DNA Replication Flashcards
What are nitrogenous bases linked by?
Hydrogen bonds (C and G form 3 H-bonds and A and T form 2 H-bonds).
What are the two strands of DNA linked by?
They are linked by hydrogen bonds only.
What are adenines and guanines called?
Purines. They have 2 cycles fused together (2 rings).
What is a nucleotide made of?
A nitrogenous base, a sugar, and a phosphate molecule ( in adenines and guanines).
What are cytosines and thymines called?
Pyrimidines. They have only one cycle (ring).
What is a nucleoside?
It is made of a sugar and a nitrogenous base but without a phosphate group (in cytosine and thymine).
What are they key enzymes evolved in DNA replication?
Helicase, Primase, DNA polymerase, and Ligase.
What is the role of Helicase?
It unwinds the DNA strand.
What is the role of Primase?
It adds a short segment of RNA (primer).
What is the role of DNA polymerase?
It adds complementary nucleotides to the leading and lagging strands of the parent DNA.
What is the role of ligase?
It seals and binds.
What is a characteristic of the replication of DNA?
It is semi conservative (50% old and 50% new).
With each new strand that is synthesized where does each strand come from?
One strand comes from the parent strand (old) and the other comes from the daughter strand (new).
What is the difference between bacterial chromosomes and eukaryotes chromosomes in DNA replication?
Bacteria DNA has a single point or origin aud replicates in both directions while eukaryotes have 50 to 100 sites of replication. Evenso, both replications are bidirectional.
What is the direction of DNA synthesis?
It can only be done in 5’ to 3’ direction on the daughter strand because the third carbon on the ring is the only one that can attach a complementary nucleotide (DNA polymerase).
