Ch 9 Respiration and Fermentation

Chapter 9

Lesson 9.1 Intro to Respiration

*Organisms get the energy they need from food. A calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius. The Calorie (capitol C) that is used on food labels is a kilocalorie, or 1000 calories.

Cells can use all sorts of molecules for food, including fats, proteins, and carbohydrates.

1 gram of carb = 4 Calories
1 gram of protein = 4 Calories
1 gram of fat (lipid) = 9 Calories

But, unlike this burning marshmallow, cells don't release all the stored energy in food at once.

Cellular respiration is the process that releases energy from food in the presence of oxygen.

The chemical equation that represents cellular respiration is

6O2 + C6H12O6 ------->   6CO2 + 6H2O + Energy

or

Oxygen + Glucose ---------> Carbon Dioxide + Water + Energy

If cellular respiration took place in one step, however, all of the energy from glucose would be released at once, and most of it would be lost in the form of light and heat. 

STAGES OF CELLULAR RESPIRATION

Cellular respiration captures the energy from food in three main stages

Glycolysis - the splitting of glucose (extracts only 10% of energy in glucose) into 2 pyruvic acids

Krebs Cycle - a series of energy extracting reactions that breaks down pyruvic acid into CO2

Electron Transport Chain - uses all the energy captured in first two processes to generate ATP

Aerobic - requires Oxygen
Anaerobic - does not require Oxygen

Gycolysis - anaerobic, occurs in cytoplasm
Krebs Cycle - aerobic, occurs in mitochondria
ETC - aerobic, occurs in mitochondria

Photosynthesis removes carbon dioxide from the atmosphere, and cellular respiration puts it back.  Photosynthesis releases oxygen into the atmosphere, and cellular respiration uses that oxygen to release energy from food.

Photosynthesis and Cellular Respiration are opposite processes.





For 9.1 Powerpoint click here

https://docs.google.com/presentation/d/1VUHSuLo03bNmLdFQS0ZRnkPC_AeT17i5gRosOKaJJLY/edit?usp=sharing


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Lesson 9.2 The Process of Cellular Respiration

Food Burns!



Flour is so flammable that it has caused several explosions, including the one seen here at London's City Flour Mills in 1872. More recently, a sugar factory exploded along the Savannah river.
Glycolysis
**The benefits of glycolysis are that it happens very fast and does not require oxygen!**

To initiate glycolysis, an investment of 2 ATP (activation energy) must be made.

During Glycolysis, 1 molecule of glucose, a 6-carbon compound, is transformed into 2 molecules of Pyruvic Acid, a 3-carbon compound. Energy is released in the form of high energy electrons when the bonds are broken and is captured by the "energy police" NAD+ and carried away to the ETC.

In addition, 4 ATPs come from Glycolysis with a net yield of +2ATP

The products of Glycolysis, 2 Pyruvic Acids, can now move into the mitochondria and go through the 2nd process of respiration, the Krebs Cycle.

THE KREBS CYCLE

In the Krebs Cycle, which occurs in the matrix of the mitochondria, Pyruvic Acid is broken down to CO2 in a series of energy-extracting reactions.

These include:

Pyruvic Acid
to
Acetic Acid + C(exhaled as CO2)
to
Acetic Acid is attached to CoenzymeA
becoming
Acetyl-CoA
which bonds with a 4-Carbon cyclic molecule forming

Citric Acid

Citric Acid is broken to

a 5-Carbon molecule + CO2
then
a 4-Carbon molecule + CO2

**Each time bonds are broken, "Energy police" NAD+ and FAD swoop in and collect the high energy electrons lost and carry them away to the ETC!

In addition, 1 ATP comes from each turn of the Krebs Cycle. Each glucose molecule spins 2 Krebs cycles from it's 2 molecules of Pyruvic Acid. So, Krebs spits out 2 ATPS from each glucose!

