Gene expression 1 Flashcards
What encodes a protein?
Gene.
What regulated gene expression?
A combination of transcription factors that determine cell identify and fucntion?
When is the primary control points for gene expression?
During the initiation point of gene transcription.
This is an effective control points as many proteins can be made from a singular mRNA molecule.
How does the cell avoid expressing many genes at any one time?
Transcription regulators work to increased and prevent transcription to keep the balance.
How could environmental conditions affect prokaryotic gene expression?
Regulatory proteins controlled by nutrient availability.
This allow organisms to adjust transcription factors in response to environment.
How could environmental change affect eukaryotic cells?
Environment cause cause promoter sites to move far away from production of transcription factors in the cell?
What are the two stages of gene expression?
Transcription - mRNA produced from DNA
Translation - mRNA converted into amino acid sequence.
Forms of RNA
snRNA, miRNA, rRNA, mRNA, tRNA.
What type of reaction links nucleotides together and explain this.
Condensation.
5’-3’.
Phosphate-OH end.
Transcription components?
Nucleotide triphosphate (ATP,GTP,CTP.UTP)
Substrates (Mg2+)
RNA polymerase enzyme
DNA template strand
What part of the gene determines where transcription starts?
Promoter
What catalyses RNA transcription?
RNA polymerase.
Difference between DNA + RNA polymerase?
RNA polymerase do not need primers and do not proof read.
3 steps of transcription?
Initiation, elongation and termination.
Stages in intiation?
- Sigma factors and transcription fators bind to promoter and recruit RNA polymerase
-Promoter directs enzyme to starting point.
-DNA unwound
-Transcription begins
Stages of Elongation?
-RNA polymerase continues to unwind DNA 10 bp at time (3’-5’)
-Transcript antiparallel to DNA
-RNA polymerase doesn’t proofread and corrects mistakes
-RNA polymerase used nucleotide triphosphates as substrates: two phosphate groups removed from each substrate molecule, energy used to drive polymerization.
Stages of termination?
-For some genes transcript forms a loop and falls away from DNA
-For others a protein binds to transcript and causes it to detach from DNA
-When RNA polymerase reaches termination site, RNA transcript is set free.
