Biochemistry Flashcards
which substance is decreased in acetaminophen intoxication allowing the damaged of liver injury and why?
- Glutathion→ detoxifies free radicals
and peroxides.
Is the fundament of treatment with N- acetyl cysteine
which is the cause of I cell disease?
Defect in N-acetylglucosaminyl-1-phosphotransferase - failure of the Golgi to phosphorylate mannose residues (FAILURE IN TARGET)→ accumulation of serum levels lysosomal enzymes
Tell 8 symptoms of Scurvy
- petechiae
- poor wound healing
- hemarthrosis
- anemia
- swollen gums
- bruising
- perifollicular and periosteal hemorrhages
- weakened immune response
Alkaptonuria
AR Deficiency of homogentisate oxidase-- degredative pathway from tyrosine to fumarate accumulate homogentisic acid in tissue benign dark pigment in tissue--- sclerae, urine artharlgias
Homocystinuria vs Marfan sx
- Homocystinuria: Cystathione synthase deficiency, -intelectual disability, thrombosis. Marfanoid habitus
- Marfan sx: Fibrillin -1 gene mutation: No intelectual disability, no thrombosis.
Mc Ardle disease
AR
Glycogen storage disease— deficiency of glucogen phosphorylase (myophosphorylase) degrades glycogen in glycogen 1 phosphate (impaired muscle glycolysis)
Exercise intolerance – muscle pain and cramping
Dopamine Beta Hydroxylase deficiency
impaired sympathetic adrenergic activity
Infants: Hypotension, failure to thrive and hypothermia
Adults: postural hypotension, exercise intolerance, nasal cogestion and ejaculatory problems.
Which is the main characteristic of G- coupled receptors?
7 transmembrane hidrophobic alpha helical domain
Median chain acyl coa dehydrogenase deficiency
AR
disorder in fatty acid oxidation– decreased the ability to break down fatty acids into acetyl CoA
Hypoketotic hypoglycemia
lethargy, seizures, coma and liver disfunction (hematomegaly)
MODY
maturity onset diabetes of the young: AD, impaired insulin secretion, minimal or no effects in insulin action.
mutations in GLUCOKINASE (regularory role in pancreatic cells to insulin secretions) gene or transcripction factors—— Hyperglycemia is mild, as no longer need medication.
The only purely ketogenic a.a
lysine and leucine
essential a.a
- methionine
- valine
- histidine
- threonine
- isoleucine
- phenylalanine
- tryptophan
- leucine
- lysine
Glucogenic a.a
- methionine
- valine
- histidine
N- acetyl synthase deficiency
required cofactor carbamoyl phosphate synthase I
Absence of N- acetylglutamate—- hyperammonemia
neonates: poorly regulated respiration and body temperature, poor feeding, development delay, intellectual disability
Identical presentation of carbamoyl phosphate synthase I deficiency
Which enzyme is increased as a result of Lesch Nyhan syndrome
Phosphoribosyl pyrophosphate amidotransferase increased it activity because accumulation of uric acid leading increased production of purines.
Vit A toxicity
Acute: nausea, vomiting, vertigo and blurred vision
Chronic: alopecia, dry skin, hepatic toxicity, hepatomegaly, papilledema (pseudotumor cerebri) benign intracranial hypertension
teratogenic: cleft palate, cardiac abnormalities
AUG, UAG, UAA, UGA
Initiation codon (methionine) stop codons Do not code for a.a or bind to tRNA When the ribosome encounters a stop codon --- releasing factor protein-- bind to the ribosome--- dissolution ribosome/mRNA coupling
In porphyrin synthasis
the rate limit enzyme is ALA synthase (cofactor B6)
tRNA structure
- 3´ CCA— acceptor stem
- D loop— proper aminoacyl tRNA synthase
- Anticodon loop—- bind to mRNA codon
- T loop—- TyC sequence —binds to ribosome
Glucagon functions by…
bind to G protein receptor coupled—- increasing cAMP intracellular—- activating protein Kinase A
B12 vitamin es a cofactor
- conversion of methylmalonic acid to succinyl coA (Fatty acid metabolism) — the accumulation of methylmalonic acid damage myelin
- Homocysteine to methione (as methal donor)
Hormone sensitive lipase
In adipose tissue catalyses the movilization of TAG into free fatty acids and glycerol
Activated by Catecholamines, glucagon and acth
inhibited by insulin
biotin
B7
cofactor
- Pyruvate carboxylase: pyruvate to succinil coA (gluconeogenesis)
- Acetyl CoA carboxylase: Acetyl coA to malonyl coA (fatty acid syntehsis)
- Propionyl coA Carboxylase: propionyl Coa to Methyl malonyl coA (fatty acid oxidation)
Propyomelnocortin POMC
Polypeptide precursor produce:
- beta endorphins
- ACTH
Splicing
postranscriptional modification that removes noncoding DNA regions (introns) from precursor mRNA.
