KA2 U1 Flashcards
DNA consists of?
Units called nucleotides, twisted into a double stranded helix.
Nucleotides are made of 3 parts
•Deoxyribose sugar
•Phosphate
•base
Rulings of carbons attached to D and P
•Deoxyribose has in a nucleotide has a base attached to its carbon 1
•and a phosphate attached to its carbon 5
Nucleotides are joined by what to form a strand with sugar phosphate backbone
•Nucleotides are joined by their deoxyribose sugar and phosphate to form a strand with a sugar phosphate backbone
What does the sequence of DNA form
Genetic code
Based on opposite strands are held together by what?
•Weak hydrogen bonds between complementary base pairs
Anti parrarel structure
• the two DNA strands have their sugar phosphate backbones running opposite directions from each other
•this is a double stranded antiparrarek structure.
•Each strand has a deoxyribose sugar at 3 end and a phosphate at the 5 end
D3 P5
DNA replication is replicated using what enzyme
DNA polymerase
Why do primers need to start replacation
As they can only add nucleotides in one direction
To the 3 end of the new strand
A primer is what
A short strand of nucleotide
Where do primers bind
3end of the template DNA strands allowing DNA polymerase to add nucleotides
Stages of DNA replication
S1: DNA molecules unwinds
S2: Hydrogen bonds between base pairs break to from two template strands
S3: a primer binds to the 3 end of the originally template strand
S4: DNA polymerase enzyme adds nucleotides using complementary base pairing to the 3 end of the new strand
S5: this results in the leading strand replicating continually
S6: lagging strand nucleotides are added by DNA polymerase to form fragments
7 Ligase joins DNA fragments on the lagging strand to form a complete strand
What is PCR
A technique used to amplify specific target sequences of DNA
What does PCR USE to do this
Primers which are complementary to specific target sequences at the two end of DNA to be amplified
Stage1 PCR
DNA is heated between 92-98 degrease to seperate DNA strands
Stage 2 PCR
it’s then cooled between 50-65 degrees to allow primers to bind to target sequence
Stage 3
It’s the heated between 70 and 80 degrease to allow heat tolerant DNA polymerase to replicate the region of DNA
Stage 4
Two identical copies of DNA made after first cycle
Repeated cycles of heating and cooling amplify the target region of DNA and allow billions of copies to be produced
Practical applications of PCR
•Solve crimes
•settle paternity suites
•diagnose paternity suits
