U1 - DNA Replication and PCR Flashcards
the replication of DNA is _______
semi-conservative
state the 5 requirements for DNA replication
DNA template, ATP, DNA primers, free nucleotides, enzymes
state the function of enzyme polymerase in DNA replication
enzyme polymerase adds free nucleotides during DNA replication
state the function of enzyme ligase in DNA replication
ligase joins fragments of DNA together
describe the process of DNA replication
DNA is unzipped and unwound as hydrogen bonds are broken. two template strands are left and bases are exposed. on the leading strand: primer binds to the 3’ end of the DNA and DNA polymerase adds nucleotides in a 3’ to 5’ direction. leading strand is synthesized continuously. On the lagging strand: DNA polymerase adds nucleotides in fragments as nucleotides can only be added from 3’ to 5’. These fragments are then joined together by enzyme ligase. 2 new strands twist to form a double helix - each identical to the original strand
what is PCR
PCR is a technique for the amplification of DNA in vitros
state the 5 requirements for PCR
complementary primers to target DNA sequences, heat tolerant polymerase, DNA template, free nucleotides, buffer solution (CHDFB)
state two uses of PCR
amplifying samples from crime scenes (forensics); paternity testing
describe the process of PCR
solution is heated to 95 degrees and DNA becomes denatured and hydrogen bonds are broken. solution is cooled to 60 degrees to allow primers to anneal to complementary DNA sequence. solution is heated to 72 degrees to allow heat tolerant polymerase to add nucleotides. cycle is repeated
explain the importance of primers in PCR
primers allow PCR to be highly specific
state the role of enzyme polymerase in DNA replication
adds nucleotides
state the role of enzyme ligase in DNA replication
joins fragments of DNA together
state practical applications of PCR
amplifying DNA in forensics, paternity testing, medical applications such as diagnosis of HIV
why can DNA polymerase tolerate high temperatures
it comes from bacteria which is adapted to live in hot springs
