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183 Cards in this Set
- Front
- Back
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What is the dissociation constant of water? |
1.8 x 10^-16 |
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What are the biological buffers? |
* Phosphate * Bicarbonate * Proteins |
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What are the components of a buffer? |
A week acid and the conjugate base. |
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What is Ka? |
The Ka is the ionization constant of an acid.
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What is pKa? |
The pKa is the negative log of Ka. It is the pH at which 50% dissociation occurs. |
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What is pH? |
It is the negative log of the concentration of Hydrogen ions present in a solution. |
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What is the [OH] or [H+] concentration if given the molarity of a solution of strong acid or base? |
If the concentration of a strong base or acid is given, then the concentration of Hydroxide or Hydrogen ion is equivalent to that of the concentration of the base or acid. |
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What are zwitterions? |
All amino acids are zwitterions. At physiologic pH (7.4), the amino acids are zwitterions. Amino group is positively charged and the carboxylate is negative charged. |
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What is glycosylation? |
Glycosylation is the reaction in which a carbohydrate is attached to a hydroxyl or other functional group of another molecule. It increases the stability of the protein. |
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What is lipidation? |
Lipidation is the addition of hydrophobic molecules to a protein or chemical compound. |
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What is the pKa of Aspartate? |
It is part of the acid amino acids. pKa of 3.9. |
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What is the pKa of Glutamate? |
It is part of the acid amino acids. pKa of 4.1. |
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What is the pKa of Histidine? |
It is part of the Basic amino acids. pKa of 6.0 |
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What is the pKa of Lysine? |
It is part of the Basic amino acids. pKa of 10.5 |
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What is the pKa of Arginine? |
It is part of the Basic amino acids. pKa of 12.5. |
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What is the pKa of Cysteine? |
It is part of sulfur containing amino acids. pKa of 8.4 |
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What is the pKa of Tyrosine? |
It is part of the aromatic amino acids. pKa of 10.5 |
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What is the pKa of the Carboxyl group of an amino acid? |
Approx. pH 1.8. If environmental pH is higher then it is ionized. |
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What is the pKa of the Amino group of an amino acid? |
Approx. pH 9.3. If environmental pH is higher then it is ionized to NH2. |
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What is the Ka and Kd of Myoglobin? Where in the body can it be found? |
Myoglobin has a high Ka and a low Kd. An enzyme with a high Ka and a low Kd will bind ligand tightly. It is found in the heart and skeletal muscle and the binding is simple/ first order.
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Amino acids join together in what type of reaction to form a primary sequence? |
Condensation reaction. |
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Describe the properties of amino acid Histidine. |
* Histidine has a pKA of 6.04. It acts as a strong base in physiological pH. * It can be ligand for Zinc or Iron. * The two N atoms on the ring can be a nucleophile or an electrophile depending on which is protonated. **It is integral for the oxygen binding to hemoglobin. |
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Describe the properties of Glutamine. |
* Part of the amide amino acids. * Carries ammonia within the cell. |
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Describe the properties of Glutamate. |
*Part of the acid amino acids. It is charged. * Neurotransmitter * Used for the synthesis of other amino acids. * Used to make glutathione, which is a tripeptide of glutamate, glycine, and cysteine. It is a reducing agent in red blood cells. |
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Describe the properties of Alanine. |
* Part of the aliphatic amino acids. Non-polar, hydrophobic. * Involved in the Alanine-Glutamine shuttle in muscle * Caries ammonia **Deaminated to form pyruvate |
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What are the amino acids that can be phosphorylated? |
* Serine (acid) * Threonine (acid) * Tyrosine (aromatic) |
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Tyrosine is the precursor to what? |
* Neurotransmitters * Dopamine |
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Describe the properties of Cysteine. |
* Cysteine forms disulfide bonds * Increases structural integrity of proteins |
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Describe the properties of Methionine. |
* Translation start amino acid * Can be metabolized to homocysteine |
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What happens if there is a mutation in a primary structure or improper folding? |
* This can impact both structure and function. * Amyloids. |
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What are the properties of Tertiary Structure? |
* Tertiary structures are the association of secondary motifs or structures. * Include actin fold * Nucleotide binding fold |
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What are the properties of Quaternary Structure? |
* Quaternary Structure are the association of individual polypeptide chains (dimer, tetramer, or oligomer) * Can be hetero or homo meric. |
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What is the difference between apoprotein vs. holoprotein? |
Apoprotein are proteins lacking heme groups. Holoprotein are proteins with heme groups. |
