Module 5- Protein metabolism Flashcards
(283 cards)
1
Q
what is protein
A
organic compound in feed that contains N
2
Q
T or F: animals require amino acids, not proteins
A
T
3
Q
how many amino acids are there
A
20
4
Q
T or F: skeletal muscle is a storage for amino acids
A
F
5
Q
what % of protein is found in skeletal muscle vs body organs, skin & blood
A
40, 25
6
Q
T or F: all enzymes in our body are proteins
A
T
7
Q
hydrolases
A
cleave compounds
8
Q
isomerases
A
transfer atoms in a molecule
9
Q
ligases
A
join compounds
10
Q
oxidoreductases
A
transfer electrons
11
Q
transferases
A
move functional groups
12
Q
hormones
A
produced in endocrine glands
- transported through bloodstream to target tissues
13
Q
T or F: all hormones are proteins
A
F
14
Q
what 3 hormones are made of proteins
A
1) insulin
2) growth hormone
3) glucagon
15
Q
2 contractile proteins
A
actin & myosin
16
Q
fibrous proteins
A
keratin & collagen
17
Q
2 groups of functional proteins
A
1) transporters
2) nutrient transporters
18
Q
ceruloplasmin
A
transport copper
19
Q
nutrient transporters function
A
expressed in cell membrane, responsible for uptake of nutrients into the cell
20
Q
transporters function
A
transports different metabolites in the body
21
Q
Na-dependent amino acid transporter
A
responsible for uptake of Na & AA
22
Q
T or F: proteins can act as buffers
A
T
23
Q
how do proteins act as acid-base buffers?
A
1) low pH -> AA accept H ions to increase pH
2) high pH -> AA release H ions = decrease pH
24
Q
how does too much protein impact fertility?
A
ammonia can make acidic uterine environment
25
4 parts to an AA structure
1) central C atom
2) carboxylic group
3) amino group
4) side chain/R group -> what differs
26
physiological pH
7
27
at physiological pH, what form is the carboxylic group in?
dissociated
COO- + H
28
conditionally essential AA + example
requirement based on physiological state
- glycine in poultry
29
T or F: cysteine can reduce amount of dietary methionine required
T
30
phenylketonuria
elevation of phenylalanine in blood
31
aliphatic amino acids
have aliphatic side chains (methyl groups)
32
what are the 2 sulfur containing amino acids
cystenine & methionine
33
dicarboxylic AA
have 2 carboxylic acid groups = negatively charged
34
bibasic AA
have 2 amino groups
postive net charge
35
neutral AA
1 carboxylic + 1 amino group
36
negatively charged AA have an additional ( ) group while positively charged AA have additional ( ) group
carboxylic, amino
37
what 2 forms do AA exist in
L & D
38
what forms of AA are more abundant
L
39
monosaccharide enzymes recognize what form of AA
D
40
T or F: D isomers can be converted to L isomers but not vice versa
T
41
T or F: no enzymes available to convert L to D form of lysine
T
42
peptide bond links ( ) AA together
2
43
polypeptides vs proteins
polypeptides: less then 20 AA
proteins: more than 20 AA
44
T or F: no 2 proteins will be the same
T
45
how do proteins differ?
their sequence of AA
46
what is the sequence of AA determined by?
genetically by DNA
47
T or F: polypeptide backbones do not differ in AA
T
48
T or F: misfolded proteins are not functional
T
49
proteins in the ( ) structure are harder to digest
beta sheet
50
secondary structure of proteins
electrostatic attractions cause it to fold within itself
- alpha helix
- b sheets
51
tertiary structure of proteins have a ( ) bond
disulfide
52
quaternary structure of proteins
2+ polypeptide chains are interacting with each other
53
lactosynthase
synthesizes lactose in mammary gland
54
example of protein with a quaternary structure
hemoglobin
55
what 2 things does a primary protein structure determine?
