Unit 4 (CH 16) Flashcards
DNA consists of two strands of nucleotide monomers repetitively linked together.
□ At the ______’ end of each strand is a free ________________ group.
□ At the ______’ end of each strand is a free ________________ group.
□ At the 5’ end of each strand is a free phosphate group.
□ At the 3’ end of each strand is a free hydroxyl group (-OH).
In the polymerization of DNA, a phosphodiester bond is formed between a phosphate group of the nucleotide being added and which of the following atoms or molecules of the last
nucleotide in the DNA strand?
a) The 5’ phosphate group.
c) The 3’ OH.
b) C6.
d) A nitrogen from the nitrogen-containing base.
c) The 3’ OH.
**________ Model: replicated DNA molecules have one old/parental strand & one newly-built strand.
**Old/parental strands separate & act as templates to synthesize new DNA that’s complementary to it.
**Semi-Conservative Model: replicated DNA molecules have one old/parental strand & one newly-built strand.
**Old/parental strands separate & act as templates to synthesize new DNA that’s complementary to it.
The Meselson-Stahl experiment demonstrated that DNA replication produces new molecules of DNA each containing…
one parental (old) strand and one newly synthesized strand.
This enzyme relieves DNA supercoiling ahead of the replication fork.
Topoisomerase
This enzyme unwinds the DNA double helix at the replication fork.
Helicase
These proteins bind to and stabilize single-stranded DNA.
Single-Stranded Binding Protein
This enzyme creates RNA primers to start DNA synthesis.
Primase
This enzyme builds a new DNA strand using the old strand as a template.
DNA Polymerase III (Prokaryotes)
This enzyme replaces RNA primers with DNA.
DNA Polymerase I
This enzyme joins Okazaki fragments on the lagging strand.
DNA ligase
DNA replication begins at specific DNA sequences called the _______________ of Replication (ORI).
origin
Prokaryotes have small _________________ chromosomes with just _____ ORI
circular; one
Eukaryotes have large __________________ chromosomes with ____________________ ORI
linear; multiple.
_______ relieves strain caused by DNA supercoiling. Supercoiling can hinder DNA replication.
Topoisomerase relieves strain caused by DNA supercoiling. Supercoiling can hinder DNA replication.
Helicase breaks ____________________ bonds to create ______________-stranded DNA.
hydrogen; single
________prevent reannealing of separated strands.
Single-Strand Binding Proteins (SSB) prevent reannealing of separated strands.
The primary enzymes responsible for building new DNA strands are
DNA polymerase
New DNA strands are built in the ______ ➝ ______ direction, elongating from the free 3’ ______ group.
5’; 3’; OH
In prokaryotes, DNA Polymerase ________ is the primary enzyme for elongation.
III
All DNA polymerases require two things: a ____________ strand and a ____________.
template; primer
The primer is a small RNA molecule built by the enzyme _______________.
primase
Upon separation, there are ___ single-stranded DNA molecules at each fork.
**The _____ strand is replicated continuously with the movement of the replication fork.
**The ____ strand is replicated in the opposite direction of the fork.
**The _____ strand forms small segments called _____ fragments.
**_____ fragments are joined together by DNA ____.
**Only the _____ strand requires multiple RNA primers.
Upon separation, there are two single-stranded DNA molecules at each fork.
**The leading strand is replicated continuously with the movement of the replication fork.
**The lagging strand is replicated in the opposite direction of the fork.
**The lagging strand forms small segments called Okazaki fragments.
**Okazaki fragments are joined together by DNA ligase.
**Only the lagging strand requires multiple RNA primers.
An enzymes that Relieving strain in the DNA ahead of the replication fork
topoisomerase
