DNA Replication Flashcards

Flashcards about DNA Replication

DNA Replication

The process where the entire DNA content is copied into new strands of DNA, making new chromosomes.

Semi-conservative Replication

Each strand of the original DNA molecule serves as a template for making a copy; daughter cells receive double-stranded DNA built from one 'old' strand and one newly synthesized strand.

Origins of Replication

Specific sites on the chromosomes where DNA replication starts.

Theta (Θ) Replication

Observed in bacteria with double-stranded, circular DNA, where replication progresses from two replication forks in opposite directions until they meet.

DNA Gyrase

Enzyme that unwinds DNA, helped by helicases, by disrupting base pairing to allow for replication.

Single-Strand Binding Proteins (SSB)

Proteins that cover unwound DNA strands to prevent re-annealing.

DNA Polymerases

Enzymes that create phosphodiester bridges between individual DNA nucleotides, using a template strand to synthesize a complementary and anti-parallel new strand.

RNA Primer

A short RNA strand, synthesized by primase, that is complementary and anti-parallel to the template DNA strand, required by DNA polymerases to initiate DNA synthesis.

Primase

Enzyme that synthesizes the RNA primer needed for DNA polymerase to start synthesis.

DNA Ligase

Enzyme that connects discontinuous strands of DNA.

DNA Polymerase III (in bacteria)

Synthesizes the bulk of new DNA in bacteria.

DNA Polymerase I (in bacteria)

Removes primers and replaces RNA nucleotides with DNA nucleotides in bacteria; also performs proofreading.

DNA Polymerase II (in bacteria)

Functions as a DNA repair enzyme, independent of the replication process in bacteria.

DNA Polymerase γ

DNA polymerase found in mitochondria that replicates mitochondrial DNA.

Leading Strand

Synthesizes new DNA in the 5’-to-3’ direction; strand that is readily duplicated in a continuous fashion.

Okazaki Fragments

RNA and DNA fragments formed during discontinuous DNA synthesis.

Lagging Strand

Strand where DNA synthesis is discontinuous and contains Okazaki fragments.

Telomeres

Specialized structures at the ends of chromosomes consisting of GC-rich, tandemly repeating sequences.

Telomerases

Enzymes that replicate the tips of chromosomes to prevent shortening during DNA replication.

RNA-dependent RNA Polymerases

Enzymes that viruses like flu and COVID-19 use to copy their RNA into new RNA molecules.

Reverse Transcriptase

An enzyme possessed by viruses like HIV, also known as RNA-directed DNA polymerase, which turns RNA into DNA.

Retroviruses

Viruses that synthesize DNA from the 5' to 3' end using their RNA genome as the template.

Gene Recombination

Rearrangement of genetic information to form new associations.

Homologous Recombination

Exchange between similar sequences of DNA among homologous chromosomes during meiosis.

Non-homologous Recombination

Recombination of very different DNA sequences between non-homologous chromosomes.

Transposon

The insertion of genetic information into a DNA molecule.