chapter 7 pt 2

DNA ligase

An enzyme that repairs irregularities or breaks in the backbone of double-stranded DNA molecules.

Okazaki fragments

Short DNA fragments formed during the replication of double-stranded DNA that are synthesized in a fragmented manner.

Leading strand

The strand of DNA that is synthesized continuously in the 5' to 3' direction during DNA replication.

Lagging strand

The strand of DNA that is synthesized in short, discontinuous segments (Okazaki fragments) in the 5' to 3' direction.

Codon

A triple sequence of DNA or RNA that corresponds to a specific amino acid.

Anticodon

A sequence of three bases on tRNA that pairs with a corresponding codon on mRNA during protein synthesis.

Lac operon

A system of DNA that contains sequences of genes that regulate the synthesis of enzymes for protein synthesis.

Promoter region

A site that promotes and controls the transcription of structural genes or mRNA.

Operator region

A region that contains a switch to decide whether transcription should take place or not.

Inducer

A substance that suppresses the binding of the repressor protein to the operator, activating the operon.

Positive control of Lac operon

A mechanism where the presence of lactose allows RNA polymerase to transcribe mRNA by inhibiting the repressor.

Negative control of Lac operon

A mechanism that inhibits mRNA transcription when the repressor binds to the operator in the absence of lactose.