1.2 Flashcards
what is DNA composed of
nucleotides
what holds two strands of DNA together
two strands are joined together by hydrogen bonds that link complementary pairs of nucleotide bases
what does a nucleotide consist of
- sugar phosphate
- base
- deoxyribose sugar
describe the antiparallel structure of DNA
the 5’ end has a phosphate attached and the 3’ end has the deoxyribose exposed.
what do chromosomes consist of
chromosomes consist of tightly coiled DNA and are packaged with associated proteins.
what is a primer
a primer is a short sequence of nucleotides which binds to the 3’ end of the template DNA strand allowing polymerase to bind
what does replication of DNA require
it requires the enzyme DNA polymerase
what happens in the Beginning of DNA replication
DNA is unwound and hydrogen bonds between bases are broken to form two templates.
second stage of DNA replication
primers bind to the 3’ end of the template DNA strand
what does DNA polymerase require to start replication
primer
what happens for a lagging strand and leading strand to form
a lagging strand and leading strand form because DNA polymerase can only add DNA nucleotides to the 3’ end of the DNA template .
leading strand
replicated continously
lagging strand
replicated in fragments that are joined together by the enzyme ligase
what is the polymerase chain reaction
a technique used for the amplification of DNA in vitro and involves the use of a thermal cycler
what does pcr produce
many copies of a specific section of DNA
PCR CYCLE
1- DNA TO BE REPLICATED IS HEATED BETWEEN 92-98 DEGAREES TO SEPARATE STANDS
2- COOLING TO 50-65 DEGREES ALLOWS PRIMERS TO BINF TO TARGET SEQUENCES
3-HEAT TOLERANT DNA POLYMERASE THEN REPLICATES THE REGIONS OF DNA BETWWEN 70-80 DEGREES
PRACTTICAL APPLICATIONS OF PCR
- HELP SOLVE CRIMES
-PATERNITY ISSUES
-DIAGNOSE GENETIC DISORDERS