Alternative splicing: different combinations of DNA coding regions are included or excluded —- alternet sets of proteins
Dihydrobiopterine reductase deficiency
Hyperphenylalanemia: BH4 is a cofactor of phenylalanine hydroxylase
Elevated prolactin: BH4 is a cofactor of DOPA decarboxylase (decreasing Dopa levels—- there is not inhibition of prolaction———— increased levels)
Where is the location of heme production?
mitochondria
In erythrocyte precursors
which kind of proteins are synthesized by RER and smooth endoplasmic reticulum?
RER: secretory, lysosomal and membrane proteins
SER: steroid proteins and phospholipid biosynthesis
Ketogenic a.a
lysine and leucine
Acyl coA dehydrogenase deficiency
Hypoketotic hypoglycemia
Defective in Fatty acid beta oxidation
Integrins
transmembrane protein receptors —- interact with extracellular matrix by binding to collagen, fibronectin and laminin.
* differential expression of integrin subtypes affects the interaction properties—-correlates with malignant behavior (melanoma)
Telomerase
ribonucleoprotease that adds TTAGGG repeats to 3´ end of chromosome (telomere region)
Similar to other reverse transcriptase enzymes (synthesize a single stranded DNA from a single stranded of RNA)
Stem cells hace very long telomerase (have a great telomerase activity) like in basal layer of epidermis
which substrates need to convert pyruvate in phoenolpyruvate in gluconeogenesis?
pyruvate to PEP cannot convert directly because pyrvate kinase is unidirectionaly
- The reaction is catalyzed by pyruvate carboxylase (convert pyruvate in oxaloacetate)— is activated by acetyl coA (produced by beta oxidation of fatty acids)
DNA Laddering
DNA fragments in multiples of 180 base pairs: indicating apoptosis
- laddering arises from the action of endonucleases during karryorrhexis
Internal ribosome entry
alternative method of translatiion when eukaryotic initiation factors are degradated by apoptosis.
Cell differentiation is determined by…
transcription factor
G protein coupled receptors
Bind glycoprotein hormones (TSH- LH- FSH) contain three major domains:
- extracellular domain (ligand binding)
- transmembrane domain (hydrophobic a.a)
- intracellular domain (coupled with G protein)
hydrophobic a.a
valine, leucine, isoleucine, alanine, methionine, proline, glycine, thyptophan, phenylalanine.
Ribosomes
free ribosomes: floating cytosol, translated proteins that find in cytosol, nucleosome, mytochondrial membrane and peroxisomes.
Attached with RER: synthesized membrane proteins, nuclear membrane proteins, lysosomes.
Reticulocyte
is larger and bluer that mature RBC
lacks nucleus but remains basophilic reticular residual ribosomal RNA
Phosphatidil choline
equal of lecithin
lecithin/ sphingomyelin ratio=lung maturiry turns to be equal in third trimester because lecithin is going increase
> 35 weeks: L/S= 2:1 of higher
two that produce glucose in fasting
liver and kidney has capability to produce glucose in fasting ( gluconeogenesis)
Fabry disease
alpha galactosidase A deficiency
Accumulation of alpha galactosidase A and globotriasulceramide (Gb3)ceramide trihexoside
Neuropathic pain, hpohydrosis, angyokeratomas and telangiectasias
cerebrovascular and cardian disease
renal failure
increase alpha feto protein in amniotic fluid
fetal neural tube defect
The nucleolus contains
Ribosomal DNA
Encodes 28 S, 5.8S, 18 S ribosomal RNA components — are translated in cytoplasm from mRNA
Primary function of nucleolus is synthesis of 60 and 40 S Ribosomal subunits— then are exported to fully mature in cytoplasm
MC Ardley disease
myophosphorylase (Glycogen phosphorylase)– Glycogeolysis deficiency
