biochem Flashcards
lac operon
Lac I regulatory gene - repressor protein - constitutively expressed
Lap p promoter region (RNA pol wil bind during inititation)
lac o operator region
three structural gens: lac, Z, Y and A
Lac Z - b galactosidase (hydrolysis of lactose to glucose and galactose)
-Lac Y permease - which allows lactose to enter the bacterium
lac operon regulation
- increased glucose, decreases the activity of adenyl cyclase –> decreased cAMP
- but increased cAMP –> CAP catobolite activator protein which is upstream the promoter and is a positive regulator
second
- repressor protein is always on and bound to operator - negative regulation
- lactose the inducer, bunds to repressor protein, the proteins conformation changes and now it cant bind to the operator.
Very long chainr and some branched chain fatty acids like phytanic acid) cannot undergod mitochondrial beta-oxidation. These fatty acids are metabolized by a special form of beta oxidation (ver long chain fatty acids) or be alpha oxidation (branched) in peroxisomes
Peroxisomal disease:
zellweger syndrome
- infants are unable to properly form myelin in the CNS. Symptoms:
- hypotonia, seizures
- hepatomegaly
- mental retardation and early dead
treatment: strict avoidance of chlorophyll in the diet
P bodies are in cytoplasm
-distinct foci found within eukaryotes that are involved with RNA turnover
fundamental role in:
-translation repression, mRNA decar, contain RNA exonucleases, mRNA decapping enzymes and microRNA-induced mRNA silencing, they also seem to function as a form of mRNA storage
pyridoxal phosphate is a necessary cofactor for heme synthesis
specifically the synthesis of delta-aminovulinic acid
-which is elevated in cases of lead poisoning
exposure to radiation
induces DNA damage through DNA double strand fractures and the formation of oxygen free radicals
Val, Ile, Met and Thr, odd numbered fatty acids and cholesterol side chains eventually lead to what?
propinoyl CoA
- propionul coA is converted to methylmalonyl CoA via propionyl CoA carboxylase
- methylmalonyl CoA is then isomerized to succinyl CoA and enters the TCA
-propionyl CoA carboxylase deficiency:
propionic acidemia:
-poor feeding, vomiting, hypotonia, lethargy, dehydration and anion gap acidosis
Leptin decreases food intake by:
- decreasing the production of neuropeptide Y, a potent appetide stimulant, in the arcuate nucleus of the hypothalamus
- Leptin stimulates the production of proopiomelanocortin (POMC) in the arcuate nucleus. Alpha-melanocute-stimulating hormone(alpha-MSH) is produced by cleavage of POMC and inhibits food intake
decreasing functioning of pyruvate dehydrogenase will increase the conversion of
pyruvate to lactate by the enzyme lacatate dehydrogenase in an effort to regenerate NAD+
activating mutation of PRPP
5’phosphoribosyl-1’-pryophosphate
PRPP synthetase is the enzyme that makes activated ribose needed for de novo synthesis of purine and pyrimidine
-too much – > more degradation of purines –> build up uric acid –> hyperuricemia
gout –> inflammation, neutrophils are the primary cell responsible for the intense inflammatory response due to phagocytosis of monsodum urate crystals
cochicine
- reduces inflammatory repspose by:
- interfering with adhesion molecules and microtubule formation responsible for neutrophil chemotaxis
- decreases tyrosine phosphorylation in response to monosodium urate cyrstals, which results in decreased neutrophil activation
BH$ is a cofactor used in hydroxylase enzymes
-needed for the synthesis of tyrosing, dopa , serotonin and NO
tyrptophan makes serotonin
homeobox
highly conserved DNA sequence usually about 180 nucleotides in length
-homeobox genese typically code for DNA binding transcription factors
aminotransferase enzyemes
-almost all aminotransferase enzymes use alpha ketoglutarate as the amino group acceptor. Thus aminogroups are funneled into glutamate during protein catabolism.
- glutame is further metabolzed by glutamate dehydrogenase which liberates free ammonia and regenerates alpha-ketoglutarate.
- ammonia then enters the urea cycle
c-jun
can bind directly to DNA as a transcription activator
homocystinura more commonly caused by cystahionine synthetase deficiency
- the enzyme doesnt work or there is less affinity for pyridoxal phosphate
treatment: more B6
findings:
sorta like marfans
-intellectual disability, osteoporosis, tall stature, kyphosis, lens subluxation (downward and inward), thrombosis, and atherosclerosis (stroke and MI)
sickling is promoted by conditions associated with low oxygen levels, increased acidity or low blood volume (dehydration)
-organs that blood moves slowing in - spleein, liver, kidney are more predisposed and organs with high metabolic demands like brain, muscles and placenta promote sickling by extracting more oxygen from the blood
growth factors can stimulate cell proliferation by altering the expression of certain genes, this requires the use of signal transuction systems tha can transfer signal to nucleus
examples:
Ras/Map kindase P13K/Akt/mTOR Inositol phospholipid pathway cAMP pathway JAK/STAT pathway
Ras-MAP kinase pathway
- growth factor finds to receptor tyrosine kinase –> autophophorylation of the receptor
- phspotyrosine pridcyes then interacts with a number of proteins, SH2-domain proteins and SOS protein, leading to Ras activation
- Ras is G-protein that exists in active and inactive forms
- inactive Ras contains GDP
- active Ras contains GTP
- Activated Ras begins phophorylation cascade starting with activation of Raf kinase —— —- —- > activation of MAPkinasewhich enters the nucleus
note GAP deactivates Ras by GTPase activating protein which induces hydrolysis of GTP to GDP
DNA pol 1 has 5’-3’’ exonuclease activity in addition to its 5’ to 3’ polymerase and 3’ to 5’ exonuclease acitivites.
The 5’-3’ exonuclease is used to remove the RNA primer (which initiates DNA polymerization) and to remove damaged DNA
Histone H1
is located outside of the nucleosome core and helpts to package nucleopsomes into more compact structures by binding and linking DNA between adjacent nucleosome
malignant PKU
-decrease in BH4 cofactor
Deficiency in dihydrobiopterin reductase
no BH4
issues making: typrosine, DOPA, serotonin, and NO
Long term signed of chronic toxicity of Vitamin A ingestion:
0alopecia, dry skin, hyperlipidemia, hepatotoxcity, hepatosplenomagaly and visual difficulties
- cerebral edema in the setting of benign intracranial HTN (pseudotumor cerebra). –> papilledema
- teratogenic effects of excessive vitamin A ingestion include microcephaly, cardiac abnormalities and fetal death
biological active form of vitamin B5 pantothenate is
coenzyme A
-needed for acyl transfers like in pyruvate dehydrogenase
and fatty acid synthase
