Unit 2 Review for Test Flashcards
In the malate aspartate shuttle, glutamate is converted to ______ in the mitochondria while aspartate is converted to _____ in the cytosol.
Alpha-ketoglutarate
Oxaloacetate
What compound is used to move the reducing equivalents for NADH from cytosol to mitochondria?
Malate
Pyruvate dehydrogenase kinase catalyzes a reaction that results in which of the following results?
Phosphorylation and inactivation of E1 subunit of Pyruvate Dehydrogenase Complex
All of the following stimulate the release of insulin except:
AA
epinephrine
Glucose
Epinephrine (counter regulatory hormone)
The last cytochrome in the ETC , cytochrome oxidase, passes electrons to O2. It can do this beacuse?
It has a lower Km for oxygen then hemoglobin
- allows it to “pull” the Oxygen from hemoglobin/myoglobin
How many electrons can the last cytochrome in ETC collect for the reduction of oxygen?
4 electrons
The reduction of NAD+ is often coupled to the oxidation of an alcohol. In this reaction NAD+ obtains what from the oxidized compound?
Two electrons as hydride ion
A pyruvate carboxylase deficiency will lead to lactic academia due to what in the mitochondira?
Accumulation of Acetyl-CoA will inhibit the Pyruvate Dehydrogenase so Pyruvate accumulates and turns into lactic acid
-due to lack of oxaloacetate avaliable for TCA and acetyl-CoA
What is the description of the Km and the Vmax of phosphofructokinase-1 in the presence of AMP?
Km is decreased
No change in Vmax
Hydrogen peroxide is generated through what reaction?
Oxidation of a very-long chain acyl CoA
-inside perioxisomes
After oxidation of odd-chain fatty acids, carbon atoms of the fatty acids would be found in what?
Liver and kidneys
The driving force for the citrate synthase reaction, with its large negative Delta G, is what?
Hydrolysis of a high-energy thioester bond
(H20 used to cleave the thioester bond in Aceytl-CoA
The TCA cycle is deemed “cyclic” because of the utilization and regeneration of what?
Oxaloacetate
What is used as a substrate by Alpha-ketoglutarate dehydrogenase
CoAsh
makes Succinyl Co-A
What two compounds are used to transport reducing equivalents across the inner mitochondrial membrane?
Malate and Glycerol-3-P
A freshly prepared mitochondrial suspension is treated with antimycin A. Oxygen and malate are then added to the mixture. After 5 minutes, which components of the electron transfer chain are reduced?
Antimycin A blocks electron flow from Complex III to cytochrome C
Complex 1, CoQ, and complex III are reduced and the complexes after them are oxidized
CO2 production by the TCA cycle would be increased to the greatest extent by a genetic abnormality that resulted in what?
A 50% increase in the concentration of ADP in matrix
ADP is an activator of isocitrate dehydrogenase, which would speed up this reaction and increase flux
Cytochrome c transfers electrons between which of the following ?
Complex III (b-c1) to Complex IV (cytochrome c oxidase)
The formation of double bonds is most commonly coupled to the reduction of _____ because it can accept two electron donors. ____ is usually coupled with the oxidation of alcohols as it can accept one electron donor.
FAD
NAD+
Mechanical work is best described as the conversion of a high energy bond, such as that in an ATP bond, to instigate a ….?
conformational change in a protein
ex: energy required to change the conformation of hemoglobin
The addition of Dinitrophenol (DNT) to the ETC will lead to an increase in O2 consumption, this is an example of ?
Uncoupler
-dissipating the proton gradient across the inner mitochondrial membrane, can not make ATP
Uncoupling of oxidative phosphorylation results in increased ______ consumption and heat production as electron flow and proton pumping attempt to maintain the electrochemical gradient.
Oxygen
This uncoupling protein is found in brown fat and specialized for nonshivering thermogenesis?
Thermogenin
The lower Km for oxygen allows _______ ______ to “pull” oxygen from myoglobin and hemoglobin, additionally it is bound to copper ions that allows for the collection of ____ electrons required for the reduction of oxygen.
cytochrome oxidase
4 (electrons)
In the case of an exothermic reaction, what would Delta G0 be ?
Negative (spontaneous)
Delta S is the change in _____ or an increase in disorder, this value is often negligible.
Entropy (increase in disorder)
Delta H is the change in ____, or heat content.
Enthalpy
- What is Delta G?
Change in gibbs free energy (can be influenced by concentration of substrates and products, temp, pH, and pressure
What is Delta G0?
Energy change starting at concentration of 1M of each product and substrate (different than Delta G0’)
What is Delta G0’ ?
The value for Delta G0 (1M of substrate and product) under standard conditions (25C and pH=7.0)
What does this mean in words:
Delta G = Delta H - T(Delta S)
Change in Gibbs free energy =
Change in enthalpy minus the absolute temperature multiplied by the change in entropy (increase in disorder)
The release of insulin from the pancreatic B-cells is mediated by what process related to calcium?
