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131 Cards in this Set
- Front
- Back
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Protein quality depends on what three things?
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Depends on essential AA content
depends on digestibility depends on evaluation of protein quality |
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T/F there is just one way in which to assess protein quality
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FALSE, there is NOT just one way
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what are the 4 ways we evaluate protein quality?
what is the 1 way we assess protein needs? |
evaluate protein quality:
1. amino acid score 2. Protein efficiency ratio (PER) 3. biological value (BV) 4. net protein utilization (NPU) assessing protein needs 1. nitrogen balance |
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amino acid score and equation
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calculates the essential AA composition of food compared to a reference protein (usually egg whites)
% AA score = (content of each essential AA in food protein looking at (mg/g) / content of each essential AA in reference protein (mg/g)) x 100 The lowest % found of an essential AA is the LIMITING AA; this becomes the score for the whole protein "you are only as good as your weakest player" |
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Protein efficiency ratio (PER) and equation
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measures weight gain of a growing animal and compares it to the animal's protein intake
PER= gain in body weight (g) / (g) of protein consumed used in food labels for infant formulas and baby food a limitation is that body weight gained could be from fat OR muscle mass |
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Biological Value (BV) and equation
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measures efficiency in supporting body's needs
a given protein is fed as the sole protein in the diet and nitrogen RETAINED is measured from a given amount of nitrogen ABSORBED a BV of 100 means 100% retention BV = (Nitrogen retained / Nitrogen absorbed) x 100 measure retained through fecal and urine losses measure absorbed through only fecal losses a limitation is that it doesn't calculate nitrogen from INSENSIBLE LOSSES (losses of nitrogen from hair and nails) |
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Net Protein Utilization (NPU) and equation
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amount of nitrogen retained from a given amount eaten (consumed)
NPU = (N retained / N consumed) x 100 measures the WHOLE carcass |
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Nitrogen Balance
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nitrogen inputs vs. outputs <-- AVG healthy adult
equilibrium --> (input = output) positive balance --> (input > output) - retaining more than excreting negative balance --> (input < output) - excreting more than retaining |
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what people are at risk for positive nitrogen balance?
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growing infants and children
pregnant women weight lifters |
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what people are at risk for negative nitrogen balance?
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people with burns and injury
people with infection requires a lot of protein to heal, so we want to change this Intake < Output to equilibrium |
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how do you calculate grams of protein into grams of nitrogen (if a patient is given 80g of protein, how many grams of nitrogen is that?)
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protein is 16% nitrogen
80g protein (.16) = 12.8g N OR 80g protein / 6.25 = 12.8g N |
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what happens in the mouth in terms of digestion of protein?
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NOTHING chemically, but still mechanically (chewing)
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where does the primary digestion of protein take place
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in the stomach
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what 2 things (a hormone and a neuropeptide) create HCL?
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Gastrin (hormone)
Gastrin releasing peptide (GRP) (neuropeptide) |
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what cells is HCL from?
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parietal cells
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what does HCL do in the stomach?
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denatures (uncoils) protein (quaternary, tertiary, and secondary, NOT primary)
kills bacteria in the food activated pepsinogen |
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what is the term for the inactive form of an enzyme
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zymogen
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what is the active form of pepsinogen
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pepsin
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what cells do pepsin come from?
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chief cells
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what are the end products of protein digestion in the stomach?
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smaller polypeptide (still large, just smaller than the protein)
oligopeptides free amino acids |
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what are endopectidases and where are they located?
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they cleave peptide bonds INSIDE the protein, polypeptide, or oligopeptide
they are located in the stomach |
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what are exopectidases and where are they located?
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they cleave peptide bonds off the END of the protein, polypeptide, or oligopeptide, generating free AAs
they are located in the small intestine |
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is pepsin an endopectidase or an exopeptidase?
