Download Cellular Respiration Notes

Cellular Respiration Notes
Name: ______________________________
1. Food serves as a source of _________________.
2. Cells don’t actually “burn” glucose; they gradually release the ___________ from glucose and other food
compounds.
3. The process of releasing energy from food begins with a pathway called _______________.
4. Glycolysis takes place in the ______________ of a cell and only releases a small amount of ___________.
5. If __________ is present, glycolysis leads to oxidative respiration, which includes two other pathways that release
a great deal of energy.
6. Both plant and animal cells carry out these final two pathways of cellular respiration in organelles called
______________. One of these organelles is called a ________________.
7. If oxygen is present, glycolysis is followed by the ___________ cycle and the ________________
_______________ chain.
8. Glycolysis, Kreb’s cycle, and electron transport chain make up a process called _____________________.
9. Cellular respiration is a process that releases _______________ by breaking down food molecules in the
presence of ________________.
10. Write the balanced equation for cellular respiration below:
11. The products of cellular respiration are _________________ and _________________. The water is released in
your ______________ and the ________________ when you exhale.
12. The first set of reactions in cellular respiration is _____________________-meaning breaking glucose.
13. Remember that there is lots of energy stored in bonds of glucose that came from the sun. Draw the molecular
structure of glucose below.
14. We are going to concentrate on the electrons in the bonds of glucose between the C-H. The energy from the
electrons will be released to make ___________.
15. There are lots of electrons “living” in the bonds of a glucose molecule that is then bonded to hundreds of other
glucose molecules to make a polysaccharide that many plants build to store their excess glucose called
______________.
16. Let’s think about where that glucose comes from in our bodies. We eat something like a potato (starch), break it
down using enzymes during digestion into ______________ monomers, then absorb those monomers through
the lining of our intestines into our bloodstream. The blood carried that glucose molecule to the cells and tissues
in our body. This glucose is the source of energy for that cell/tissue to do work (metabolism). So let’s say that the
glucose molecule has arrived at our brain to help provide energy for our brain cells in order to process these notes.
Part 2-Glycolysis
17. So the glucose molecule containing high energy electrons has diffused from your blood into one of your brain
cells. The process of _______________ is where the glucose molecule containing the electrons will be broken in
half, producing two molecules of _____________ _____________ which is a 3-carbon compound.
18. In order to get glycolysis going, your brain has to put forth a little energy. Therefore, at the beginning of
glycolysis, two ________ molecules are used up. Your cells will get a return on the investment because when
glycolysis is complete, _____ ATP molecules will be produced. Therefore, the net gain of ATP molecules from
glycolysis is _______.
19. Enzymes in the cytoplasm catalyze the process of breaking the glucose molecule into two pyruvic acids. When
the glucose is ripped apart, four high energy electrons are torn out of the molecule. Where do these electrons go?
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Floating around in the cytoplasm are molecules of NAD+. Remember NADP+ from photosynthesis? NAD+ is just
like it. Its full name is _________________________________________________.
Just like NADP+, the NAD+ is a high energy ______________ carrier. When some of the electrons get ripped
out of the glucose, the NAD+ picks them up.
After the NAD+ pick up electrons, the carrier is called __________________ (and it’s now “full”).
The point is that now NADH molecules are carrying some of the energy that was in the glucose molecule. Where
will these NADH molecules go now? They are going to the __________________________ chain in the
mitochondria in your brain.
The energy yield from glycolysis is small, but the process is fast. Another advantage of glycolysis is that it does
not require _____________. Therefore, even when cells do not have any oxygen, glycolysis can proceed and
supply the cell with energy in the form of _________ molecules.
However, the cells in a multicellular organism like you cannot rely on glycolysis alone to supply all the ATP it
needs. There are not that many NAD+ molecules floating around in the cytoplasm. Once all of the available
NAD+ molecules are “filled up” with high-energy electrons, the cell cannot keep glycolysis going; therefore, at
that point ________ production stops.
So let’s sum up the end results of glycolysis:
a. The glucose molecule has been broken apart into two 3-carbon molecules called _________________.
These molecules still contain about _____ of the chemical energy that was trapped in the original glucose
molecule. The energy is still trapped in the _____________ bonds of the pyruvic acid molecules, locked
in the high energy _____________.
b. Your cell has gained _______ net ATP molecules from glycolysis.
c. Two molecules of __________ are carrying the energy in the form of high energy electrons.
d. If there is no oxygen present in the cell glycolysis will be followed by a process called
________________. This process releases energy from __________ molecules in the absence of oxygen.
However, you are breathing just fine and your brain has plenty of oxygen so we’re going onto the next
part of this reaction and get ready for the Kreb’s cycle.
Part 2B-Getting ready for the Kreb’s Cycle
26. Recall that oxygen is very greedy for electrons; oxygen is extremely __________________________.
27. Oxygen is one of the world’s most powerful electron __________________.
28. The final steps of cellular respiration require ______________; because of this, these next pathways of cellular
respiration are said to be _______________.
29. The two ______________________ molecules from glycolysis still contain 90% of the energy that was in the
original glucose that you had eaten at lunch, found in the high energy _______________.
30. These two pyruvic acids are in the cytoplasm of your brain cell, but they move into the _________________.
Draw the cross section of the mitochondrion below making sure to label the inner membrane, outer membrane,
matrix, and cristae.
31. There is a transport protein built into the inner mitochondrial membrane that moves the pyruvic acid molecules
from the cytoplasm into the mitochondrial matrix. Each pyruvic acid will lose a carbon atom that eventually
becomes part of ____________ ____________ that you will eventually exhale.