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What type of cooperativity does myoglobin show? |
Non-cooperative |
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pH is considered what type of effector of O2 binding? |
It is considered an allosteric effector. |
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What are Transferases? |
Transferases is a class of enzyme that catalyzes the transfer of a specific functional group between molecules. They can be kinases that transfer phosphate groups, usually from ATP to another molecule (such as hexokinase and glucokinase, that phosphosphorylate glucose and protein kinases, that phosphorylate protein hydroxyl groups.) |
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What are acyltransferases? |
They are transferases that transfer fatty acyl groups. |
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What are hydrolases? |
They are hydrolysis reactions that refer to the cleavage of bonds by the addition of a water molecule. |
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What are Caspases? |
They are involved in cleaving peptide bonds, under the umbrella of Hydrolases. They are key mediators of apoptosis. |
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What is the protease BACE? |
BACE is an aspartyl protease involved in the amyloid peptide generation of Alzheimer's disease. |
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What is the protease Matrix metalloproteinases? |
Matrix metalloproteinases are a family of enzymes that are responsible for the degradation of extracellular matrix components such as collagen, laminin, and proteoglycans. |
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What are Serine Protease and what are examples of them ? |
Chymotrypsin is a member of the serine protease superfamily, enzymes that use a serine in the active site to form a covalent intermediate during proteolysis. |
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What are Lyase? What are examples? |
This is a class of enzymes that are involved in cleaving bonds by means other than hydrolysis or oxidation. Aldosases and Thiaolases. |
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In glycolysis, fructose 1, 6-biphosphate are cleaved by what enzyme? |
Fructose 1, 6-biphosphate are cleaved by aldolase. |
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What type of enzyme is pyruvate carboxylase? |
It is a ligase and it is a key enzyme in gluconeogenesis. |
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Thiamin phosphate is an example of what type of cofactor? |
It is an example of the activation-transfer coenzymes. Other examples of this are CoA, biotin, and PLP. |
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NAD+ and flavin adenine dinucleotide (FAD) are what type of cofactors? |
These cofactors are for oxidation reduction reactions. |
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What is initial velocity and what is the effect of substrate concentration on enzyme velocity for a single subunit enzyme ? |
The rate of all enzymes depends on substrate concentration. Enzymes exhibit saturation kinetics; their rate increases with increasing substrate concentration [S], but it reaches a maximum velocity (Vmax) when the enzyme is saturated with substrate. |
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What is the difference between glucokinase and hexokinase? |
Hexokinase catalyzes the first step in glucose metabolism in most cells. It transfers a phosphate from ATP to glucose to form glucose 6-phophate. It has a low KM/ Low VMax. Hexokinase can be found in the brain. The low Km means that it can produce glucose even at low concentrations and the low Vmax means it can become easily saturated and can't sequester glucose. Glucokinase is found in the liver and pancreas. It has a high Km when meant it is produced only at high concentrations and high Vmax means it can store glucose. |
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What does high and low Km mean? |
An equation with a low Km value indicates a large binding affinity, as the reaction will approach Vmax more rapidly. An equation with a high Km indicates that the enzymes does not bind as efficiently with the substrate, and Vmax will only be reached if the substrate concentration is high enough to saturate the enzyme. |
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What happens to the Km and Vmax when a competitive inhibitor is involved? |
With a competitive inhibitor, The Km is increased and the Vmax is left unchanged. |
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What happens to the Km and Vmax when a noncompetitive inhibitor is involved? |
A Km is unchanged, but the Vmax is decreased. |
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What is proteolysis? |
Although many enzymes undergo some cleavage during synthesis, other enter lysosomes, secretory vesicles and are secreted as proenzymes, which are precursor proteins that must undergo proteolytic cleavage to become fully function. Unlike most other forms of regulation, proteolytic cleavage is irreversible. |
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Movement of ammonia from an amino acid to an alpha-keto acid involves a family of enzymes categorizes as? |
Transferases. Specifically Aminotransferase. |
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What are the three different domains that are exposed and necessary for steroid hormone receptors to functions as a transcriptional modulators? |
* Transactivation Domain * Ligand Binding Doman * DNA Binding Domain |
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What are phosphatidylserine, phosphatidylethanolamine, and phosphatidylinosolitol in the plasma membrane? |
They can function as signaling moiety. They can be cleaved off through signaling reactions and function as second messengers. They can also provide a charge to the inner leaflet, which is primarily negative because the phosphatidylserine. This charge contributes to membrane potential and is important for the binding of proteins to the inner membrane. |
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What are Ankyrin, Actin, Spectrin?
