cellular respiration

Views:
 
Category: Education
     
 

Presentation Description

No description available.

Comments

Presentation Transcript

:

Alvero , Clarice Anne M Gutierrez, Shertoni A.

CELLULAR RESPIRATION:

CELLULAR RESPIRATION (AEROBIC & ANAEROBIC RESPIRATION)

TOPIC OUTLINE ::

TOPIC OUTLINE : Cellular Respiration Glycolysis Aerobic Respiration Oxidation of Pyruvic Acid Citric Acid Cycle Anaerobic respiration Alcoholic Fermentation Lactic Acid Fermentation

KEYWORDS::

KEYWORDS: Respiration ATP(Adenosine Triphosphate ) Glycolysis Aerobic respiration Pyruvate Krebs cycle Electron transport chain Anaerobic respiration Alcoholic respiration Lactic Acid Fermentation KEY PERSON: Sir Hans Krebs

DISCUSSION::

DISCUSSION: Cellular respiration It is where energy in food molecules is released and converted to a form that can be used by the cell, which is ATP. The term respiration is often used to mean breathing or simply “the process of inhaling .” For clarity, the term cellular respiration is used to refer specifically to a series of enzymatic reactions that can occur in the presence or absence of oxygen and make energy available to cell. Cellular respiration is to two types – aerobic and anaerobic respiration. Aerobic respiration is cellular respiration that occurs in the presence of oxygen while anaerobic respiration or fermentation is cellular respiration that occurs in the absence of oxygen.

Glycolysis:

Glycolysis It is the initial step in both aerobic and anaerobic respiration. It occurs in the cytoplasmic fluid in an anaerobic condition. It involves the breakdown of glucose, a six-carbon sugar, into two molecules of a three-carbon compound called pyruvate ( pyruvic acid). It is also results in a net energy yield of two ATP molecules per glucose molecules that enters this reaction. The energy carried by these ATP molecules accounts only for about 2% of the total chemical energy in glucose. The remaining energy remains in the chemical bonds of pyruvate that must be further broken down.

Glycolysis has two main phases- the preparatory phase or energy investment phase (steps 1-4) and the energy payoff phase (steps 5-9). It can be summarized as follows::

Glycolysis has two main phases- the preparatory phase or energy investment phase (steps 1-4) and the energy payoff phase (steps 5-9). It can be summarized as follows: Steps 1-3 – Glucose molecule is energized, using ATP. In this series of three chemical reactions, glucose is first phosphorylated to gulcose-6-phosphate (step1), which is rearranged to form fructose-6-phosphate (step2). Another phosphate group is added to form fructose 1,6-diphosphate (step3). The cell invests two molecules of ATP in steps 1 and 3 to energize one glucose molecule and form fructose, 1,6-biphosphate, which is unstable and reactive.

:

Step 4- Fructose 1,6-diphosphate is converted into two molecules of glyceraldehyde 3-phosphate (PGAL) . Since there are two molecules of PGAL produced, step 5-9 occur twice per glucose molecule.

:

Step 5-Reduction of PGAL produces NADH. This step is the first payoff step. PGAL donates a hydrogen atom and two electron to NAD ( nicotinamide adenine dinuclear ), reducing it to NADH.NADH, an electron carrier has a similar structure to NADH except that it has one less phosphate group attached to the ribose.

:

Step 6-9-ATP and pyruvic acids are produced. A sequence of four chemical reactions completes the breakdown of glucose into two molecules of pyruvic acid. For every molecule of the glucose ,four molecules of ATPs are formed in steps 6 and 9 . Since two molecules of ATP have been invested in the preparatory phase, a net gain of two ATP molecules per glucose molecules results from glycolysis .

:

The overall reaction can be expressed this way: Glucose + 2 NAD +pi+2 ADP +2 NADH+ATP 2H*+2H2O

Aerobic Respiration :

Aerobic Respiration - Is cellular respiration that occurs in that presence of oxygen.

Oxydation of Pyruvic Acid:

Oxydation of Pyruvic Acid Is occurs in the mitochondrial matrix. In the stage, each molecule of NAD is reduced to NADH. A carbon atom is also removed from pyruvic acid and release as CO2,forming a two-carbon molecule called acetyl group. This acetyl group finally combines with a compound derived from a B vitamin called coenzyme A, forming acetyl - CoA . The overall reactions can be summarized by the following equation : 2 pyruvic acid + 2NAD 2acetly group +2 NADH+ 2CO 2 2 acetyl group + 2CoA 2 acetyl- CoA

:

Energy is temporarily store in the NADH, which will later be used to convert ADP molecules to ATPs. The two acetyl- CoA molecules, on the other hand, will proceed to the third phase of aerobic respiration, that is the krebs cycle.