1) AA profile
2) quantities of AA available
56
T or F: feather meal is not digestible due to beta sheets
T
57
how can feed with low digestibility be altered to improve it?
hydroylze
58
T or F: barley is very digestible bc it contains very little beta sheets
T
59
tertiary & quaternary structure of a protein are more involved with ( ) rather than nutrition
protein functionality
60
exogenous
derived in diet
61
example of a plant vs animal derived exogenous protein source
plant: soybean, canola meal
animals: fish meal
62
3 things that will decrease ability of GI tract to reclaim endogenous proteins
1) high fiber
2) anti-nutritional factors
3) tannins
63
protease enzymes perform
hydrolysis
64
T or F: protein digestion takes place in the monogastric mouth
F
65
chemical digestion in monogastric stomach
HCI + pepsin
66
pepsin is the ( ) form of pepsinogen
active
67
what do chief cells produce
gastric lipase
68
what is pepsinogen activated by
HCI
69
HCI function in stomach
denatures proteins = larger surface area
70
monogastric stomach pH
1-2
71
why does the pancreas not secrete enzymes instead of proenzymes?
bc they will break don the pancreas
72
T or F: proenzymes are active
F
73
what does acidic chyme in the proximal duodenum stimulate?
pancreatic juice which contains secretin & CCK to neutralize the chyme
74
endopeptidases vs exopeptidases
endo: digest polypeptide chain from the middle
exo: digest polypeptide chain from carboxylic end
75
3 examples of endopeptidases
1) pepsin
2) trypsin
3) chymotrypsin
76
2 examples of exopeptideases
1) carboxypeptidases A & B
2) aminopeptidases
77
aminopeptidases are ( ) enzymes
brush border
78
aminopeptidases
group of protease enzymes produced by enterocytes
79
enterocytes are ( ) enzymes
brush border
80
exopeptidase digestion end product
free AA
81
endopeptidase digestion end products
oligopeptides & small peptides
82
major absorption pathway for AA in monogastrics
facilitated by pept1
83
PEPT-1
hydrogen dependent transport system
84
passive diffusion of AA
via tight junctions
85
3 AA transporters
1) Na dependent
2) H dependent
3) Na independent
86
ionic gradients of H dependent transport is maintained by the
Na pump
87
4 steps of Na dependent AA transporter
1) Na binds to binding site on transporter
2) increases affinity for transporter for AA
3) AA binds to its binding site
4) both Na & AA are transported together into enterocyte & into the cell
88
why is AA transport through the Na K ATPase pump not the primary pathway?
it is an energy dependent process
89
what enzyme activates trypsinogen to trypsin
enteropeptidase
90
sodium hydrogen exchanger
removes H from cell in exchange for Na
91
what membrane does the Na K ATPase pump operate on?
basolateral membrane
92
why would there be more N in the duodenum than contained in the diet?
b/c of endogenous proteins
93
what N source is most abundant in feces
microbial N
94
microbial N
N from growth of microorganism in the hind gut + endogenous proteins
95
4 major sources of N in a monogastric diet
1) microbial N
2) sloughed off epithelial cells
3) enzymes
4) undigested feed nitrogen
96
what is the major source of N in monogastric diet
undigested feed N
97
why must all endogenous proteins not be lost
no growth / production bc losing more N than consuming
98
2 examples of anti-nutritional factors
1) trypsin inhibitor
2) tannins
99
what do trypsin inhibitors do
change shape of trypsin & chymotrypsin = unable to digest proteins
100
how to remove trypsin inhibitors and tannins from the feed
heat
101
tannins
phenolic compounds that bind proteins = reduce solubility of protein = reduced digestion
102
how are mallard products formed
when feed ingredients are heat treated = makes proteins less soluble = reduces digestibility
103
T or F: mallard reactions are undesirable in monogastrics
T
104
T or F: heat decreases protein solubility
T
105
3 AA used most extensively by small intestine during absorption
1) glutamate
2) glutamine
3) aspartate
106
T or F: lots of glucose is absorbed by small intestine for energy
F
107
glutamate -> a-ketoglutarate is a ( ) reaction
transamination
108
how does the small intestine get energy from glutamate, glutamine & aspartate
1) deamination reaction: glutamine -> glutamate
2) transamination reaction: glutamate -> a-ketoglutarate = can now enter TCA cycle for energy
109
what is used for ureagenesis
ammonia
110
glutamine, glutamate & aspartate are ( ) to produce energy
oxidized
111
glutathione is an
antioxidant
112
what organ is the major use of amino acids? for what function?