As a result of Kreb's Cycle, each Pyruvic Acid (3 Carbons) is broken down releasing 3 CO2s into the air while the energy from these bonds was collected and sent to the ATP Factory, the Electron Transport Chain (ETC).

THE KREBS CYCLE

Similar to the ETC in photosynthesis, the ETC in respiration uses high energy electrons from glycolysis and the Krebs cycle to convert ADP into ATP.

The "energy police" (high energy electron carriers) NAD+ and FAD carry electrons loaded with energy to the ETC.

NAD+  + 2e- + H+   ------->   NADH
and
FAD + 2e- + 2H+  -------->  FADH2

The ETC occurs in the inner membrane of the mitochondria where transport proteins are embedded. NADH and FADH2 drop off their high energy electrons in the membrane where they move from protein to protein passing on their energy to them. The job of the transport proteins is to pump H+ ions across the membrane against their concentration gradient from low to high concentration (active transport). This causes an extreme concentration gradient with the high being in the Intermembrane Space (between the two membranes) and the low being in the matrix. As are the laws of nature, H+ will gladly diffuse (passive transport) from high to low concentration and does this through the good sport enzyme protein, ATP Synthase. When H+ ions fly through ATP Synthase trying to escape the crowd, this causes ATP Synthase to spin, and this energy is used to add P (phosphates) to ADP making ATPs.

As it turns out, after the electrons have given away all their energy, they are accepted by Oxygen, which joins with the Hydrogens dropped off by NADH and FADH2 forming Water molecules (H2O) which are exhaled with the CO2 released during the Krebs Cycle.

The ETC is an ATP Machine and spits out 32 ATPS for every Glucose molecule.

Together, Glycolysis, the Krebs cycle, and the ETC release about 36 molecules of ATP per molecule of Glucose!

Under aerobic conditions these pathways enable the cell to produce 18 times as much energy as can be generated by anaerobic glycolysis alone.

Our diets contain much more than glucose, of course, but that's no problem for the cell. 

Complex carbs are broken down to simple sugars like glucose. Lipids and proteins can be broken down into molecules that enter the Krebs cycle or glycolysis at one of several places.

36%

The 36 ATP molecules generated during respiration of one glucose represent only 36% of the total energy of glucose. What happens to the remaining 64%? It is released as heat, which is what keeps our bodies warm! 

Powerpoint 9.2 click here:

https://docs.google.com/presentation/d/1TSmwY6QK2q2hXsVynW7x9VwJK29SQvoyeBMKiwlJdNU/edit?usp=sharing

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Lesson 9.3 Fermentation

What if Oxygen is not around?

What happens when you hold your breath and dive under water, or use up oxygen more quickly than you can replace it?

Recall that glycolysis is an anaerobic process which can produce ATP quickly. But, when a cell generates large amts of AP from glycolysis, it runs into a problem.

In just a few seconds, all of the cell's available NAD+ molecules used to collect high energy electrons from Glycolysis will get used up if the ETC does not occur (an aerobic process). This will leave the cell with no available NAD+ an therefore, will shut down Glycolysis and production of ATPs.

In the absence of O2, fermentation, which takes place in the cytoplasm,  releases energy from food molecules producing ATP!

During fermentation, cells convert NADH to NAD+ by passing high energy electrons back to Pyruvic Acid.  This action concerts NADH back into the electron carrier NAD+, allowing glycolysis to produce a steady supply of ATP.

Fermentation can take two pathways:

Alcoholic Fermentation
and
Lactic Acid Fermentation

In Alcoholic Fermentation, which is carried out by yeasts and a few other microorganisms, the Pyruvic Acid accepts the high energy electrons from glycolysis and is broken down to ethyl alcohol and carbon dioxide while relieving NADH of it's electrons so that it becomes NAD+ again and recycles back through glycolysis, keeping it going.

In industry, yeast are used to make breads and alcohols

In Lactic Acid Fermentation, which is carried out by most other organisms, Pyruvic Acid accepts the high energy electrons from glycolysis and is converted to Lactic Acid, another 3 Carbon molecule, releasing the high energy electrons from NADH so that it becomes NAD+ again and recycles back through glycolysis, keeping it going.