The Krebs Cycle or Citric Acid Cycle:

The Krebs Cycle or Citric Acid Cycle - The series of complex chemical react5ions which each acetyl- CoA molecule produced during the oxidation of pyruvic acid passes through. It is named after a German scientist, Sir Hans Krebs (1900-1981), who discovered and studied the workings of this cycle. This set of reactions is also referred to as the citric acid cycle. Like the oxidation of the pyruvate molecules, the krebs cycle also occurs in the mitochondrial matrix. The cycle begins as enzymes strip the CoA portion from the acetyl- CoA . Only the two-carbon acetyl part actually participates in the krebs cycle.

:

The acetyl group then combines with a four-carbon compound called oxaloacetic acid (already in the mitochondrion), to form a six-carbon compound called citric acid. The citric acid is then oxidized to form a five-carbon compound with the release of CO2. The five-carbon compound is oxidized to form a fou -carbon compound also release of CO2 . Finally, this four-carbon compound is converted through a series of reactions to oxaloacetic acid, which can again pick up another acetyl group, thus starting the cycle again. To summariz . The following are produced for every glucose molecule that goes through glycolysis and the krebs cycle: Four ATP molecules Ten molecules of NADH Two molecules Six molecules of carbon dioxide

Electron Transport Chain:

Electron Transport Chain - This process occurs in the inner membrane of the mitochondrion. It is similar to the transport of electrons in the thylakoids during photosynthesis. The four ATP molecules gained from glycolysis and krebs cycle represent just a small fraction of energy stored in a glucose molecule. An estimated 36 ATP molecules are gained from the entire process of aerobic respiration. - 3ATP/NADH and 2 ATP/FADH 2 3ATP/NADH (2 NADH generated via glycolysis ) it will produce 6 ATP.

Anaerobic respiration:

Anaerobic respiration - Is cellular respiration that occurs in the absence of oxygen.

Alcoholic fermentation :

Alcoholic fermentation In this respiration, the pyruvic acid produced via glycolysis is converteed to ethanol or ethyl alcohol, (C 2 H 5 OH). This process consists of two steps. Firstly, CO 2 is release from pyruvate , which is then converted to two-carbon compound called acetyl aldehyde . Secondly, acetyl aldehyde is reduced to ethyl alcohol by NADH. This regenerates the supply of NAD Needed for glycolysis . Alcoholic respiration in yeast is used in brewing and wine-making. 2 pyruvic acid + 2 NADH 2 acetaldehyde +2 CO 2 2 ethanol +2 NAD

Lactic Acid Fermentation :

Lactic Acid Fermentation During this fermentation the pyruvic acid is directly reduced to lactic acid by NADH without the release of CO2. this type of fermentation by certain bacteria and yeast is used in the dairy industry particularly in making cheese and yogurt. In the human skeletal muscle cells, ATP is produced by lactic acid fermentation. This occurs in the early stages of strenous exercise, when the rate of glycolysis is faster than the intake of oxygen. Under these conditions, the cells switch from aerobic respiration to fermentation. The accumulated lactic acid causes muscle fatigue and pain, but is gradually transpoted by the blood to the liver. Lactate is converted back to pyruvate by the liver cells. 2 pyruvic acid +2 NADH 2 lactic acid +2 NAD

SUMMARY ::

SUMMARY : Cellular respiration is the process of breaking down food (glucose)in order to release the energy from it in the form of ATP. There are two typesa of respiration – aerobic and anaerobic respiration or fermentation. Aerobic respiration occurs in the mitochondrial matrix in the presence of oxygen. The major events in this process are oxidation of pyruvic acid, krebs cycle, and the electron transport chain. It results in the net production of 36 ATP molecules per glucose molecule.

:

Anaerobic respiration or fermentation occurs in the absence of oxygen that converts pyruvic acid into ethyl alcohol (alcoholic fermentation) or lactic acid (lactic fermentation). It only produces only 2 ATP molecules per glucose molecule. Glycolysis is the process of breaking down glucose into pyruvic acid. It occurs in the cytosol and initiates both aerobic and anaerobic respiration.

EXERCISES::

EXERCISES: Which process produces the most number of ATP molecule oxidized? In this process, the Pyruvic acid is directly reduced to lactic acid by NADH without the release of CO 2 . This process is called _______. This is where the 4 ATP molecules gained from the glycolysis and krebs cycle that represent just a small fraction of energy are stored. Two molecules of a three-carbon compound is called______________.

:

It refers to a series of enzymatic reaction that can occur in the presence of oxygen and make energy available to cell. A carbon atom is also removed from the pyruvic acid and released as CO 2 forming a two carbon molecule called____________. He is a German scientist who discovered and studied the workings of krebs cycle. In ______,the pyruvic acid produced via glycolysis is converted to ethanol or ethyl alcohol(C 2 H 5 OH).

:

9 . What does ATP stands for? 10 . What are the two main phases of glycolysis ?

REFERENCES::

REFERENCES: Breaking through biology (pp.114-122) Wikipidea.com Merriam Webster Dictionary

authorStream Live Help