Unit 6 gene expression and regulation

Activator

A protein that increases gene transcription by binding to an enhancer or promoter region of DNA, facilitating the recruitment of transcription machinery.

anticodon

A sequence of three nucleotides in transfer RNA (tRNA) that pairs with a complementary codon in messenger RNA (mRNA) during protein synthesis.

antiparallel

Describes the opposite orientation of complementary DNA strands, where one strand runs 5' to 3' and the other runs 3' to 5'. This orientation is crucial for replication and transcription processes.

bidirectional replication

the process where DNA replication occurs in two opposite directions on the same DNA strand.

chargaff’s rule

The observation that in any given DNA molecule, the amounts of adenine and thymine are equal, as are the amounts of cytosine and guanine. This fundamental principle helped establish the base-pairing rules in DNA.

codon

a sequence of three nucleotides that corresponds to a specific amino acid or stop signal during protein synthesis.

coding/sense srand

The strand of DNA that contains the same sequence as the RNA transcript, coding for a specific protein. It runs in the 5' to 3' direction and is complementary to the template strand.

leading strand

The DNA strand that is replicated continuously during DNA replication, serving as a template for RNA polymerase.

ligase

An enzyme that facilitates the joining of DNA strands together by forming phosphodiester bonds. It plays a crucial role in DNA replication and repair.

lysogenetic pathway

A viral replication mechanism in which a virus integrates its genetic material into the host cell's genome, leading to the propagation of the viral DNA without destroying the host cell.

lytic pathway

A viral replication process where the virus hijacks the host cell's machinery to produce new virions, ultimately causing the lysis and death of the host cell.

messenger RNA

A type of RNA that conveys genetic information from DNA to the ribosome, where it directs protein synthesis.

mutation

A permanent alteration in the DNA sequence of a gene that can lead to changes in phenotype or function.

nucleotide

Building blocks of nucleic acids, consisting of a sugar, phosphate group, and a nitrogenous base.

okazaki fragment

Short DNA segments formed during DNA replication on the lagging strand, which are later joined together by DNA ligase.