32. Remember that pyruvic acid is a three carbon molecule and when it loses CO2, now becomes a two carbon
fragment called an ____________ __________. When the CO2 is ripped off, hydrogen electrons are ripped off
too. A carrier called _______ picks up the electrons, making a full carrier called ______________.
33. The NADH will carry their electrons to the ______________ _______________ chain.
34. The two carbon acetyl groups will then join to an enzyme complex called ____________________ now making
___________________.
35. The acetyl-coA is still carrying a great deal of energy in the form of the high energy _______________.
36. These two acetyl-coA molecules will now move onto the next stage of cellular respiration known as
___________________.
Part 3-Kreb’s Cycle
37. The acetyl-coA molecules combine with a 4-carbon compound already sitting in the Kreb’s cycle called
___________________________ (OAA). One acetyl-coA combines into the cycle at a time. The acetyl-coA still
has the energy from the high energy ______________.
38. As the acetyl-coA molecule bonds with the OAA, the coenzyme A detaches. This forms a six carbon molecule
called ____________________.
39. Now as this molecule “moves”, a carbon atom is ripped out of the citric acid. This carbon becomes part of a
__________ molecule that Harry exhales. When the CO2 is ripped out, electrons are also lost in the form of
hydrogens. The electrons with their energy are picked up by NAD+ making ____________. Where do you think
the NADH will carry these energy rich electrons? _________________________
40. Now this 5-carbon molecule will suffer the same fate again. A ________ is ripped out and electrons are lost in
the form of hydrogens. The CO2 is exhaled and the electrons are picked up by NAD+ making NADH. These
electrons will also go to the _________________________.
41. The cycle will continue around making one more electron carrier ________ and one molecule of an energy
storage compound called _______________ for each turn of the cycle.
42. The remaining 4-carbon compound will be rearranged some more by ripping off electrons. But these electrons are
picked up by __________________________ better known as FAD. The FADH2 are now carrying the electrons
that were ripped off and it takes them to the ______________ ____________ chain.
43. The 4-carbon compound _________ will be left at the end of one turn of the cycle and we will repeat the cycle
one more time. The coA will allow the second acetyl group to enter the cycle and combine with _______. This
makes more CO2, more electron carriers ____________ and ____________, and one more ___________.
Let’s Review What We Have…..
44. The Kreb’s cycle takes place in the _________ of the _________________.
45. For each turn of the Kreb’s cycle, we make _____ molecules of ATP, _____ molecules of NADH (carrying high
energy electrons), and _____ molecule of FADH2 (carrying high energy electrons)
46. Remember there are two molecules of acetyl-coA for every one molecule of glucose. So the above numbers get
multiplied by two to get the totals from the Kreb’s cycle for every one molecule of glucose.
47. The waste product of the Kreb’s cycle is _________ which you are exhaling.
Part 4-Electron Transport Chain
48. Remember that the high energy electrons are now being carried by high energy electron carriers called _________
and ______________.
49. NADH and FADH2 carry these high energy electrons to the _____________ ______________ chain.
50. The electron transport chain uses the high energy _____________ to convert ADP + P into __________.
51. To understand this process, we are going to sketch a portion of the mitochondrial membrane. Be sure to label
properly. There are actually nine proteins carriers embedded in the membrane but we are only going to
concentrate on five. It should look familiar.
52. Our little high energy electrons are carried to the electron transport chain carrier proteins by NADH and FADHs.
There the high energy electrons are passed from one carrier protein to another and so on and their energy is taken
from them. How is their energy used? It is used to transport ____ ions (also called protons) from the matrix of
the mitochondrion across the inner membrane, into the _________________ space.
53. What is the point of all of these H+ building up in the intermembrane space? The point is that this space will
become ______________ charged. The other side of the membrane, from which the H+ ions have been taken,
becomes ________________ charged.
54. How does your cell use the charge differences that build up as a result of the electron transport? All of these H+
ions crowded together in the intermembrane space results in a situation where the H+ ions really want to get
away from each other. The only way for the H+ ions to escape is to flow through the channels of _____________
______________ molecules.
55. As the hydrogen ions flow through the channels of the ATP synthase, the ATP synthase will begin to spin. Each
time the ATP synthase spins, it “grabs” a low-energy _________ molecule and attaches a _______________,
forming a high-energy ATP.
56. On average, each pair of high energy electrons that moves down the electron transport chain provides enough
energy to convert ________ ADP into ________ ATP molecules. This is an extremely good thing for you since
your brain needs lots of ATP.
57. The high energy electrons have been passed down the electron transport chain from left to right, losing their
energy. They will eventually be grabbed by the last acceptor on the chain _____________. Oxygen is very
greedy for electrons; it is very ____________________. Since you have been breathing just fine, there is plenty
of oxygen molecules available.
58. Oxygen is waiting at the end of the chain for the electrons to arrive. An enzyme combines the electrons from the
electron transport chain with hydrogen ions and the oxygen to make _________________. The water will end up
being excreted when you _____________.
59. The oxygen serves are the final _______________ __________________. If the oxygen was not present in the
cell, neither the Kreb’s cycle nor electron transport chain would function and the cell will not make enough
_________ to survive.
The Final Summary
For each molecule of glucose,
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Glycolysis produces two molecules of ____________.
The Kreb’s cycle and electron transport chain produce _______ molecules of ATP.
The waste products are ____________ and _____________ ________________.
In making a grand total of _________ ATP, cellular respiration captures about __________ % of the total energy
of glucose. What happens to the remaining 62% of the energy? This energy is released as __________.
If at the end of glycolysis, oxygen is NOT available then the cell will go through fermentation. Refer to the end of
part 2 in your note packet.
Glycolysis
Alcohol Fermentation
Lactic Acid Fermentation