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endopectidase
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T/F enzymes are secreted in the inactive form and need to be activated
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TRUE
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T/F there are endopectidases and exopeptidases in the stomach. this is why free AAs are formed
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FALSE, exopeptidases are NOT in the stomach. free AAs are cleaved due to MECHANICAL functions (churning)
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in a protein structure, there is a ___-terminal end and a ___-terminal end
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N-terminal end and C-terminal end
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what 2 hormones are made in the small intestine and where do they travel to?
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secretin and CCK
they travel to the acinar cells of the pancreas |
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what 5 zymogens are released from the pancreas and travel to the small intestine to be activated?
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trypsinogen
chymotrypsinogen procarboxypeptidase A & B proelastase collagenase |
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what are the functions of proelastase and collagenase?
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used in digestion of elastin and collagen in proteins
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trypsinogen can become what by which two enzymes?
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trypsinogen-----> trypsin
*enteropeptidase *trypsin |
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trypsin is an endopectidase or exopectidase?
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endopectidase
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T/F enteropeptidases are brush boarder enzymes and endopectidases
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true
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trypsin is an (exopeptidase/endopeptidase)
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endopeptidase
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what happens when there is no more need for trypsin due to an increased concentration?
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NEGATIVE FEEDBACK - prevents the pancreas (acinar cells) from secreting trypsin
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chymotrypsinogen ------> ?
* ?? |
chymotrypsinogen ------> chymotrypsin
* trypsin |
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chymotrypsin is an (exopeptidase/endopeptidase)
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endopeptidase
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procarboxypeptidase A & B ------> ?
* ?? |
procarboxypeptidase A & B ------>carboxypeptidase A & B
*trypsin |
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carboxypeptidase A & B is an (exopeptidase/endopeptidase)
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exopeptidase
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which terminal end of the protein does carboxypeptidase A & B cleave at?
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at the c-terminal end
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which mineral is carboxypeptidase A & B dependent on? what does this mean if you don't get enough zinc in the diet?
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it is zinc-dependent
if zinc deficient, protein can't be metabolized. this influences growth and development |
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what do aminopeptidases work on?
where are they located? which end of the protein do they work on? |
work on oligopeptides
BB enzymes works on the N-terminal end of the protein |
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what is the function of di and tripeptidases?
where are they located? |
they cleave di and tripeptides (if its a tripeptide, a free AA is cleaved and then the dipeptide is cleaved)
BB enzymes |
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which enzymes are of the greatest concentration?
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both di and tripeptidases
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what are the end products of protein digestion in the lumen of the SI? what are their ratios of which absorption occurs?
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dipeptides
tripeptides free AA di and tri are 2/3, while free AAs are 1/3 |
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what takes AA from the lumen into the enterocyte?
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a carrier
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what system determines if an AA is carried across the BB by a sodium dependent process or independent?
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lettering system
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which AAs are carried across the BB by sodium dependent process?
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uppercase except for "L"
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which AAs are carried across the BB by sodium independent process?
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lower case AAs
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what are the cytoplasmic peptidases in the cytosol of the enterocyte?
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dipeptides
tripeptides |
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ultimately, where are free AAs mostly?
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in the blood
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what are the three key points about absorption in the enterocyte?
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1) competition between AAs for carriers/uptake
2) essential AAs are absorbed faster than non-essential AAs 3) peptides are absorbed faster than individual AAs and by different receptors |
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what do AAs and peptides cross to get from the enterocyte to the blood?
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BLM (basolateral membrane)
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the blood is also known as the ______ system
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vascular system
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where are the contents in the blood headed to?
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to the liver
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when levels of AAs are low in the blood, what process is used to transport them from the enterocyte?
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a sodium dependent process is used
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how do AAs cross the BLM?
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diffusion and sodium independent transport (at normal physiological levels of AAs)
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what are the 5 fats of the AAs in the enterocyte?