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Anchor proteins that give the membrane flexibility. In the case of RBC it helps not coagulate.
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What is the difference between primary active transport and secondary active transport? |
Primary active transport is used to concentrate a compound. Secondary active transport is used to generate a gradient. |
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What are the immune system chemical messengers? |
Cytokines and chemokines. |
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In the presence of cortisol, what dissociates from the glucocorticoid receptor? |
Heat shock protein (HSP). |
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Grb2 has what type of domains? This protein is used in what cell surface receptor pathway? |
SH2 domains and Grb2 is used in the Tyrosine Kinase and the Insulin Receptor Kinase. |
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After the Grb2 protein binds to a phosphorylated tyrosine kinase domain, what protein is recruited? What happens after? |
The SOS-RasGDP is recruited. The Ras protein exchanges the GDP for GTP and bind to the Raf protein to make the Ras-Raf complex. This initiates the MAP kinase pathway. |
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Once phosphatidylinositol is phosphorylated to _______, what kinase phosphorylates it further? |
Phosphatidylinositol is phosphorylated to PI-4,5 bisphosphate. After PI-4,5bisphosphate can be further phosphorylated to PI-3,4,5 triphosphate by PI 3 Kinase. That allows it to becomes a docking site for pleckstrin homology domains. |
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If PI-4,5 bisphosphate is not phosphorylated, what other pathway can it follow? |
It can be cleaved by PLC (phospholipase C) into DAG and IP3. |
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True or False. Jak-STAT proteins autophosphorylate once it has interaction with a ligand. |
False. Ligand binding leads to dimerization of the receptor and JAK binds. JAK phosphorylates each other and the receptor. |
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Serine-threonine kinase forms what type of dimers? What phosphorylates the receptor? |
Once a Transforming Growth Factor Beta (TGF-B) binds to type 2 receptor, the activated type 2 receptor recruits a type 1 receptor, which forms a heterodimer. The Type 2 receptor phosphorylates the type 1 serine domain.