liver, energy
113
2 fates of AA
1) liver
2) other tissues
114
what % of amino acids in portal circulation absorbed from the small intestine are used by the liver?
50%
115
T or F: protein turnover is continual
T
116
rate of protein synthesis is ( ) than rate of protein degradation in animals that are growing
higher
117
Ks vs kd
Ks- protein synthesis
Kd- protein degradation
118
Ks > Kd =
protein accretion
119
when does catabolism of amino acids occur?
when carbohydrate intake is limited
120
what 2 catabolic states increase amino acid catabolism
sepsis & metabolic acidosis
121
ureagenesis
pathway to detoxify ammonia
122
ammonia is toxic to the ( ) system
central nervous system
123
how are non-essential amino acids synthesized?
transamination reactions
124
3 most active aminotransferases / 3 major players in transamination reactions
1) alanine
2) aspartate
3) glutamate
125
alanine gives up amino group to a-ketoglutarate to become
glutamate
126
aspartate becomes
oxaloacetate
127
alanine becomes
pyruvate
128
oxidative deamination
amino acid releases amino group to produce ammonia + a-ketoglutarate
129
transamination vs deamination reactions
T: no release of free ammonia, occur in lots of diff tissues
D: release of free ammonia, occur mostly in liver
130
2 causes of livestock ammonia toxicity
1) overfeed urea
2) genetic defects in urea cycle
131
primary site of catabolism of glutamine & glutamate
skeletal muscle
132
transamination of branched chain amino acids in skeletal muscle results in the production of
glutamine and glutamate
133
during transamination reaction, glutamine ( ) amino group and glutamate ( ) amino group
accepts, donates
134
mechanism that prevents releasing ammonia into the bloodstream
alanine glucose cycle
135
alanine glucose cycle
1) alanine transports the amino group from skeletal muscle to liver
2) glucose is released by liver -> skeletal muscle -> carbon skeleton of alanine
136
cost of urea synthesis
4 high energy phosphate bonds
137
where does the N in urea come from
catabolism of AA
138
arginine is important for the resynthesis of
orthinine
139
orthinine function
limits ability of urea cycle to operate
140
why do diets low in arginine impact the urea cycle?
reduces ability to regenerate orthonine which is needed for the urea cycle to operate
141
1 oxaloacetate is used to synthesize ( ) for the production of fumarate
aspartate
142
problem with urea excretion
urea is very rapidly degraded in the environment = ammonia production
143
ammonotelic refers to what species
aquatic species
144
ureotelic refers to what species
mammals
145
uricotelic refers to what species
birds/reptiles
146
what causes pasty form of bird poop
uric acid
147
T or F: there is little loss of water with uric acid excretion
T
148
T or F: uricogenic animals require more energy to excrete uric acid
T
149
how many ATP are hydrolyzed in ureagenesis
4
150
animal that secrete urea have a ( ) proportion of N b/c uric acid is higher in energy costs, therefore ( ) N content
higher
151
4 major sources of N in uric acid
1) glycine
2) glutamine
3) glutamate
4) aspartate
152
what is required in broiler diets for uric acid synthesis?
