Molecular Biology Flashcards
(27 cards)
What 3 structures make up a nucleotide?
pentose sugar
nitrogenous base
phosphate group
What is the difference between a nucleoside and a nucleotise?
nucleoside has no phosphate group
Which nucleotides are pyrimidines?
cytosine, thymine, uracil
which nucleotides are purines?
adenine, guanine
what has to happen to a nucleotide before it can become DNA?
add two phosphate groups
In DNA, which bases pair?
A-T
C-G
In RNA, which bases pair?
A-U
G-C
In which segments of DNA does methylation occur?
segments with repeating CG patterns
Which nucleotides are methylated?
cytosines
What type of response does unmethylated CG cause? why?
immune response, b/c Bacterial DNA differs from mammalian DNA by the presence of unmethylated cytosine-phosphate-guanosine (CpG) motifs
What is a nucleosome made up of?
histones + DNA
What gives histones the property necessary for binding with the DNA backbone?
They contain a lot of basic amino acids (lysine and arginine) which have a positive charge at human pH, allowing them to interact with the negativly charged DNA phosphate backbone.
What is the role of H1 in DNA structure? What chemical properties allow it to do this?
they tie the “beads on a string” together, condensing the DNA.
H1 is more basic and larger
antibodies to which part of DNA are implicated in drug-induced lupus?
Histones: anti-histone antibodies are present in >95% of DIL cases.
Classic drugs associated with drug induced lupus?
Hydralazine (BP/HF)
procainamide (antiarrhythmic)
isoniazid (TB)
what type of genes would be found in areas of heterochromatin? why?
genes that are not essential for cellular functions/not actively needed b/c heterochromatin is very condensed and DNA is heavily methylated
what type of genes would be found in areas of euchromatin? why?
genes needed for regular cellular function b/c euchromatin is less condensed, with heavy histone acetylation (alters accessibility of chromatin and allows DNA binding proteins to interact with exposed sites to activate gene transcription and downstream cellular functions.)
Which part of histones undergo acetylation?
acetyl groups are added to lysine in the histones
what is the effect of histone acetylation? deacetylation?
acetylation causes the chromatin to relax for transcription of genes, deacetylation causes chromatin to close-up
Transcription is induced by which modification?
histone acetylation
Is DNA or RNA synthesized first?
RNA, then converted (remove OH group) to deoxyribonucleic acids (DNA)
which type of nucleotides tend to act as second messengers?
adenosine and guanosine
cAMP - blood flow
cGMP - second messenger
what are the purine ingredients?
ribose phosphate
amino acids
carbons from THF or CO2
What is PRPP?
first intermediate in purine synthesis, add phosphate group to ribose -5-phosphate