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What proteins do the Serine-Threonine kinase ultimately recruit? |
The r-Smad, which makes a heterodimer with the Co-Smad. |
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Once a hormone binds to a 7-helix receptor (GPCR), a conformational change happens where? |
A conformation change happens in the G-protein on the cytosolic side, specifically G-alpha protein bound to GDP. GDP is released and exchanged with GTP. |
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What activates adenylyl cyclase? What does adenylyl cyclase produce? |
An alpha-G protein that is bound to a GTP activates adenylyl cyclase, once the G-protein is dissociated. Adenylyl cyclase produce cAMP. |
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What does phosphodiesterase do? |
It can degrade cAMP and terminate any related cascade signal. |
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What proteins make a nucleosome core? |
* H2A * H2B * H3 * H4 |
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What links nucleosome cores? |
H1 histone |
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What does acetylation do to histone? |
Since histones have larges amounts of lysine and arginine, which have positive charge, acetylation reduces the positive charge that would release DNA. |
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What are the purine nucleotide? |
Adenosine and Guanine |
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What are the pyrimidines? |
Cytosine and Thymine/Uracil. |
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Purine Synthesis: What is required before the first committed step of Purine synthesis? |
Since purines are built on a ribose base, an activated form of ribose is used to initiate the purine biosynthetic pathway. 5-Phosphoribosyl-1-pyrophosphate (PRPP) is synthesized from ATP and a ribose 5'phosphate. The enzyme required for this step is PRPP synthetase. |
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What regulates PRPP synthase? |
It requires Mg 2+ as a cofactor. It is inhibited by purine ribonucleotides. (AMP, GMP, etc) |
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Purine Synthesis: What is the first committed step in purine synthesis? |
The conversion of PRPP to 5-phosphoribosyl 1-amine with the use of the enzyme Glutamine Phosphoribosyl Amidotransferase (GPRT). |
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What regulates Glutamine Phosphoribosyl Amidotransferase (GRPT)? |
The presences of BOTH GMP and AMP at high levels inhibit the enzyme. It is activated by PRPP. |
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Purine synthesis: After 5-Phosphoribosyl 1-amine is synthesized, what is the next step? |
After a series of reactions, Inosine Monophosphate (IMP) is synthesized. |
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Where is IMP (Inosine Monophosphate) found?
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It is not found on DNA. It is found on the anticodon of tRNA and it is critical for wobble base pairing. |
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Purine Synthesis: After IMP is produced, what is the next step of purine synthesis? |
With IMP available, either GMP or AMP can be synthesized. |
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Purine Synthesis: How is AMP produced? |
With Inosine monophosphate (IMP) available, the production of AMP additionally requires GTP, Aspertate (acid amino acid), and Adenylosuccinate synthase. |
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What is Adenylosuccinate synthase and how is it regulated? |
Adenylosuccinate synthase is an enzyme required for the production of AMP from IMP. It is regulated by the production of AMP. |
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Purine Synthesis: How is GMP produced? |
With Inosine Monophosphate available, the production of GMP additionally required ATP, Glutamine (amide amino acid), and IMP dehydrogenase. |
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What is IMP dehydrogenase and how is it regulated? |
IMP dehydrogenase is an enzyme used for the synthesis of GMP from IMP. It is regulated by the production of GMP. |
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Why are purines recycled? |
Purines are recycled because they are bicyclic molecules. They cannot be fully cleaved or broken down. They are recycled.
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If I wanted to recycle AMP to Adenosine, what enzyme would I use? |
5'-nucleotidase. |
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If I use AMP deaminase on AMP, what is my product. |
IMP |
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If I use adenosine deaminase on adenosine, what is my product? |
Inosine. |
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If I want AMP from adenosine, what enzyme would I need? |
Adenosine Kinase and ATP. |
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If I use 5'-nuceloside on IMP, what is my product? |
Inosine. |
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What is HGPRT and what is it's importance? |
HGPRT is the hypoxanthine-guanine phosphoribosyltransferase. It is responsible for adding a 5 carbon sugar to Hypoxanthine and Guanine. It is important in the recycle pathway of those bases. |
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What could cause an over production of Guanine and Hypoxanthine? |
Loss of HGPRT (hypoxanthine-guanine phosphoribsyltransfera). |
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What happens if there is an over production of Guanine and Hypoxanthine?
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This will cause an overproduction of Xanthine which in turn will cause an over production of uric acid which causes Gout. |
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What is one way to prevent overproduction of Xanthine and Uric Acid? |
Use the drug Allopurinol to inhibit Xanthine oxidase, the enzyme that produces Xanthine and uric acid. |
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Is folate or any of its derivatives used in the production of purines? |
It is used for the production of IMP, which is a precursor to AMP and GMP. |
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What are the substrates for purine synthesis? |
* PRPP * Glycine (aliphatic) * glutamine (amide) * Aspartate (acid) * THF (tetrahydra folate) |
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Pyrimidine synthesis: What is the first step of pyrimidine synthesis? |
The first step of pyrimidine synthesis is the synthesis of the carbomoyl phosphate, which will be part of the original of the Pyrimidine base ring. Glutamine combines with Bicarbonate and ATP to form the carbomoyl phosphate. The reaction is catalyzed by the enzyme Carbomoyl Phosphate Synthetase II (CPSII). |
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What is Carbomoyl Phosphate Synthetase II (CPSII) and how is it regulated? |
CPSII is the enzyme used to synthesize carbomoyl phosphate, which is the first step of pyrimidine synthesis.
