Cellular Respiration Unit 5

Question 1

What is the relationship between photosynthesis and cell respiration?

Answer 1

They are in a sense, reverse processes in terms of inputs and outputs, but do not have the exact same steps in reverse

Question 2

What is cellular respiration?

Answer 2

The oxidation of glucose (and other molecules) and the capture of energy in a form that is useful to the cell

net reaction of aerobic cellular respiration:
C6H12O6+ 6O2–> 6CO2+ 6H2O + energy (ATP)

Question 3

What are the four(4) processes of cellular respiration?

Answer 3

Glycolysis, Pyruvate oxidation, Citric acid cycle, & Oxidative phosphorylation (electron transport & chemosmosis

Question 4

What are other functions of cell respiration? (2)

Answer 4

Creates precursors in biosynthetic reactions, and heat (endotherms), waste for exotherms

Question 5

Where does glycolysis take place?

Answer 5

Cytosol

Question 6

What structure is of Bacterium is homologous with Eukaryotes?

Answer 6

Interior of bacterium, Cytosol

Question 7

Describe the process of glycolysis.

Answer 7

It begins the oxidation of glucose; it nets the cell 2ATP (usable energy) and 2NADH (carrier of high energy electrons that can do useful work later)

Question 8

What are the 3 steps in the oxidation of pyruvate?

Answer 8

1. Pyruvate arising from glycolysis is transported to the mitochondrial matrix and decarboxylated (CO2 removed)
2. The resulting 2-carbon acetyl fragment is attached to coenzyme A, a molecule that carries acetyl groups from one set of reactions to another
3. More NADH (reducing power) is formed by this reaction.

Question 9

What guides the pyruvate from the cytosol to the Mitochondria?

Answer 9

Transport proteins

Question 10

What are the four(4) products of the citric acid cycle (Krebs cycle)?

Answer 10

ATP
NADH (reducing power)
FADH2 (reducing power)
CO2 (waste)

Question 11

During one turn of the citric acid cycle (krebs) what is the ratio of Acetyl group to CO2

Answer 11

1:2 ratio

Question 12

What is a biochemical cycle? (citric acid)

Answer 12

A set of reactions in which the starting molecule is regenerated ex. Start w/ acetyl, end with acetyl. Constantly reoccurring molecules cyclic

Question 13

What are the two(2) types of biochemical cycles?

Answer 13

Cyclic (reoccurring molecules), & linear

Question 14

What is the last process in cell respiration?

Answer 14

Oxidative phosphorylation

Question 15

What occurs in oxidative phosphorylation?

Answer 15

Electron transport & ATP synthesis

Question 16

What are the five(5) steps of oxidative phosphorylation?

Answer 16

1. Reduced NADH and FADH2 pass their electrons to the electron transport chain in the inner mitochondrial membrane
2. The electrons lose energy as they move from electron carrier to electron carrier
3. Some of that energy is used to pump H+ions, against their electrochemical gradient, into the inter-membrane space between the inner and outer membrane of the mitochondrion.
4. The energy stored in the form of the H+gradient is used by ATP synthase to make ATP.
5. The terminal electron acceptor: O2

Question 17

Why is O2 so important in cell respiration?

Answer 17

Oxidation of glucose, but more specific the terminal electron acceptor of the electron transport chain within the inner mitochondrial membrane

Question 18

How can ATP synthesis be stopped? (3)

Answer 18

Suffocation- carrier would’t be able to receive anymore electrons (electron transport stops, pumping of protons stop, ATP synthesis)

Poisons- can block electron transport to O2 (similar to suffocation)

Uncoupler molecules- allow electron transport to continue, but dissipate the H+ gradient

Question 19

Is much ATP stored in cells?

Answer 19

No, not an energy storage molecule

Question 20

What is thermogenin?

Answer 20

An uncoupling protein that functions as a proton transporter and produces heat (important for when you’re cold) brown fat

Question 21

What is the function of fermentation?

Answer 21

It allows the NADH that is formed in glycolysis to dump its electrons and cycle back to glycolysis as NAD+, thus keeping glycolysis and its ATP production going

Question 22

What is fermentation?

Answer 22

Occurs when there is no oxygen; in this event, electron transport and the citric acid cycle cannot take place

Question 23

What are examples of organisms (2) that can get by via glycolysis from ATP?

Answer 23

Fungi, & yeast

Question 24

What is pyruvate converted to in fermentation?

Answer 24

It is converted to lactate or ethanol instead of acetyl-CoA.

Question 25

What steps in cellular respiration can you find proteins (amino acids)?

Answer 25

Pyruvate, Citric acid cycle, & acetyl-CoA.

Question 26

What steps in cellular respiration can you find fats (fatty acids)

Answer 26

Glycolysis (glycerol), Fatty acids (acetyl-CoA)

Question 27

What steps in cellular respiration can you find carbohydrates?

Answer 27

Glycolysis (glucose)

Question 28

What are the functions of the krebs cycle?

Answer 28

oxidizes acetate to CO2, making ATP, NADH and FADH2

in the process. It also makes precursors for many biosynthetic reactions.

Question 29

If you work or exercise so hard that your muscles use up all the oxygen available to them, what molecule will build up and why?

Answer 29

Lactate will build up because, in the absence of oxygen, pyruvate produced by glycolysis will be converted to lactate in a fermentation reaction

Question 30

What sort of phosphorylation produces ATP in glycolysis? the Krebs cycle? the inner mitochondrial membrane?

Answer 30

substrate level phosphorylation; substrate level phosphorylation; oxidative phosphorylation

Question 31

Why is glycolysis thought to be an ancient process?

Answer 31

All organisms do it; it does not require oxygen (there was little or no oxygen in the early earth’s atmosphere); and it occurs in the cytosol of eukaryotic cells, a compartment that is descended from the interior of bacterial cells, where their glycolysis occurs also.

Question 32

Why is cellular respiration more efficient than glycolysis/fermentation?

Answer 32

Respiration yields approximately 36-38 molecules of ATP per molecule of glucose. Glycolysis, followed by fermentation, yields only two molecules of ATP per molecule of glucose.

Question 33

How do uncouplers work? If you swallowed an uncoupling agent, what effects would you experience over the next few hours (assuming you lived)?

Answer 33

Uncouplers do not affect electron transport, but they ‘uncouple’ this process from ATP synthesis by providing H+ with an alternative route through the inner mitochondrial membrane, a route that does not power ATP synthesis. Taking an uncoupling agent such as dinitrophenol (DNP) would causes your cells to maintain a high level of respiration, because your cells would be continually short of ATP; this in turn would release heat, and you would sweat and appear flushed. In extreme cases you could experience heat stroke. Some people have died taking uncouplers as a weight-loss strategy.