Transcript 2106lecture 6b powerpoint

Lecture 6b-10 February 2016
Most of this lecture taken from
Chapters 6,7 of Rolfes et al(Understanding
Normal and Clinical Nutrition
(Nutrition 2104/2106 text)
Lecture 6b-10 February 2016
Protein metabolism and regulation
Outline of lectures 6a,b
Amino acids
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Definition of amino acid
Structure of amino acid
Non-essential amino acids
Essential amino acids
Conditionally essential amino acids
Class exercise
Outline of lectures 6a,b
Proteins
• Definition of protein
• Amino acid chains
• Amino acid sequence
• Protein shapes
• Protein functions
• Protein denaturation
• Digestion
• Absorption
• Transport
Outline of lectures 6a,b
Metabolism
• Amino acid anabolism
• Protein anabolism
• Protein catabolism
• Amino acid catabolism
• Nitrogen balance
• Regulation of amino acid and protein
metabolism
More detailed comments
Proteins
Absorption
-specific carriers move amino acids and
a few dipeptides and
tripeptides into intestinal cells
-once inside intestinal cells amino acids
can be used for energy or to
synthesise some proteins
Proteins
Transport
-rest of amino acids put directly into
blood and taken to liver
-are amino acid carriers required for
free amino acids to transport those
free amino acids in the blood?
Proteins
Class exercise
-what happens to protein functions if there
are insufficient:
a) essential amino acids in the diet?
why?
b) non-essential amino acids in the diet?
Explain
-what happens to protein functions if there
are sufficient?
c) essential amino acids in the diet?
explain
Metabolism
Protein anabolism
amino acids joined to amino acids
figure 6-7 Rolfes et al
Fig. 6-7, p. 188
Metabolism
Protein catabolism
-digestion in stomach and small
intestine
-non gi tract catabolism
Metabolism
Amino acid catabolism
-figure 7-13 Rolfes
-figure 7.24 Gropper
- get urea which is excreted in urine
© 2009 Cengage - Wadsworth
Metabolism
Nitrogen balance
-equilibrium
N in = N out
healthy adult
-negative nitrogen balance
N in < N out
illness, starvation
-positive nitrogen balance
N in > N out
-person recovering from illness
-growing child
Regulation of amino acid and protein metabolism
-demand for amino acid and protein
anabolism -eg if need positive N balance
or to keep in N equilibrium
-if lots of glucose available
-demand for amino acid and protein
catabolism-eg if in negative N balance or
to keep in N equilibrium
-if short of glucose
Relation of protein metabolism to carbohydrate
and lipid metabolism
-figure 7-8 Rolfes et al.
© 2009 Cengage - Wadsworth
Class exercise
Explain the importance of dietary
carbohydrate to protein metabolism
Explain the importance of dietary lipid to
protein metabolism
Explain the importance of dietary protein to
protein metabolism