It is activated by the presence of PRPP and inhibited by UTP. |
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Pyrimidine synthesis:
After carbomoyl phosphate is synthesized, what is the next step? |
Once carbomoyl phosphate is present, Aspartate (acid amino acid) is used to closed the ring to created Ortoic acid or Orotate. |
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Pyrimidine synthesis: Once orotate is synthesized, what is the next step? |
With orotate available, PRPP (5-phosphoribosyl-1-pyrophosphate) adds a ring to create UMP.
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What is required to make CTP? What about dCTP? |
An amino group, derived from glutamine, is added to UTP by CTP synthetase. dCTP is synthesized with CTP available and ribonucleotide reductase. |
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What is required to make dTTP? |
Once UMP is synthesized with orotate and PRPP, UMP is phosphorylated to UDP and with ribonucleotide reductase, converted to dUDP. dUDP is not used in DNA, so it is dephosphorylated to dUMP. dUMP with Thymidylate synthase and Folate synthesize dTMP. dTMP is then phosphorylated to ultimately make dTTP. |
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What does Methotrexate do? |
Specifically, it stops the regeneration of folate from dihydrofolate, which is a by-product of the synthesis of dTMP. |
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What does 5-Fluorouracil do? |
Specifically, it inhibits the enzyme Thymidylate synthase, which is used for the synthesis of dTMP from dUMP. |
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What is the rate limiting step of purine and pyrimidine synthesis?
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Folate |
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What is ribonucleotide reductase? |
Ribonucleotide reductase is an enzyme used for the formation of deoxyribonucleotides. |
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What activated Ribonucleotide Reductase? What inhibits it? |
ATP activates Ribonucleotide Reductase. dATP inhibits it. |
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When ATP is bound to Ribonucleotide Reductase, what activity can occur? |
When ATP is bound to Ribonucleotide Reductase, initially the reduction of the pyrimidines (CDP and UDP) to dCDP and dUDP takes places. |
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When ATP is bound to Ribonucleotide Reductase, and dTTP is available and bound to the enzyme, what reaction/product can occur? |
With ATP bound to Ribonucleotide Reductase, as well as dTTP bound to the enzyme, the reduction of GDP to dGDP occurs. |
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When ATP is bound to Ribonucleotide Reductase, and dGTP is available and bound to the enzyme, what reaction/product can occur? |
With ATP bound to Ribonucleotide Reductase, as well as dGTP bound to the enzyme, the reduction of ADP to dADP occurs. |
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During what phase of the cell cycle does DNA replication occur? What happens? |
In the second or S phase of the cell cycle DNA replicates. Throughout the S phase, the synthesis of histones and other proteins associated with DNA is markedly increased. The amounts of DNA and histones both double, and chromosomes are duplicated. Histones complex with DNA, and nucleosomes are formed very rapidly behind advancing replication forks. |
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How many bonds are made between Guanosine and Cytidine? |
Three (3) hydrogen bonds. |
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How many bonds are made between Thymidine and Adenosine? |
Two (2) hydrogen bonds. |
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During DNA replication, what creates primers in prokaryotes? |
During DNA replication in prokaryotes, Primase synthesizes RNA primers. |
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What does DNA polymerase alpha do?
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This is a polymerase in eukaryotic DNA replication and and it synthesizes RNA primers.