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1) oxidized for energy -- glutamine
2) make apoproteins (needed for lipoproteins) 3) make digestive enzymes (ex. peptidases) 4) make hormones 5) make N-containing compounds (glutathione <-- antioxidant) |
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glucogenic AAs
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AAs can be converted into glucose through gluconeogenesis. must come from (come in as) pyruvate or a TCA cycle intermediate (OAA, fumarate, succinate, succinyl coA, or a alpha-ketoglutarate)
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ketogenic AA
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AA converted into ketone bodies and comes from acetyl CoA
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what are the 2 functions of the liver in terms of protein metabolism and function?
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1) synthesize certain proteins so the body can use them (example: albumin- transport protein, way to measure protein status)
2) releases AAs into the blood for other tissues |
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once AAs are released into the blood.. where do they go?
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tissues and organs
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what are the 3 functions of AAs in the tissues and organs?
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1) synthesis replacement tissue (ex. hair, nails, skin, etc. is broken down and re-synthesized)
2) make enzymes (ex. creatine kinase) 3) make nitrogen-containing compounds (ex. creatine--made up of methionine, argenine, glycine) |
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where is creatine produced? processed? sent?
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creatine is produced in the kidneys, processed in the liver (ultimately made), and sent to the muscle
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creatine ------> ?
* ?? enzyme ?? ATP --> ADP or ADP --> ATP?? |
creatine ----> phosphorylated creatine
* creatine kinase ATP ---> ADP |
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phosphorylated creatine ----> ??
*?? enzyme?? ATP --> ADP or ADP --> ATP?? |
phosphorylated creatine ----> creatine
*creatine kinase ADP --> ATP |
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what is the importance of phosphorylated creatine in the muscle?
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for energy (immediate energy system)
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what ratio of phosphorylated creatine is stored to be used later?
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1/2
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at what levels are ATP when this conversion of creatine to PCR and back occurs?
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ATP is low
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T/F body cells can store excess AAs
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FALSE
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AAs can be deaminated or _________?
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transaminated
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deamination
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forms ketoacid
liver converts amine groups which are removed from the AA to urea (ammonia travels to the liver) urea is excreted by the kidneys (urine) |
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what 2 parts does the AA break into in deamination?
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ketoacid (Carbon skeleton)
amine group (NH2) |
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NH2 --> ? or ?
(amine group) |
NH2 -------------> NH3 or NH4
(amine group) (ammonia) (ammonium) |
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T/F all deamination uses dehydratase and PLP
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FALSE, not all deamination uses dehydratase, but all uses PLP
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what is PLP exactly?
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the coenzyme form of vitamin B6
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if a person is B6 deficient, what would be effected?
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the ability to metabolize some AAs would be effected
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in deamination, there is a removal of ________ and a formation of ________
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removal of the amine group and a formation of an alpha-keto acid
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transamination
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forms a new keto acid and a dispensable (non-essential) AA
the way the body makes non-essential AAs from other non-essential AAs or essential AAs (this is transamination reaxtion's PRIMARY purpose) |
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alanine ----> ?
alpha-keto acid ----> ? **both converted using ? and ? is this ketogenic or glucogenic? |
alanine ----> pyruvate
alpha-keto acid (typically alpha-ketoglutarate) ----> alpha-amino acid (typically glutamate) **both converted using PLP and Alanine amino-transferase (ALT)** GLUCOGENIC |
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alanine is AA #?
alpha-amino acid (glutamate) is AA #? pyruvate is alpha-KA #? alpha-keto acid (alpha-ketoglutarate) is alpha-KA #? |
alanine is AA #1
alpha-amino acid (glutamate) is AA #2 pyruvate is alpha-KA #2 alpha-keto acid (alpha-ketoglutarate) is alpha-KA #1 |
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what is the role of ALT in this reaction?
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transfers the amino group from alanine to an alpha-keto acid, usually alpha-ketoglutarate
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what organs is ALT involved in?
