Module 3- Carbohydrate metabolism Flashcards
(169 cards)
1
Q
major source of energy in the diet
A
carbs
2
Q
carbs make up (%) of caloric intake in monogastrics & ruminants
A
50
3
Q
what is the most important carb in plants
A
starch
4
Q
T or F: lignin is a carb
A
F
5
Q
3 roles of carbs in plants
A
1) tissue synthesis
2) energy reserve
3) structural support
6
Q
T or F: very little storage of carbs in animals
A
T
7
Q
what 3 body compartments hold the little bit of stored carbs
A
bloodstream, liver & muscle
8
Q
carbs can make up to what % in animals diets
A
70%
9
Q
T or F: less than 1% of carbs are stored in the body
A
T
10
Q
how are carbs classified
A
based on number of sugar units
11
Q
lactose
A
glucose + galactose
12
Q
sucrose
A
glucose + fructose
13
Q
maltose
A
glucose + glucose
14
Q
what are the 2 most important carb groups from a nutritional & functional standpoint
A
1) pentose
2) hexoses -> glucose
15
Q
what configuration of glucose is recognized by the digestive enzymes in the GI tract
A
D
16
Q
T or F: animals cannot utilize L forms of glucose
A
T
17
Q
3 most important hexoses
A
1) glucose
2) galactose
3) fructose
18
Q
2 major end products of fermentative digestion
A
1) VFA in rumen
2) glucose in small intestine
19
Q
2 most important pentose sugars. why?
A
ribose + deoxyribose
- need for DNA/RNA synthesis
20
Q
adenosine =
A
ribose & adenine
21
Q
major function of ribose
A
structural component of NAD & NADH
22
Q
NADH is the ( ) form
A
reduced
23
Q
riboflavin is a component of ( ) and ( )
A
FAD & FMN -> co factors in electron transfer REDOX reactions
24
Q
T or F: ribose can covert tryptophan into niacin
A
T
25
glycosidic linkage
OH group on anomeric C
26
anomeric carbon
carbon double bonded with O2
27
alpha vs beta glucose
alpha: OH group is on amomeric carbon OPPOSITE side of ring structure
beta: OH group on anomeric carbon is on SAME side of ring structure
28
what dictates if glycosidic linkage is alpha or beta
orientation of OH group on carbon #1
29
monogastrics can only digest ( ) linkages
alpha
30
lactose has ( ) linkage
beta
31
maltose has ( ) linkage
alpha
32
partial digestion yields ( ) in small intestine
maltose
33
( ) is an intermediate in digestion
maltose
34
3 examples of polysacharides
starch, cellulose & glycogen
35
2 classes of polysaccharides + examples
1) homo: made of same monosaccharide units (cellulose)
2) hetero: made of diff monosaccharide units (hemicellulose)
36
2 types of starch granules
1) amylose
2) amylopectin
37
how do amylose & amylopectin differ?
structure
38
high amylose = ( ) amylopectin
low
39
amylose is ( ) digested
slowly
- pulses: peas & lentils
40
amylopectin is ( ) digested
rapidly, cereal crops
41
what happens to amylose structure as it is dissolved in water?
the straight unbranched chain turns into a helical structure to reduce surface area for digestive enzymes to digest polysaccharide chains
42
resistant starch is ( ) in amylose content
higher
43
amylose structure
long unbranched chains of glucose
- a (1,4) linkage
44
amylopectin structure
branched chain polymer with a (1,4) and a (1,6) linkages
45
why is amylopectin digested at a faster rate?
branches = more surface area for enzymes
46
what is the storage form of glucose in animals
glycogen
47
T or F: plants have glycogen
F
48
difference between glycogen storage in liver vs skeletal muscle
liver: glycogen is not used locally
skeletal muscle: glucose is used locally (does not go to other tissues)
49
cellulose
long linear polymer of repeating glucose
- b (1,4) linkage
50
difference between cellulose & starch
cellulose: b (1,4) linkage
starch: a (1,4) linkage
51
hemicellulose
heterogenous group of polysaccharide substances
- b (1,4) linkages
52
poly-phenolic compound example
lignin
53
lignin content ( ) as plant matures
increases
54
hemicellulose has ( ) backbones & side chains
sugar
55
pectin is not digestible by mammalian enzymes but it is susceptible to
microbial fermentation
56
b-glucans linkages
b (1,3) + b (1,4)
57
T or F: cellulose is insoluble in water
T
58
T or F: b-glucans are water soluble
T
59
example of soluble fiber
b-glucans
60
soluble fiber
forms a viscous material in GI tract which reduces penetration of digestive enzymes and reduces digestion
61
what 2 feeds are high in b-glucans
barley & oats
- must add beta-glucanase to reduce visocity
- only done in monogastric & poultry diets
62
soluble xylans
form viscous environment that reduces nutrient digestibility
63
xylanase
breaks down xylans
64
2 major sources of xylans
barley & wheat
65
dietary fiber
component of xylan foods that you are eating
-intrinisic component
66
functional fiber
supplement added into diet
- components: pectins & xylans
67
2 components of functional fiber
pectins & xylans
68
why is high viscosity of fibre beneficial in human diets?
