chapter 6 Flashcards
a special protein molecule that is the core around which the DNA strand wraps
histone
a small circular section of DNA found in the cytosol of bacteria; replicates independently of the chromosomal DNA
plasmid
the complete set of an organism’s hereditary information
genome
a change in a genotype or phenotype caused by the direct uptake of genetic material by a cell
transformation
a virus that infects bacteria
bacteriophage
a class of nitrogenous bases with a double-ring structure; adenine and guanine are purines
purine
a class of nitrogenous bases with a single-ring structure; thymine and cytosine are pyrimidines
pyrimidine
the chemical tendency of adenine to form hydrogen bonds with thymine, and cytosine to form hydrogen bonds with guanine
complementary base pairing
a mechanism of DNA replication in which each of the two strands of parent DNA is incorporated into a new double-stranded DNA molecule
semiconservative replication
a specific sequence of DNA that acts as a starting point for replication
replication origin
the point of separation of the two parent DNA strands during replication
replication fork
a replication enzyme that separates and unwinds the DNA strands
helicase
a class of enzymes that relieve tension caused by the unwinding of parent DNA; they cleave one or two of the DNA strands, allow the strand(s) to untwist, and then rejoin the strand(s)
topoisomerases
a replication enzyme that prevents parent DNA strands from annealing to each other once they have been separated by helicase
single strand binding protein (SSB)
the separating of DNA in both directions during replication
replication bubble
a building block and energy source for replicating DNA
nucleoside triphosphate
a replication enzyme that produces RNA primers
RNA primase
a replication molecule that acts as a starting point for replication
RNA primer
a prokaryotic replication enzyme that builds new DNA strands from nucleotides
DNA polymerase III
the DNA strand that is copied in the direction toward the replication fork
leading strand
the DNA strand that is copied in the direction away from the replication fork
lagging strand
the piece of new DNA on the lagging strand
Okazaki fragment
a prokaryotic replication enzyme that fills in gaps in the lagging strand between Okazaki fragments; also proofreads the final strands
DNA polymerase I
an enzyme that catalyzes the formation of a phosphodiester bond between two DNA strands, as well as between Okazaki fragments
DNA ligase
a prokaryotic replication enzyme that repairs damage to DNA, including damage that occurs between replication events
DNA polymerase II
a unit of DNA storage, consisting of eight histones with DNA strands wrapped around them; the DNA around each nucleosome is about 147 nucleotides in length
nucleosome
a group of six nucleosomes
solenoid
the continuous twisting of prokaryotic DNA that reduces the volume of the DNA
supercoiling
a repeating sequence of DNA at the end of a chromosome that protects coding regions from being lost during replication
telomere
the period in a cell’s lifespan when it loses the ability to divide and grow; often referred to as cell aging
cell senescence
the total number of times that a normal cell can divide
Hayflick limit
an enzyme that adds new telomere sequences to the ends of chromosomes
telomerase
