KEY: Chapter 9 Study ?’s (part 2): Glycolysis and the Krebs Cycle
1) Complete the table below to summarize the first two stages of cellular respiration:
Name of stage:
Where does it occur?
Cytosol / Cytoplasm
Glycolysis
Matrix of mitochondria
Kreb’s
matrix of mitochondria
Summary description of events:
Glucose in  2 pyruvate out;
invest 2 ATP to get
4 ATP (net = +2 ATP through
substrate level phosphor.);
2NADH out
2 pyruvate  2 Acetyl Co-A in
link reaction; yields 2 NADH &
2 CO2
2 Acetyl Co-A enter Kreb’s
Cycle & join with oxaloacetate;
yields 6 NADH, 2 FADH2, 2
substrate level ATP, & 4 CO2
2) Create a chart or table in which you distinguish between: oxidative phosphorylation and substrate-level
phosphorylation. (Include: their differences in location, method of phosphorylation, in which stages they
occur, and relative amounts of energy produced)
TYPE OF
LOCATION
METHOD
WHEN
AMT. ENERGY
PHOSPHORYLATION
OCCUR
PRODUCED
SUBSTRATE LEVEL
Cytosol &
Enzyme transfers a
Glycolosis
Smaller amt.
PHOSPHORYL.
Mitochondrial
phosphate group from a & Krebs
matrix
substrate to ADP
OXIDATIVE
(inner membrane Powered by redox
ETC
Larger amt.
PHOSPHORYL.
of mitochondria) reactions
3a) Summarize the energy yield of glycolysis (per 1 molecule of glucose).
2 ATP
2 NADH
(2 pyruvate)
3b) Account for the 6 carbon atoms from the original molecule of glucose that entered glycolysis. (Where are
they at the end of glycolysis?)
Two 3-Carbon sugars (pyruvate)
3c) Does glycolysis require oxygen presence to occur?
NO
4a) Prior to the Krebs cycle, the 2 pyruvate molecules from glycolysis are converted to 2 molecules of acetyl
CoA. In the space below, SUMMARIZE the 3 steps of this reaction:
1.
Carboxyl group removed & given off as CO2
2.
Remaining 2-Carbon sugar fragment is oxidized to form acetate (extracted electrons are
transferred to NAD+ to become NADH
3.
Coenzyme-A is attached to the acetate to become Acetyl Co-A
4b) What is the energy storage molecule that is generated during this intermediate step?
5a) In the Krebs cycle, what molecule is given off as “exhaust?”
NADH
CO2
5b) For what reason is the Krebs cycle appropriately named a CYCLE?
Oxaloacetate attaches to acetate (after Coenzyme-A is removed) and then at the end, oxaloacetate is
reformed ready to go around the cycle again. (start & end with oxaloacetate)
5c) For each acetate molecule that enters the Krebs cycle, list the number and type of energy molecules that
are generated.
3 NADH
1 FADH2
1 ATP
(6 NADH)
(2 FADH2)
(2 ATP )
Total for 2