1) slows gastric emptying = feel full faster
2) reduces absorption of fat
69
2 properties of soluble fiber
1) solubility
2) water holding capacity
70
2 properties of insoluble fiber
1) absorption & binding ability
2) degradability/fermentability
71
T or F: insoluble fibers act as pre-biotics
T
72
what type of carbs are the only ones that can be absorbed in monogastric GI tract
monosaccharides
73
mammalian enzymes can only breakdown what linkages
a (1,4) or a (1,6)
74
why doesn't any carb digestion happen in the stomach of monogastrics?
too acidic for salivary amylose to be active
75
T or F: a (1,6) linkage is not susceptible to salivary amylase but a (1,4) is
T
76
major enzyme that initiates carb digestion in the mouth in monogastrics
salivary amylase
77
where can a (1,6) linkages be broken down in monogastrics
small intestine
78
how are dextrins formed
formed from initial digestion of starch in the mouth
79
limitation to carb digestion in mouths of monogastrics
short amount of time food stays in the mouth
80
what is flowing out of the mouth -> stomach during monogastric carb digestion
dextrins & starch (amylose & amylopectin)
81
stomach pH of monogastrics
1-2
82
issue with carb digestion in the stomach
too acidic
83
where is pancreatic juice secreted into during monogastric carb digestion
duodenum
84
T or F: pancreatic amylase cannot digest a (1,6) linkages
T
85
limit dextrins vs dextrins
limit dextrins are smaller but still have branch points
86
maltase
digests maltose to produce 2 glucose units
87
what is the only enzyme that can digest a (1,6) linkages? where is it located?
alpha-dextrinase
- brush border enzyme -> located on villi/microvilli
88
lactase
breaks down lactose to produce glucose & galactose
89
difference between lactose & sucrose
lactose has b (1,4) linkages
90
absorption of monosaccharides in monogastrics uses what 2 types of transport?
active & facilitated transport
91
basolateral membrane
where blood is flowing, nutrients are absorbed here
92
glucose is ( ) in concentration that galactose in monogastrics
higher
93
SLGT-1
receptor that is expressed in villi & microvilli
- function depends on presence of sodium
94
SLGT-1 uses GLUT ( ) to transport glucose from ( ) to ()
2, enterocyte, bloodstream
95
Na/K ATPase pump
pumps 3 Na out & 2 K in
96
what % of energy is dedicated to the Na/K ATPase pump
40-50%
97
how does glucose facilitated transport work
glucose concentration on luminal side is higher than in cell = move from high to low concentration (aka into bloodstream)
98
how is fructose transported into the cell?
uses GLUT 5 transporter to be facilitated inside cell then GLUT 2 to move to bloodstream
99
hydrolysis of ATP
ATP -> ADP
100
glucose is metabolized by the ( ) and released into ( ) to be used by other tissues
liver, peripheral circulation
101
how do galactose & fructose provide energy?
they get converted into glucose derivates via phosphorylation reactions so they can now enter glucose metabolic pathways
102
what 2 GLUT are most important for transporting glucose from bloodstream -> into cell
GLUT 2 & GLUT 4
103
where is SLGT-1 expressed?
only the small intestine
104
what GLUT is insulin dependent
GLUT 4
105
insulin is released in response to
glucose
106
what GLUT are insulin independent?
all but GLUT 4
107
GLUT 1
basic supply of glucose to cells
108
GLUT 2
low infinity transporter
glucose -> blood
109
GLUT 3
high affinity transporter for brain & other glucose dependent tissues
110
GLUT 4
insulin sensitive
muscle & tissues
111
GLUT 5
fructose
112
1 mol of glucose when completely oxidized yields ( ) mols of ATP
38
113
2 glucose fates
1) complete oxidation via glycolysis
2) fatty acid synthesis/energy storage
114
what kind of relationship is present between the rumen & its microorganisms
symbiotic
115
by-product of pre-gastric carb fermentation in ruminants
VFAs
116
structural carbs
mostly grazed, fermentative digestion allows nutrients to get energy from these
117
glucose metabolism to VFA yields ( ) mols of ATP
2-4
118
anaerobic vs aerobic conditions: ATP yields
anaerobic: 1 mol of glucose = 2-4 mols ATP
aerobic: 1 mol glucose = 38 mols ATP
119
what is produced when acetate & butyrate are produced
H ions
120
methane loss is associated with a significant energy loss of ( )
H
121
the more acetate & butyrate produced = more ( ) produced in rumen
methane
122
T or F: propionate does not produce H ions
T
123
why is it favourable to have more propionate in the rumen compared to acetate & butyrate?
