Nucleic Acids, Structure, Chemistry and DNA Sequences Flashcards
What is the direction of DNA and RNA?
5’ to 3’
What are the TWO Purines?
- Adenine
- Guanine
What are the THREE Pyrimidines?
- Cytosine
- Thymine (DNA)
- Uracil (RNA)
What is the structure of DNA?
- Nitrogenous base
- Phosphate
- Pentose sugar (deoxyribose)
What is the structure of RNA?
- Nitrogenous base
- Phosphate
- Pentose sugar (ribose)
What is the difference in structure of a Ribonucleotide and a Deoxyribonucleotide?
- Ribonucleotide has OH at 2’C
- Deoxyribonucleotide has H at 2’C
What bonds link nucleotides?
Phosphodiester
* 5’ OH of one ribose is linked to the 3’ OH of the next ribose
Covalent backbone
How many bonds does A-T have?
2
How many bonds does G-C have?
3
What is the structure of DNA?
Right handed double helix
* Complementary strands
* Anti-parallel
* Flexible
What happens in DNA during deamination (loss of amino groups)?
Cytosine changed to Uracil
How does loss of purines happen?
Due to hydrolysis of bond between base and pentose AP or apurinic site
What does radiation damage do to nucleotides and nucleic acids?
- UV light: Cyclobutane pyrimidine dimers
- Ionising radiation: Ring opening, breaks in backbone
What are some chemicals that cause mutations in nucleotides and nucleic acids?
- Deminating agents
- Alkylating agents
What are some examples of oxidative damage to nucleotides and nucleic acids?
- Hydrogen peroxide
- Hydrogen radicals
Where do Hairpin Loop structures occur?
In single DNA strand or RNA
Where do Cruciform structures occur?
Double strands
Why is DNA and RNA secondary structure important for function?
- Sites for binding of regulatory proteins
- Catalytic activity: removal of introns from DNA
- Transfer RNA: an adapter molecule in protein synthesis
What does the melting point of DNA depend on?
- pH
- Ionic strength
- Size
- Base composition
What is HOMODUPLEX DNA?
Both strands are from the same species
What is HETERODUPLEX DNA?
Strands from different species with some bases unpaired
What is the technique for detecting identical or similar DNA from different species called?
Hybridisation
What are some applications of Near-Complimentary Hybrids in DNA and RNA?
- Detection of a specific DNA molecule in complex mixture
- Amplification of specific DNA fragments
- Evolutionary relationships
- Antisense oligonucleotides
What are Genes?
Segments of DNA that code for polypeptides and RNAs
What is Sanger Sequencing?
- DNA polymerase used to introduce a labelled nucleotide complimentary to nucleotide in template DNA strand
- Introduces ddNTP analogs to interupt DNA synthesis
- Fragments then separated and nucleotide sequence is then read
How many base pair fragments is “Next Gen” sequencing now able to sequence?
400-550