During extreme exercise or lack of O2, Lactic Acid will build up in the cells building an "Oxygen Debt" which has to be paid back by heavy breathing in humans.

Lactic Acid Fermentation is used in industry to make several different foods including sour cream, yogurt, sauerkraut, buttermilk, pickles and cheese

Where does our body get the energy it needs for quick energy?

For short, quick bursts of energy, the body uses ATP already in muscles as well as ATP made by lactic acid fermentation. For exercise longer than about 90 seconds, cellular respiration is the only way to continue generating a supply of ATP.

1. 4-6 seconds worth from ATP already stored in the cells

2. About 90 seconds worth from Fermentation

3. From Cellular Respiration

After using Fermentation, heavy breathing must happen to "pay back" the Oxygen debt owed by using Fermentation. Cellular Respiration releases energy more slowly than Fermentation which is why even well-conditioned athletes have to pace themselves during a long race. 

Glycogen

Your body stores energy in muscle and other tissues in the form of glycogen. Glycogen is broken down to glucose. These stores are usually only enough to last for 15-20 minutes of activity. After that, your body begins to break down other stored molecules, including fats, for energy. 

Bears rely on the stores of fat to be broken down for energy while they are hibernating.

Powerpoint 9.3 click here:

https://docs.google.com/presentation/d/1rTcDKXVzqWIfEekpY4aPSDq63YYDmtk-hXoh70Q1m8s/edit?usp=sharing

Ch 8 Photosynthesis

Photosynthesis!

Even Spongebob likes it!

Homeostasis takes energy. Where does it come from?

Energy is the ability to do work.

Organisms are doing work all the time. Even when at rest, organisms are using energy for things such as transporting molecules across the cell membrane, building proteins, responses to chemical signals, and contracting muscles. The sodium-potassium pump is a protein pump commonly found in cell membranes. ATP keeps this pump working.

Energy can be found in many forms including light, sound, heat, and chemical. Living organisms use chemical fuel. One of the most widely used chemical used for energy in organisms is ATP, or adenosine triphosphate. ATP consists of adenine, a 5-carbon sugar called ribose, and three phosphate groups.

The energy used in ATP is found in the bonds between the phosphate groups.

Storing Energy

ADP (adenosine diphosphate) is a compound that looks almost like ATP, except that it has two phosphate groups instead of three.
Small amounts of energy are stored in the bonds which hold the phosphate molecules together. When cells have extra energy, phosphates are added to ADP to make ATP. When energy is needed, the third phosphate is broken off and energy is released and used by the cell.

This characteristic of ATP makes it exceptionally useful as a basic energy source for all cells. Most cells only have a small amount of ATP, enough to last for a few seconds of activity. ATP is a great molecule for transferring energy, but, it is not a good one for storing large amounts of energy over the long term. After ATP is used up, cells must turn to breaking down glucose molecule in the presence of oxygen (respiration). With foods like glucose, cells can regenerate ATP from ADP as needed.

Analogy
When a phosphate group is added to an ADP molecule, ATP is produced. ADP contains some energy, but not as much as ATP. In this way, ADP is like a partially charged battery that can be fully charged by the addition of a phosphate group.

Heterotrophs and Autotrophs

The energy for all organisms to live ultimately comes from the sun. Plants, algae, and some bacteria are able to use light energy from the sun to produce food.

Autotroph - organisms that make their own food from the sun's energy.

The process by which autotrophs use energy of sunlight to produce high-energy carbohydrates - sugars and starches - that can be used as food is known as photosynthesis.

Photosynthesis comes from the Greek words photo, meaning "light" and synthesis, meaning "putting together". 

In the process of photosynthesis, plants convert the energy of sunlight into chemical energy stored in the bonds of carbohydrates.

Organisms that obtain energy from food by consuming other living things are known as heterotrophs.

