Vocabulary Unit 6 1-4 Flashcards
Purine
a base (such as adenine or guanine) that is a constituent of DNA or RNA
Pyrimidines
a base (such as cytosine, thymine, or uracil) that is a constituent of DNA or RNA
Antiparallel
parallel but oppositely directed or oriented
Plasmids
an extrachromosomal ring of DNA especially of bacteria that replicates autonomously
RNA
any of various nucleic acids that contain ribose and uracil as structural components and are associated with the control of cellular chemical activities
DNA
any of various nucleic acids that are usually the molecular basis of heredity, are constructed of a double helix held together by hydrogen bonds between purine and pyrimidine bases (see BASE entry 1 sense 6b) which project inward from two chains containing alternate links of deoxyribose and phosphate, and that in eukaryotes are localized chiefly in cell nuclei
Origins of Replication
An origin of replication is a sequence of DNA at which replication is initiated on a chromosome, plasmid or virus.
Replication Fork
The point at which the two strands of DNA are separated to allow replication of each strand.
Helicase
any of various enzymes that catalyze the unwinding and separation of double-stranded DNA or RNA during its replication
Topoisomerase
any of a class of enzymes that reduce supercoiling in DNA by breaking and rejoining one or both strands of the DNA molecule
Primase
an enzyme that synthesizes short RNA sequences called primers, which serve as starting points for DNA synthesis.
Primers
a molecule (such as a short strand of RNA or DNA) whose presence is required for formation of another molecule (such as a longer chain of DNA)
DNAP III
the primary enzyme complex involved in prokaryotic DNA replication.
DNAP I
a type of enzyme that is responsible for forming new copies of DNA, in the form of nucleic acid molecules.
Leading Strand
The leading strand is a single DNA strand that, during DNA replication, is replicated in the 3’ – 5’ direction (same direction as the replication fork).
Lagging Strand
a single DNA strand that, during DNA replication, is replicated in the 5′ – 3′ direction (opposite direction to the replication fork).
Okazaki Fragments
Relatively short fragment of DNA synthesized on the lagging strand during DNA replication.
DNA Ligase
An enzyme that closes nicks or discontinuities in one strand of double-stranded DNA by creating an ester bond between adjacent 3’ OH and 5’ PO4
Telomeres
the natural end of a eukaryotic chromosome composed of a usually repetitive DNA sequence and serving to stabilize the chromosome
Telomerase
a DNA polymerase that is a ribonucleoprotein catalyzing the elongation of chromosomal telomeres in eukaryotic cell division and is particularly active in cancer cells
Nuclease
any of various enzymes that promote hydrolysis of nucleic acids
Mismatch repair
Describes cells that have mutations (changes) in certain genes that are involved in correcting mistakes made when DNA is copied in a cell.
Transcription
the process of constructing a messenger RNA molecule using a DNA molecule as a template with resulting transfer of genetic information to the messenger RNA
Gene Expression
the appearance in a phenotype of a characteristic or effect attributed to a particular gene.