Exam 4 Flashcards
Discontinuous synthesis
Occurs on the lagging strand of DNA , in DNA replication, and consists of Okazaki fragments.
Complementary
In a DNA molecule, one side of the molecule is complementary, or base paired to the other side of the molecule.
Ie. A-T C-G
Semi-conservative replication
One parent molecule results in two daughter molecules.
DNA ligase
The enzyme which joins fragments of DNA together, such as Okazaki fragments, or restriction fragments.
Helicase
The enzyme which untwists the double helix, and separates the old strands so that DNA replication can occur.
Singe strand binding proteins
Proteins which bind to the unpaired strands of DNA in replication so that DNA polymerase can move down the strand and copy it.
Excision repair
Enzymes which cut out damaged segments of DNA, and randomly replaces it with nucleotides.
Transcription
Making a copy of DNA in the form of mRNA. The mRNA if formed by RNA polymerase.
Transcription unit
A gene or group of genes with a similar function, which are transcribed at the same time. It consisted of a start sequence, hundreds to thousands of nucleotides, and a stop sequence.
Triplet code?
A nearly universal code consisting of 3 nucleotides which code for a specific amino acid.
Translation
The process of making protein using mRNA, ribosomes, and tRNA.
Reading frame
The order in which the triplet code is read. Correct reading frame produces the correct protein. Incorrect reading frame produces incorrect proteins.
Transcription factors
Proteins which assist in getting RNA polymerase to bind and start transcription.
Promoter
A region of DNA, dozens of nucleotides upstream from the initiation site where transcription actually begins.
TATA box
A region rich in nitrogenous bases, 25 nucleotides upstream from the initiation site. RNA polymerase keys in on this site.
tRNA
A specialized form of RNA which has an anticodon on one end, to base pair with the codon of mRNA, and a specific amino acid attached to the top of it.
Wobble
A nonstrict base pairing of the third nucleotide of the codon and anticodon.
Ribosome
Composed of ribosomal RNA, and the actual site of protein production.
Aminoacyl-tRNA-synthethase
The enzyme used to attach the amino acid to the tRNA and uses ATP as an energy source.
DNA replication
The parent molecule opens into a replication fork, and new nucleotides are base paired into the fork, resulting into two, half old, half new daughter molecules.