Increase in intracellular calcium
Insulin stimulates fatty acid synthesis in the liver. These fatty acids are transported to the adipose tissue as ?
VLDL particles
Insulin stimulates all of the following pathways except:
- AA catabolism
- Fatty acid synthesis
- Glycogen synthesis
- Glycolysis
- AA catabolism
- Cortisol is responsible for mobilization of AA from muscle
- Insulin is an anabolic hormone not catabolic
Which GLUT transporter is an insulin insensitive GLUT transporter found primarily on the liver?
- GLUT 1
- GLUT 2
- GLUT 3
- GLUT 4
GLUT 2
-also in kidney, pancreatic B-cell
intestinal mucosa
Where are GLUT 1 transporters found?
-Blood-brain barrier
-Blood-retinal barrier
-Blood (barriers)
Human Erythrocyte
Where are GLUT 3 transporters found?
Brain (neurons)- high affinity
Where are GLUT 4 transporters found?
Adipose
Skeletal
Heart muscle
(insulin sensitive- # will increase in presence of insulin)- high affinity
Where are GLUT 5 transporters found? What makes it different from all the other GLUT transporters?
Intestinal epithelium
Spermatozoa
-ACTUALLY a fructose transporter
What are the main strongly Negative Delta G reactions in TCA?
- Acetyl CoA to citrate
- Isocitrate to A-KetoGlut
- A-KetoGLut to Succinyl CoA
Malate generated by the TCA cycle can be used as a substrate for what process?
Gluconeogenesis
Succinyl CoA generated by the TCA cycle can be used as substrate for what process?
Heme Synthesis
Citrate generated by the TCA cycle can be used as a substrate for what process?
Fatty Acid Synthesis
What two things can Alpha Keto-Glutarate generated by the TCA cycle be used for as a substrate?
AA synthesis
Neurotransmitters (Glutamate)- (GABA)
What 2 BCCA will contribute to the anapleurotic production of Propionyl CoA?
Valine
Isoleucine
What two things will produce Oxaloacetate in Anapleurotic reactions?
Asparate
Pyruvate (by Pyruvate Carboxylase that is activated by Acetyl-CoA)
What are the two most regulated enzymes in TCA ?
Isocitrate Dehydrogenase
Alpha-Keto Glutarate Dehydrogenase
At physiological pH (7.4) carboxylic acids (COOH containing acids) are :
approx 100% dissociated
-pKa of most carboxylic acids is between 2 and 5 so at 7.4pH these acids are nearly fully dissociated
Hemoglobin bound to heme is termed a ______.
Holoprotein
The heme porphyrin ring is required for oxygen binding and it is termed a ?
Prosthetic group
What does a lyase do ?
catalyzes the breaking of various chemical bonds by means other than hydrolysis and oxidation
-often forms new double bond or ring structures
What type of inhibitor best is described by increasing the Km but does not change the Vmax?
A competitive inhibitor
What inhibitor will decrease the Vmax but have no effect on the Km?
Non-competitive inhibitor
does not interfere with substrate binding
Does covalent modification (such as phosphorylation) impact Km or Vmax (kinetics)?
No
-changes enzyme activity by making it active or inactive
What inhibitor will increase Km AND decrease Vmax?
Allosteric inhibitor
competitive inhibitor will only increase Km and not effect Vmax
The activity of an enzyme is increased when the enzyme is phosphorylated on an exposed tyrosine residue. Phosphorylation of the AA is classified by what ?
Covalent modification
What is Protein ubiquitination?
Ubiquitin covalently bonds to proteins to target them for degradation by Proteasome (proteolysis- breaking peptide bonds)
What is an example of a serine threonine kinase receptor?
TGF-beta receptor
-Smad proteins are phosphorylated and activated downstream
In pyrimidine synthesis, uracil can feedback and inhibit what enzyme ?
Carbamoyl phosphate synthase II
A nucleoside contains a ?
nucleobase and a sugar
A nucleotide contains a ?
Nucleobase, sugar, phosphate (all 3)
What are the two first required substrates for the synthesis of purines?
PRPP (5-phosphoribosylpyrophosphate)
Glutamine
In the salvage of purines, Hypoxantine-guanine phosphoribosyl transferase is responsible for converting?
Guanine to Guanosine Monophosphate (GMP)
Hypoxanthine to Inosine Monophosphate (IMP)
PRPP is required for the Pi
Hypoxanthine is converted to xanthine by what ?
xanthine oxidase
What is Lesch Nyhan disease caused by ?
X-linked mutation inherited
- deficiency of enzyme HGPRT (rare)
- impaired kidney function, acute gouty arthritis, self-harm, neurological impairment
How is Lesch Nyhan syndrome treated?