Some heterotrophs get food by eating plants, while others get their food by eating animals that eat plants.  Still others, like mushrooms, obtain food by absorbing nutrients from decomposing organisms in the environment.

For Powerpoint 8.1 click here!

Lesson 8.2

Energy from the sun travels to the Earth in the form of light. Our eyes perceive this as "white light" which is made up of the visible spectrum of colors with different wavelengths. Plants gather the suns energy with light-absorbing molecules called pigments. Photosynthetic organisms capture energy from sunlight with pigments call chlorophyll.

As shown here, the pigment chlorophyll absorbs energy from wavelengths of violet, blue, and some from orange and red while reflecting the green and yellow wavelenths. This reflection is what gives chlorophyll and the plants containing them their green color. 

Only certain organisms, called photo-autotrophs, can perform photosynthesis. These include plants, cyanobacteria, and blue green algae. They require the presence of chlorophyll, a specialized pigment that absorbs certain portions of the visible spectrum and can capture energy from sunlight. 

Plants

Blue Green Algae

Cyanobacteria

Photosynthesis uses carbon dioxide and water to assemble carbohydrate molecules and release oxygen as a waste product into the atmosphere. Eukaryotic autotrophs, such as plants and algae, have organelles called chloroplasts in which photosynthesis takes place, and starch accumulates. In prokaryotes, such as cyanobacteria, the process is less localized and occurs within folded membranes, extensions of the plasma membrane, and in the cytoplasm.

Photosynthesis is a multi-step process that requires sunlight, carbon dioxide (which is low in energy), and water as substrates (Figure 3). After the process is complete, it releases oxygen and produces glyceraldehyde-3-phosphate (GA3P), simple carbohydrate molecules (which are high in energy) that can subsequently be converted into glucose, sucrose, or any of dozens of other sugar molecules. These sugar molecules contain energy and the energized carbon that all living things need to survive.

To put it simply....

Although the equation looks simple, the many steps that take place during photosynthesis are actually quite complex. Before learning the details of how photo-autotrophs turn sunlight into food, it is important to become familiar with the structures involved.

In plants, photosynthesis generally takes place in the cells of the leaves inside an organelle called a chloroplast. Chloroplasts have a double membrane envelope (composed of an outer membrane and an inner membrane). Within the chloroplast are stacked, disc-shaped structures called thylakoids. Embedded in the thylakoid membrane is chlorophyll, a pigment (molecule that absorbs light) responsible for the initial interaction between light and plant material, and numerous proteins that make up the electron transport chain. The thylakoid membrane encloses an internal space called the thylakoid lumen. As shown in, a stack of thylakoids is called a granum, and the liquid-filled space surrounding the granum is called stroma.

Photosynthesis takes place in two sequential stages: the light-dependent reactions and the light independent-reactions.

LIGHT DEPENDENT REACTION: Energy from sunlight is absorbed by chlorophyll and that energy is converted into stored chemical energy. More specifically, energy from sunlight is captured in the bonds connection a Phosphate group to ADP while also exciting 2 electrons. These "high energy" electrons are then grabbed up by the carrier molecule NADP+ to be transported out of the thylakoid to be used in the light independent reaction. NADP+ also grabs a H+ ion from splitting a water molecule and carries it away also. The leftover O2 from the water molecule is released as a byproduct of photosynthesis.

LIGHT INDEPENDENT REACTION: The chemical energy harvested during the light-dependent reactions drive the assembly of sugar molecules from carbon dioxide in a cyclic process called the Calvin Cycle. Therefore, although the light-independent reactions do not use light as a reactant, they require the products of the light-dependent reactions to function. 

 The light-dependent reactions utilize certain molecules to temporarily store the energy. These energy carriers are NADP+ and ADP.  After the energy is released, the “empty” energy carriers return to the light-dependent reaction to obtain more energy. Similarly, an oven mitt (carrier) is used to carry a hot potato (2e- and H+) and drop it off on a plate so the mitt can be used again and again.

