BIOCHEM FINAL 3
After the target protein has been degraded, ubiquitin is released as individual units to be further broken down by the body?
F
During fasting, the liver maintains blood glucose through gluconeogenesis where the nitrogen(s) of AAs are converted into glucose?
F
Glutamate is the major amino acid present when muscle (protein) is degraded it is also the major amino acid substrate for gluconeogenesis.
F
Match the amino acid with its catabolism: Histidine: leads to production of a m Tryptophan: leads to formation of serotonin, melato Lysine: leads to the synthesis of carnitine Alanine: can be converted to pyruvate Valine: can be converted to propionyl Coa
.
Match the catabolism of amino acid with type: Glucogenic amino acids: Can be used directly as fuel or converted to Glucogenic amino acids: Alanine and glutamate Ketogenic amino acids: Can be used for synthesi Ketogenic amino acids: Leucine and lysine
.
The pancreas: secretes enzymes and bicarbonate Secretes bile helps primarily in digestion of fats does not aid in the digestive process
A
A 5-year-old boy has had episodic periods during which areas of his skin would develop a rash, which would spontaneously resolve in a week to 10 days. An astute physician told the boy's parents to give him niacin the time this occurred and a high-protein diet, and when they did, the rash resolved in a day or two. A likely disorder that hits child has is which one of the following? Cystinuria Hartnup disease Grave's disease Kwashiorkor disease Phenylketonuria
B
A compound common to the urea cycle and the TCA cycle is: Glutamate Fumarate Oxaloacetate Glutamine
B
When peptides are broken down by peptidases, _____ will be formed. Proteins Fatty acids Amino acids Glucose
C
Bile enzymatically digests fats and related lipids.
F
Ubiquitination involves 3 steps of covalent binding of Ub to proteins: Place the steps in order: 1.Signaling the substrate by covalent att 2.tagged protein by 26S proteasome 3.recycle protein 4.release of free Ub
.
All of the following amino acids are glucogenic EXCEPT: Leucine Alanine Glutamate Phenylalanine
A
Many proteins have regions rich in the amino acids ________, _________, _________, _________ and are called PEST sequences, proteins with those are hydrolyzed by ubiquitin/proteasome phenylalanine, glutamate, serine, threonine proline, glutamate, serine, threonine proline, glycine, serine, threonine phenylalanine, glutamate, serine, tyrosine
B
What is the third step of the urea cycle? From pyruvate via transamination The synthesis of arginosuccinate α-keto acids and ammonia The corresponding α-keto acid
B
Which of the following enzyme reactions takes place during the synthesis of urea from ammonium ion and glutamate? Carbamoyl phosphate + citrulline = ornithine Aspartate + citrulline + ATP = argininosuccinate + AMP + PPi Argininosuccinate = aspartate + arginine CO2 + NH4+ + 2 ADP = carbamoyl phosphate + 2 ATP
B
A 45-year-old make is concerned about his risk of a heart attack since his brother just had a heart attack at the age of 46. His physician orders an HbA1C, lipid panel, and homocysteine level. A reduction in the metabolism of which one of the following amino acids can lead to the elevated homocysteine levels in the blood? Alanine Methionine Phenylalanine Cysteine Glutamate
B?
A 30-year old male has had multiple episodes of sudden, severe pain, redness, and swelling of metatarsophalangeal joint of his great toes. These problems seem to occur after he has had a night out on the town with his friends, when they go barhopping, and the night usually ends with a cab ride home for the group. This problem would also be exacerbated if the man eats which one of the following during his night out? Hamburger Hot dog Liverwurst and potato flakes Nachos and salsa Chicken wings
C
A physician working in a refugee camp in Africa notices a fair number of children with emaciated arms and legs, yet a large protruding stomach and abdomen. An analysis of the children's blood would show significantly reduced levels of which one of the following as compared with those in a healthy child Glucose Ketone Bodies Albumin Fatty Acids Glycogen
C
An infant who appeared normal at birth began to develop lethargy, hypothermia, and apnea (the cessation of breathing) within 24-hours. An analysis of blood components indicated high levels of ammonia and citrulline, and low levels of urea. The most likely defective enzyme in this child is which one of the following? Carbamoyl phosphate synthetase I Orthnithine transcarbamoylase Argininosuccinate synthetase Arginiosunncinate lyase Arginase
C
In liver disease, the transaminase enzymes AST and ALT leak into the blood from damaged liver cells. Both of these enzymes have which one of the following in common? They both transfer ammonia to alpha-keto acids to form amino acids. They both form intermediates of glycolysis from amino acids. They both required thiamine pyrophosphate as a cofactor. They both catalyze irreversible reaction of amino acids to their corresponding alpha-ketoacids. They both convert the reversible reaction of alpha-ketoglutarate to glutamate.
D
Which of the following statements about the urea cycle is correct? Argininosuccinate is lysed to urea and ornithine in the urea cycle. Carbamoyl phosphate supplies both of the nitrogen atoms of urea in the urea cycle. The formation of urea from the urea cycle yields energy. Arginine is hydrolysed to urea and ornithine in the urea cycle
D
Which of the following statements about transamination reactions is correct? Transamination reactions involve ATP hydrolysis Transamination reactions are irreversible Transamination reactions require NAD+ or NADP+. Transamination reactions require pyridoxal-5'-phophate.
D
Amino acid absorption is coupled to the active transport of sodium.
T
Amino acids are absorbed from the lumen of the small intestine by semispecific Na-dependent transport proteins. This process is a cotransport of Amino Acids and Na and is driven by low intracellular Na+ concentration.
T
Chymotrypsin, Elastase and Carboxypeptidases would not be converted from chymotrypsinogen proelastase and procarboxypeptidases without the action of Trypsin?
T
Enzymes involved in the breakdown of peptides into amino acids are called proteases
T
HCl activates pepsinogen to pepsin, lowers pH to denature protein while Pepsin sets the stage for proteases to breakdown peptide bond?
T
In the formation of citrulline, the carbamoyl portion of carbamoyl phosphate is transferred to ornithine by ornithine transcarbamoylase to form citrulline, which is transported to the cytosol.
T
In the second phase of amino acid catabolism the carbon skeletons of the α-keto acids are converted to common intermediates of energy producing metabolic pathways. (The compounds are metabolized to CO2, water, glucose, fatty acids, or ketone bodies).
T
In the stomach, pepsinogen is secreted by chief cells in the stomach and gastric acid secreted by parietal cells.
T
Non-essential amino acids are derived from modifications of metabolic intermediates form glycolysis and the TCA cycle?
T
Proteins that are degraded via the proteasomal complex are tagged via the addition of an ubiquitin signal.
T
Pyruvate can be transaminated to alanine in a transamination catalyzed by alanine transaminase, ALT.
T
Short-term regulation of the urea cycle is by activation of CPSI (the enzyme just prior to the urea cycle) by its required allosteric activator N-acetylglutamate. High levels of "arginine" stimulate production of Nacetylglutamate.
T
The CPS I enzyme of the urea cycle is the first committed step and is allosterically activated by N-acetyl-glutamate?
T
The first two reactions of the urea cycle occur in the mitochondria?
T
The flux of ammonia through the urea cycle is regulated by two factors: availability of substrates and allosteric activation of CPS-I?
T
The main source for all of our digestive enzymes (including proteases) is the pancreas?
T
Trypsin is the pancreatic enzyme responsible for activating all the other pancreatic enzymes?
T
Trypsin, chymotrypsin, and elastase are all serine proteases? True False
T
