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A review of the key terms from the DNA topic.


Adenine and guanine


Cytosine and thymine

DNA nucleotide

Phosphate, sugar, base


Direction DNA replication occurs in


Breaks the hydrogen bonds of the double helix and splits it into two template strands

DNA polymerase III

Adds nucleotides in 5'-->3' direction on one strand, on the other starts replication next to RNA primer and adds nucleotides in a 5'-->3' direction

RNA primase

acts as a primer by adding short length of RNA to the template strand

Okazaki fragments

short lengths of DNA formed between RNA primers

DNA polymerase I

removes RNA primer and replaces it with DNA

DNA ligase

seals up nick of Okazaki fragments

Helicase, DNA polymerase III, RNA primase, DNA polymerase I, DNA ligase

order of enzymes in DNA replication


globular structure containing eight histone proteins with DNA wrapped around another histone that bonds the structure together

Satellite DNA

repetitive base sequences which are not translated


sequences of bases that are transcribed but not translated


sequences of bases that are transcribed AND translated

DNA replication

copying DNA to produce new molecules with the same base sequence

DNA transcription

copying genetic message onto mRNA


decoding the mRNA to create polypeptide


a group of three bases on mRNA

Sense strand

DNA strand that has the same base sequence as the mRNA

Antisense strand

DNA strand that forms the template for transcription

Triplet code

Three bases found on DNA that code for one amino acid


Multiple codons which code for the same amino acid

tRNA activating enzymes

attach one particular amino acid to all of the molecules that have an anticodon corresponding to that amino acid

Free ribosomes

ribosomes in the cytoplasm that synthesize proteins for use in the cell

Bound ribosomes

ribosomes attached to membranes of the endoplasmic reticulum that synthesize proteins for secretion from the cell

Peptide bond

the linkage between amino acids by a condensation reaction


group of ribosomes moving along the same mRNA as they simultaneously translate it


special steps needed to start translation


special steps required to stop translation

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