AP Exam Flashcards
Conjugation in Bacteria
One bacterium transfers genetic material to another through direct contact. Donor bacterium carries a DNA sequence called the fertility factor, or F-factor. The F-factor allows the donor to produce a thin, tubelike structure called a pilus, which the donor uses to contact the recipient. The pilus then draws the two bacteria together, at which time the donor bacterium transfers genetic material to the recipient bacterium.
Transduction
Viruses called bacteriophages are able to infect bacterial cells and use them as hosts to make more viruses. After multiplying, these viruses assemble and occasionally remove a portion of the host cell’s bacterial DNA.
Operon (inducible)
Inducible operons have proteins that can bind to either activate or repress transcription depending on the local environment and the needs of the cell.
Operon (repressible)
on except in the presence of some molecule (called a corepressor) that suppresses gene expression.
Transformation
the direct uptake and incorporation of DNA from its surroundings and taken up through the cell membrane
Plasmid
A small DNA molecule that is physically separate from, and can replicate independently of, chromosomal DNA within a cell. Most commonly found as small circular, double-stranded DNA molecules in bacteria
PCR
polymerase chain reaction, a biochemical technology in molecular biology used to amplify a single or a few copies of a piece of DNA across several orders of magnitude
Gel Electrophoresis
a method for separation and analysis of macromolecules (DNA, RNA and proteins) and their fragments, based on their size and charge. Shorter molecules move faster and migrate farther than longer ones because shorter molecules migrate more easily through the pores of the gel.
DNA Ligase
a specific type of enzyme, single-strand breaks are repaired by DNA ligase using the complementary strand of the double helix as a template
DNA Polymerases
enzymes that create DNA molecules by assembling nucleotides, “reads” the existing DNA strands to create two new strands that match the existing ones.
Okazaki Fragments
short, newly synthesized DNA fragments that are formed on the lagging template strand complementary, together forming short double-stranded DNA sections.
Leading strand
The leading strand is the strand of nascent DNA which is being synthesized in the same direction as the growing replication fork.
Lagging strand
the strand of nascent DNA whose direction of synthesis is opposite to the direction of the growing replication fork, synthesized in short, separated segments, primase “reads” the template DNA and initiates synthesis of a short complementary RNA primer. A DNA polymerase extends the primed segments, forming Okazaki fragments. The RNA primers are then removed and replaced with DNA, and the fragments of DNA are joined together by DNA ligase
Primer
a strand of nucleic acid that serves as a starting point for DNA synthesis
Replication fork
a structure that forms within the nucleus during DNA replication. It is created by helicases, which break the hydrogen bonds holding the two DNA strands together. The resulting structure has two branching “prongs”, each one made up of a single strand of DNA. These two strands serve as the template for the leading and lagging strands
