Transcript 2106lecture 3a-powerpoint

Question of the week
Suggestion box and other input please
Please use only your CBU emails when
communicating with me.
Please check your CBU emails frequently
including for messages from me.
Lecture 3a- 18 January 2016
Most of this lecture derived from
Chapter 4 of Gropper,
Chapter 4,7 of Rolfes et al(Understanding Normal
and Clinical Nutrition(Nutrition 2104/2108 text)
Insel et al.(Nutrition)
and page 96 of Smolin and Grosvenor (NutritionScience and Applications)
TODAY’S LECTURE
Carbohydrate metabolism and regulation
Outline of lectures 3a and 3b
Carbohydrates
-forms
-monosaccharides
-disaccharides
-oligosaccharides
-polysaccharides
-fibre-next week
Outline of lectures 3a and 3b
Carbohydrates
-foods where each is found
-monosaccharides
-disaccharides
-oligosaccharides
-polysaccharides
Outline of lectures 3a and 3b
-definitions
-monosaccharides
-disaccharides
-oligosaccharides
-polysaccharides
Outline of lecture 3a and 3b
-digestion
-monosaccharides
-disaccharides
-oligosaccharides
-polysaccharides
Outline of lectures 3a and 3b
-absorption, transport and distribution
-monosaccharides
-disaccharides
-oligosaccharides
-polysaccharides
-glucose transporters
Outline of lectures 3a and 3b
-metabolism
-glycogenesis
-glycogenolysis
-glycolysis
-nicotinamide adenine dinucleotide
-hexose monophosphate shunt
-Krebs cycle
-gluconeogenesis
-regulation
-allosteric
-hormonal
-changes in equilibrium
-rate limiting enzymes
More detailed comments-lecture 3a
Carbohydrates
-forms
-simple carbohydrates
-monosaccharides
-glucose, fructose, galactose
-disaccharides
-maltose(glucose and glucose),
-sucrose(glucose and fructose),
-lactose(glucose and galactose)
Carbohydrates
-forms
-complex carbohydrates
-oligosaccharides-three to ten saccharide
units(some texts define as 2-10
units)-eg breakdown of
starch digestion
-polysaccharides-more than 10
saccharides units-eg starch,
glycogen
Examples of foods where each is found
-monosaccharides-glucose-rare in foods as monosaccharide
(except mother's milk and sports
drinks) but is found in foods as
disaccharides and starch
-fructose-fruits and honey
-galactose-seldom occurs free in nature
Examples of foods where each is found
-disaccharides
-maltose- part of starch
- minor component of few foods
-sucrose-fruits, vegetables and grain
-sugar cane- gives rise to table sugar
-sugar beets-give rise to table sugar
-lactose-dairy products (eg milk)
Examples of foods where each is found
-oligosaccharides- eg raffinose and stachyose
are found in beans and other legumes
-polysaccharides
-glycogen-(storage carbohydrate
in animal muscle and liver)
-most of this is lost when meat is
slaughtered
-starch-(storage carbohydrate in plants)potatoes
Definitions
carbohydrate
A compound or molecule that is
composed of carbon, oxygen and
hydrogen in the ratio of 1C:2H:1O
carbo = carbon
hydrate = H20
Definitions
-monosaccharides-single carbohydrate units;
-contain 3-7 carbons(trioses, tetraoses,
pentoses, hexoses, heptoses)
-disaccharides-two saccharide units
-oligosaccharides-3-10 saccharide units
-polysaccharides-more that 10 saccharide units
Digestion
-monosaccharides-pass untouched into small
intestinal capillaries
-disaccharides
-maltose- untouched until maltase in small
intestine
-maltase produces two glucoses
-sucrose-untouched until sucrase in small
intestine
-sucrase produces glucose and
fructose
Digestion
-disaccharides
-lactose-untouched until lactase in small
intestine
-lactase produces glucose and
galactose
-oligosaccharides-undigested in stomach or small
intestine-must be digested by colon bacteria which
produce abdominal discomfort and flatulence and
short chain fatty acids (acetic, proprionic and
butyric acids)
Digestion
-polysaccharides
-starch digestion mildly in mouth-salivary
amylase (alpha-amylase), minimally in stomach via
hydrochloric acid and mostly by pancreatic
amylase in small intestine
-maltose units ultimately produced followed
by maltase digestion
Digestion
-polysaccharides
-resistant starch-common in legumes, raw
potatoes and unripe bananas
-resistant to starch digestion
as above due individual inefficiency in
digesting starches (class discussion) and
physical properties of food
Digestion
-polysaccharides
-resistant starch
bacteria in colon ferment resistant
starches and produce water gas
and short chain fatty acids (acetic,
proprionic and butyric acids)
Absorption, transport and distribution
-monosaccharides-pass untouched into small
intestinal capillaries
-glucose and galactose enter by
active transport and
both go to liver
-fructose enters by facilitated
diffusion and goes to
liver
-glucose goes to liver(some
glycogen produced and other
metabolic pathways)
Absorption, transport and distribution
-monosaccharides-fructose and galactose converted to
glucose in liver
-glucose also goes to directly to other
tissues eg voluntary muscle(some
glycogen produced and other
metabolic pathways are followed)
Absorption, transport and distribution
oligosaccharides-undigested in stomach or small
intestine-must be digested by colon bacteria which
produce short chain fatty acids, abdominal
discomfort and flatulence
Absorption, transport and distribution
-polysaccharides-starch digestion mildy in
mouth-salivary amylase (alpha-amylase),
minimally in stomach via hydrochloric
acid and mostly by pancreatic amylase
in small intestine
-maltose units ultimately
producing glucose
which is handled as above
Absorption, transport and distribution
-glucose transporters-proteins required to get
glucose into cells
-table 4.2 Gropper
-metabolism
-glycogenesis
-conversion of glucose to
glycogen(storage form of
carbohydrate in humans)
-occurs in liver and muscle (cytoplast)
-glucose converted to glycogen
precursors
-most of glycogen arises from
gluconeogenic precursors rather
than glucose directly
-figure 4.11 Gropper
-metabolism
-glycogenolysis
-conversion of glycogen to glucose
(usable form of carbohydrate in
humans for energy and anabolism)
Note:The end of the molecule containing a free
carbon number one on glucose is called a reducing
end. The other ends are all called non-reducing
ends.
-occurs in cytoplast
-figure 4.12 Gropper
-regulation-figure 4.13 Gropper
-metabolism
-metabolism
-glycolysis
-catabolism of glucose to yield energy and
products for anabolism(e.g.
gluconeogenesis-see below)
-anaerobic
-occurs in cytoplast
-figure 4.14 Gropper