Notes course ‘Essentials of Nutritional
Physiology’ (HAP32303)
Content
Notes week 1 2
Learning goals week 1 2
1.1 Basic concepts and processes metabolism 2
1.2 Glycolysis and mitochondrial ATP production 9
1.3 Assignments 24
1.4 Self-test 24
Notes week 2 25
Learning goals week 2 25
2.1 Carbohydrates and protein catabolism 25
2.2 Assignments 48
2.3 Self-test week 2 48
Notes week 3 49
Learning goals week 3 49
3.1 Fatty acid and triacylglycerol metabolism 49
3.2 Assignments 62
3.3 Self-test 63
1
‘Essentials of Nutritional Physiology’ (HAP32303)
,Notes week 1
Learning goals week 1
● Describe the process of glycolysis
● Explain the function of the TCA cycle and NADH shuttles
● Describe the process of oxidative phosphorylation
● Analyze the pathways of mitochondrial ATP production
● Calculate the energy derived from glucose
1.1 Basic concepts and processes metabolism
1.1a Introduction into metabolism reading
Define a reaction pathway
Key points to appreciate are:
● Reactions involve molecular conversion of
substrates into products
● In living organisms, reactions never occur in
isolation. The product of one reaction goes
on to become a substrate in another
subsequent reaction
● A set of consecutive reactions is described
as a ‘pathway’. Components of the pathway
are known as ‘intermediates’.
Source: Appleton, A. et al (2015) Crash Course: Metabolism and
Nutrition Updated Edition: Elsevier eBook on VitalSource (4th
ed).
Understand the definitions of catabolic and anabolic pathways
Anabolic pathways generate complex molecules from smaller substrates, whilst catabolic
pathways break down complex molecules into smaller products. Anabolic pathways
consume energy. They are synthetic, energy-demanding processes. The suffix of a synthetic
pathway is ‘-genesis,’ e.g. glycogenogenesis (glycogen synthesis). Anabolism is analogous
to ‘construction’; construction requires raw materials and energy. Catabolic pathways
release intrinsic chemical energy from biological molecules. They involve sequential
molecular degradation. Catabolic pathways are suffixed with ‘-lysis’, e.g. glycolysis (glucose
degradation).
2
‘Essentials of Nutritional Physiology’ (HAP32303)
,Source: Appleton, A. et al (2015) Crash Course: Metabolism and Nutrition Updated Edition: Elsevier eBook on
VitalSource (4th ed).
Appreciate the vital role of enzymes in metabolism
Enzymes are specialized, highly specific proteins. Each enzyme mediates a particular
biochemical reaction by functioning as a biological catalyst. Enzymes operate by temporarily
binding to their substrate molecule, imposing molecular modification and finally releasing the
altered molecule (the reaction product).
3
‘Essentials of Nutritional Physiology’ (HAP32303)
, Source: Appleton, A. et al (2015) Crash Course: Metabolism and Nutrition Updated Edition: Elsevier eBook on
VitalSource (4th ed).
Understand the basic mechanisms of enzyme regulation
There are three main control mechanisms exploited by cells to regulate metabolic pathways
in an integrated and sensitive fashion. These include substrate availability, enzymatic
modification and hormonal regulation.
[1] Pathway rate is limited by availability of the initial pathway substrate. An important
mechanism cells use to regulate the quantity of substrate is the integrated control of
membrane traffic of substrate molecules. Cells are not freely permeable to the majority of
substrate molecules; so varying the supply of substrate by regulating cellular import/export
adds an additional level of control.
[2] Cellular regulation of enzyme activity is a key pathway regulation tactic. Metabolic
pathways inevitably contain at least one irreversible reaction, known as the rate-limiting
reaction. The activity of the rate-limiting enzyme dictates the progression rate of the entire
pathway, since an increase in the rate-limiting enzyme’s turnover allows the entire pathway
to proceed at the new increased rate.
‘Allosteric regulation’ is the modification of an enzyme’s activity by modifying the enzyme’s
structure. A structural modification may be positive (increasing enzyme activity) or negative
(decreasing activity). Allosteric modulators are molecules that bind to enzymes, imposing
the structural change. Enzyme inhibitors and activators are allosteric modulators. A very
common example of allosteric modulation seen in metabolic pathways is ‘negative
feedback’. This is where a downstream intermediate or final product of a pathway
allosterically inhibits an upstream enzyme.
