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Flashcards in biochem Deck (24):
1

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

2

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.

3

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

4

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

5

pyridoxal phosphate is a necessary cofactor for heme synthesis

specifically the synthesis of delta-aminovulinic acid
-which is elevated in cases of lead poisoning

6

exposure to radiation

induces DNA damage through DNA double strand fractures and the formation of oxygen free radicals

7

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

8

Leptin decreases food intake by:

1. decreasing the production of neuropeptide Y, a potent appetide stimulant, in the arcuate nucleus of the hypothalamus
2. 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

9

decreasing functioning of pyruvate dehydrogenase will increase the conversion of

pyruvate to lactate by the enzyme lacatate dehydrogenase in an effort to regenerate NAD+

10

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

11

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

12

BH$ is a cofactor used in hydroxylase enzymes

-needed for the synthesis of tyrosing, dopa , serotonin and NO

tyrptophan makes serotonin

13

homeobox

highly conserved DNA sequence usually about 180 nucleotides in length
-homeobox genese typically code for DNA binding transcription factors

14

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

15

c-jun

can bind directly to DNA as a transcription activator

16

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)

17

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

18

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

19

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

20

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

21

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

22

malignant PKU

-decrease in BH4 cofactor
Deficiency in dihydrobiopterin reductase
no BH4

issues making: typrosine, DOPA, serotonin, and NO

23

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

24

biological active form of vitamin B5 pantothenate is

coenzyme A
-needed for acyl transfers like in pyruvate dehydrogenase
and fatty acid synthase