college bio DNA replication, translation transcription

DNA replication

The process of copying DNA, where each new DNA molecule consists of one parental strand and one newly synthesized strand.

Semiconservative replication

A method of DNA replication where each new DNA molecule contains one strand from the original molecule and one newly created strand.

Origin of replication

The specific location on the DNA where replication begins.

DNA gyrase

An enzyme that unwinds supercoiled DNA during replication.

Helicase

An enzyme that unwinds the DNA double helix, creating single-stranded DNA.

Single-stranded binding protein (SSB)

A protein that binds to single-stranded DNA to maintain its stability during replication.

Primase

An enzyme that synthesizes a short RNA primer, which starts the DNA replication process.

Leading strand

The strand of DNA that is synthesized continuously during DNA replication.

Lagging strand

The strand of DNA that is synthesized discontinuously in short fragments known as Okazaki fragments.

Okazaki fragments

Short segments of DNA synthesized on the lagging strand during DNA replication.

Bacterial DNA polymerase I

An enzyme that removes RNA primers and replaces them with DNA nucleotides.

DNA ligase

An enzyme that seals gaps between Okazaki fragments in the lagging strand.

Transcription

The process of synthesizing RNA from a DNA template.

RNA polymerase

The enzyme responsible for synthesizing RNA by adding complementary RNA nucleotides.

Promoter

A specific DNA sequence where RNA polymerase binds to initiate transcription.

Termination of transcription

The process by which RNA polymerase stops synthesizing RNA upon encountering specific DNA sequences.

Eukaryotic pre-mRNA

An immature form of mRNA in eukaryotes that undergoes modifications before becoming mature mRNA.

5' methylguanosine cap

A modification added to the 5' end of eukaryotic mRNA for protection and export.

Poly-A tail

A sequence of adenine nucleotides added to the 3' end of eukaryotic mRNA for stability.

Splicing

The process of removing introns and reconnecting exons in pre-mRNA.

Translation

The process of synthesizing polypeptides based on the sequence of mRNA.

tRNA (transfer RNA)

RNA molecules that carry amino acids to the ribosome during translation.

Ribosome

A complex composed of rRNA and proteins that facilitates the translation process.

Genetic code

The set of rules that determines how sequences of nucleotides correspond to amino acids.

Point mutation

A mutation that affects a single base pair in DNA.

Missense mutation

A point mutation that results in a different amino acid being incorporated into a protein.

Nonsense mutation

A point mutation that creates a stop codon, leading to premature termination of protein synthesis.

Frameshift mutation

A mutation caused by insertion or deletion of nucleotides that alters the reading frame of the genetic code.

Spontaneous mutations

Mutations that occur naturally due to errors in DNA replication.

Induced mutations

Mutations that result from exposure to external agents called mutagens.

Mutagenic agents

Substances that cause mutations and may be carcinogenic.

Ionizing radiation

High-energy radiation (like X-rays) that can break DNA strands and chemically modify bases.

Nonionizing radiation

Radiation (like ultraviolet light) that can cause mutations by introducing thymine dimers.