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Gene regulation - Coggle Diagram
Gene regulation
Post-translational
Amino acids modified
(Modification by cAMP)
Non protein groups added
Protein folds and shortens
Formation of disulphide bridges
Transcriptional (DOES TRANSCRIPTION OCCUR)
Operons
Lac operon: Glucose is the preferred substrate so lactose only needs to metabolised if glucose is in short supply 1) If glucose present,
repressor protein binds to operator
which prevents RNA polymerase from binding and transcribing (
down regulation
) 2) if no glucose is present but lactose is,
lactose binds to the repressor protein
, changing its shape, it can no longer bind to the operator so
RNA polymerase attaches to promoter
and begins transcription
Save resources as if certain products are not needed all genes involved in production are switched off
Cyclic AMP
Causes up-regulation, movement of glucose into cells reduced amount of cAMP reducing transcription of genes that are responsible for metabolism of lactose
Histone modification
Methylation causes DNA to bind more tightly
Acetylation or phosphorylation reduces positive charge of histones, so DNA coils less tightly
EPIGENETICS = Control of gene expression by modification of DNA
Chromatin remodelling
Euchromatin
Loosely wound DNA, allows for transcription: present in interphase
Heterochromatin
Tightly wound DNA, prevents transcription, present during cell division
Translational (DOES PROTEIN SYNTHESIS OCCUR)
Activation of
initiation factors which aid the binding of mRNA
to the ribosome
Degradation of mRNA, more resistant molecules last longer in cytoplasm and more of the corresponding protein will be produced
Binding of
inhibitory proteins to mRNA
prevent binding to ribosome
Post-transcriptional (IN NUCLEUS)
RNA processing
Formation of mature RNA, cap and tail is added to help stabilise mRNA and delay its degradation in the cytoplasm, cap aids binding to the ribosome
Splicing removes introns and exons are joined
RNA editing
Bases can be deleted, added or substituted as in a point mutation: single mRNA can code for a range of proteins