Hormones
What's the opposed effects of insulin and glucagon on 2 key enzymes?
Glucagon in fasting states increases cAMP and PKA activity phosphorylating Glycogen phosphorylase and Glycogen synthase leading to increased activity of the former and decreased activity of the latter, thus promoting glucose release to blood stream. Insulin has the reverse effect by phosphatase activity by increased PKG activity.
What is lineweaver-burk plot?
Reciprocal m. menten equation. Intercept with x-axis yields -1/km. Intercept with y-axis yields 1/Vmax
A 2-year-old boy who attends daycare is brought to the emergency department due to diarrhea, fatigue, and abdominal cramps.The parents also state that he has foul-smelling, frothy stools.The boy is admitted for rehydration and subsequently diagnosed with giardiasis, which is treated with metronidazole.He improves and is discharged home.One week after discharge, the boy is seen by the primary health care provider for recurrent symptoms of frothy, loose stools and abdominal bloating and cramping.Which of the following steps of this pathway is most likely impaired in this patient?
(see lisa for screenshot)
E
What test is typically used to screen for HIV?
Fourth-generation HIV antigen/antibody immunoassay
Evaluates for the presence of HIV p24 antigen and HIV-1 and HIV-2 antibodies but does not differentiate between HIV-1 and HIV-2. Positive test usually followed by confirmatory HIV-1/HIV-2 antibody differentiation immunoassay.
What is the function of protein kinases
Protein kinases phosphorylates, often tyrosine, to regulate enzyme activity, increasing or decreasing available enzymes and Vmax. CREB's are phosphorylated to allow gene regulation. Phosphatases reverse the above.
Describe mechanism of G-protein (Gs + Gi)
Consists of 3 subunits, a b and y. Inactive form a is bound to GDP. When hormone binds, GDP is replaced with GTP, allowing a subunit to dissociate and subseq regulate adenylate cyclase (either s -> activitae or i -> inhibit.
What are Vmax and km
Vmax is the maximal reaction rate of the enzyme-substrate -> enzyme + product reaction. km is the concentration at which the rate is half of the potential Vmax. Ie km is a marker of affinity
Researchers are working to identify new targets for drug development to treat idiopathic pulmonary fibrosis.After obtaining lung tissue samples from affected patients, they conduct a series of experiments to measure the expression and activity of various profibrotic proteins.The results for one such protein, galectin-3, are as follows:
mRNA concentration normal
Protein concentration increased
Protein activity intact
Decreased ubiquitination of the Galectin-3 protein
In Gram stain:
1. Gram-positive bacteria, which have a (thick/thin) layer of peptidoglycan, appear (pink/purple).
2. Gram-negative bacteria, which have a (thick/thin) layer of peptidoglycan, appear (pink/purple).
In Gram stain:
1. Gram-positive bacteria, which have a (thick) layer of peptidoglycan, appear (purple).
2. Gram-negative bacteria, which have a (thin) layer of peptidoglycan, appear (pink).
Kwashiokor is
Negative nitrogen balanced associated with oedema (starvation, uncontrolled diabetes, deficiency of essential a.acids., malnutrition)
How does ANF and NO respectively relax smooth muscle cells?
cGMP mediated. ANF binds to ANF receptor with intrinsic Guanylate cyclase activity that generates cGMP from GTP. NO on the other hand diffuses into cell cytosol and activates a soluble guanylate cyclase. cGMP activates protein kinase G (PKG) that causes relaxation of smooth muscle tissue.
There are _ essential amino acids. Mnemonic
10. Pvt. TIM A. HILL
Phenylalanine, valine, threonine, Tryptophan, isoleucine, methionine, Histidine, Leucine, Lycine, Argininine*
A 5-year-old boy is brought to the office by his parents to establish medical care.The family recently immigrated to the United States from Nigeria.Both parents have sickle cell trait, and the patient was diagnosed with homozygous sickle cell disease (HbSS) at the age of 6 months.He has had several prior vasoocclusive crises and takes folic acid and hydroxyurea.Physical examination shows no abnormalities.Hemoglobin electrophoresis in this patient is most likely to reveal which of the following predominant hemoglobin patterns?