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What does DNA polymerase III do? |
This is a prokaryotic polymerase and it does the nucleotide synthesizing during DNA replication. |
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What does DNA polymerase epsilon and DNA polymerase delta do? |
These are eukaryotic polymerases and they synthesize nucleotides during DNA polymerase. Epsilon on the leading strand (3-5) |
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If RNaseH is malfunctioning, what would occur? |
IF RNaseH is malfunctioning, primer removal in eukaryotes would not be removed. |
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What does DNA polymerase I do in eukaryotes? |
Nothing. DNA polymerase I is a prokaryotic polymerase in charge of removing primers. |
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What is the difference between topoisomerase and helicase? |
Helicase unwinds and zips while topoisomerase relieves the strain from unwinding. |
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What does DNA ligase do? |
DNA ligase is responsible for creating phosphodiester bonds using 3' OH and 5' phosphate group. |
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What is the difference between nucleotide excision and base excision? |
Nucleotide excision is large torsional change and base excision is small change. |
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In base excision, glycosylase does what? |
It removes a single base. |
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What is retrotransposase?
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Retrotransposons are similar to transposons except they involve an RNA intermediate. Reverse transcriptase makes a single-stranded DNA copy of the RNA. A double-stranded DNA is then produced that is inserted in the genome of a new location. |
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What does RNA polymerase I transcribe? |
* rRNAs * 28S * 18S * 5.8s |
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What does RNA polymerase II transcribe? |
* mRNA * snRNA |
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What does RNA polymerase III transcribe? |
* tRNAs * 5S rRNA * snRNA |
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Upstream is to the left or right of the transcription start? |
To the left |
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What is the TATA box comprised of? |
It is thymine and adenosine rich region. |
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The 5' cap for mRNA is comprised of what? |
Guanine |
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The 3' poly A tail for mRNA is comprised of what?
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Adenine nucleotides |
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What are some post-translation modification for tRNA? |
The removal of introns and the addition of CAA to the 3' end. |
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Modified bases can found on which RNA? |
tRNA. |
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How is the 80S ribosome synthesized? |
45s rRNA precursor are synthesized as well as a 5s rRNA precursor is synthesized. They interact with proteins to make a 5s + 45s complex. This complex is cleaved into a 20s and 32s+5S complex . The 20s ribosome is converted to 18s, which ultimately makes the 40S ribosomal subunit of the 80S ribosome. The 32s + 5s ultimately becomes the 60S ribosomal subunit of the 80S ribosome. |
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What does Aminoacyl tRNA Synthetase do ? |
The initial step in translation requires the charging of an amino acid onto a tRNA by aminoacyl tRNA synthetase. It is required for the formation of the ester bond onto the tRNA. |
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What is the difference between eEF1A*GTP and eEF2A*GTP? |
Both are elongation factors for the elongation of a polypeptide. eEF1A*GTP is used to catalyze the tRNA with the appropriate amino acid to the A site of the rRNA. eEF2A*GTP is used to catalyze the movement of the amino acid from the P site to the E site. |
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What is the function of Histone acetyl transferase (HATs)? |
Histone acetyl transferase (HATs) transfers an acetyl group from acetyl-coenzyme A (acetyl-COA) to lysine residues in the tail. This reaction removes a positive charge from the epsilon-amino group of the lysine, thereby reducing the electrostatic interactions between the histones and the negatively charged DNA, make it easier for DNA to unwind from the histones. |
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What is microRNA? |
MicroRNAs are small RNA molecules that regulate protein expression at a post transcriptional level. A miRNA can either induce the degradation of a target mRNA, or block translation of the target mRNA. In either event, the end result is reduced expression of the target mRNA. |
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DNA arrangement can be seen in the synthesis of what? |
Antibodies |
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What is the difference between cortisol and thyroid hormone receptors? |
Cortisol hormone receptor are form homodimers that translocate to the nucleus to INCREASE transcription. Thyroid hormone receptor form heterodimers. In the absences of a ligand (T3), the heterodimer binds the a DNA sequence and REPRESSES transcription via HDAC (Histone Deacetylation Domain). In the presence of a ligand, the HAC domain is activated and transcription is ACTIVATED. |
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What are examples of DNA binding proteins? |
* Zinc finger * Leucine zippers * Helix-turn-helix *Helix-loop-helix |
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What is the DNA binding protein that forms a coil through hydrophobic interactions (homo or hetero dimers)? |
Leucine zippers |
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What is the DNA binding protein that is a helix that fits into the major groove, stable monomers, regulate homeobox proteins during development? |
Helix-turn-helix |
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What is the DNA binding protein that forms through hydrophobic interactions, involved in cell differentiation? |
Helix-loop-helix |
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What is the DNA binding protein that binds Zn to generate a small folded domain, 2-6 Zn domains, estrogen and steroid receptor (dimers)? |
Zinc finger |
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What are two examples of post transcriptional processing? |
* Alternative splicing * mRNA editing |
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Is mRNA editing a modification of a base on a pre or post spliced mRNA? |
It is a modification on a post-Spliced mRNA |
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What does glycosylation do? |
It is a post-translational modification. It helps protect from proteolysis, the breakdown of lipids into amino acids. |
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Lipid addition is common to which amino residue?
