Unit 6 Flashcards
Chapters 16 + 17
Transformation
The change in genotype and phenotype due to assimilation of foreign DNA
Bacteriophages
Viruses that infect and replicate within bacteria/archaea; used for genetic research
Virus
DNA (sometimes RNA) enclosed by a protective coat that is often a protein
Double Helix
The twisted structure of the DNA molecule
Sugar-Phosphate Backbone
Describes the alternating pattern of deoxyribose and phosphate group that makes up the sides of DNA molecule
Nitrogenous Bases
Make up the “rungs” of DNA ladder; adenine, thymine, guanine, cytosine, (uracil)
Antiparallel
The tendency of DNA backbones to run in opposite directions
Purines
Double-ringed (larger) nitrogenous bases; adenine and guanine
Pyrimidines
Single-ringed (smaller) nitrogenous bases; thymine and cytosine
Origin of Replication
Specific points along the DNA molecules where the strands are separated to form a “bubble” where replication can start
Replication Fork
Where new DNA strands are elongated
Helicase
An enzyme responsible for untwisting the double helix at the replication forks
Single-Strand Binding Proteins
Proteins that bind to the untwisted strands of DNA for stabilization
Topoisomerase
Enzyme that corrects over winding ahead of the replication fork
DNA Polymerase
Enzyme that attaches new nucleotides; cannot start the chain of replicated DNA; works only in the 5’ to 3’ direction
Primase
Enzyme that attaches a short segment known as an RNA primer to unraveled DNA so that polymerase has an open 3’ to attach new nucleotides to
Leading Strand
The strand of new DNA that is being replicated towards the replication fork; typically faster
Lagging Strand
The strand of new DNA that is being replicated away from the replication fork; typically slower due to additional synthesis of Okazaki fragments
Okazaki Fragments
Segments of 3 nucleotides added to the lagging strand in units
DNA Ligase
Enzyme responsible for joining together Okazaki fragments
DNA Replication Machine
Proteins used in DNA replication form a large, stationary complex
Mismatch Repair
Ability of some polymerase enzymes to proofread DNA and replace incorrect nucleotides
Carcinogens
Harmful chemicals/physical agents that can damage DNA and cause cancers
Mutations
Spontaneous changes to DNA sequence
Nuclease
Enzyme that cuts out and replaces damaged stretches of DNA
Telomeres
Nucleotide sequences at the ends of chromosomal DNA used to slow the erosion of genes; lengthened by telomerase