U1KA2 Flashcards
What is the structure of DNA
two complementary strands of nucleotides joined together by complementary bases.
What is a DNA nucleotide?
a basic unit consisting of a deoxyribose sugar, phosphate and the base.
What is a strong sugar-phosphate chemical bond?
its a strong chemical bond between sugar molecules of one nucleotide and phosphate molecule of another.
What are the 4 DNA bases?
adenine. thymine, guanine and cytosine.
What is the complementary rule of DNA bases?
adenine w thymine
guanine w cytosine
what is the bond between the bases called
weak hydrogen bond.
why is the weak hydrogen bond not a strong chemical bond like the sugar-phosphate backbone?
because the two strands need to get seperated for replication which requires the weak hydrogen bond to break.
the complementary strands of DNA run ____ to each other, meaning ______
antiparallel, meaning they run in opposite directions.
Which molecule is found at 5’ end and which molecule is found at 3’ end?
phosphate at 5’end and deoxyribose sugar at 3’ end.
Why must DNA be replicated before cell division?
to ensure that daughter cells produced are identical to the original parent cells.
Does DNA replication require ATP?
yes.
What are the stages of DNA replication in the leading strand?
1) DNA strand unwinds, and hydrogen bond breaks.
2) A primer attaches.
3) DNA polymerase adds complementary nucleotides continuously from the 3’ end to the 5’ end of the DNA strand.
What is a primer?
a short sequence of nucleotides.
What is DNA polymerase?
an enzyme that adds complementary nucleotides continuously from the 3’ end to the 5’ end of the DNA strand. It uses the primer as a starting point.
What are the stages of DNA replication in the lagging strand?
1) several primers attach
2) DNA polymerase adds nucleotides from the 3’ -> 5’ direction.
3) ligase joins fragments together.
Why is the 3’ end of the lagging strand not accessible as the DNA unzips?
Because the 2 DNA strands are antiparallel. The lagging strand starts at 5’ end when the DNA strand unzips. DNA replication MUST always occur in the 3’->5’ direction.
What is ligase?
it’s an enzyme that joins fragments of DNA together on the lagging strand.
What is PCR?
a laboratory technique used to amplify or make copies of DNA sequences.
What is PCR used for?
solving crimes or genetic research.
What is the enzyme used in PCR called?
heat tolerant DNA polymerase.
What is stage 1 of pcr
dna is collected, heated at 95 C which causes the hydrogen bonds between complementary bases to break.
what is stage 2 of pcr
cool to 60C allowing the primer to bind
what is stage 3 of pcr
heat up at 75 C which is optimum temp for heat-tolerant DNA polymerase to add nucleotides.
