Chapter 14 Flashcards
a virus that infects bacteria
bacteriophages
an infectious agent that contains either DNA or RNA surrounded by a protein coat
virus
a purine that base-pairs with either thymine in DNA or uracil in RNA
adenine
a purine that base-pairs with cytosine in nucleic acids
guanine
a pyrimidine that base-pairs with adenine
thymine
a pyrimidine that base-pairs with guanine in nucleic acids
cytosine
structure in a polynucleotide chain that is formed when deoxyribose sugar(in DNA) or ribose sugars(in RNA) are linked by phosphate groups in an alternating sugar-phosphate-sugar-phosphate pattern
sugar-phosphate backbone
the end of a polynucleotide chain at which a phosphate group is bound to the 5? carbon of a deoxyribose sugar
5’ end
the end of a poly nucleotide chain at which a hydoxyl group is bonded to the 3’ carbon of a deoxyribose sugar
3’ end
method for deducing the position of atoms in a molecule
X-ray diffraction
model of DNA consisting of 2 polynucleotide strands twisted around each other
double-helical model
feature of DNA in which the specific purine-pyrimidine base pairs A-T and G-C occur to bridge the 2 sugar-phosphate backbones
complementary base pairing
strands of double-stranded DNA that run in opposite directions with the 3’ end of one strand opposite the 5’ end of the other strand
antiparallel
the process of DNA replication in which the 2 parental strands separate and each serves as a template for the synthesis of new progeny double-stranded DNA molecular
semiconservative replication
a protein that encircles the DNA and binds to the DNA polymerase to tether the enzyme to the template, thereby making replication more efficient
sliding DNA clamp
a specific region at which DNA replication commences. Bacterial chromosomes have single origins of replication whereas eukaryotic chromosomes have multiple origins
origin of replication (ori)
an enzyme that catalyzes the unwinding of DNA template strands
DNA helicase
region of DNA synthesis where the parental strands separate and 2 new daughter strands elongate
replication fork
protein that coats single-stranded segments of DNA, stabilizing the DNA for the replication process
single-stranded binding protein (SSBs)
an enzyme that relieves the overtwisting and strain of DNA ahead of replication fork
topoisomerase
a short nucleotide chain made of RNA that is laid down as the first series of nucleotides in a new DNA strand, or made of DNA for use in the polymerase chain reaction (PCR)
primer
an enzyme that assembles the primer for a new DNA strand during DNA replication
primase
replication in which a DNA strand is formed in short lengths that are synthesized in the direction opposite of DNA unwinding
discontinuous replication
the short lengths of lagging strand DNA produced by discontinuous replication
Okazaki fragments
new DNA strand synthesized during replication in the direction of DNA unwinding
leading strand
DNA template strand for the leading strand
leading strand template
the new DNA strand synthesized discontinuously during replication in the direction opposite to that of DNA unwinding
lagging strand
the large, doublestranded helical molecule that contains the genetic material of all living organisms
deoxyribonucleic acid (DNA)
the principal replication polymerase in E. coli that synthesizes the majority of the new DNA
DNA polymerase III
in E. coli the replication enzyme that replaces the RNA primer at the start of a new DNA segment with DNA
DNA polymerase I
the 2 Y-shaped replication forks joined together at the tops of the Ys after DNA is unwound at an origin of replication
replication bubble
an enzyme that adds telomere repeats to chromosome ends
telomerase
an error in the assembly of a new nucleotide chain in which bases other than the correct ones pair together
base-pair mismatches
mechanism during DNA replication in which DNA polymerase backs up and removes a mispaired nucleotide from a newly synthesized DNA strand and then adds the correct nucleotide to the growing chain
proofreading mechanism
mechanism to correct base-pair mismatches that escape proofreading
DNA repair mechanisms
repair system that removes mismatched bases from newly synthesized DNA strands
mismatch repair
a histone and nonhistone protein associated with DNA in a eukaryotic nuclear chromosome
chromosomal protein
any assemblage of eukaryotic nuclear DNA molecules and their associated proteins
chromatin
a small positively charged(basic) protein that is complexed with DNA in the chromosomes of eukaryotes
histones
the basic structural unit of chromatin in eukaryotes consisting of DNA wrapped around a histone core
nucleosome
an 8-protein particle formed by the combination of 2 molecules each of H2A, H2B, H3, and H4 around which DNA winds for almost 2 turns
nucleosome core particle
a short segment of DNA extending between 1 nucleosome and the next in a eukaryotic chromosome
linker
most fundamental level of chromatin packing of a eukaryotic chromosome in which DNA winds for almost 2 turns around an 8-protein nucleosome and linker DNA extends between adjacent nucleosomes. the result is a beads-on-a-string type of structure with a 10-nm diameter
10 nm chromatin fiber
level of chromatin packing of a eukaryotic chromosome in which histone H1 binds to the 10-nm chromatin fiber causing it to package into a coiled structure about 30 nm in diameter and with about 6 nucleosomes per solenoid
30-nm chromatin fiber
all the proteins associated with DNA in a eukaryotic chromosome that are not histones
nonhistone proteins
DNA molecule in bacteria in which hereditary information is encoded
bacterial chromosome
the central region of a prokaryotic cell with no boundary membrane separating it from the cytoplasm, where DNA replication and RNA transcription occur
nucleoid
A DNA molecule in the cytoplasm of certain prokaryotes, which often contain genes with functions that supplement those in the nucleoid and which can replicate independently of the nucleoid DNA and be passed along during cell division
plasmids
