Nucleic acids Flashcards
What are the two types of nucleic acids and what is their role?
DNA and RNA. They have roles in the storage and transfer of genetic information and the synthesis of proteins
What elements do nucleic acids have?
Carbon, hydrogen, oxygen, nitrogen and phosphorus
What are nucleic acids made of?
They are polymers, made up of nucleotides (monomers) joined together.
What is a nucleotide made of?
A pentose sugar, a phosphate group and a nitrogenous base.
How are nucleotides linked together?
Condensation reaction, to form a phosphodiester bond between a phosphate group and the OH group on carbon 3.
Forms a sugar-phosphate backbone
Why is the bond called phosphodiester?
It consists of a phosphate group and 2 ester bonds.
How are phosphodiester bonds broken?
Hydrolysis reaction.
How is DNA different from RNA?
It has a deoxyribose sugar, rather than a ribose sugar like in RNA.
It has cytosine as a base rather than uracil.
It is double stranded, whereas RNA is single stranded
RNA is much shorter than DNA
What is a pyrimidine?
The smaller bases, single carbon ring structure.
Thymine and cytosine.
What is a purine?
The larger bases, double carbon ring structure.
Adenine and guanine
How many bonds do the bases form and what is the rule for complementary base pairing?
A-T 2 bonds
C-G 3 bonds
A purine always pairs with a pyrimidine- which ensures that there is a constant distance between the DNA backbones
How are the two strands in the double helix held together and arranged?
Hydrogen bonds between the bases holds them together.
The two strands run in opposite directions- antiparallel (5’ to 3’ and 3’ to 5’)
How can DNA be extracted from plant?
Grind in mortar and pestle- break down cell wall
Mix with detergent- break down cell membrane
Add salt- breaks hydrogen bonds
Add protease enzyme- breaks down the proteins (histones) associated with the DNA.
Add ethanol- causes DNA to precipitate out of the solution