 Please see below for extra instruction, notecards and videos!!!!!

... and to have a little fun...

For Class Powerpoint 8.2 

Click Here!...https://docs.google.com/presentation/d/1X5x4ltbNgk9sQ2dffDhsdVt8at5Eo4UZdm6pyRJmtb8/edit?usp=sharing

Lesson 8.3

To view the 8.3 Powerpoint click the following link!

https://docs.google.com/presentation/d/1tYoVHqGazRoK9C01M2UFgel9PIxgQqeI_xvodNrtZz0/edit?usp=sharing

Photosynthesis: The "Light" and the "Dark" of it

Light Reaction:  Energy from sunlight is used to produce O2 and convert ADP and NADP+ to energy carriers ATP and NADPH.

Light Dependent: Photosystem II and Photosystem I - Photosystems are clusters of chlorophyll and proteins.

PSII

In PSII Light energy absorbed by PSII produces high energy electrons. Water molecules are split to replace those electrons, releasing H+ ions and oxygen.=« 

Electron Transport: High-energy electrons move down the electron transport chain, to PSI. Energy generated is used to pump H+ ions across the thylakoid membrane and into the thylakoid space.

PSII: Electrons are reenergized in PSI. A second electron transport chain then transfers these electrons to NADP+, production NADPH!

As the thylakoid space fills up with positively charged H+ ions, the inside of the thylakoid membrane becomes positively charged relative to the outside of the membrane. H+ ions pass back across the thylakoid membrane through ATP synthase. As the ions pass through, the ATP synthase molecule rotates and the energy produced is used to convert ADP to ATP.

THE DARK SIDE

ATP and NADPH now move on to the "Dark Reaction" called this because it is light independent. 

The Calvin Cycle

Named after Melvin Calvin who worked out the details of this remarkable cycle!

As 6 CO2 molecules from the atmosphere enter the Calvin cycle, they are combined with six 5-carbon molecules in the very first step of the cycle. This produces twelve 3-carbon compounds. 

This produces 12 3-carbon molecules

Then ATP and NADPH add Energy to the compounds!

Now, two of the high energy compounds are broken off to make a 6 carbon molecule of 

Glucose!! Yummy!!

The other ten 3-carbon molecules continue on through the cycle where they pick up some more E from ATP so that they can form bonds to make 5-carbon molecules again.

Factors Affecting Photosynthesis

The most important factors that affect photosynthesis are temperature, 

light intensity, 

and the availability of water! 

- Reactions of photosynthesis work best between 0 and 35 degrees C 

                         ... above or below that may affect enzymes, slowing down the rate of rxn

- High light intensity increases the rate of photosynthesis and vise versa

- A shortage of water can slow or stop photosynthesis since H20 is essential to the process

             .........Some plants like desert plants and conifers have waxy coatings to prevent water loss

The graph shows how the rate of photosynthesis changes in response to the light intensity

Extreme Conditions

Most plants under bright, hot conditions close their small openings in their leaves that normally admit CO2. While preserving water, this causes photosynthesis to slow or stop. 

C4 Plants:  forms 4 carbon molecules instead of 3 carbon molecules

.....this enables photosynthesis to keep working under intense light and high temps

while keeping their stoma closed and taking in very small amts of CO2

.... these plants include corn, sugar cane, and sorghum

Corn

Sugar Cane

CAM Plants: Adapted to dry climates have to minimize water loss. CAM plants do this by only admitting air into their leaves only at night. In the cool darkness, CO2 is combined with existing molecules to produce organic acids, trapping Carbon within the leaves.  Then, during the daytime, when leaf pores are sealed to prevent the loss of water, these compounds release CO2 into the Calvin Cycle. CAM stands for Crassulacean Acid Metabolism. 

CAM Plants include Pineapple Trees, Desert Cacti, and Ice Plants

ALL DONE!!!!

For Powerpoint 8.3 Click here!