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liver/heart function (elevated levels if disease)
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alpha-ketoacid ----> ??
aspartate --------> ?? * ?? and ?? |
alpha-ketoacid (alpha-ketoglutarate) ----> alpha-amino acid (glutamate)
aspartate --------> oxaloacetate * PLP and Aspartate amino-transferase (AST) * |
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oxaloacetate is alpha-KA #?
alpha-keto acid (alpha-ketoglutarate) is alpha-KA #? aspartate is AA #? alpha-amino acid (glutamate) is AA #? |
oxaloacetate is alpha-KA #2
alpha-keto acid (alpha-ketoglutarate) is alpha-KA #1 aspartate is AA #1 alpha-amino acid (glutamate) is AA #2 |
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what is the role of AST in this reaction?
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transfers amino group from aspartate to an alpha-keto acid, usually alpha-ketoglutarate
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what does PLP mean
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peridoxyl phosphate
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what are the 2 fates of AAs in protein metabolism and function?
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1) sent to the liver (urea) to be excreted
2) sent to another compound to make non-essential AAs |
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what are the 5 things the keto acid (carbon skeleton) is used for?
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1) energy generation
2) glucose - glucogenic AA 3) ketone body production - ketogenic AA 4) cholesterol production - leucine is primary in production of cholesterol (make HMG CoA to make cholesterol) 5) fatty acid production (from carbon skeletons alone (comes in as Acetyl CoA) |
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which of the 5 things the keto acid (carbon skeleton) uses is in the fasted/exercise state and which is in the FED state?
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FASTED/EXERCISE STATE
1) energy generation 2) glucose - glucogenic AA 3) ketone body production - ketogenic AA FED STATE 4) cholesterol production - leucine is primary in production of cholesterol (make HMG CoA to make cholesterol) 5) fatty acid production (from carbon skeletons alone (comes in as Acetyl CoA) |
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ATP production from the carbon skeleton is indirect/direct
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DIRECT
AA -----> acetyl CoA |
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T/F protein requirement varies in the life cycle
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true
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what is the AMDR for total kcals of protein?
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10-35% of total kcals should be protein
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what is the RDA for g/kg of body weight for protein?
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0.8g/kg of BW
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T/F most people don't consume enough protein
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FALSE, most people consume too much protein
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what % of total AA requirement should be essential AAs?
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10-15%
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name one (Active form) zinc-dependent enzyme which functions as an exopeptidase
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carboxypeptidase A or B
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the coenzyme _______ is needed for the ALT and AST transamination reactions
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PLP
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what enzyme is activated as a result of the action of enteropeptidase?
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trypsinogen
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HCl secreted from the ________ cells functions to activate pepsinogen secreted from the ______ cells
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HCl secreted from the parietal cells functions to activate pepsinogen secreted from the chief cells
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name the method of assessment of protein quality which has the following formula:
(gain in body weight (g) / grams of protein consumed) x 100 |
protein efficiency ratio (PER)
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define amphibolic pathway and give an example
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an amphibolic pathway is catabolic and anabolic in nature. it not only functions in the oxidative catabolism of CHOs, fatty acids, and amino acids but also provides precursors for many biosynthetic pathways, particularly gluconeogenesis (intermediates like OAA)
example: TCA cycle - catabolic because it handles the breakdown of all the macronutrients, can also be anabolic by providing precursors for biosynthetic pathways like gluconeogenesis |
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CHO can be converted into _______ and _________ of fat; however, only _________ of fat can be converted to CHO.
why? |
CHO can be converted into glycerol (used as glycerol backbone for TG synthesis) and fatty acid components (used in fat synthesis) of fat (TG); however, only the glycerol portion of fat can be converted to CHO.
This is because: 1) PEP ---> pyruvate is IRREVERSIBLE 2) glycerol --> glycerol-3-phosphate *glycerol kinase 3) glycerol-3-phosphate ---> DHAP *glycerol phosphate dehydrogenase * this is a reversible reaction |
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fatty acids cannot be converted to CHO because the _________ reaction is irreversible
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fatty acids cannot be converted to CHO because the following reaction is irreversible:
pyruvate --------> acetyl CoA *pyruvate dehydrogenase * is irreversible |
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because acetyl CoA cannot be converted to pyruvate, it is forced to make other things. what things?
