Download A2 Populations and Environment JLL The Biochemistry of R

A2 Populations and Environment
The Biochemistry of Respiration
JLL
Aerobic Respiration occurs in four stages, and in three different locations within the cell:
Stage
Location
1. GLYCOLYSIS: This involves the __________ of glucose to ___________, with a
net gain of __________ and _________________
Why is this an oxidation reaction?
Summary of Glycolysis:
GLYCOLYSIS IS THE OXIDATION OF GLUCOSE TO PYRUVATE WITH A NET GAIN
OF ATP AND REDUCED NAD
2. THE LINK REATION: The ____________ produced during glycolysis combines
with coenzyme A to produce______________.
At the start of the link reaction, pyruvate produced by the
process of glycolysis, leaves the cytoplasm and enters the
matrix of the mitochondria.
In the mitochondria, NAD oxidises the pyruvate (by the removal
of electrons) to a 2 carbon acetate molecule and CO2.
The acetate molecule is picked up by a carrier molecule called
COENZYME A, forming ACETYLCOENZYME A
Because a carbon atom has been removed from pyruvate in this process, and because the
pyruvate is oxidised, this reaction is called is called OXIDATIVE DECARBOXYLATION.
A2 Populations and Environment
Summary of the Link Reaction:
JLL
IN THE LINK REACTION, PYRUVATE COMBINES WITH COENZYME A TO PRODUCE
ACETYLCOENZYME A
Acetylcoenzyme A formed during the link reaction carries the 2 carbon compound into the
KREBS cycle where further oxidation begins.
3. The KREBS CYCLE (named after Hans Krebs)
This occurs in the _________ of the mitochondria.
The Krebs cycle is important because it produces the coenzymes which can be used to
make ATP in the final stage of anaerobic respiration; the Electron Transport Chain.
A2 Populations and Environment
JLL
1. At the start of Krebs cycle, _____________________ joins to a _____ carbon
acceptor molecule
2. A ____ carbon acid is formed
3. Oxidation-reduction reactions then occur, and electrons and hydrogen are
transferred to ______ to produce __________________
4. Carbon dioxide is removed to form a ______ carbon compound.
5. Another molecule of ________ is removed, and further oxidation- reduction
reactions occur as electrons and hydrogen are transferred to the coenzymes NAD
and FAD to produce reduced NAD and reduced FAD. THESE MOLECULES ARE
USED LATER IN THE ELECTRON TRANSPORT CHAIN) The energy released
during these oxidation-reduction reactions is used to form 2 ATP.
6. The 4 carbon acceptor molecule is ____________
POINTS TO NOTE ABOUT THE KREBS CYCLE!
A. For each glucose molecule, 2 acetylcoenzyme molecules enter the Krebs cycle
B. During the link reaction and Krebs cycle, all 3 carbon atoms have been removed
from pyruvate and are released as CO2
C. All the electrons removed from the 3 carbon atoms in the pyruvate have been
transferred to NAD or FAD to produce reduced NAD and reduced FAD.
In a series of oxidation-reduction reactions, the Krebs cycle generates reduced
coenzymes and ATP by substrate-level phosphorylation, and carbon dioxide is lost.
Activities:
1. Highlight in yellow all the molecules in the Krebs cycle that have been oxidised, highlight
in pink, all the molecules that have been reduced.
2. What happens to the reduced NAD and reduced FAD?
3. What is the chemical formula for glucose? Describe what has happened to each of
these atoms by the end of Krebs cycle.