Unit 2 - Structure and Replication of DNA Flashcards
What 3 components make up a nucleotide
A base, deoxiribo sugar and a phosphate
name the 4 types of bases found in a DNA molecule
Adenine, Thymine, Guanine and Cytosine
what is the pairing rule of the bases
A - T
G - C
what carbon in the deoxiribo sugar is bonded to the base
1’ / one prime
which carbon bonds with a phosphate
5’ / 5 prime
which end of the the carbon is left with the deoxiribo sugar
3’ / three prime
what is a single strand of a DNA held together by
each strand of DNA is held together by a strong chemical bond between the sugar of one nucleotide and the phosphate of the next
what are bases bonded by
bases are bound by weak hydrogen bonds
what is the shape that DNA is wound into
a double stranded helix
what name is given to the structure of the DNA molecule and why
it is called an Anti-Parallel structure, as each strand faces in opposite directions
what does each 5’ DNA strand have at the end
a phosphate group
what does each 3’ DNA strand have at the end
a dexoiribo sugar
what enzyme is used to replicate DNA
prior to cell division a DNA polymerase is used to replicate the DNA
what is needed to start replication of DNA
a primer is needed to start replication of DNA
what is a primer
a primer is a short strand of nucleotides which binds to the 3’ end of the template strand of DNA
how does DNA polymerase add DNA nucleotides
DNA polymerase adds DNA nucleotides by using complementary base pairings to the deoxyribose end of the new forming DNA strand
why is the hydrogen bonds broken in a DNA nucleotide
when the DNA is unwound the hydrogen bonds between the bases break to form two new template strands
what happens to the other strand untouched by DNA polymerase and why?
DNA polymerase can only add DNA nucleotides in one direction resulting in the leading strand being replicated continuously and a strand lagging replicated in fragments.
what are the fragments of DNA joined by
fragments of DNA are joined by ligase
what does PCR stand for
Polymerase Chain Reaction
what is a primers function in relation to PCR
a primer is a short strand of nucleotides which are complementary to specific target sequences at the two ends of the region of DNA to be amplified.
what amplifies the target region of DNA
a repeated cycle of heating and cooling will amplify the target region of DNA
why is the DNA heated between 92 and 98°C in a PCR
DNA is heated between 92 and 98°C to separate the strands of the DNA
why is the DNA cooled to between 50 and 65°C in a PCR
DNA is cooled between 50 and 65°C to allow the primers to bind to the target sequence
why is the DNA heated to between 70 and 80°C in a PCR
DNA is heated between 70 and 80°C for the heatc tolerant DNA polymerase to replicate the region of DNA
what are the practical applications of a PCR
PCR can amplify DNA to help solve crimes, settle paternity suits and diagnose genetic disorders.