glycine
153
are plant or animal proteins higher in glycine
animal
154
urea is what % N
47
155
uric acid is what % N
33
156
uric acid synthesis has a ( ) energy cost
higher
157
ammonia -> uric acid vs uric acid -> ammonia on water requirements & energy cost
a->u : higher energy cost, lower water requirement
u->a: lower energy cost, higher water requirement
158
disposal of carbon skeleton occurs primary through
ureagenesis
159
T or F: carbon skeleton from any amino acid can be used to generate energy through the krebs cycle
T
160
T or F: some carbon skeletons are used exclusively for glucose synthesis
T
161
glucogenic carbon skeletons end up as? (5)
- a-ketoglutarate
- succinyl CoA
- fumarate
- oxaloacetate
- pyruvate
162
ketogenic carbon skeletons end up as? (2)
- acetyl CoA
- acetoacetyl CoA
163
phenylalanine is a ( )genic AA
glucogenic & ketogenic
164
why it it inefficient to catabolize AA for energy?
b/c have to dispose of amino group which costs energy & heat increment increases
165
heat increment definition
change in heat production after a meal
166
Kwashiorkor
protein deficiency with swelling
167
marasmus
protein and energy deficiency, no swelling
168
T or F: marasmus is more severe than kwashiorkor
T
169
T or F: protein synthesis is an all or nothing event
T
170
T or F: genetics determine an animal's capacity for lean meat deposition
T
171
what is the 1st limiting amino acid in pigs vs poultry
pigs- lysine
poultry- methionine
172
2 major factors of protein quality
1) AA content determined by sequence/primary structure of AA sequence
2) digestibility of protein -> constituents being released
173
what 2 methods are amino acid requirements based on?
1) limiting amino acid requirements
2) ideal protein balance
174
what is a first limiting amino acid?
supplied in the least amount in diet relative to an animals requirement
- protein synthesis can only take place to the extent that lysine can support
175
what is the 1st limiting amino acid in monogastrics
lysine
176
why is methionine the 1st limiting amino acid in poultry?
bc feathers are very high in methionine
177
T or F: without synthetic AA, it is hard to formulate balanced diets for monogastrics
T
178
ideal protein balance concept
perfect balance of EAA that will meet requirements for maintenance & production but everything is expressed relative to the lysine or the limiting amino acid
- expressed as a % of lysine
179
5 advantages of using the ideal protein concept
1) balanced EAA composition
2) maximize growth
3) avoid under-feeding
4) reduces cost of diet
5) less N excretion bc proteins are in proper proportions
180
why is lysine set to 100 in ideal protein
only used for protein synthesize
181
T or F: age is a major factor that influences ideal protein ratios
T
182
T or F: only lysine is static in ideal protein ratios, the rest are all different
T
183
( ) requirements continues to increase to support protein accretion as the animal gets heavier
lysine
184
advantage & disadvantage of matching EAA content
A: save costs, less AA oxidation
D: difficult to manage
185
why is it called apparent digesibility?
bc not accounting for sloughed off epithelial cells & enzymes
186
T or F: apparent digestibility is used to formulate diets
F- it is very misleading bc it does not account for endogenous protein losses
187
T or F: microorganisms have lysine requirements
T
188
problem with measuring endogenous losses
digestive function
189
T or F: apparent fecal & ileal AA digestibility is used to calculate diets
F
190
what digestibility calculation is used to formulate diets
true ileal AA digestibility
191
2 methods to measure amino acid requirements
1) broken line model
2) quadratic model
192
broken line model
add more AA until weight gain plateaus
- not biologically correct
193
quadratic model
add more AA until find peak in weight gain curve
- decreases are due to toxic effects
194
what is the major source of AA in ruminants vs monogastrics
ruminants- microbial protein
monogastrics- dietary protein
195
true proteins + example
AA linked by peptide bonds to form large polypeptides
- canola meal
196
2 major sources of NPN in ruminant diet
1) urea in diet
2) ammonia in fermented forages
197
urea makes up to (%) of DM in ruminant rations
2%
198
major NPN in forages is
ammonia
199
degradation of NPN produces
ammonia
200
RUP is digested in ( ) to provide ( )
small intestine, AA
201
RDP are degraded in the ( ) to provide ()
rumen, nitrogenous compounds
202
T or F: microbial proteins require ATP to synthesize microbial proteins
T
203
metabolizable protein =
microbial protein + RUP
204
3 fates of ammonia in rumen
1) absorbed by rumen wall
2) go to bloodstream for excretion as urea
3) recycled back in saliva
205
2 components of dietary protein
RUP + RDP
206
true proteins are degraded to
AA & small peptides
207
T or F: protein degradation is initially an extracellular process
T
208
carbon skeletons from AA are degraded to produce ( ) in ruminants
VFAs
209
the process of dietary protein -> amino acid occurs ( ) and small peptides -> VFAs occur ( )
extracellularly, intracellularly
210
what % of rumen bacteria are proteolytic
30-50
211
difference between bacteria & protozoa
bacteria: use ammonia as N source for bacterial protein synthesis
protozoa: major source of N is the bacteria they consume
212
T or F: there is high urease activity in the rumen
T
213
T or F: urease is expressed everywhere in the rumen
T
214
what is required for microorganisms to use ammonia to synthesize AA?