less energy is wasted as methane
124
energy for ruminants comes from
fermentation
125
cellulolytic microorganisms
ferment fiber -> cellulose, hemicellulose, pectin
- produce acetate (acetate like fermentation)
- neutral pH bc more fiber = more chewing
126
amylolytic microorganisms
ferment starch
- produce propionate (propionate like fermentation)
- more acidic rumen
127
T or F: butyrate will always stay at same proportion but acetate & propionate will change
T
128
starch is ( ) fermentable than fiber which means more ( ) are produced
more, VFAs
129
90% of VFAs are absorbed in the
rumen
130
higher feed intake = more ( ) and less ( )
propionate, acetate
131
lower frequency of feeding = more ( ), less ( )
propionate, acetate
132
4 ways to increase acetate production in the rumen
1) feed more frequently
2) increase dietary forage
3) larger particle size
4) buffers
133
rumensin function
increase propionate production = decrease methane = increase feed efficiency
- prouce acetate type fermentation
134
gram ( ) bacteria decrease with rumensin
positive
135
how does rumensin prevent acidosis
decreases lactate
136
T or F: rumensin does not change stomach pH
T
137
how are VFAs absorbed?
across rumen wall into blood stream via passive & facilitated diffusion
138
once absorbed, acetate & butyrate are metabolized into ( )
ketone bodies
139
what ketone bodies are acetate & butyrate metabolized into?
B-hydroxybutyrate & acetoacetate
140
t or F: propionate is not metabolized in rumen epithelium during absorption
T
141
major function of propionate
produce glucose via gluconeogenesis
142
post-absorptive metabolism of VFAs (how do they each enter TCA cycle?)
acetate & butyrate: enter TCA cycle as acetyl CoA
propionate: enter TCA cycle as succinyl CoA
143
what is the only VFA that can produce glucose?
propionate
144
why would no propionate be shown in a blood sample?
bc all of it is extracted by the liver
145
what VFA is absorbed in the largest amounts
acetate
146
what is the major circulating energy substrate in ruminants vs monogastrics
r- acetate
m- glucose
147
oxaloacetate is used to produce
glucose
148
2 major fates of acetate & butyrate
1) generation of energy via TCA cycle
2) lipid synthesis
149
2 mol of acetate = ( ) ATP
24
150
what is the only gluconeogenic VFA
propionate
151
why are circulating blood glucose levels lower in ruminants than monogastrics?
glucose is reserved exclusively for vita functions like in the brain so they absorb very little glucose from small intestine and rely on gluconeogenesis for the glucose they need
152
bloat
viscous frothy foam in rumen that prevents eructation
153
2 causes of rumen acidosis
VFA accumulation
lactic acid accumulation
154
2 types of bloat
- frothy
- dry gas
155
frothy bloat
bacteria produces slime in rumen that traps gases
156
dry gas bloat
gas rises to space above digesta but animal is unable to release gas through eruptation
157
2 causes of dry gas bloat
- physical blockage of esophagus
- damage to vagus nerve -> no signal to brain for rumen contractions to get rid of gases
158
home remedy for bloat
vinegar
159
trochar
used to release gas in cows who have bloat
160
T or F: a trochar will not help with frothy bloat bc it needs an anti-foaming agent
T
161
how to treat frothy bloat
stomach tube anti-foaming agent
162
what is the digesta flowing into the stomach of monogastrics
amylopectin and dextrins
163
T or F: no complete digestion of amylopectin without alpha dextrins present
T
164
SARA
sub-acute ruminal acidosis
165
SARA is more common in ( ) cattle than ( ) cattle
dairy, beef
166
what is a major lactate producing bacteria in the rumen that may lead to SARA
strep. bovis
167
lactic acid promotes growth of ( ) which will produce lots of lactic acid in rumen = acidosis
lactobacilli
168
2 forms of lactic acid
1) L -> used by liver to produce glucose, can be metabolized
2) D: stays in bloodstream, cannot be metabolized
169
3 symptoms of SARA
1) reduced or erratic feed intake
2) reduced rumination
3) lameness
