SI Worksheet #10 (Chapter 9)

BY 123

Meeting 10/8/2015

Chapter 9:

  1. Write the overall reaction for cellular respiration.
  1. What is the literal meaning of glycolysis?

Sugar splitting

  1. Where in the cell does glycolysis take place?

In the cytosol

  1. What is the advantage of glycolysis taking place stepwise?

If energy is released all at once it cannot be harnessed. Organic molecules are broken down in a series of steps to harness all of the energy.

  1. How many ATP are used (changed to ADP) in the first half of glycolysis?

2

  1. How many ATP are made from ADP in the second half of glycolysis?

4

  1. What is the net gain of ATP in glycolysis?

2

  1. How many molecules of pyruvic acid are made from a single molecule of glucose?

2

  1. What molecule stores the high-energy electrons (and hydrogen) removed from glucose in glycolysis?

NADH

  1. Glucose Activation

During the first four steps of glycolysis, two phosphate groups are transferred to glucose via phosphorylation, where ATP is converted to ADP. The end product is fructose 1, 6-bisphosphate.

  1. Sugar Splitting

Fructose 1,6-bisphosphate gets split into two fragments, dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (G3P). DHAP then gets converted into G3P by the enzyme isomerase.

  1. Oxidation

Both molecules of G3P become oxidized using NAD+, which becomes NADH. This process releases energy which is used to attach phosphates to the sugars, making them 1,3-bisphosphoglycerate.

  1. Formation of ATP

During the last four steps of glycolysis, the phosphate groups of the molecules are transferred to ADPby the enzyme phosphoglycerate kinase creating ATP. This is done via the process of substrate-level-phosphorylation.

  1. The three metabolic stages of cellular respiration
  1. Glycolysis
  2. Citric Acid Cycle
  3. Electron Transport Chain and chemiosmosis: oxidative phosphorylation
  1. In which of the three stages is most of the cell’s ATP produced?Electron Transport Chain
  2. Where in the cell does the citric acid cycle take place?Mitochondria
  3. What must happen to pyruvate before entering the citric acid cycle? How does this process occur?It must be converted into Acetyl CoA. It occurs in 3 steps
  4. Pyruvates carbonyl group is given to CO2
  5. Remaining carbon oxidized forming acetate
  6. Coenzyme A attached
  7. Where does the oxaloacetate that Acetyl CoA combines with come from? What does this joining produce?It comes from the previous Citric Acid Cycle. Acetyl CoA + oxaloacetate = citrate
  8. What do the next 7 steps of the citric acid cycle do to citrate?

Decomposes citrate back to oxaloacetate. 1 ATP generated per pyruvate. We get 2 pyruvates from glycolysis so 2 ATP are produced.

  1. Fill in the table telling the energy rich molecules and amounts of each energy rich molecule produced in the citric acid cycle.

Energy Rich Molecule / Number produced
NADH / 8
FADH2 / 2
CO2 / 6
ATP / 2
  1. Where is the electron transport chain located in an eukaryotic organism? In a prokaryotic organism? Eukaryote: mitochondria Prokaryote: plasma membrane
  2. How does the structure of the mitochondria allow space for thousands of copies of the electron transport chain?Folding of the cristae increases surface area allowing space for thousands of copies of the electron transport chain
  3. What are most of the components of the electron transport chain? How do these components exist within the chain? Most components of the electron transport chain are proteins existing in multiprotein complexes tightly bound with non-protein prosthetic groups
  4. Electron carries alternate between reduced and oxidized states as they accept and donate electrons.
  1. As you move down the electron transport chain, each electron carrier becomes more electronegative with the most electronegative carrier being oxygen.
  2. Electrons are transferred from NADHto the first molecule in the electron transport chain in complex I.
  3. What are cytochromes?Prosthetic groups (heme group), that accept and donate electrons
  4. FADH2 adds electrons to complex II first.
  5. What is chemiosmosis?The movement of ions across a selectively permeable membrane, down their electrochemical gradient; relates to the generation of ATP by the movement of hydrogen ions across a membrane during cellular respiration.
  6. What is the structure of ATP synthase?

Part of ATP Synthase: catalytic knob, internal knob, rotor, stator

  1. What is the role of ATP synthase in chemiosmosis?

Serve as sites that allow protons to diffuse back across the membrane

  1. Fermentation and anaerobic respiration enables cells to produce ATP without the use of oxygen.
  2. Can organisms living in environments without oxygen have electron transport chains? If so, how? Yes, their final electron acceptor is something other than oxygen
  3. What are the two type of fermentation discussed in this chapter?
  1. Alcoholic Fermentation: pyruvate is converted to ethanol
  2. Co2 released from pyruvate  acetaldehyde
  3. Acetaldehyde reduced by NADH to ethanol
  4. Lactic Acid Fermentation: pyruvate reduced directly by NADH to form lactate (no CO2 produced)
  1. What is an obligate anaerobe?Cannot survive in oxygen
  2. What is a facultative anaerobe? Can make ATP and survive using fermentation or aerobic respiration in the presence of oxygen.