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DNA Repair and Transcription
Biochemistry
30
Other
Professional
06/17/2010

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Term
Abasic Site
Definition
A site created when a base is removed by DNA Glycosylase during a Base Excision Repair (BER) The gap is later filled in by polymerase and sealed by ligase
Term
Apoptosis
Definition
When cells kill themselves (ex. skin peeling due to pyrimidine dimers)
Term
Base Excision Repair
Definition
Recognition, removal and replacement of a single base alteration.
Glycolase-removes base
polymerase-adds new base
ligase-connects
Term
Cis-acting element
Definition
Sequences that are involved in gene expression
They do not move in the cell
They only affect the DNA or RNA molecules to which it is attched
EX. -10, -35, TATA box sequences
Term
Trans-acting
Definition
Proteins and RNA molecules that bond to Cis-acting elements
Free to move throughout the cell
Can interact with unlinked targets
EX. sigma protein, TATA box binding protein
Term
Consensus Sequence
Definition
A compilation of the bases that will occur most often at each of the posititions in a DNA-binding site for a protein
THe closer a binding site is to the consensus the more effeceintly it will bind to the protein
Term
Deamination
Definition
The removal of an amine group from a base
Form of spontaneous DNA Damage
Converts a cytosine to Uracil
It can be corrected
Term
Depurination
Depyrimidation
Definition
The spontaneous removal of either a purine of pyrimidine
Due to the instability of the glycosidic bond
Results in an abasic site
Can be corrected by the insertion oh another base
Term
DNA Adduct
Definition
The formation of a covalent bond between a chemical and a base in DNA
They can block DNA replication and cause incorrect base pairing
Interrupts the 3D structure of DNA
Term
DNA Ligase
Definition
seals nicks during repair of DNA damage
Term
Enhancer
Repressor
Definition
Proteins bound to DNA sequences in order to increase the frequency of transcription or to inhibit transcription
Term
Exonucleases
Definition
Proofreaders
Correct mistakes made by DNA polymerase
Removes incorrect nucleotides so that polymerase can add the right one in
Term
Glycosylase
Definition
Exonucleases remove mismatched base
DNA polymerase and ligase fill in the nucleotide and seal the gap
Errors in mismatch repair can cause hereditary nonpolyposis corectal cancer
Term
mRNA
Definition
Encode information to synthesize proteins
Bacerial mRNA sequences are the same as gene sequences
Eukaryotic mRNA is initially the same as the gene sequence but it is later altered
Term
tRNA
Definition
Carries amino acids to Ribosome for protein synthesis
Term
rRNA
Definition
translates mRNA sequences into proteins
Makes up the majority of the cellular mRNA mass
Located in ribosome and carry out its functions
There are 3 types of rRNA in prokaryotes and 4 types of rRNA in eukaryotes
Term
Mutation
Definition
a change in the DNA sequence
Can cause cancer and other diseases
Term
Nucleotide Excision Repair
Definition
Recognizes large adducts or pyrimidine dimers
Nuclease marks sequence section for removal
Helicase removes section of the sequence
polymerase adds nucleotides to fill in section and ligase seals nicks
Term
Pyrimidine Dimer
Definition
2 Pyrimidines which are covalently bonded due to UV radiation
Type of environmental DNA damage
Results in blockage of replication due to the change in spacing of the bases
Repaired by Nucleotide Excision Repair
Can result in apoptosis
Term
Reactive Oxygen Species
Definition
Environmental DNA damage
Oxidative DNA damage which is caused by the formation of an OH radical
Can cleave the deoxyribose or the phosphate backbone or damage the base
Term
TATA Box
Definition
Sequence of 'T's and 'A's found in the promoter region of DNA
Binding site of transcription factors and histones
Involved in transcription using RNA polymerase II
Cis-acting element
Term
Tautomer
Definition
Alternate form of a base due to a proton shift
Can leade to base mis-pairing
T and G are normally found in Keto form
A and C are found in Amine form
Term
Transcription Factor
Definition
Proteins that bind cis and trans acting sequences
Enhancer sequences
Repressor sequences
Term
Checkpoints
Definition
Phases in eukaryotic multicellular organisms where the cell can respond to DNA damage by repairing it or by apoptosis (cell death)
G1 and G2
Term
Closed Complex
Definition
Initial DNA-RNA polymerase complex that is formed prior to transcription before the DNA is unwound.
Occurs when sigma subunit binds DNA promoter sequence with RNA polymerase
Term
Open Complex
Definition
When DNA is unwound as RNA polymerase binds the first nucleotide with the base at the start site to begin transcription
Term
Activation Domain
Definition
Region of transcription factors (enhancers) which bind to other proteins to promote recruitment of TFIID or RNA polymerase II
Term
DNA Binding Domain
Definition
Region of transcription factors (enhancers) that bind to a specific DNA sequence
Term
Promoter
Definition
Element of DNA that indicates the start site for transcription
It is a short DNA sequence found at the 5' end of DNA
Term
Glycosylase
Definition
Specific to each base and recognizes and removes the damaged base during base excision repair
Also recognizes a normal but mis-incorporated base
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