carbon skeleton from VFAs
215
fiber digesting microorganisms prefer( ) as an N source for microbial protein synthesis
ammonia
216
coupled fermentation
nitrogenous compounds are available at the same time as ATP that drives microbial protein synthesis
217
protozoa preferred source of N is
bacteria
218
what is the most efficient protein synthesis in the rumen?
coupled fermentation
219
energy sources are fermented to produce
ATP
220
sugars are ( ) rapidly fermented than steam flaked corn / ground barley
more
221
why add sugars in diet to help with microbial protein synthesis?
sugars ferment rapidly like urea so they will ferment together = efficient microbial protein synthesis
222
T or F: rumen ammonia concentration is more stable when ammonia & ATP release are matched
T
223
what occurs with uncoupled fermentation
protein source is fermented faster than carb source = no ATP available = ammonia is absorbed into bloodstream = wasted N
224
what happens when you maximize microbial protein production
minimize RUP
225
3 factors that affect rumen microbial protein production
1) rumen NH3 levels
2) available energy
3) AA/peptides
226
How does an acidic rumen affect microbial protein synthesis?
suppresses it
227
SF22 effect on microbial N
b/c of rapid production of VFA = decrease in rumen pH
228
T or F: rumen NH3 concentration is very dynamic
T
229
T or F: forages are quite high in ammonia
T
230
T or F: a more fermentable carb = more stable ammonia production in rumen
T
231
rumen dilution rate
proportion of total volume leaving the rumen per hour
232
faster rumen dilution rate = ( ) outflow of microbial protein
more efficient
233
2 reasons why a faster rumen dilution rate causes a greater rate of outflow of microbial protein
1) protozoa
- faster = less opportunity to eat bacteria = more will reach small intestine
2) keep more bugs in rumen = can support growth of new organisms
234
protozoa make up (%) of rumen microbial mass
20-70%
235
protozoa make up (%) of total rumen N
10-40%
236
what % of rumen protozoa wash out to lower gut
20-40%
237
T or F: protozoa have small contribution to metabolizable protein
T
238
2 main microorganisms responsible for protein degradation
1) protozoa
2) bacteria
239
how often do bacteria double their numbers in the rumen?
every 60 mins
240
how often do protozoa double their numbers in the rumen?