A.
HbS and HbF
B.
HbS, HbA, and HbA2
C.
HbS, HbA, HbA2, and HbF
D.
HbS, HbA, and HbF
E.
HbS, HbC, and HbF
A Hbs and HbF
What is the most common cause of lung abscess?
Aspiration of oropharyngeal bacteria.
Mixture of upper respiratory aerobic organisms and oral cavity anaerobes (eg, Peptostreptococcus).
Proteins are tagged for destruction in _ by _
proteasomes by covalent ubiquitin tags
What type of receptor is insulin receptor?
Tyrosine kinase. Insulin binding leads to autophosphorylation and binding of insulin receptor substrate (IRS) and phosphorylation of its tyrosine residues follows. Other proteins are phosphorylated too, including phosphatidylinositol-3 kinase, which upregulates GLUT-4 in adipose and muscle tissues. Some phosphatases are also paradoxycally activated.
Asparagine during translation has and undergoes:
Cysteine is important for shape due to:
N-groups that can be glycosylated in the ER (co-trans mod.)
- sulfur that makes disulfide bonds. Destruction of these denatures proteins
A 22-year-old woman comes to the hospital due to a 5-day history of nausea, constipation, and severe, poorly localized abdominal pain.She also reports anxiety, difficulty concentrating, poor sleep quality, and tingling of the limbs.The patient has had several similar episodes in the past.She does not take any medications or use tobacco, alcohol, or illicit drugs.The patient has been restricting her diet to lose weight.On examination, the abdomen is soft, nontender, and nondistended.Bowel sounds are decreased.The patient receives an intravenous infusion of a heme preparation that leads to rapid resolution of her symptoms.The improvement in symptoms is most likely due to treatment-induced downregulation of which of the following enzymes
Aminolevulinate synthase
______ - viruses are the most common cause of viral meningitis.
Enteroviruses are the most common cause of viral meningitis.
Examples: coxsackievirus, echovirus, enterovirus.
Characteristic of water soluble hormones:
And of lipid hormones:
1. in cell membrane. Employs second messengers such as cAMP.. Employs phosphorylation of kinases to regulate activity (minutes). Gene expression control by cAMP response element binding proteins (CREB).
2. Receptors inside cell. Receptor-hormone omplex binds to response elements on DNA to regulate gene expression.
Mechanism of Gq G-protein?
Gq binds Phosphatidylinositol bisphosphate (PIP2) which binds and activates phopsholipase C that generates inositol triphosphate that enables calcium release from the ER. Furthermore DAG is activated which in symphony with calcium activates protein kinase C which like PKA can phosphorylate enzymes (not CREB though).
Serine and threonine are:
Sites for o-linked glycosylization in golgi apparatus (posttrans. mod.)
A researcher is studying the role of glucose metabolites in normal cellular function.A specific human cell type is incubated in glucose-rich media.Intracellular levels of glucose metabolizing enzymes, intermediate products, and generated ATP are measured.In these cells, glycolysis of a single glucose molecule always yields pyruvate but sometimes generates no net ATP.Which of the following cells is most likely being studied in this experiment?
A adipocytes
B Erythrocytes
C Hepatocytes
D Neurons
E Skeletal muscle cells
B
State whether or not each of the following bacteria ferment lactose.
1. Enterobacter:
2. Escherichia coli:
3. Klebsiella:
4. Proteus:
5. Pseudomonas:
6. Salmonella:
7. Shigella:
1. Enterobacter: yes
2. Escherichia coli: yes
3. Klebsiella: yes
4. Proteus: no
5. Pseudomonas: no
6. Salmonella: no
7. Shigella: no
Phenylalanine and tyrosine are:
Tryptophan is a precurser to:
Valine, leucine and isoleucine are:
Precursers to catecholamines
Serotonin and niacin
Branched-chain amino acids abnormally metabolized in maple syrup disease