Nucleic Acid Structures Flashcards
join the 3’-carbon of one sugar to the 5’-carbon of the next sugar
Phosphodiester bonds
DNA chains are ______ meaning on side runs from 5’ to 3’ while the other side runs from 3’ to 5’ end
antiparallel
located on the outside of the double helix
phosphate groups. Used in phosphodiester bonds
is right-handed and contains ______ per turn.
B form of DNA; 10 base pairs
Alkali or heat causes the strands of DNA to separate but does not break phosphodiester bonds.
Denaturing
If strands of DNA are separated by heat and then the temperature is slowly decreased under the appropriate conditions, base pairs reform, and complementary strands of DNA come back together.
Renaturing/annealing
A single strand of DNA or RNA pairs with complementary base sequen- ces on another strand of DNA or RNA.
Hybridization
a segment of a DNA molecule that contains the information required for the synthesis of a functional biological product, whether protein or RNA
gene
only known functions of DNA:
storage of biological information transmission of that information to the next generation
Pneumococcus type:
- Live (smooth bacteria):
- Heat-killed (smooth bacteria:
- Live (rough bacteria)
- Mixture of Heat-killed (smooth bacteria) + Live (rough bacteria)
Mouse fate?
- Mouse dies
- Mouse lives
- Mouse lives
- Mouse dies
- protein injection:
- lipids injection:
- carbohydrates injection:
- nucleic acids fraction:
- mouse lives
- mouse lives
- mouse lives
- mouse dies
Gene flow
replication (DNA) transcription/reverse transcription (RNA) translation protein
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associated with gene silencing
methylation (5-methylcytosine)
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Catalyzes the formation of DNA chains
DNA Polymerase
short (typically < 50 nucleotides) nucleic acid
oligonucleotide
longer nucleic acid
polynucleotide
All nucleic acid sequences are written in a ________ direction
5’ to 3’ direction
Severs p-type linkage
Endonuclease
severs d-type linkage
exonucleases (cleavage on the edges of the strand)
Classes of RNA:
- ribosomal RNAs (rRNAs) = components of ribosomes
- messenger RNAs (mRNAs) = intermediates in protein synthesis
- transfer RNAs (tRNAs) = adapter molecules that translate the information in mRNA into a specific amino acid sequence
- noncoding RNAs (ncRNAs) = wide variety of functions
4 Basic Molecular Genetic Processes
- Transcription
- RNA Processing
- mRNA translation
- Replication
Formation of 3’ to 5’ Linkage
How phoshodiester bonds are linked 3’ to 5’ dispite the strand still going from 5’ to 3’ end.
The normal form of DNA found in mammals
Most stable for a random-sequence DNA molecule under physiological conditions
characteristic:
B form
perpendicular bases
right-handed double helix with a wider helix, 11 bp/turn, and a tilted plane
favored in solutions devoid of water
A-form DNA
left-handed helix with 12 bp/turn and a backbone with a zig-zag appearance
appears more slender and elongated
Z-form DNA
Comparison of A, B, and Z forms of DNA
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Stabilizing Forces of DNA
- Hydrophobic Interactions Among the Bases
- Electrostatic Interactions of the Negatively Charged Phosphate Groups; Counter-ions Such as Mg++; and Basic Proteins
- Hydrogen Bonds (weak forces)
the observed decrease in the absorption of UV light when complementary strands are paired
hypochromic effect
Stabilization of the DNA Double Helix
- metal cations that shield the negative charges of backbone phosphates
- base stacking interactions between successive base pairs
- successive G≡C or C≡G are stronger than successive A=T or T=A
- duplexes with higher G≡C context are more stable
the observed increase in the absorption of UV light when a double-stranded nucleic acid is denatured
hyperchromic effect
monitoring UV absorption at ______nmcan detect the transition from double-stranded to single-stranded DNA
260 nm