Module 10: Nucleic Acids Flashcards
NAD & FAD are…
enzyme co-factors
what are nucleotides & what are they made of?
building blocks of nucleic acids
ribose sugar, nitrogenous base & phosphate
what is the cycled form of ribose in nucleotides?
beta-D-ribofuranose
how many rings do pyrimidines & purines?
pyrimidines: 1 ring
purines: 2 rings
what 3 bases are found in both DNA & RNA?
adenine, guanine & cytosine
what base is only found in DNA?
Thymine
what base is only found in RNA?
Uracil
how do nitrogenous bases link to ribose?
though N-glycosidic bonds
what carbon do nitrogenous bases link to?
C1
in purines, the N-glycosidic bond is to what position on the nitrogenous base?
N9
in pyrimidines, the N-glycosidic bond is to what position on the nitrogenous base?
N1
how do nucleotides and nucleosides differ?
whether they are phosphorylated at the C5 position
what suffix is used for nucleosides?
osine
what suffix is used for nucleotides?
late
what is AMP formed by?
formed from ATP in a reaction catalyzed by adenylyl cylcase
what do phosphodiester bonds do?
join nucleotides in nucleic acids
nucleotides form linear nucleic strands through…
3-5 phosphodiester linkages
sickle cell anemia is caused by the…
change of 1 nitrogenous base
can RNA adopt 3D structures?
yes
what percentage of rRNA is found in ribosomes?
80%
what does tRNA do?
transport amino acids to ribosomes for protein synthesis
what does mRNA do?
code for proteins
what does miRNA do?
regulation of gene expression
how long are oligonucleotides?
22-24
what idea did Watson & Crick develop?
DNA consists of 2 anti-parallel chains in right handed double helical arrangement
where are sugar-phosphate backbones and nitrogenous bases on the helix?
sugar-phosphates: outside
Nitrogenous bases: inside
Adenine pairs with ( )
Thymine
Guanine pairs with ( )
Cytosine
what is Chargaffs rule?
A + G = T + C
In duplex DNA, what the ratio of purines to pyrimidines?
of purines = # of pyrimidines
what is the hydrophobic effect of the double helix?
hides purine & pyrimidine rings inside helix
what are stacking interactions?
stacked base pairs form van der waals contacts
electrostatic repulsion of negatively shared phosphate groups is decreased by…
cations (Mg) & cationic proteins
how many grooves does a double helix have?
2 (major & minor)
are grooves in double helix the same length?
no
what do restriction endonucleases do?
recognize & cleave specific DNA sequences
what is methylation?
when host cells protect their own DNA by covalent modification of bases at the restriction site
where do restriction enzymes cut?
at palindrome sequences
what are restriction enzymes used as?
molecular scissors
what does RFLP stand for?
restriction fragment length polymorphisms
what is denaturation?
complete separation of double-stranded DNA by heat or chemical agents
what is annealing?
reforming the double stranded helix to form single strands
what is the melting point? (Tm)
the temperature at which 1/2 DNA has become single stranded
what are the substrates for synthesis?
nucleotide triphosphate
where are incoming residues added to in DNA?
3’ end of the growing strand
what is polymerase chain reaction (PCR)?
uses heat-stable enzymes to make new DNA
what does PCR allow?
exponential amplification of short regions of DNA very quickly
who discovered PCR?
Kary Mullis
what is the 1st level of packaging eukaryotic DNA?
involves information of nucleosomes
Histones are ( ) packaging proteins
DNA
Nucleosome composed of:
2 of each: H2A, H2B, H3, H4 and 146 base pairs of DNA
( ) binds to the region of the linked DNA
H1
how many nucleotides make a codon?
3
what are introns?
non-coding intervening sequences
what are plasmids?
non-chromosomal DNA
what kind of genome does bacteria have?
closed, circular genome
what shape are eukaryotic chromosomes?
linear
what are telomeres / where are they found?
repeating sequences at the end of chromosomes
what are exons?
cotton protein-coding information
what is an advantage of introns?
multiple mRNAs can be generated from 1 gene
what modification is used in epigenetics?
methylation of cytosine residues
what is epigenetics?
changes to the genome that do not involve a change in nucleotide sequence