Consists of a phosphate group, a pentose sugar (either ribose or deoxyribose) and a nitrogenous base. They are bound together by PHOSPHODIESTER LINKAGES at the 3' end
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Purines
Adenine and guanine
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Pyrimidines
Cytosine, thymine, uracil
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Nucleosome
DNA wrapped around a histone core
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Chromatin
Many bundles of nucleosomes. Many of these form loops which are then condensed and form chromosomes
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Heterochromatin
Highly condensed region of interphase chromosome. Most abundant in cells which are less active
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Euchromatin
Chromatin that is prevalent in gene rich areas. It is less compact, allowing access for proteins involved in transcription
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Leading
The DNA strand which (during DNA replication) DNA polymerase systematically adds nucleotides in the 5' to 3' direction
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Lagging
The DNA strand which (during DNA replication) undergoes replication discontinuously in small fragments
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Topoisomerase
This enzyme unwinds the tightly wound double helix during DNA replication
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DNA helicase
This enzyme breaks the hydrogen bonds between bases of DNA
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RNA primer
This initiates the adding of nucleotides. It is added by DNA primase. It is eventually erased and replaced by DNA
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DNA polymerase
The enzyme which adds free nucleotides to the strand
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DNA ligase
The enzyme which joins the nucleotides together by phosphodiester linkages
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Transcription factor
Any proteins involved in transcribing DNA into RNA
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TATA box
A short sequence of DNA found ~25bp upstream (near 5' end) from the start of transcription
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TFIID
A multiprotein complex consisting of TATA binding proteins (TBP) and TBP associating factors (TAF). It recognises the DNA sequence of the TATA box and binds to it, causing a 'kink' in the DNA
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RNA polymerase ii
The enzyme which adds nucleotides during transcription. It is recruited by the transcription factors surrounding the TATA box. The entire complex is called the pre-initation complex (PIC)
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Activator
These proteins can bind to enhancers (regions of DNA) to increase rate of transcription
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Repressor
These proteins can bind to the operator region of a promoter, to decrease rate of transcription
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Guanine cap
This is added during gene transcription (at the elongation phase) to protect the RNA from being degraded
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Poly-A tail
This is formed at the end of gene transcription. Poly-adenylate polymerase adds many adenines to the end of the pre-RNA to terminate transcription
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Introns
Regions of DNA that are discarded after gene transcription, so RNA is not an identical copy of DNA. (Exons are those still expressed)
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Codon
Three nucleotide sequence that is read by ribosomes. They code for a specific amino acid. There are 64 possible combinations
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tRNA
An RNA that has the same codon as an mRNA sequence which "picks up" amino acids with the complementary codon and delivers them to ribosomes to be added to a peptide chain
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Other cards in this set
Card 2
Front
Adenine and guanine
Back
Purines
Card 3
Front
Cytosine, thymine, uracil
Back
Card 4
Front
DNA wrapped around a histone core
Back
Card 5
Front
Many bundles of nucleosomes. Many of these form loops which are then condensed and form chromosomes
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