Chapter 13 ENZYMES AND PROTEINS AND SUCH Flashcards
What is DNA polymerase I?
an enzyme that proofreads and repairs mis-paired nucleotides during replication.
What is DNA polymerase III?
an enzyme that performs base pairing using the parent strand as a template
(requires RNA primer to attach at the Origin of Replication, is an ancient molecule, replicates leading and lagging strand at the same time, is highly conserved)
what are restriction enzymes?
a type of enzymes that recognizes and cuts DNA molcs (at restriction sites) that are foreign to a bacterium
what are plasmids?
small, circular, double stranded DNA molecs that carry away genes separate from those of a bacterial chromosome
-used as vectors
histone
small proteins with a high proportion of positively charged amino acids that bind to the negatively charged DNA and play a key role in chromatin structure
what is a nucleosome>
the basic, bead-like unit of DNA packing in eukaryotes, consisting of a segment of DNA wound around a protein core composed of 2 copies of each of 4 types of histone
what are chromatin?
complex regions of DNA and proteins fitting into the nucleus of a eukaryotic cell
what is a nucleoid?
dense regions of DNA in a bacterium that are not surrounding with a nuclear envelope
what is nuclease?
an enzyme that cuts DNA or RNA, either removing one or a few bases, or hydrolyzing the DNA or RNA completely into its component nucleotides
what is DNA ligase?
an enzyme that catalyzes the covalent bonding of the 3’ end of one DNA fragment to the 5’ end of another DNA fragment
what is DNA polymerase
an enzyme that catalyzes the elongation of new DNA by the addition of nucleotides to the 3’ end of an existing chain
what is primase?
a enzyme that joints RNA nucleotide to make a primer during DNA replication, using the parental DNA strand as a template
what is a primer?
a short polynucleotide with a free 3’ end, bound by complementary base pairing to the template strand and elongated with DNA nucleotide during DNA replication
topoisomerase
a protein that breakers, swivels, and rejoins DNA strands (relieve strain in the double helix ahead of the replication fork)
Single-strand binding protiens
a protein that binds to the unpaired DNA strands during DNA replication, stabilizing and holding them apart while serving as templates for the synthesis of complementary strands of DNA
Helicase
an enzyme that untwists the double helix of DNA at replication forks
