BIOCHEMISTRY- Molecular/ videos Flashcards
What is attached to the last 3’ Carbon of DNA?
OH (Hydroxyl)
What is attached to the 5’ Carbon of DNA?
Phosphate
What makes the difference between each human DNA?
Sequence of Nitrogen bases
Which bond allows Nucleotides to be atteched to each other in the same strand?
Phosphodiester bond
What holds together the double stranded DNA?
Hidrogen bonds
Which is the DNA tha predominates?
B-DNA right handed helix
How many bases are found in each turn of helix?
10 bases approximately
What forms chromatin?
DNA + Protein
What forms nucleosome?
DNA + Histone Octamer
How are DNA and histones stick together?
Because histones have positive charges and DNA negative
Which aminoacids are included in Histones?
Arginine and Lisine
Where are Barr bodies found?
Heterochromatin
Which drugs work at S phase?
5’ FU
Methotrexate
Which drugs work at G2 phase?
Bleomycin
Which drugs work at Mitosis phase?
Paclitaxel, Vincristin, Vinblastine
Drugs non cell cycle specific
Cyclophosphamide
Cisplatin
Which Purine has amino group?
Adenine
Which enzyme deaminates Adenine to become Guanine?
Adenosine deaminase
What is the result of Adenosine deaminase?
Form Guanine from Adenosine by deaminating it
Which pyrimidin has amino group?
Cytosine
What is the result of cytosine deamination?
Uracyl
Which pyrimidine is in both DNA and RNA?
Cytosine
What is the difference between Uracil and Thymine?
Metil Group
Which drug inhibits thymidilate synthase?
5- FU
When does Nucleoside is called Deoxi?
When it lacks OH in 2’ Carbon
Which Pentose Carbon is attached to base?
1’ Carbon
What is the function of Telomerase?
To make telomers in order to degrade DNA
Associated to oncogen cells
Which is the small arm of chromosomes?
p (petit), q (long arm)
Main characteristics of synthesis
Is always complementary and antiparallel
How is DNA template read by DNA polymerase?
3’ —> 5’
Order of DNA and RNA production
5’ —> 3’
Does RNA polymerase requires RNA primer?
No, just DNA requires RNA primer
Which is the direction of exonuclease repair in proofreading?
3’ —> 5’
Does RNA polymerase has proofreading repair of wrong bases?
No, just DNA
Which pathology has antibodies against topoisomerase?
Scleroderma
Heterochromatin or Euchromoatin…. has dark staining
Heterochromatin
Heterochromatin or Euchromoatin… has active genes
Euchromatin
Which DNA type is more sensitive to nuclease?
the 10 nm
Types of DNA
10 nm
30 nm
Proteins included in histone
2A, 2B, 3, 4 each double forming the octamers
Which structures form euchromatin?
DNA double helix —> 10 nm chromatin —> 30 nm chromatin —> 30 Fibre forms loops attached to proteins
What structure forms heterochromatin?
Higher order Packaging (includes all Euchromatin structures)
What is the function of Nucleolus?
Formation of Ribosomes
What happens in DNA methylation?
Inactive transcription
What happens in Histone acethylation/ Histone phosphorylation?
More active transcription, more gene expression
What causes thymine dimers damage?
By UV radiation
Which the recognition enzyme for thymine repair?
Excision endonuclease
When is excision endonuclease deficient in thymine repair?
Xeroderma pigmentosum
Which enzymes repair DNA damage?
DNA polymerase and DNA ligase
When does Thymine dimer repair occur?
During G1
When does Mismatched base repair happens?
During G2
Which are the two genes that may be affected in Mismatched repair?
hMSH2 or hMLH1
Alternative name for Hereditary Nonpolyposis Colorectal Cancer (HNPCC)?
Lynch syndrome, predisposes to cancer
What explains HNPCC?
Accumulation of mutations due to defective mismatched repair
When does Cytosine deamination occurs?
During G2
What causes Cytosine deamination?
Spontaneous Heat
Which enzyme corrects if Uracil is present in DNA?
Uracil Glycosylase
AP endonuclase
Clinical manifestations of Xeroderma pigmentosum
Extreme UV sensitivity (vampire existanse)
Excessive Freckling
Multiple skin cancers
Corneal Ulcerations
Which is the function of DNA ligase?
Reconect Fosfodiester bonds
What is accumulated in cytosine deamination?
Uracil in DNA
What is the effect of p 53 in case DNA repair is not done correctly after slowing down DNA repliaction?
Induces Apoptosis
Which virus block p53 action?
Hepatitis B and HPV
di and tri nucleotide repeats that occur throughout the genome but typically occur in noncoding sequences of DNA
Microsatellites
What happens to microsatellites in cells that lack mismatch base repair?
Number of microsatellites will differ in the mutated cells (called microsatellite instability)
What does RNA polymerase initially looks for in Transcription?
Initially finds and binds to the promoter, not the coding region