Energy
and
Cellular Respiration
All organisms need energy
to maintain homeostasis.
The main energy source of cells is a molecule called ATP.
Ultimately almost all energy comes from the Sun!
Energy
ATP = Adenosine Triphosphate
The chemical bond attaching the 3rd phosphate is unstable and has the most energy.
ADP stands for Adenosine Diphosphate
When the 3rd Phosphate is broken off of ATP energy is released and it becomes ADP.
The Phosphate is removed by a process called hydrolysis.
Food provides you with energy but not directly. First foods are broken down by your digestive system into smaller molecules such as glucose.
Cellular respiration is a process by which chemical energy from sugars and other carbon-based molecules (Such as G3P) are released to make ATP when oxygen is present.
Cellular respiration takes place in the mitochondria.
Cellular respiration is an aerobic process, which means that it needs oxygen to take place.
Mitochondria make most of the cell’s ATP, which is why they are known as the “powerhouses” of the cell.
The formula for cellular respiration is:
C6H12O6 + 6O2 6CO2 + 6H2O + Energy
Glucose
Oxygen
Carbon
Dioxide
Water
ATP
Cellular Respiration
Cellular Respiration takes place in four different processes:
Oxidative Phosphorylation
Cellular Respiration
There are two kinds of respiration:
Anaerobic Respiration
Aerobic Respiration
28
Glycolysis
Glyco = Sugar
Lysis = To Split
Glycolysis must take place before cellular respiration can happen.
Glycolysis takes place in the cytoplasm of the cell and is an anaerobic process, meaning it does not require oxygen to take place.
Glucose (C6H12O6) is split into 2 molecules of Pyruvate (C3H6O3).
Glycolysis uses 2 ATP to get started. After glucose is split, 4 ATP are produced. Thus, a net of 2 ATP are produced.
These 2 molecules of C3H6O3 are called Pyruvate molecules.
The process of glycolysis uses enzymes, a lot of different enzymes.
Glycolysis (cont.)
NAD+ and NADH are what we call Hydrogen (or Proton) and energy or electron carriers.
Glycolysis also produces 2 NADH molecules.
Glycolysis (cont.)
Glycolysis (cont.)
Molecules needed
for Glycolysis
Molecules produced
by Glycolysis
1 Glucose
2 ATP
4 ATP (or net of 2 ATP)
2 Pyruvate
2 NADH
The 2 Pyruvate and 2 NADH produced will move on to the next step, but that step is determined by whether oxygen is available.
If Oxygen is not available
If Oxygen is available
Moves on to Fermentation
Moves on to Cellular Respiration
AFTER GLYCOLYSIS – THEN WHERE?
Fermentation
Fermentation is an anaerobic process that happens in the cytoplasm of the cell.
Fermentation does not make ATP itself but removes electrons from the NADH molecules and recycles the NAD+ molecules for glycolysis. Without the NAD+ to pick up high-energy electrons from the splitting of glucose, glycolysis would stop.
Prokaryotes (bacteria) make ethyl alcohol and carbon dioxide (CO2).
Eukaryotes (Humans) make Lactic Acid.
Fermentation (cont.)
Molecules needed for Fermentation
Molecules produced
by Fermentation
Fermentation (cont.)
28
Link Reaction
If oxygen is present after Glycolysis the products will enter the Link Reaction.
In Prokaryotes – Happens in the cytoplasm
In Eukaryotes – Happens in the interior space
of the mitochondria called the matrix.
Link Reaction (cont.)
In the link reaction a pyruvate molecule is oxidized, which means a carbon is removed from the pyruvate to bind with two oxygen atoms to form a molecule of carbon dioxide (CO2).
The carbon dioxide is released as a waste product when you breathe out.
Link Reaction (cont.)
The two remaining carbon atoms from the breakdown of the pyruvate binds to Coenzyme A, to form acetyl CoA.
Molecules needed for the Link Rx
Molecules produced
by Link Rx
Glycolysis makes 2 Pyruvate, so the numbers above are doubled.
The acetyl CoA now enters the Krebs cycle and binds to a 4-carbon molecule to form Citric acid.
Krebs Cycle (Citric Acid Cycle)
The Krebs cycle is an aerobic process which takes place in the matrix of the mitochondria.
Acetyl CoA enters the Krebs Cycle to bind to a 4-carbon molecule to form Citric Acid.
Since this is the first product of the Krebs cycle, it is also known as the Citric Acid cycle.
