A1.2 Nucleic Acids

Flashcards from lecture notes.

DNA

Polymer made of monomers called nucleotides; hereditary information passed to offspring.

Phosphate Group

A group attached to the fifth carbon of pentose sugar in a nucleotide.

Nitrogenous Base

Attached to the first carbon of pentose sugar in a nucleotide (adenine, guanine, cytosine, thymine).

Phosphodiester bonds

The bonds that link nucleotides between one nucleotide’s phosphate group and another pentose sugar, formed via condensation reactions.

Purine Bases

adenine, guanine

Pyrimidine Bases

cytosine, thymine, uracil

DNA replication is semiconservative

Each daughter DNA molecule has one strand of the original one.

RNA

A single-stranded polymer of nucleotides.

Complementary base pairing

adenine bonds with thymine and cytosine bonds with guanine - no exceptions → maintains genetic sequence during replication

Structural Differences Between DNA and RNA

DNA uses deoxyribose sugar while RNA uses ribose sugar

New Nucleotides

New nucleotides can only be added to the 3’ end of a DNA polymer

Gene expression

Using the genetic codes/sequences in DNA to synthesize a protein

Directionality of RNA and DNA

Carbon of the pentose sugar are numbered 1-5 - signifies 5’ and 3’ end (#3 carbon and #5 carbon)

Nucleosome

DNA wrapped twice around a core of 8 histone proteins - additional H1 histone stabilizes the nucleosome, condenses the DNA

Hershey-Chase Experiment

Scientists injected two groups of bacteriophages (containing a protein capsid and DNA) with radioactive 35 S (sulphur) and 32 P (phosphorus) to determine what the genetic material was.

Chargaff’s Conclusion

genetic sequences vary between organisms, DNA is not a tetranucleotide