3.8 nucleic acids Flashcards
what are nucleic acids, what do they do and what elements do they contain?
they are polymers of nucleotides they contain C H O N & P
they store/transfer genetic information& are used in synthesising polypeptides.
whats a nucleotide and what are they made up of?
Monomers of nucleic acids
they are made from pentose sugar, nitrogenous base & phosphate group
what are the different nitrogenous bases
PURINE - Adenine, Guanine
PYRIMIDINE - Cytosine, Thymine, Uracil
how are nucleotides joined together
condensation between hydroxyl (3’) & phosphate (5’)
phosphodiester bonds form sugar-phosphate backbone
Polymerase enzymes can only add nucleotides onto the _____ group of the [3’/5’] end of the nucleotide.
the hydroxyl group of the 3’ end
What is the difference between pyrimidine & purine nitrogenous bases?
Pyrimidine bases have a single carbon ring structure and Purine bases have a double carbon ring
what does pyrimadine and purine complementary base pairing ensure
the DNA strand width remains the same
what number of H bonds do each complementary base pair have
C and G has 3 bonds
A and T has 2 bonds
what is complementary base pairing
Hydrogen bonding
between specific nitrogenous bases.
Adenine bonds to Thymine, Guanine bonds to Cytosine
describe the structure of DNA (5)
SUGAR-PHOSPHATE BACKBONE
DOUBLE HELIX
strands twist
ANTIPARALLEL
strands run in opposite directions
DOUBLE STRANDED
2 polynucleotide strands held together by hydrogen bonds
COMPLEMENTARY BASE PAIRING
specific hydrogen bonding between complementary nitrogenous bases
what is RNA
A Polynucleotide its involved in copying & transfer of genetic material from DNA
What are the similarites and differences of the structure of DNA and RNA
SIMILARITIES
pentose sugar
phosphodiester bonds between nucleotides
polymer of nucleotides
DIFFERENCES
DNA has deoxyribose sugar, RNA has ribose
RNA has Uracil base instead of Thymine
RNA single stranded, DNA double stranded
Why can DNA not be used directly to transfer genetic information to the ribosome?
its too large to leave nucleus
and also could be damaged in transport, so template (RNA) used
Outline the process by which DNA can be extracted from a tissue sample, explaining the reasoning behind the steps:
Grind sample
Breaks down cell walls & provides large surface area
Add detergent
Dissolves phospholipid bilayer of membranes
Add salt
Makes DNA less soluble in water by breaking hydrogen bonds between DNA + H2O
Add protease
Breaks down enzymes involved in DNA degradation
Add ethanol
DNA insoluble in ethanol & salt, ∴ forms precipitate
Pick out DNA using hook
