Biochemistry High Yeild Flashcards
How is uracil formed?
Deamination of the pyrimidine cytosine.
Uracil is found in RNA and replaces thyamine that binds with adenine.
Which of the nucleotides has a methyl group?
Thymine.
Which three amino acids are needed for the formation of purines?
GAG
Glycine
Aspartate
Glutamine
which group of the nucleotides requires the most steps in synthesis?
Pyrimidines, which are formed from orotic acid.
Purines start with sugar and phosphate and just need a base added.
What can happen when there is an adenosine deaminase deficiency?
Leads to decreasd DNA synthesis due to excessive ATP and dATP balance.
Ultimately lowers lymphocyte counts resulting in SCID.
What is Lesch-Nyhan syndrome?
Defective purine salvage due to absent HGPRT which converts hypoxanthine to IMP and Guanine to GMP.
Results in excessive uric acid production and de novo purine synthesis. X-linked recessive.
Which medication inhibits prokaryotic topoisomerase II and topoisomerase IV?
Fluoroquinolones!
Prevents the repair of strand breakage in DNA.
What does the enzyme primase do?
Makes an RNA primer that DNA polymerase III can act on to initiate replication.
Where can DNA polymerase III be found?
This is found in prokaryotes only and elongates the leading strand by adding deoxynucleotides to the 3’ end.
Thus it has 5’->3’ synthesis and 3’->5’ proofreading.
What does the DNA polymerase I do?
Found in prokaryotes only.
Degrades the RNA primer and replaces it with DNA.
What does telomerase do?
RNA dependent DNA polymerase that adds DNA to the 3’ ends of chromosomes to avoid loss of genetic material with every duplication…
Found in eukaryotes only.
Compare a transition DNA mutation vs a transversion.
Transition is a purine swapped with another purine.
Transversion is a purine swapped for a pyrimidine.
Describe... Silent mutation Missenese mutation Nonsense mutation Frameshift mutation
Silent mutation: Nucleotide substitution coding for same amino acid.
Missense mutation: Results in a changed amino acid ex: Sickle cell disease!!!! Glutamic acid swapped for a valine.
Nonsense mutation: Nucleotide substituion resulting in an early stop codon.
Frameshift: Deletion or insertion. Think Duchenne muscular dystrophy!!!
What type of repair occurs in G1 vs G2 phase of growth?
G1 is nuceotide excision repair. Occuring in xeroderma pigmentosum with pyrimidine dimers from UV light.
Mismatch repair occurs in the G2 phase of the cell cycle. Defective in nonpolyposis colorectal cancer.
What is the promoter region?
Site where RNA polymerase II and multiple other transcription factors bind to DNA upstream.
What is the enhancer region?
Stretch of DNA that alters gene expression by binding transcription factors.
Describe RNA pol I
RNA pol II
RNA pol III
RNA pol1 is for rRNA
RNA pol 2 is for mRNA
RNA pol 3 is for tRNA
***Amanitin in mushrooms inhibits RNA pol II.
Rifampin binds RNA polymerase in procaryotes.
Actinomycin D inihibits RNA pol in prokaryotes and eukaryotes.
Describe the ribosomyl locations in elognation.
The A site is the site for incoming aminoacyl-tRNA.
The P site accomodates the growing peptide.
The E site holds the empty tRNA as it Exits.
Moves from the 5’ to 3’ ends.
What are chaperone proteins?
These are intracellular proteins involved in facilitating/maintaining protein folding.
What are nissle bodies responsible for?
The synthesis of peptide neurotransmitters for ecretion.
Think of mucus goblet cells as well which occurs in the rough endoplasmic reticulum.
I-cell disease
mutation in N-acetylglucosaminy-1-phosphotransferase.
Golgi is unable to send things to lysosomes, instead they get secreted and build up.
Signal recognition partecle SRP
Abundant cytosolic robonucleoprotein that traffics proteins from the ribosome to the RER.
When absent, dysfunctional proteins accumulate in the cytosol.
COP I
COP II
clathrin
COP I sends from the golgi to the ER. Retrograde.
COP II Sends from the ER to the Cis golgi. Anterograde.
Clathrin: Trans golgi to the lysosomes
What is the role of the peroxisome?
Proteasome?
Peroxisomes deal with the catabolism of long chain fatty acids, branched chain fatty acids, and amino acids.
Proteasomes are barrel shaped protein complexes that break down ubiquinated targets.
What’s the diference between intermediate filaments and microtubules?
Intermediate filaments give the cell structure and consist of vimentin, desmin, cytokeratin etc.
Microtubules allow for cellular division and movement and consist of cilia, flagella the mitotic spindels etc/
Kartageber syndrome
Immotile cilia due to a dynein arm defect resulting in male and female infertility.
Think microtubule cilia problem.
How many sodium are exchanged for potassium at the pump?
Three sodium are pumped out of the cell for two potassium to enter the cell using ATP.
Ouabbain inhibits it by binding the the potassium site.
Type I collagen
Type II collagen
Type III collagen
Type IV collagen
Type I Bone tendon, dentin
Type II Cartwolage
Type III Skin, reticulum, etc.
Type IV Basement membrane, basal lamina etc.
“Type IV under the floor”
Which amino acids are typically used in collagen synthesis?
Lysine and proline.
These are hydroxylated and require vitamin C for proper formation.
Thus Vit C deficiency leads to scurvy and bleeding cums.
note normally collagen is a triple helix of alpha chains.
Osteogenesis imperfecta
Autosomal dominant Genetic bone disorder with decreased type I collagen formation.
Look for blue sclerae, hearing loss, dental imperfections etc.