Krebs Cycle (Citric Acid Cycle)
1 Pyruvate produces:
2 CO2 (Waste product)
1 ATP molecule
1 FADH2 (Goes to ETC)
3 NADH (Goes to ETC)
Krebs Cycle (Citric Acid Cycle)
Remember Glycolysis produces 2 pyruvates, so double the number above to obtain the totals from 1 glucose molecule.
Krebs Cycle (Citric Acid Cycle)
The Krebs cycle’s purpose is to produce molecules that carry high energy electrons to the second part of cellular respiration (Electron Transport Chain – ETC).
These molecules are the NADH and FADH2.
Electron Transport Chain (ETC)
The ETC takes place in and across the inner membrane of the mitochondria.
The NADH and FADH2 provide electrons and energy to pump protons (H+ ions) across the inner membrane of the mitochondria.
Electron Transport Chain (ETC)
The high concentration of H+ ions will diffuse through the membrane protein called ATP Synthase.
The flow of H+ ions through the ATP Synthase will “turn the turbine” and create energy.
The energy created in the ATP Synthase is stored by adding another phosphate to ADP molecules, which creates ATP molecules needed by cells.
Electron Transport Chain (ETC)
Electron Transport Chain (ETC)
The H+ ions that flow through the ATP Synthase can then combine with the oxygen to form molecules of water.
How many water molecules are formed for every 1 glucose molecule broken down?
6 H2O
Electron Transport Chain (ETC)
Each NADH has enough energy to produce 2.5 ATP.
Each FADH2 has enough energy to produce 1.5 ATP.
The Hydrogen from the NADH and FADH2 will combine with oxygen at the end of the chain to form 6 water molecules.
Total ATP production for Cellular Respiration
2 net ATP produced in glycolysis
2 ATP produced in the Krebs cycle
2 FADH2 from Krebs cycle
10 NADH from Glycolysis, Link Rx, and Krebs cycle
2 FADH2 X 1.5 = 3 ATP
10 NADH X 2.5 = 25 ATP
2 ATP
3 ATP
2 ATP
25 ATP
Total ATP =
32 ATP
C6H12O6
6O2
6CO2
6 H2O
ATP (32)
Glycolysis
ETC
ETC (28)
ETC
Glycolysis (2)
Krebs Cycle (4 CO2)
Link Reaction (2 CO2)
Krebs Cycle (2)
6 CO2
Cellular Respiration Equation
Summary of products from Cellular Respiration
- Glycolysis makes:
- Krebs Cycle makes (2 rounds – 1 for each pyruvate):
- Electron Transport Chain (ETC) makes:
- Link Reaction (Link Rx) makes (2 rounds – 1 for each pyruvate):
Objective 3: Explain how matter and energy flow through different organizational levels of living things, and how chemical elements are recombined in different ways to form different products.
What are the 4 main categories of macromolecules in the body of living organisms?
Carbohydrates
Lipids
Proteins
Nucleic Acids
What elements do these macro-molecules have in common?
Carbohydrate review
Function: Short-term energy
Monomer: Monosaccharide or a single ringed sugar such as glucose
Polymer: Polysaccharide (Ex. Starches or glycogen)
Lipid Review
Function: Energy storage and cushioning
Smaller components: Glycerol and Fatty Acid Tails
Examples: Saturated and unsaturated fats (Ex. Butter, animal fat, and bacon grease)
Protein Review
Function: Forms bones and muscle, controls cell processes, and serves as enzymes
Monomers: Amino acids
Polymers: Proteins (Ex. Meat and eggs)
Nucleic Acid Review
Function: To store and transmit genetic information
Monomer: Nucleotide
Polymer: Nucleic acids (Ex. DNA and RNA)
What is the Carbon Cycle?
It is where carbon dioxide (CO2) is recycled into living tissue by photosynthesis and its return to the atmosphere through respiration, the decay of dead organisms, and the burning of fossil fuels.
A series of processes by which carbon compounds are recycled in the environment.
Remember, carbon is in everything!
Read Pages 405-406
Areas that store carbon over long periods of time are known as carbon sinks.
2 Major reservoirs of carbon dioxide are the atmosphere and the ocean
Where is most carbon found?
What two processes help cycle carbon and oxygen through ecosystems?
Photosynthesis and
Cellular Respiration
How does carbon get into the soil?
Defecation (animal waste) and decomposing plants and animals
If things don’t decompose, they can be turned into fossil fuels over millions of years.
What kind of human activities can add carbon dioxide to the atmosphere?
Burning of fossil fuels,
forest fires, and
cellular respiration