Gene expression I from gene to RNA Flashcards
Cistron
Segment of DNA corresponding to one polypeptide
What is the regulatory element possessed by all genes?
Promoter and enhancer
Rna polymerase
Enzyme that synthesizes the formation of RNA from a DNA template during transcription
Pol I
Transcribes ribsomal RNA genes
Pol II
Transcribes protein encoding genes and small nuclear RNA
Pol II
Transcribes transfer RNA, rRNA and snRNA
What is TBP?
- Transcription factor/binding protein for the TATA promoter sequence.
- Acts w/ minor DNA groove
Promoter
Region of DNA that defines transcription start sites and its direction
Constitutive
When a mutation in the operator sequence of a gene becomes permanently switched on
Substrates for operons…
Induce them
Products of biosynthetic operons…
repress them
TFIID
TBP protein and other proteins surrounding
Leader/spacer
Section of DNA which is nontranslated
Cistron
Segment of DNA corresponding to one polypeptide
Catabolite repression
System of gene control in prokaryotes, when glucose is exhausted, cAMP levels increase and bind to CRP/CAP which binds to the promoter sequence at the lac operon.
Phosphorylation of a transcription factor can:
- Change its conformation
- Increase +ve
- Alter its location in a cell
Repressor
DNA/RNA binding protein that inhibits expression of genes by binding to the operator or related silencers.
Blocks attachment of RNA polymerase to promoter.
Inducer
Molecule that regulates gene expression. Can bind to repressors, disabling them.
Co-repressor
Effector molecules that binds to a repressor molecule to prevent transcription of a gene.
Operator
Short region of DNA that lies within promoters and interacts with regulatory proteins controlling transcription of the operon.
Operon
Set of genes transcribed by the same promoter that gives rise to a polycistronic mRNA
DNA binding domain (DBD)
Protein structure with a high affinity to DNA, so binds when present. E.g. transcription factors
Transcription activation domain
Regions of transcription factor which which with DBD can activate transcription from a promoter, by signalling relevant machinery
Enhancer
Short DNA region that can bind to regulatory proteins to increase possible transcription of a gene.
Nucleosome
Basic unit of chromatin packaging. Made from coil of DNA wound round a histone core
Co activator
Transcriptional coregulator that binds to an activator to increase rate of transcription
Histone acetylases
Alters accessibility of chromatin, allowing DNA bind proteins to interact with DNA.
Second messenger
Mediates cell activity by relaying extracellular information to inside the cell.
Kinase
Catalyses transfer of phosphate groups from high energy, phosphate donating molecules to specific substrates.
tRNA
binds to codon of RNA and matches appropriate amino acid
Phosphorylation of a transcription factor would make it more negatively charged? T/F
TRUE
Phosphorylation of a transcription factor would make it more negatively charged? T/F
TRUE
RNA 2’ structure is important for
Catalysis
Organisation
Recognition
RNA 2’ structure is important for
Catalysis
Organisation
Recognition
Palindrome
Sequence which reads the same forwards as it does backwards
RNA 2’ structure is important for
Catalysis
Organisation
Recognition
Open reading frame
Sequence of codons running from a specific start codon to a specific stop codon
Wobble
Allows unconventional base pairing between 3rd base in codon & 1st base in anticodon
Aminoacetyl-tRNA synthetases
Catalyse transfer of amino acid to tRNA
Anticodon
Complementary code to codon on mRNA
Initiation
Initiation codon identification and assembly
Elongation
Polymerisation
Translocation
Energy driven
Termination
Energy driven
GTP in translation
Provides energy by hydrolysis
GTP -> GDP + Pi
GTP in initation
Addition of large subunit
GTP in elongation
Addition of aminoacyl-tRNA by EF-Tu peptide synthesis and translocation
GTP in termination
Release of peptide chain and dissociation of ribosome
Cis acting element
Only regulate DNA directly joined to
Trans acting factor
Regulates any gene
Mutations in regulatory elements
Cis acting
Cant be fixed
Mutations altering regulatory proteins
Trans acting
Affect many genes
Can be fixed
Lac operon switched on/off with lactose and glucose present?
Switched off
Lac operon switched on/off with lactose present but no glucose present
Switched on