10-60 hours
241
T or F: population density of protozoa are lower than bacteria
T
242
2 main problems with protozoa
1) not providing AA to the animal by staying in the rumen
2) using up rumen energy
243
2 ways protozoa remain in the rumen
1) stick to feed particles
2) attach to rumen epithelium
244
defaunation of protozoa ( ) rumen N efficiency
improves
245
what is the universal response to when protozoa are not present in the rumen?
rumen ammonia & N concentration decreases
246
what will happen to fiber digestion if there is no protozoa in the rumen?
it will decrease bc they are important for fiber digestion
247
2 functions of protozoa in the rumen
1) fiber digestion
2) energy
248
how do young ruminants establish a protozoa population?
cross inoculation from staying on dam
249
why do feedlot animals not have protozoa in their rumens?
high concentrate diet makes protozoa eat too much start and then they explode
250
T or F: unsaturated fats are toxic to protozoa
T
251
T or F: ruminants have requirement for microbial protein
T
252
3 factors that influence the extent of rumen degradation
1) protein structure
2) rumen passage rate
3) rumen pH & diet type
253
how do denatured proteins impact digestibility in monogastrics vs ruminants
monogastrics: uncoils & makes more accessible to enzymes
ruminants: reduce solubility in rumen fluid = reduces degradation
254
what makes good sources of RUP?
proteins coiled amongst themselves = lowers solubility
255
animal proteins are ( ) undergradable in the rumen compared to plant proteins
more
256
why are animal proteins less degradable in the rumen?
high in disulfide linkages = less soluble in rumen = less degradable
257
4 factors that limit the use of animal proteins in the diet
1) cost
2) availability
3) consumer perceptions
4) CFIA regulations
258
why can meat/bone meal not be fed to ruminants
bc of mad cow disease
259
a reduction in particle size = ( ) degradation
improved b/c increases surface area
260
optimal pH for proteases
5.5-7
261
acidic rumen conditions ( ) protein degradation/ why?
decrease, microorganisms responsible for protein degradation are sensitive to acidic conditions
262
2 advantages of lowering protein degradation in the rumen
1) lower ammonia production
2) increase rumen by pass protein
263
fermentation is slowed when protein degradation is
decreased
264
T or F: mature cows on pasture have no requirement for RUP
T
265
low protein diets depend on ( ) to provide N for microbial protein synthesis
urea recycling
266
2 methods of ammonia absorption
- do they use NH3 or NH4
1) passive diffusion (NH3)
- across rumen wall into bloodstream
2) potassium channels (NH4)
- cannot freely diffuse so must use potassium channels
267
NH3 vs NH4
NH3- ammonia
NH4- ammonium
268
3 factors that impact ammonia absorption from the rumen
1) rumen ammonia levels
- higher levels = more absorbed
2) ATP supply
- more ATP = lower ammonia concentration
3) rumen pH
- more alkaline pH = more absorption bc ammonia exists in NH3 form = passive diffusion is more rapid
269
3 fates of blood urea
1) urine
2) milk
3) liver
4) saliva
270
a high fiber diet will ( ) the amount of urea recycled via saliva
increase
271
2 transporters that secrete urea directly into rumen via rumen wall
1) urea transporters
2) aquaporins
272
why is ATP required for urea use in the rumen
protozoa cannot use urea as a source of N so bacteria need ATP to drive this process
273
as CP increases, the amount of urea that is recycled ( )
decreases
274
what % of protein is in a ruminant diet
14-16%
275
T or F: more N in the diet will decrease urea recycling
T
276
T or F: high ammonia concentration in the rumen has inhibitory effects on urea recyling
T
277
impacts on urea recycling in high vs low blood urea concentrations
high= facilitate movement of urea into the blood
low= less urea moved
278
T or F: any microbial protein production in large intestine will not provide energy
T
279
what animals will benefit from microbial protein production in the large intestine
rabbits -> coprophagy
280
2 disadvantages to rumen protein degradation
1) rumen microbes are proteolytic = degrade any N compounds = waste
2) most dietary N is absorbed as NH3, not as AA = not useful to animal
- also need to detoxify via ureagenesis which costs ATP
281
monogastric vs ruminant source of essential AA
monogastrics: dietary protein
ruminants: microbial protein + RUP
282
a-ketoglutarate is the alpha-keto acid of
glutamate
283
T or F: ruminants do not have dietary requirement for essential amino acids
T- required but do not have to be supplied in the diet