4
‘Essentials of Nutritional Physiology’ (HAP32303)
Physiology’ (HAP32303)
Content
Notes week 1 2
Learning goals week 1 2
1.1 Basic concepts and processes metabolism 2
1.2 Glycolysis and mitochondrial ATP production 9
1.3 Assignments 24
1.4 Self-test 24
Notes week 2 25
Learning goals week 2 25
2.1 Carbohydrates and protein catabolism 25
2.2 Assignments 48
2.3 Self-test week 2 48
Notes week 3 49
Learning goals week 3 49
3.1 Fatty acid and triacylglycerol metabolism 49
3.2 Assignments 62
3.3 Self-test 63
1
‘Essentials of Nutritional Physiology’ (HAP32303)
,Notes week 1
Learning goals week 1
● Describe the process of glycolysis
● Explain the function of the TCA cycle and NADH shuttles
● Describe the process of oxidative phosphorylation
● Analyze the pathways of mitochondrial ATP production
● Calculate the energy derived from glucose
1.1 Basic concepts and processes metabolism
1.1a Introduction into metabolism reading
Define a reaction pathway
Key points to appreciate are:
● Reactions involve molecular conversion of
substrates into products
● In living organisms, reactions never occur in
isolation. The product of one reaction goes
on to become a substrate in another
subsequent reaction
● A set of consecutive reactions is described
as a ‘pathway’. Components of the pathway
are known as ‘intermediates’.
Source: Appleton, A. et al (2015) Crash Course: Metabolism and
Nutrition Updated Edition: Elsevier eBook on VitalSource (4th
ed).
Understand the definitions of catabolic and anabolic pathways
Anabolic pathways generate complex molecules from smaller substrates, whilst catabolic
pathways break down complex molecules into smaller products. Anabolic pathways
consume energy. They are synthetic, energy-demanding processes. The suffix of a synthetic
pathway is ‘-genesis,’ e.g. glycogenogenesis (glycogen synthesis). Anabolism is analogous
to ‘construction’; construction requires raw materials and energy. Catabolic pathways
release intrinsic chemical energy from biological molecules. They involve sequential
molecular degradation. Catabolic pathways are suffixed with ‘-lysis’, e.g. glycolysis (glucose
degradation).
2
‘Essentials of Nutritional Physiology’ (HAP32303)
,Source: Appleton, A. et al (2015) Crash Course: Metabolism and Nutrition Updated Edition: Elsevier eBook on
VitalSource (4th ed).
Appreciate the vital role of enzymes in metabolism
Enzymes are specialized, highly specific proteins. Each enzyme mediates a particular
biochemical reaction by functioning as a biological catalyst. Enzymes operate by temporarily
binding to their substrate molecule, imposing molecular modification and finally releasing the
altered molecule (the reaction product).
3
‘Essentials of Nutritional Physiology’ (HAP32303)
, Source: Appleton, A. et al (2015) Crash Course: Metabolism and Nutrition Updated Edition: Elsevier eBook on
VitalSource (4th ed).
Understand the basic mechanisms of enzyme regulation
There are three main control mechanisms exploited by cells to regulate metabolic pathways
in an integrated and sensitive fashion. These include substrate availability, enzymatic
modification and hormonal regulation.
[1] Pathway rate is limited by availability of the initial pathway substrate. An important
mechanism cells use to regulate the quantity of substrate is the integrated control of
membrane traffic of substrate molecules. Cells are not freely permeable to the majority of
substrate molecules; so varying the supply of substrate by regulating cellular import/export
adds an additional level of control.
[2] Cellular regulation of enzyme activity is a key pathway regulation tactic. Metabolic
pathways inevitably contain at least one irreversible reaction, known as the rate-limiting
reaction. The activity of the rate-limiting enzyme dictates the progression rate of the entire
pathway, since an increase in the rate-limiting enzyme’s turnover allows the entire pathway
to proceed at the new increased rate.
‘Allosteric regulation’ is the modification of an enzyme’s activity by modifying the enzyme’s
structure. A structural modification may be positive (increasing enzyme activity) or negative
(decreasing activity). Allosteric modulators are molecules that bind to enzymes, imposing
the structural change. Enzyme inhibitors and activators are allosteric modulators. A very
common example of allosteric modulation seen in metabolic pathways is ‘negative
feedback’. This is where a downstream intermediate or final product of a pathway
allosterically inhibits an upstream enzyme.
4
‘Essentials of Nutritional Physiology’ (HAP32303)