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Cysteine residue.
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What is the term probe? |
A probe is a labelled fragment that anneals with high levels of specificity. It is a single-stranded polynucleotide of DNA or RNA that is used to identify a complementary sequence on a larger single-stranded DNA or RNA molecule. |
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What are the three (3) basic requirements of plasmids? |
- Ability to self replicate within host (ORI) - Possession of selection marker - Must be capable of being digested |
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If you want to check large DNA expansion or deletions, which blotting procedure would you use? |
Southern Blot, with DNA probe |
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If you want to check for changes in amount or size of mRNA, which blotting procedure would you use? |
Northern Blot, with RNA/DNA probe |
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If you want to check for changes in the amount or size of protein, which blotting procedure would you use? |
Western Blot, with antibody probe |
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What is Phenylketonuria? What are some causes of it? |
Phenylketonuria is the accumulation of Phenylalanine. This occurs when Phenylalanine can not be converted into tyrosine. Mental retardation can occur.
This usually occurs through a deficient enzyme, *Phenylalanine hydroxylase*.
This can also be caused by a BH4 (tetrahydrobiopterin) deficiency. |
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What is Homocystinuria and what are the causes of it? |
Homocystinuria is a deficiency in the production of cysteine. The main cause of homocystinuria is a deficiency of cystathionine Beta-synthase, the enzyme in charge of converting homocysteine into Cystathionine, which ultimately becomes Cysteine. Another cause of homocystinuria is a deficiency of Cobalamin (B12)/Folate and or PLP (B6). Cobalamin and Folate convert Homocysteine into Methionine. PLP (B6) converts homocysteine to cystathionine. |
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What is Maple Syrup Disease? What causes it?
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Maple Syrup Disease is an accumulation of branched-chain a-keto acid, which causes a sweet odor. A deficiency in the a-keto acid dehydrogenase. |
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What does the enzyme dihyropteridine do? |
It regenerates Tetrahydrobiopterin (BH4), which is important for the conversion of Phenylalanine to Tyrosine. |
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What are the essential amino acids? |
Essential amino acids are the amino acids that need to be provided through the diet. PVT TIM HALL * Phenylalanine (aromatic) * Valine (aliphatic, branch) * Threonine (alcohol) * Tryptophan (aromatic) * Isoleucine (aliphatic) * Methionine (sulfur) * Histidine (aliphatic) * Arginine (Basic) (?) * Leucine * Lysine |
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What is the co-factor PLP (B6) used for? |
Transamination. |
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What is the co-factor Cobalamin (B12) used for? |
Methylation |
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What is the importance of BH4 (tetrahydrobiopterin)? |
It is important for conversion of phenylalanine to tyrosine. |
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What is S-adenosylmethinoine (SAM)? |
SAM participates in the synthesis of many compounds that contain methyl groups. It is used in the conversion of Methionine to Homocysteine. SAM is synthesized by from methionine and adenosine triphosphate (ATP). |
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What are the reactions that require cobalamin? |
The conversion of Homocysteine to Methionine. The conversion of Methylmalonyl CoA to Succinyl CoA. |
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What are the intermediates that can enter the TCA cycle? |
* Pyruvate * Oxaloacetate * Glutamate * A-Ketoglutarate * Succinyl CoA |
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Glycine and Folate are used to make what important component in purine synthesis? |
Make the base of the purine. |
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The metabolism of BCAA requires which important co-factor? (Hint: same co-factor used in pyruvate dehydrogenase) |
Thiamine. |
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What can cause Albinism?
