Download Chapter 9 Cellular Respiration.notebook

Chapter 9 Cellular Respiration.notebook
February 22, 2016
Chapter 9 Cellular Respiration
Key Concepts
What is cellular respiration?
What happens during the process of glycolysis?
What are the two main types of fermentation?
How are chemical energy and food related?
we get chemical energy from the food we eat
food serves as a source of energy
How much energy is actually in food?
from one gram sugar (glucose C6H12O6) when burned in the presence of O2, releases 3811 calories of heat energy "burning calories" ­ release energy from glucose and other food compounds
Calorie
amount of energy needed to raise the temperature of 1 gram
of water 1 degree Celsius
a unit of energy
food labels "C" ­ are actually a kilocalorie 250 cal candy bar = 250,000 calories
to gain 1 lb of fat = 3500 extra calories above your needs
Cellular Respiration
process that releases energy by breaking down glucose and other food molecules in the PRESENCE of oxygen
occurs in the cytoplasm and the mitochondria
Equation
6O2 + C6H12O6 6CO2 + 6H2O + Energy
Three stages to cellular respiration:
Glycolysis, Krebs Cycle, Electron Transport
Each of the three stages of cellular respiration captures
some of the chemical energy available in food and uses it to produce ATP (the cell's basic energy source)
1. Glycolysis
"breaking glucose"
occurs in the cytoplasm
breaks down 1 molecule of glucose in half, producing 2 molecules of pyruvic acid, a 3 ­ carbon compound
Where does it show energy being used?
In the beginning to start glycolysis, 2 molecules of ATP are used creating 2 ADP.
When glycolysis is complete, 4 ATP molecules have been produced which results in a net gain of 2 ATP.
In glycolysis, high­energy electrons, are passed to an electron carrier called NAD+ to create a molecule of NADH.
NADH will hold these electrons until it can be transferred to another molecule
The process of glycolysis is so fast that cells can produce 1000's of ATP in a few milliseconds.
We will be discussing the other two stages of Cellular Respiration
in the next section
Glycolisis occurs in a different manner when there is no O2.
Anaerobic "not in air"
rxn that can occur without oxygen
http://www.ck12.org/biology/Fermentation/enrichment/Fermentation/?referrer=concept_details&conceptLevel=at+grade&conceptSource=ck12
Fermentation
releases energy from food molecules by producing ATP in the absence of oxygen
During fermentation, cells convert NADH to NAD+ by passing h­e electrons back to pyruvic acid so glycolysis can continue to happen to produce ATP.
Two types:
Alcoholic Fermentation
produces alcohol and CO2 as waste products
produces NAD+ as an electron carrier
Equation
pyruvic acid + NADH
alcohol + CO2 + NAD+
Used by yeast and a few microorganisms
When the yeast in the bread dough runs out of O2, it begins to ferment, which produce gas bubbles = CO2, alcohol is evaporated as something is baked
Lactic Acid Fermentation
pyruvic acid accumulates and due to glycolysis it produces lactic acid and renews NAD+
NAD+ needed so glycolysis can continue
Equation
pyruvic acid + NADH
lactic acid + NAD+
When your muscles use up the oxygen in your muscles, your
body can not produce enough ATP that is needed. That is why you breathe harder when you are working out. Your body is trying to keep up with the supply of oxygen that is needed. Your body now produces ATP through lactic acid fermentation. The product of latic acid fermentation is ATP and latic acid which caused the pain in your muscles. You may feel this pain for only a few seconds or for a few days. The pain goes away when the oxygen is replenished.
Why is lactic acid fermentation considered anaerobic and glycolysis is not?
Lactic acid occurs without oxygen while glycolysis can occur with oxygen.
Dec 22­8:53 AM
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Chapter 9 Cellular Respiration.notebook
February 22, 2016
9­2 The Krebs Cycle and Electron Transport
Key Concepts
What happens during the Krebs cycle?
How are high­energy electrons used by the electron transport chain?
https://www.youtube.com/watch?v=F6vQKrRjQcQ
Anaerobic = no oxygen
Aerobic = oxygen
The Krebs Cycle
Most of energy (about 90%) from the glucose is unused and locked into the h­e electrons of pyruvic acid.
To extract this energy the cell uses O2 as a electron acceptor.
Oxygen is required for the final steps of cellular respiration.
Citric acid is the first compound produced in the Krebs Cycle,
so it is also known as the Citric Acid Cycle.
Summary:
In the presence of oxygen, pyruvic acid produced in
glycolysis is passed to the second stage of cellular
respiration, the Krebs Cycle.
Pyruvic acid is broken down into carbon dioxide in a series of energy­extracting reactions. Krebs Cycle occurs in mitochondrial matrix.
Steps in the Krebs Cycle
1. Pyruvic acid from glycolsis enters the mitochondrion.
2. One Carbon from pyruvic acid becomes part of the molecule CO2, which will be released into the air later.
3. The other 2 carbon atoms are used to create a compound called ­ coenzyme A.
4. Coenzyme A joins a 2 carbon molecule to form acetyl­CoA. 5. The actyl group adds 2 carbon to a 4 carbon molecule which produces a 6 carbon molecule called citric acid.
6. Now, CO2 is released. 7. Electrons are added changing NAD+ to NADH.
8. Citric acid is broken down into a 5­carbon compound. 9. Once again C is removed to form CO2 and it is released.
10. Electrons join with NAD+ and FAD.
11. 1 molecule of ATP is formed.
12. 5 different spots 2 h­e electrons are accepted by h­e carriers changing NAD+ to NADH and FAD to FADH2.
The Krebs Cycle produces all of the CO2 that is exhaled from your breathing. All of the electrons are used to create huge amounts of ATP.
Electron Transport
The third and final stage of cellular respiration, the electron
uses h­e electrons from the Krebs cycle to convert ADP to ATP.
This takes place in the inner membrane of the mitochondrion.
H­e electrons are passed from NADH and FADH2 to the electron
transport chain from one carrier protein to the next. At the end of chain is an enzyme that combines electrons with
hydrogen ions and oxygen to form H2O which is a waste
product.
The enzyme ATP synthase in the membrane turns ADP into ATP.
Glycolysis produces just 2 ATP molecules per molecule of glucose in the presence of O2.
Energy is used to import the NADHs from glycolysis from the
cytoplasm into the mitochondrion.
Total ATP created through 3 stages of cellular respiration = 36
Figure 9­8 shows production process of ATP totals.
Jan 6­8:57 AM
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