Purines

What is the central dogma?

flow of information from DNA -> RNA -> protein

What are the 3 steps of the central dogma?

1. DNA replication: genetic information is copied and transmitted to daughter cells

2. Transcription: expression of genetic information from DNA

3. Translation: messenger RNA molecules are translated

Purine contains what 2 nitrogen bases?

- adenine

- guanine

T/F: Adenine & Guanine are in DNA & RNA?

true

Pyrimidines contains what 3 nitrogen bases?

- cytosine

- thymine

- uracil

Cytosine is in...?

DNA & RNA

Thymine is in...?

DNA

Uracil is in...?

RNA

What are 2 examples of nucleosides?

- ribose

- deoxyribose

Deoxyribone is in _____?

DNA

Ribose is in _____?

RNA

Sugars are linked to the heterocycle by an ________ bond?

a-N-glycosidic

Nucleosides consists of what?

- nitrogenous base

- sugar

Nucleotides consists of what?

- nitrogenous base

- sugar

- phosphate

Nucleotides are the _______ units of the nucleic acids?

monomeric

5-methylcytosine is the modification of....?

bacterial & human DNA

5-hydroxymethylcytosine is the modification of....?

bacterial & viral nucleic acids

What purine residues are in tea?

theophylline

What purine residues are in cocoa?

theobromine

What purine residues are in coffee?

caffeine

Nucleotides are used in clinical medicine for what 2 drugs?

- chemotherapy

- immunosuppressants

What is the MOA of chemotherapy?

1. inhibitions of enzymes essential for nucleic acid synthesis

2. inhibitions of G1/DNA synthesis

3. Cell cycle arrest

Allopurinol is used to treat what 2 things?

- hyperuricemia

- gout

Azathioprine is an ______?

immunosuppressant

What is the 1st step of de novo purine synthesis?

ribose-5-phosphate + ATP + PRPP synthetase -> PRPP

What is the 2nd step of de novo purine synthesis?

PRPP + amido phosphoribosyl transferase -> phosphoribosylamine

Phosphoribosylamine produces ____?

IMP (inosine monophosphate)

What is the rate limiting step of de novo purine synthesis?

amido phosphoribosyl transferase

What inhibits PRPP synthetase?

- ADP

- GDP

- AMP

- GMP

What is the salvage pathway of purine synthesis?

recovers nucleosides or bases during RNA or DNA degradation

Through the salvage pathway, adenine produces _____?

AMP

Through the salvage pathway, guanine produces _____?

GMP

Through the salvage pathway, hypoxanthine produces ____?

IMP

What enzymes converts hypoxanthine -> xanthine -> urate?

xanthine oxidase

Gout is a metabolic disorder where crystals of ______ deposit in tissue?

sodium urate

Increase in blood uric acid causes what 3 things?

1. increased purine intake (proteins)

2. increased turnover or production

3. decreased uric acid elimination by kidneys

Uric acid is the predominant form in ____?

acidic urine

Urate anion is the predominant form in ____?

blood

What are the factors of serum urate concentration?

- high consumptions of purines, frutose, ethanol

- obesity

- high tissue turnover

- compromised kidney function

What significantly enhances the body's accumulation of uric acid?

- fructose

- alcohol

What is the lesch-nyhan syndrome (LNS)

- inherited disorder

- deficiency of the hypoxanthine-guanine phosphoribosyl transferase (HGPRT)'

- build up of uric acid

What are the complications of LNS?

- involuntary muscle movements

- neurologic impariment

- impaired kidney function

- acute gouty arthritis

What is Von Gierke Disease?

- type 1 glycogen storage disease (GSD1)

- glucose-6-phosphatase deficiency

- purine overproduction & hyperuricemia