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30 terms

IB DNA Review

A review of the key terms from the DNA topic.
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Purines
Adenine and guanine
Pyridimines
Cytosine and thymine
DNA nucleotide
Phosphate, sugar, base
5'-->3'
Direction DNA replication occurs in
Helicase
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
Nucleosome
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
Introns
sequences of bases that are transcribed but not translated
Exons
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
translation
decoding the mRNA to create polypeptide
Codon
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
Degenerate
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
Polysomes
group of ribosomes moving along the same mRNA as they simultaneously translate it
Initiation
special steps needed to start translation
Termination
special steps required to stop translation