Download Metabolism of fats and proteins

Metabolism
• Metabolism =
• Energy released during catabolic metabolism goes to:
• How is metabolism regulated?
Important in Metabolic Pathways
• Oxidation/Reduction reactions
• Substrate-level phosphorylations
• Oxidative phosphorylation
• Decarboxylations
• Coupled reactions
Oxidation/Reduction
NAD+
Glyceraldehyde 3-phosphate
NADH + H+
3-phosphoglycerate
Pi
Figure 4-5
Substrate-level phosphorylation
Glycolysis
(glyco = sugar; lysis = to break down)
Where do reactions of glycolysis occur in
the cell?
Where does the glucose (or other sugar)
come from?
Do these reactions need oxygen to
generate energy?
What is the end-product of glycolysis?
Figure 4-13
Test Your Knowledge:
• Put a
next to any oxidation/reduction
reaction
• Put a
next to any substrate-level
phosphorylation reaction
• Which reactions do you think have a DG
that is negative (exergonic)? Label them
with a
• Which reactions do you think have a DG
that is positive (endergonic)? Label them
with a
• How many ATP are made by the breakdown
of one glucose to two pyruvate molecules?
• How many ATP are utilized to break down
one glucose molecule into two pyruvate
molecules?
• What do you think happens to the two
pyruvate molecules generated?
• What else is made in glycolysis that might
eventually produce energy?
Figure 4-14
Energy Production in Glycolysis
Anaerobic vs. Aerobic Metabolism of Pyruvate
From glycolysis
From glycolysis
Figure 4-15
pyruvate
Figure 4-16
pyruvate
CO2
NAD+
NADH
• What types of
reactions do you
see occurring
frequently in this
cycle?
• Is oxygen required
in this cycle?
• How many ATP (or
other high energy
nucleotides) are
generated from one
pyruvate molecule?
Figure 4-16
High Energy Electrons carried by NADH and FADH2
Go to the Electron Transport Chain
TEST YOUR KNOWLEDGE
Where is the electron transport chain located?
What kind of biomolecules make up the electron transport chain?
What are the important functions of these biomolecules?
Is oxygen required for the electron transport chain to function? If so,
what is its role?
The electron transport chain is where oxidative phosphorylation occurs.
Where does the oxidation occur? How about the phosphorylation?
High-energy electrons are carried by NADH +H+ or FADH2
Electron transport proteins: two functions
ATP synthase
O2 and H2O
Figure 4-17
Test Your Knowledge:
Follow one glucose molecule through glycolysis, the Krebs cycle, and the
electron transport chain. Calculate:
1. How many NADH + H+ molecules are generated
2. How many FADH2 molecules are generated
3. How many ATPs are produced by substrate-level phosphorylation
4. How many ATPs are produced by oxidative phosphorylation
5. How many CO2 molecules are produced
6. How many O2 molecules are consumed (used)
7. How many H2O molecules are produced
Table 4-5
What about sugars besides glucose?
ADP
ATP
Fructose 6-phosphate
glycolysis
hexokinase
• galactose from milk
sugar (lactose) to
glucose-6-phosphate (1
ATP used)
• Mannose from
polysaccharrides and
glycoproteins to
fructose-6-phosphate
to glucose-6 phosphate
(1 ATP used)
Figure 4-18
Figure 4-19a
Figure 4-19b
Figure 4-19c
Carbon skeleton determines
the fate of the amino acid
glucogenic vs. ketogenic
Alanine
pyruvate
One NADH and one FADH2 made for
each 2-carbons cut from the chain in
b oxidation
Problem: If lipase cuts
off a 16-carbon fatty
acid from a triglyceride,
and it is metabolized
completely, how many
ATPs will be produced?
Figure 4-20
Figure 4-21
Figure 4-22 - Overview
Regulation of Metabolism
•
•
•
•
•
Major role is to regulate blood glucose
Regulation in response to ATP/ADP ratio
Regulation to adjust NAD+/NADH ratio
Regulates to reduce loss of energy
All regulation occurs through changes in
enzyme activity
Which enzymes in glycolysis
do you think might be
regulated? For what reason?
List at least 3 and the
reason why you think they
would need to be regulated.