3.8 NUCLEIC ACIDS Flashcards
Why are some acids ‘nucleic’?
as they were found in the nucleus of a cell (and are quite acidic when in a solution) - by Friedrich Miescher in 1868.
What components do almost every human cell contain?
46 chromosomes, 2 metres of DNA, around 3 billion nucleotides
What are them main nucleic acids?
DNA and RNA
How do base pairs bond with each other?
under neutral conditions the remaining OH group of the phosphate is deprotonated, and oxygen atoms bear a positive charge - this masks the basic properties of the phosphate, allowing hydrogen bonds to form between the base pairs.
What are nucleotides?
monomers of nucleic acids (nucleic acids are polymers of nucleotides)
What are the three subunits of a nucleotide?
Phosphate group, Pentose sugar, a nitrogenous base.
What are the components/ types of nitrogenous base?
Adenine, Thymine (Uracil as RNA), Guanine, Cytosine.
They are organic, and are made of nitrogen and carbon.
What are the components of the phosphate group?
Inorganic, PO4 2-.
One phosphorous and 4 oxygen (bottom one is double bonded 3 are single bonded).
What are the components of a pentose sugar?
organic, monosaccharide, 5 carbon sugar, 3’ joins to next nucleotide.
What are the differences between RNA and DNA?
DNA is double stranded, RNA is single stranded.
DNA has deoxyribose pentose sugar, RNA has ribose pentose sugar.
Adenine pairs with Uracil in RNA, and Thymine in DNA.
Found in nucleus in eukaryote and cytoplasm in prokaryote in DNA, found in/out of nucleus in eukaryote, and cytoplasm in prokaryote.
What is the symbol equation for DNA/ RNA?
DNA = C5 H10 O4
RNA = C5 H10 O5
What are the pyrimidine bases in DNA and RNA?
Cytosine/ Thymine (Uracil)
They are the smaller bases.
What are the purine bases in DNA and RNA?
Adenine/ Guanine
They are the larger bases.
What does planar mean?
Flat - a component of the nitrogenous bases.
How many bonds are between Thymine (uracil) and Adenine?
2 Hydrogen bonds
How many bonds are between Cytosine and Guanine?
3 hydrogen bonds
How many DNA base pairs are there on Earth?
5.0 x 10 37
mass of 50 billion tonnes
What does base pairing allow?
Allows DNA polymerase to replicate DNA and RNA polymerase to transcribe DNA to RNA.
What are phosphodiester bonds?
Strong covalent bonds which hold polynucleotide together (sugar to the next phosphate)
How can the two DNA stands be held together?
The first strand runs in a 5’ to 3’ direction and acts as a template strand. The second strand is antiparallel and runs in a 3’ to 5’ direction.
What is Uracil?
Demethylated form of Thymine found in RNA.
What type of base pair does Uracil form with Adenine in RNA?
Watson- Crick base pair with only two hydrogen bonds in between.
In what form is RNA found in nature as?
A single stranded molecule, folded onto itself, shorter than a DNA molecule.
What shape does DNA form?
A double helix
What does labile mean?
RNA is more labile than DNA so it breaks down easier making it more unstable. This lowers the activation energy needed for hydrolysis.
How do many viruses encode their genetic information?
Using an RNA genome
What rough structure does tRNA from?
A cloverleaf structure - folding and hydrogen bonding on itself with its own base pairs.
What are the steps of DNA extraction from a plant material?
- Grind sample in pestle and mortar - breaks down the cell walls.
- Mix sample with detergent - breaks down cell surface membrane, releasing cell contents into solution.
- Add salt - breaks Hydrogen bonds
- Add protease enzymes - break down proteins associated with DNA in nuclei
- Add a layer of alcohol (ethanol) - causes DNA to precipitate.
- DNA is picked up by spooling it onto a glass rod - DNA will be seen as white strands forming between the layer of sample and the layer of alcohol.