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1) production of energy
2) cholesterol 3) ketogenesis 4) fat synthesis (lipogenesis) NOT GLUCOSE |
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T/F pyruvate --------> acetyl CoA is irreversible
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true
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what are some conversions where CHO can be converted into glycerol?
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1) glycolysis: glucose is phosphorylated into DHAP
2) DHAP --> glycerol-3-phosphate *glycerol phosphate dehydrogenase |
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what are some conversions where CHO can be converted into fatty acids?
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1) glycolysis: CHO --> glucose ---> pyruvate --> acetyl CoA (needed for fat synthesis)
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why can't acetyl CoA fatty acids provide a source of glucose directly?
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because the PDH reaction is irreversible and there is no NET gain of carbons in the TCA cycle if acetyl CoA is the intermediate in which it enters the TCA cycle
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amino acids capable of being converted to glucose are termed _________
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glucogenic AAs
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glucogenic AAs are AAs that form _____ of a _________
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glucogenic AAs are AAs that form pyruvate of a TCA cycle intermediate
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amino acids are capable of generating ketones (acetyl CoA; acetoacetyl CoA) are termed ______________
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amino acids are capable of generating ketones (acetyl CoA; acetoacetyl CoA) are termed ketogenic AAs
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do ketogenic AAs form TCA cycle intermediates?
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no
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what do ketone bodies do?
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they are oxidized: acetoacetate, beta-hydroxybutarate, acetone (fruity breath in diabetic patients)
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the two AAs that are purely ketogenic are _______ and _______. this means they can only form ___, not _____
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leucine and lysine
can only form ketones, not CHO |
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although possible, glucogenic AAs are not readily converted to fat, unless protein supplies a high percentage of ________.
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calories
* in a catabolic state (fasted) * make CHO, not fat * make glucose/energy |
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if liver gluconeogenesis increases, liver lipid and protein synthesis ____________. why?
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decreases because when the cell places priority on synthesizing a particular component, another energy producing material must be catabolized (it is a fasted/exercise state)
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if hepatic lipogenesis increases, glucose is used to make _______ (in the Pentose phosphate pathway) and _____ necessary for converting acetyl CoA to _________
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if hepatic lipogenesis increases, glucose is used to make NADPH (in the Pentose phosphate pathway) and ATP necessary for converting acetyl CoA to fatty acids
some CHO goes into fat synthesis, but most goes into priming the fat synthesis process |
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STUDY 2ND SHEET OF INTEGRATION/METABOLISM!!!
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!!!!!!!
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what hormone is involved in the FED state and is it increased or decreased? what is the major pathway?
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insulin increases
major pathway is glycolysis |
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what is the major pathway in the first 3-12 hours of post-absorptive state? later 12-18 hours of post-absorptive state?
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3-12 hours- glyconeogenesis
12-18 hours- gluconeogenesis |
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what enzyme decreases in post-absorptive state?
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blood glucose decreases because body uses liver glycogen
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what is the key hormone in post-absorptive state?
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glucagon because it targets the liver - slowly releases glucose from glycogen (glycogenolysis)
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in gluconeogenesis, what hormones increase and why?
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epinephrin and nor-epinephrin (in muscle tissue) increase because they are needed to release AAs
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how many hours after eating does early fasting start?
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18 hours
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what is the key player in early fasting and does it increase or decrease?
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gluconeogenesis
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in even later fasting, body uses _____ as the precursor, SOME _______, even SOME ______
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in even later fasting, body uses AAs as the precursor, SOME lactate, even SOME ketone bodies
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what state is lipolysis and ketogenesis involved in?
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early fasting state
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what hormones are involved in early fasting and do they increase or decrease?
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very little glucagon increases, mostly epinephrin and nor-ephin increases, and some cortisol increases
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how long since eating is it when a body is in the starvation stage?
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3 days - a few weeks
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what process decreases, and what process increases in starvation?
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gluconeogenesis decreases, while lipolysis increases to continue to supply energy to the body
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what is the key player in starvation?
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glycerol
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