Respiration And Osmosis Biology

CHAPTER 12: RESPIRATION
Respiration: is the controlled release of energy from food. It is a catabolic reaction and each step is controlled by enzymes.
Parts of the mitochondria:

* Outer membrane
* Inner membrane
* Lumen
* Crista(e)
* Loop of DNA
Two types of respiration:
ANAEROBIC (Short) | AEROBIC (Long) |
Controlled release of energy from food in the absence ofoxygen | Controlled release of energy from food in the presence of oxygen |
Partial breakdown of C-C bond (lactic acid: 3C, ethanol:2C) | Complete breakdown of C-C bond (glucose: C6H12O6) |
Few ATP made per glucose molecule: 2ATP | Lots of ATP made per glucose molecule: 38ATP |
By products made: lactic acid and ethanol: * Large * Difficult to excrete (stay in cells, can be toxic) | Byproducts made CO2 and water: * Small * Easy to excrete |
Reactions take place in citosol (Glycolysis only) | Reactions take place in citosol (Glycolysis) and in mitochondrion (Kreb’s cycle and Hydrogen transfer) |

ANAEROBIC RESPIRATION:

Glycolysis begins with a glucose molecule in the citosol which is gradually broken down by enzymes into two 3C pyruvic acids. The energy released issufficient to join 2 ADP and 2P together to make 2ATP. Four hydrogen atoms are released in the citosol. Glycolysis is always anaerobic: no oxygen involved or needed.
The two 3C pyruvic acids react with the four hydrogen atoms. Two lactic acids in muscle cells or two ethanol molecules and two carbon dioxide molecules in yeast cells are formed in the citosol.
Muscle cells (facultative anaerobes: have achoice between aerobic or anaerobic respiration)
In strenuous exercise, anaerobic respiration is involved.
* Cells need energy for movement
* Heart and lungs are not fit enough to pump more oxygen to muscle cells.
Lactic acids are made, stay in the citosol, cool down and made the muscle stiffness. Oxygen is repaid to muscle cells during warm down that helps the breakdown of lactic acidsquickly as possible.

AEROBIC RESPIRATION

Glycolysis begins with a glucose molecule in the citosol which is gradually broken down by enzymes into two 3C pyruvic acids. The energy released is sufficient to join 2 ATP and 2P together to make 2 ATP. Four hydrogens are released in the citosol. Glycolysis is always anaerobic: no oxygen involved or needed.
In aerobic conditions, the two pyruvicacids and the four hydrogen atoms enter the mitochondria. Each pyruvic acid is converted by an enzyme (present in the lumen of mitochondria) into 2C Acetyl-CO-A with the release of carbon dioxide and two hydrogen atoms.
The 2C Acetyl-CO-A joins the Kreb’s cycle combining with 4 hydrogen atoms from the previous cycle and form 6C citric acid, this 6C acid is broken down to 5C acid, releasing CO2 and2H, which in turn is broken down to 4C acid releasing CO2 and 6H. Kreb’s cycle takes place twice for each Glycolysis, resulting in the formation of 6CO2 and 20H.
The hydrogen atoms, 24 altogether, 4H from Glycolysis and 20 from Kreb’s cycle, are broken up into protons (H+) and electrons (e-). They pass through the electron transfer chain by carriers (on the Crista of mitochondria) to join withthe oxygen and form water. The fist career is NAD+. The 24 hydrogen atoms pass through the carriers, two at time, and in each transfer between carriers there is sufficient energy released to join ADP with P to form ATP.
2H generate 3 ATP. 24H generate 36 ATP during the hydrogen transfer. 38 ATP are produced by glucose molecule (2 in citosol and 36 in mitochondria)
C6H12O6 + 6O2 38 ATP + 6 H20 +6 CO2

TO PREPARE AND SHOW THE PRODUCTION OF ALCOHOL BY YEAST
* Yeast + glucose solution (made up with cooled boiling water to eliminate gases from the solution, as O2, forming aerobic conditions)
* Control: glucose solution only
* Water bath 30º in incubator overnight, is the optimum temperature for most enzymes
* Fermentation lock with bubbles of CO2 escaping
*...