Nucleic Acids Flashcards
What are the functions of nucleotides?
monomers; used for energy metabolism, enzyme cofactors, and signal transduction
What are the functions of nucleic acids?
polymers; used for storage of genetic information (DNA), transmission of genetic information (mRNA), processing genetic information (ribosomes), and protein synthesis (tRNA and rRNA)
Nucleotide:
N base+pentose+phosphate
Nucleoside:
N base+pentose
Traits of the phosphate group:
- PO4
- negative (at neutral pH0
- typically attached to 5’ carbon
Nucleic acids are build using the 5’ _____ version of the nucleotides (_TP, _TP, _TP, and _TP)
triphosphate/A/C/G/T
What happens if the phosphate group isn’t attached to the 5’ C?
It leads to specialized functions
Which pentose is used for DNA and which is used for RNA?
Deoxyribose and ribose
N bases are either _____ (two rings) or _____ (one ring)
purine/pyrimidine
What are the characteristics of the N bases?
heteroaromatic, planar, absorb UV light
Which bases are in DNA?
A, T, C, G
Which bases are in RNA?
A, U, C, G
__, ___, and ___ are pyrimidines, ___ and ___ are purines
C/U/T/A/G
Pentose is attaches to N-base via ____ ____ from position N__ (purines) or N__ (pyrimidines), ___ conformation has a bond angle of 0* and ___ conformation has a bond angle of 180*
glycosidic linkage/9/1/syn/anti
A ____ _____ is related to bond 4, it limits the angle of torsion for the N-glycosidic bond between the N base and the pentose
Ring pucker
Modification is done after DNA synthesis, it makes ____ nucleosides; ____, ____, ____, ____, and ____
- minor
- 5-methylcytosine, N6-methyladenoside, epigenetic markers, inosine, pseudouridine
Polynucleotides: formed by ______ bonds (____ linkages) between nucleotides to form a ____-charged backbone that is _____ with ______
covalent/phosphodiester/negatively/linear/directionality
Base pairs form between __ + __ and __ + __, there are __ per turn of the helix and the strands are complementary ____.
A/T/C/G/10.5/antiparallel
__ is the predominant form of DNA but there is also __ (11bp/turn) and __ (left turn, 12bp/turn).
B/A/Z
Steps of DNA replication: (basic outline)
1) strands separate, each is a template for a new strand
2) DNA polymerase catalyzes synthesis
3) new DNA is formed with one daughter and one parent strand
mRNA:
messenger RNA
- synthesized using DNA template
- ribose instead of deoxyribose
- uracil instead of thymine
- transfers genetic into into proteins
What are the two types of mRNA?
1) monocistronic: only codes for one gene
2) polycistronic: codes for more than one gene
RNA hydrolysis occurs in _____ conditions or is catalyzed by ____. The __‘-hydroxyl acts as a _____ in intramolecular displacement, since DNA doesn’t have a __‘-hydroxyl it is unstable under these conditions
alkaline/RNase/2/nucleophile/2
_____ cause many problems because they mix up the DNA, problems include hairpins and cruciforms
Palindromes
DNA ____: induced by high temperatures or pH changes, can be ______. If the _____ bonds remain intact so does the genetic code, if the __ bonds break the strands split, is the ____ ____ ____ is lost UV absorption increases
denaturation/reversible/covalent/H/base pair stacking
Annealing:
reversal of DNA denaturation
Midpoint of melting
Tm: depends on the base pair composition (more C/G instates Tm), longer DNA has a higher Tm, more salt increases Tm, more
Mechanisms of spontaneous mutagenesis:
1) deamination: removal of NH2, causes slow reactions with a large number of residues, C becomes U
2) depurination: N-glycosidic bonds are hydrolyzed and the purines split
Mechanisms of radiation:
1) UV light: induces dimerization (neighbouring pyrimidines join via a dimer) which causes kinks in DNA
2) ionizing radiation: causes rings to open and strands to break
Mutations are ___ to fix, accumulating mutations are linked to ___ and ____
hard/ageing/carcinogenesis
_____ nucleotide triphosphates provides energy to ___ some enzymatic reactions
Hydrolyzing/catalyze
What are some coenzymes that contain adenosine?
Coenzyme A (CoA), FAD
Nucleotides act as regulators for cell signalling, an example of this is ___, a second messenger that activates ____ _____ __ activity
cAMP/protein kinase A
