Chapter 16
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
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What are the base pairing rules?
A con T & G con C
define transformation
transformation is the change in genotype and phenotype due to assimilation of foreign DNA
what is a virus?
a virus is DNA (sometimes RNA) enclosed by a protective coat, often simply protein
what is DNA made of?
DNA is a polymer of nucleotides; consisting of a nitrogenous base, a sugar, and a phosphate group
how do the number of A&T and G&C compare?
in any species, the number of AT bases are equal and the number of GC bases are equal (understood because of the double helix)
what is the DNA molecule made up of structure wise?
A DNA molecule is made up of two strands, forming a double helix
What is semiconservative replication?
In DNA replication, each parental molecule unwinds and two new daughter strands are built based on the base pairing rules
What unwinds DNA strands?
helicase
Which strands are new and old in DNA replication?
Each daughter molecule has one old strand and one newly made strand
how were nucleotides labeled for old and new strands in experiment?
matthew meselson and franklin stahl: labeled old nucleotides with a heavy isotope and new ones with a lighter isotope
what is a replication fork?
a Y shaped region where new DNA strands are elongating at the end of each replication bubble
what are helicases?
helicases are enzymes that untwist the double helix at the replication forks
what is the goal of all the players in replication?
to copy all of the DNA to get ready for cell division
what are single-strand binding proteins?
they bind to and stabilize single-stranded DNA
what does topoisomerase do?
topoisomerase corrects “overwinding” ahead of replication forks by breaking, swiveling, and rejoining DNA strands
DNA polymerase cannot?
DNA polymerase cannot initiate synthesis of a polynucleotide; can only add nucleotides to an existing 3’ end
the initial nucleotide strand is ?
a short RNA primer
what is primase?
primase is an enzyme that can start an RNA chain from scratch and adds RNA nucleotides one at a time using the parental DNA as a template (5-10 nucleotides long, 3’ is the starting point for new DNA strand)
what does primase do?
it lays down the short RNA primer, then DNA polymerase 3 attaches to primer and starts to elongate by adding nucleotides to RNA primer
in what direction are nucleotides added?
5’ to 3’
in what direction do DNA strands elongate?
5’ to 3’
what is DNA ligase?
an enzyme that seals the bonds between restriction fragments
what do DNA polymerase do?
DNA polymerases are enzymes that catalyze the elongation of new DNA at a replication fork
what do DNA polymerases require?
DNA polymerases require a primer and a DNA template strand