Drug allopurinol (purine analog) used to control excessive amounts of uric acid (no effect on neurologic or behavior problems)
What does Xanthine oxidase do ?
catalyze:
oxidation of hypoxanthine to xanthine
then
oxidation of xanthine to uric acid (toxic)
Histone acetylation has what impact on the super structure of DNA?
Decreases the association of DNA and histones (decreases positive charge on lysine within histones. DNA is negatively charged)
DNA joining complexes utilize which class of histones?
H1
H2A, H2B, H3 and H4 are all used as nucleosome cores for histones
Which polymerase is responsible for removing RNA primers during DNA replication?
RNaseH (eukaryotes)
or Polymerase 1 (prokaryotes)
Histones have an abundance of what 2 AA?
Lysine (positive)
Arginine (positive)
- What enzyme will remove supercoil twists into circular DNA?
- What will seperate the DNA strand?
Topoisomerases
Helicase
Which DNA polymerase is the primary and which is the one that reads the fragments?
DNA poly III = primary
DNA poly 1 = reads okazaki fragments
DNA Polymerase will only read DNA in what direction?
synthesize nucleotides in what direction?
Reads: 3’ to 5’
Synthesizes: 5’ to 3’ (because Polymerase can only act on 3’-OH to add free nucleotides)
DNA damage resulting in large bulky distortions of the DNA helix are repaired by what mechanism?
Nucleotide excision repair (very important function)
DNA damage of small areas are repaired by what?
Base excision repair
When is Homologous repair used typically in DNA repair?
Nucleotide sequences are exchanged between two similar or identical molecules of DNA
-harmful breaks on BOTH strands of DNA (double-strand breaks)
What is added to the 3’ end of many eukaryotic tRNA’s after transcription and is required for the ability of the tRNA to carry AA?
Trinucleotide CCA
What is the eukaryotic equivalent of the prokaryotic Prinbow box?
Goldstein-Hogness (TATA) box
What are the three different blotting techniques and what is each one used to evaluate?
Northern blot-RNA
Southern blot-DNA
Western blot -Protein
In Electrophoresis, DNA segregate based on molecular weight and charge, what does that mean for the small fragments?
Small fragments travel furthest toward the far end positive electrode
(DNA is negatively charged)
Synthesis of tyrosine requires which what vitamins or cofactors?
(BH4) Tetrahydrobiopterin
-required for ring hydroxylation reactions
What does Phenylalanine hydroxylase do ?
Converts Phenylalanine to Tyrosine
- addition of OH group(hydroxyl)
- requires BH4 cofactor
What happens if a deficiency of Phenylalanine hydroxylase ?
Inherited disease variable severity
-most severe=phenylketonuris(PKU)- sever mental retardation, microencephaly
Classical PKU is an ______ recessive disorder, with defiiency of what enzyme (needs rr) that causes ?
autosomal
Phenylalanine hydroxylase
Accumulation of Phenylalanine in blood and brain (can’t be converted to Tyrosine- precursor for neurotransmitters)
PKU can present due to what two causes ?
BH4 (tetrahydrobiopterin) deficiency or Phenylalanine hydroxylase (classic PKU-more severe)
Metabolism of glycine requires what vitamin or cofactor?
Tetrahydrofolate (THF)
All transamination reactions require what vitamin or cofactor?
Pyridoxal Phosphate (PLP)
Ketogenic AA are metabolized to which of the following compounds:
- Oxaloacetate
- Acetyl-CoA
- Pyruvate
- Fumarate
Acetyl-CoA
-if AA is fully metabolized to AcetylCoA it does not provide excess carbons to generate glucose through gluconeogenesis
What are Glucogenic AA metabolized to ?
Glucose
Ketogenic will make Acetyl-coA
Who has higher Km and Vmax, Glucokinase(liver) or Hexokinase?
What is Glucokinase associated with?
Glucokinase has Km about 100 times higher and a higher Vmax than Hexokinase
- Glucokinase with GLUT2 transporters and regulation of Insulin release - can handle large amounts of Glucose in blood without over or under-reacting
Where does NADH regulate Glycolysis and how?
NADH will allosterically inhibit Pyruvate Dehydrogenase complex in the Mitochondria
(reduces conversion of Pyruvate to AcetylCoA)
Where does Fructose-2,6 BisP regluate Glycolysis ?
It activates and increased the activity of Phosphofructokinase 1 enzyme
-will increase conversion of Fructose 6-P to Fructose 1,6 BisP
Where does Fructose 1,6 BisP regulate Glycolysis ?
ONLY IN LIVER - increased activity of Pyruvate Kinase
- increased conversion of PEP to Pyruvate
How does AMP influence Glycogen and Glycolysis ?
Muscles contract- ATP to ADP
Adenylate Kinase -ADP to AMP
AMP will directly stimulate glycogenolysis to provide fuel - allosterically activates Glycogen phosphorylase b into phosphorylase a (active)
AMP stimulates glycolysis by activating phosphofructokinase-1
