CELLULAR RESPIRATION

Cellular respiration is the process that breaks the chemical bonds in food molecules and releases their _______________. It is the _______________ process to photosynthesis, releasing the energy that photosynthesis stored in glucose, into molecules of _______________.

The chemical equation for respiration is :

_________ + _________ --------> _________ + _________ + __________

Cellular respiration can be divided into two major phases, the _______________ phase and the _______________ phase.

Anaerobic respiration requires no _______________. The _______________ phase requires oxygen.

The anaerobic stage occurs first and consists of two parts, _______________and _______________.

GLYCOLYSIS

Glycolysis takes place in the _______________ of the cell. The glucose that diffuses into the cell is acted upon by enzymes and broken in half to form 2 molecules of _______________ and releases 4 hydrogen atoms to be combined with hydrogen acceptors. The reactions that break glucose into pyruvic acid (or pyruvate) are complex and require the use of _______________ of energy. However, 4 ATP's of energy are produced, for a net gain of _______________.

FERMENTATION

If no _______________ is available for further respiration, the pyruvic acid (pyruvate) is changed by a process called _______________. Fermentation does not produce any more energy but simply changes the pyruvic acid into other substances. Animal cells change pyruvic acid into _______________. The lack of enough oxygen during exercise causes some pyruvic acid to to converted to lactic acid. Lactic acid, and is what makes muscles _______________.

Plant cells change pyruvic acid into _______________ and _______________. This is what _______________ cells do to produce alcohol for brewing and carbon dioxide for making _______________.

AEROBIC RESPIRATION (also called Oxidative Respiration):
The second major phase of cellular respiration is called _______________ respiration. It requires oxygen and occurs mostly in the _______________. This is why the mitochondrion is called the "powerhouse of the cell". Aerobic respiration consists of two parts, the _______________Cycle and the _______________. During aerobic respiration pyruvic acid is broken down into _______________ and _______________.

The energy released during this process forms _______________ ATP's, not counting the 2 formed in glycolysis.

First, pyruvic acid is broken down into a 2-carbon acetyl group by removing a molecule of CO₂ and hydrogen from it. The acetyl group combines with coenzyme A to form a compound called _______________. The acetyl CoA diffuses into the mitochondrion where it becomes a part of _______________.

KREBS CYCLE:

The acetyl CoA tranfers the acetyl group to a 4-carbon molecule called oxalocetic acid to form a 6-carbon acid called _______________. Citric acid is broken down into a _______________ acid (alpha ketoglutaric acid) by releasing CO₂ and hydrogen. The 5-carbon acid is then broken down into the 4-carbon acid (_______________) by releasing another CO₂ molecule and more hydrogen. This 4-carbon acid then joins with _______________ to begin the cycle again.

The carbon dioxide diffuses from the cell into the blood, is carried to the _______________, and exhaled. The hydrogen atoms are trapped by _______________ and then go to the electron transport chain.

Only _______________ ATP'S of energy are produced during the Kreb's Cycle.

ELECTRON TRANSPORT CHAIN (also called Oxidative Phosphorylation)

The _______________ atoms that were trapped by NAD are passed to the electron transport chain where they form hydrogen ions and electrons. The electrons are passed from molecule to molecule as they were in _______________. During this process the positive _______________ and negative _______________ are separated from each other and form positive and negative poles on opposite sides of the mitochondrial membranes. As the protons and electrons flow through openings in the membranes they can be compared to _______________. This produces enough energy to form _______________ more ATP's. The electrons finally join with the hydrogen ions and oxygen atoms to form _______________. If no oxygen is present for this final step the hydrogen atoms stay bound to the hydrogen acceptors and no ATP's are produced