molecular biology of gene expression Flashcards
central dogma of biology
DNA -> RNA -> PROTEIN
Basic plan of genetic information flow in living cells that relates genes
(DNA), message (RNA), and proteins
what are the two essential features of living creatures?
1) ability to reproduce own genome
2) ability to manufacture own energy
Why are proteins essential?
1) cellular architecture
2) catalysts
3) controler of cellular processes
4) act as communication channels
transcription
Process by which information from DNA is converted into its RNA equivalent - making an RNA copy of the DNA code
mRNA
messenger RNA: type of single-stranded RNA involved in protein synthesis and is made from a DNA template during the process of transcription.
translation
Making a protein using the information provided by messenger RNA
What are the basic steps of transcription?
1) uncoiling DNA
2) melting the strands
3) moving histones
4) making complementary RNA molecule from DNA template
5) stopping at the end of gene
6) RNA releases and DNA re-supercoils
template
Strand of DNA used as a guide for synthesizing a new strand by complementary base-pairing
RNA polymerase
Enzyme that synthesizes RNA
Housekeeping Genes
Genes that are switched on all the time because they are needed for
essential life functions - encode proteins that are used continuously
expressed (as pertaining to genes)
Converting a DNA region into RNA and/or protein to be used by the living cell
accessory proteins and inducers control gene expression.
what are the three main types of RNA and how are they used?
1) mRNA - translated into proteins and generated by structural genes (genes that encode protein)
2) rRNA - ribosomal RNA (regulatory - not translated)
3) tRNA - transfer RNA (regulatory - not translated)
ribozymes
RNA molecule that acts as an enzyme
cistron
Segment of DNA (or RNA) that encodes a single polypeptide chain
coding region of a gene
structural gene
Sequence of DNA (or RNA) that codes for a protein or for an untranslated RNA molecule
- related to a cistron
open reading frame (orf)
Sequence of bases (either in DNA or RNA) that can be translated (at least in theory) to give a protein - not interrupted by any stop codons for protein translation
promoter
Region of DNA in front of a gene that binds RNA polymerase and so promotes gene expression - place where transcription begins
BODER DEF: sequence that tells RNA polymerase where to bind and begin
Where are the two major recognition sites for bacterial promoters?
1) the -10 region (consensus sequence: TATAA)
2) the -35 region (consensus sequence: TTGACA)
the negative sign indicates that the location is upstream (before start site)
constitutively
Term used to describe genes that are expressed during all conditions
when a gene is transcribed constitutively, the promoter will closely match the consensus
consensus sequence
The ideal sequence - A theoretical representative nucleotide or amino acid sequence in which each nucleotide or amino acid is the one which occurs most frequently at that site in the different sequences which occur in nature.
activator protein
Protein that switches a gene on - required to bind to a promoter region when a gene is expressed only during special conditions
related to transcription factors
transcription factors
Protein that regulates gene expression by binding to DNA in the control region of the gene - related to activator protein
transcription start site
Starting point where a gene is converted into its RNA copy - where RNA polymerase will start adding nucleotides