + ATP
C6H12O6 + O2 ------> H2O + CO2 + 36 ATP
a brief review of
aerobic respiratio
see the basic
reactants and
products of aerobic
respiration
...this reaction is essentially the reverse of photosynthesis!
* organisms that can perform aerobic respiration only do so when there is oxygen
present...otherwise, they carry out anaerobic respiration (fermentation)
THE 2 PHASES OF AEROBIC RESPIRATION
1) The anaerobic phase:
* the first step of aerobic respiration is GLYCOLYSIS (the breakdown of
glucose)(REMEMBER: this step does not require OXYGEN!!!)
*this step yields (gives) a net gain of 2 ATP
2) The aerobic phase:
* here, pyruvic acid (now with oxygen available) is broken down slowly in a complex
chain of events called the Krebs Cycle where hydrogen ions are kicked out
* during this cycle, 34 more ATP are produced...for a net gain of 36 ATP that is
from both steps combined" oxygen picks up the hydrogen and forms water...
O2 + 4H ----> 2H2O
* the carbon from the pyruvic acid is kicked out as carbon dioxide