First aid Biochemistry Flashcards by Z C

What type of DNA is in the nucleus and what charge does it carry?

It is densely negatively charged chromatin.

Bound around positively charged histones rich in lysine and argine.

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Describe the difference between histone methylation and histone acetylation.

Methylation generally makes DNA mute.

Acetylation relaxes DNA for transcription.

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Nucleotide vs nucleoside

Nucleotide is the base, deoxyribose, and a phosphate.

Nucleoside is just the base, deoxyribose and sugar.

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Adenosine deaminase deficiency can lead to what disease order?

Excessive ATP and dATP imbalances nucleotide pool preventing DNA synthesis and lowering lymphocyte count.

This is a common cause of SCID.

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What is Lesch-Nyhan Syndrome?

Defctive purine salvage due to abscent HGPRT which converts hypoxanthine to IMP and guanine to GMP.

Results in excess uric acid production and denovo purine synthesis!!

Intelectual diability, self mutilation, agression, hyperuricemia, and gout.

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Describe the formation of uric acid

Ribose 5 phosphate creates IMP which is then broken down to inosine an finally hypocanthine.

Xanthine oxidase is then responsible for breaking hypoxanthine down into xanthine and finally uric acid that is meant to be secreted.

Any problems in this area can lead to hyperuricemia and gout.

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Single stranded biding proteins

Keep DNA from recombining after being opened for transcription.

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DNA topoisomerases

These create single and double stranded breaks to help unwind the DNA supercoils. Fluoroquinolones inhibit this enzyme leading to DNA damage. (specifically topoisomerase II)

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Primase

Makes RNA primer for DNA polymerase to begin replication on.

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What is a silent mutation?

Nucleotide substition but codes for same amino acid.

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Missense mutation

Nucleotide substitiution resulting in changed amino acid

In sickle cell disease a glutamic acid is subtituted with a valine.

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What substitution occurs in sickle cell disease?

Glutamic acid is substituted with a valine.

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Nonsense mutation?

Nucleotide substitution that inserts a stop codon.

“Stop the nonsence”

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Duchenne muscular dystrophy is a result of….

A frameshift through deletion or subtitution of a nucleotide.

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Xeroderma pigmentosum

Sun damage leading to pyrimidine dimers because of ultralight exposure.
Generally protected by nucleotide excision repaire.

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what direction are DNA and RNA synthesized?

5’ to 3’

Protein synthesis however is N terminus to C terminus.

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What does the start codon AUG code for in eukaryotes and prokaryotes?

Eukaryotes codes for methionine

Prokaryotes codes for fMET

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mRNA stop codons

UGA You go away
UAA You are away
UAG You are gone

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RNA pol1
RNA pol2
RNA pol3

rRNA
mRNA
tRNA

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What are the eukaryotic and prokaryotic ribosomal subunits?

Eukaryotes: 40S and 60S form 80S
Prokaryotes: 30S and 50S form 70S

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What does tRNA bind to first?

Binds to the A site first.
Will then transition from the A site to the P site and finally the E site.

Elongation occurs at the P site.

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What does chaperone protein do?

It is responsible for maintaining protein folding while under stress from heat atc.

Hsp60 is specifically produced in response to heat.

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What function do p53 and Rb have in the cell cycle?

Normally inhibit G1 to S progression.

Mutations of these can lead to severe problems,

where in the cell is the site of secretory protein synthesis?

Rough ER

Nissl bodies?

RER synthesize peptide neurotransmitters for secretion

Goblet cells would have massive ammounts of which type of organelle?

RER | For the secretion proteins.

Cell site of steroid synthesis and detoxifications of drugs and poisons?

Smooth endoplasmic reticulum Expect liver hepatocytes and adrenal cortex/gonads to be rich in SER.

What is I cell disease

Lysosomal storage disorder failure for the golgi to phosphorylate mannose residues (no mannose-6-phosphate) thus proteins are sent out extracellularly instead of to lysosyme.

Proteasome

Barrel shaped protein complex that seeks out ubiquitin tagged proteins for destruction.

what role do microfilaments play?

Muscle contraction/cytokinesis | Example would be actin.

What role do intermediate filaments play?

Maintain cell structure | Examples include: Vimentin, desmin, cytokeratin, lamins, glial fibrillary acid proteins, and neurofilaments.

What role do microtubules play?

Movement, cell division | Think cilia, flagella, mitotic spindle, axonal trafficking.

What is kartagener syndrome?

Primary ciliary dyskinesia in which a dynein arm defect is present. Results in male infertility due to immotile cilia (think microtubule damage)

Which 5 drugs act on microtubules?

``` Microtubules Get Constructed Very Poorly Mebendazole Griseofulvin Colchicine Vincristine/vinblastine Paclitaxel ```

How does Ouabain interact with the Na/K channel?

Binds to the potassium portion of the 2K/3NA channel inhibiting the channel.

Type I collagen?

Bone, skin, tedon Decreased in osteogenesis imperfecta type I

Type II collagen?

Cartilage | Cartwolage

Type III Collagen

Reticulin such as skin and blood vessels.

Ehlers danlos syndrome

Deficient in type III collagen!

Type IV collagen

Basement membrane, basal lamina | Type IV under the floor.

Alport syndrome

Autoantibodies in goodpasture syndrome against type IV collagen.

Which amino acid makes up most of collagen

Glycine makes up 1/3 of it with proline and lysine being common additives. Proline and lysine are usualy hydroxylated in the formation of collagen which requires vitamin C. (scurvy)

Ehlers Danlos syndrome

Crosslinkage of collagen fibrils outside of fibroblasts. this is the last stage of collagen formation.

Osteogenesis imperfecta

Decreased production of collagen type I Will have blue sclerae, hearing loss, and dental imperfections.

Classic type of Ehlers-Danlos syndrome

Type V collagen mutation | Joint and skin conditions

Vascular type of Ehlers-Danlos syndrome

Type III collagen deficiency | Vascular and organ rupture

Marfan syndrome

Defect in fibrillin forms a sheath around elastin.

Emphysema

Alpha 1 antitrypsin deficiency leading to excessive elastase activity.

Prader willi syndrome

Maternal imprinting | Hyperphagia, obesity, intillectual disability, hypogonadism and hypotonia

Angelman syndrome

``` Paternal imprinting (gene normally silent) Maternal gene deleted. Inappropriate laughter, sezures ataxia ```

Duchenne muscular dystrophy

Frameshift mutation due to deleted dystrophin | Look for weakened muscles and waddling gaits.

Becker muscular dystrophies

X-linked disorder, non frameshift insertions in dytrophin gene. Less severe form of duchenes muscular dystrophies.

Myotonic type 1 muscular dystrophy

CTG trinucleodtide repeat | Mytonia, testicular atrophy, frontal balding and arrythmia.

Trisomy 21

Down syndrome

Edwards syndrome Trisomy 18

Low set ears, clenched hands, rocker bottom feet. Second most common trisomy

Patau syndrome

Trisomy 13 Cleft palate Holocephaly Polydactly