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A BH4 deficiency can cause albinism. When Tyrosine can't be converted to Dihydroxy Phenyl Alanine, which is ultimately converted to Melanin.
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What co-factor is required for the conversion of Tyrosine to Dopamine? |
BH4 |
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What co-factor is required for the conversion of Tryptophan to Serotonin? |
BH4 |
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Another name for B12 is? |
Cobalamin |
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Another name for B6 is? |
PLP (pyridoxal phosphate) |
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Alpha-keto acid dehydrogenase complex, important for the conversion of branched chained a-keto acid, contains which important co-enzymes? |
* Thiamine* Also: * Lipoic Acid * Niacin * Riboflavin * FAD |
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What does untreated type 1 diabetes mellitus cause? |
Untreated type 1 diabetes mellitus causes ketoacidosis. |
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The proteolytic digestive enzyme chymostrypin cleaves the peptide bonds formed by the carboxyl groups of *large, bulky uncharged amino acids.* Which amino acid falls into this category? |
The aromatic amino acids. Phenylalanine, Tyrosine, Tryptophan |
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A point mutation in DNA that changes the sixth amino acid in the Beta-Globin chain of hemoglobin from glutamate to valine is what disease? |
Sickle Cell Anemia |
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What is the cystinuria? Ultimately, how is it resolved? |
Cystinuria is an inherited amino acid substitution in the transport protein that reabsorbs cystine, arginine, and lysine. Therefore, urine contains high amounts of these amino acids. Cysteine is less soluble, which is precipitated in the urine to form renal stones. |
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Is the substitution of glutamate for valine in sickle cell hemoglobin a conservative replacement? What about the substitution of an asparate for a glutamate? |
The substitution of a glutamate for a valine is a nonconservative replacement because a negatively charged amino acid is substituted for a hydrophobic branched-chain aliphatic amino acid.
However the substitution of an aspartate for a glutamate is a conservative replacement because the two amino acids have the same polarity and nearly the same size. |
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Two different ligands (A and B) bind to the same receptor on the cell surface. The Kd for a ligand A is 10^-7M; for ligand B it is 10-9M. Which ligand has the higher affinity receptor? |
The association constant (Ka) is equal to the reciprocal of the dissociation constant (Kd). The Ka for ligand A is 10^7M^-1, whereas the ligand B it is 10^9M^-1. Ligand B has the higher affinity for the receptor, by 100-fold as compared to ligand A. |
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What is the Lesh-Nyan syndrome? |
Lesch-Nyhan syndrome is caused by a defective hypoxanthine-guanine phosphoribosyltransferase (HGPRT). In this condition, purine bases cannot be salvaged. Instead they are degraded, forming excessive amounts of uric acid. Individuals with the severe form of this syndrome suffer from mental retardation. They are also prone to chewing off their fingers and performing other acts of self mutilation. |
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Gout is caused by excessive uric acid levels in the blood and tissues. To determine whether a person with gout has developed this problem because of overproduction of purine nucleotides or because of a decreased ability to excrete uric acid, an oral dose of a 15N-labeled amino acid is sometimes used. Which amino acid would be most appropriate to use for this purpose? |
The entire glycine molecule is incorporated into the precursor of the purine nucleotides. The nitrogen of this glycine also appears in uric acid, the prod-uct of purine degradation. 15N-labeled glycinecould be used, therefore, to determine whether purines are being overproduced. |
