Biochemistry Flashcards
If a patient has opthalamoplegia, ataxia, and confusion and family believes he drinks daily, what ezymes might be defective?
Thiamine Deficiency
- Pyruvate Dehydrogenase
- Alpha-Ketoglutarate Dehydrogenase
- Transketolase
Why do neurologic symptoms occur with Thiamine deficiency?
Unable to properly utilize glucose in the sensative tissues, hence mammilary body lesions
What is the best test to uncover thiamine deficiency?
Erythrocyte Transketolase Activity – changes sugars into different forms requiring only thiamine
What nutrient deficiency has dryness on the corners of the mouth and lips, thickening of the tongue, dry skin?
Riboflavin
What enzyme in the TCA cycle is most affected by Riboflavin Deficiency, if there is a decrease in fumarate production?
Succinate Dehydrogenase
What protein breaks down glycogen for use?
Glycogen Phosphorylase
How is glycogen breakdown initiated?
Glycogen Phosphorylase is phosphorylated/activated by Phosphorylase Kinase (which was phosphorylaed by Protein A)
– Ca+2 release from SR activated Glycogen Phosphorylase as well
Where does the 30S subunit of ribosome bind in prokaryotic cells?
Upstream of Start codon of mRNA
What aminoacids should be used for diet in a patient with pyruvate dehydrogenase deficiency/
Aminoacids ONLY used for ketogenesis
- Lysine
- Leucine
What GLUT transporter is upregulated by insulin?
GLUT4 - skeletal muscle / adipocytes
How is glycogen synthase activated in hepatocytes?
Protein Phosphatase-1 (activated by PO4 by Tyrosine Kinase)
- *REMOVES PO4 from Glycogen Synthase, causes activation of it
- REMOVES PO4 from F 1,6 Bisphosphatase (stops gluconeogenesis)
If a DNA base is altered by deaminase, what method would be used to repair the DNA?
Base Excision Repair
- Glycosylase (Removes) > Endonuclease (cleaves 5’ end) > Lyase (removes 3’ end) > DNA Polymerase > Ligase
What occurs first during ischemia of brain tissue?
Red Neurons – loss of nissl and eosinophil look
– no infiltrate yet, or necrosis
What happens in ischemia around 48-72 hours?
Necrosis and PMN Infiltration
What happens in ischemia 1-2 weeks post infarction?
Reactive Gliosis and vascular proliferation – Liquefication Necrosis
What occurs in the Nucleus prior to mRNA leaving into cytoplasm?
- Poly A Tail
- 5’ Cap
- 7-methylguanosine 5-5 linkage
- interaction with snRNP (splicing)
What occurs in the cytoplasm ONLY with mRNA?
Ribosome – Translation
Association with P-Bodies (regulation of mRNA quality)
Build up of GM2-Ganglioside, diffuse weakness/motor loss, and cherry red macula?
Tay-Sachs Disease
– Defective Hexosaminase A
Bone pain and fractures, osteopenia, accumulation of Macrophages with accumulation of glucocerebroside?
Gaucher Disease
- Defective Glucocerebrosidase
- “Tissue Paper Macrophages”
Early Adulthood peripheral neuropathy and motor defects – recessive genetic disorder?
Metachromatic Leukodystrophy
- Defect Arysulfatase A Defect
- accumulation of cerebroside sulfate
What is the inheritance pattern of extremity pain, corneal changes, angiokeratomas, decreased ability to sweat?
Fabry Disease
- X-linked – mostly boys
- Defective Alpha-Galactosidase
What disorder has a build up of glycosphingolipids?
Fabry Disease
– Defective Alpha-Galactosidase
An infant is found to have a spingomyelinase deficiency, what symptoms might be expected?
Profound Neurodefects
- early death
- *Niemann Pick Disease**
- -REGRESSION OF MOTOR FUNCTION–
What amino acids are unable to be broken down in Maple Syrup disease?
- Leucine
- Isoleucine
- Valine
- *Requires Thiamine cofactor (usually)
- Alpha-Ketoacid Decarboxylase–
A patient is found to have a change in mentation with diffuse skin changes and was recently diagnosed with a GI mass, what is causing this syndrome?
Serotonin Syndrome —> Niacin Deficiency, due to over production of Serotonin from Tryptophan depleting stores.
- Dermatitis
- Diarrhea
- Dementa
What are each of the RNA Polymerases responsible for?
RNA Poly I – rRNA
RNA Poly II – mRNA, snRNA
RNA Poly III – tRNA
What DNA Polymerase can remove primers from DNA?
DNA Polymerase I
- 5’-3’ Polymerase
- 5’-3’ exonuclease
- 3-5’ proof-reading
What is the most common problem associated with Hartnup Disease? (Impaired Neutral AA uptake)
Not enough Tryptophan
- Unable to produce Serotonin / Melatonin
- Niacin Deficiency – pellagra (Dementia, Dermatitis, Diarrhea)
How can you tell the difference between Hartnup and Fanconi Syndrome?
Normal Levels of Proline, Hydroxproline, Arginine in the urine (since they are getting reabsorbed)
–Fanconi – defective proximal tubule unable to reabsorb pretty much everything across the board.
What is the best way to reverse Warfarin?
Non-life threatening – Vitamin K
Life Threatening – FFP
What are the symptoms for Riboflavin Deficiency?
Cheilosis
Glossitis
Keratitis
Corneal Vascularization
If an Rb mutation is inherited, what is the most common type of cancer?
Osteosarcoma
What amino acids are broken down into Propionyl-CoA?
Valine
Isoleucine
Threonine
Methionine
What immune acid that is involved in Maple Syrup disease is metabolized into Acetyl-CoA?
Leucine
What amino acid is cleaved to produce vasodilatory effect?
Arginine
– broken down into NO, due to ACh/Bradykinin/5HT/Substance P being released
What two vitamin deficiencies can cause defunction of dorsal column and/or corticospinal tract?
Vitamin E Deficiency
Vitamin B12 – Elevated MMA
What is the most common defect of urea cycle and where does it occur?
Ornithine Transcarbamylase
[Ornithine + Carbamoyl Phosphate –> Cirtrulline]
– Occurs inside the Mitocondria
What is required to for Ornithine Transcarbamylase to conduct its reaction?
Carbamoyl Phosphate
Produced by Acetyl-Coa + Glutamate –> N-Acetyl Glutamate
What is a missense versus nonsense mutation?
Missense – changes amino acid
Nonsense – changes to STOP codon (UGA, UAG, UAA)
Where does the female ovum stop after it has been stimulated and become dominant?
Meiosis II – Metaphase
Before it is selected, its Prophase Meiosis I
What is a common side effect of Verapamil?
Negative Inotrophy
- gingival hyperplasia
- constipation
What is the consensus sequence of PolyA tail that is placed on mRNA while in nucleus?
“AAUAAA”
– protects from degradation
What is a common characteristic of patients who develop Lupus-like drug reaction?
Slow Acetylators
- fever
- arthalgias
- rash
- pericarditis
What is unique about tRNA sequences?
They have odd abnormal amino acids present
