Bio 2 - Gene expression eukaryotes

Exam 2

Multicellularity

more complicated - respond to environment and get correct timing

HOX genes

promote transcription factors to set up body axis in certain parts of the body

eukaryotic morphology

has to be the right protein at the right time in the right cell

timing - heterochrony

when to turn gene on or off - human neck v giraffe neck

location - heterotopy

where to gene on and express it - birds + webbed feet (BNP4 Gremlin)

Amount - heterometry

how much of a gene produced in an area - bird beak shape (BMP4 CaM)

pre transcriptional regulation

acetylation + methylation

transcriptional regulation

main way - general and specific transcription factors

post transcriptional regulation

alternative splicing + mRNA tags

pre translational regulation

delay or prevent translation

post translation regulation

protein tags for degradation, destroy, and recycling

Transcription factor production - other TF

transcription factors making more transcription factors

Transcription factor production - extracellular signaling

production of different transcription factors based on the cell type triggered (cortisol - energy mobilizing hormone responding to the now threat)

Transcription factor production - environmental cues

cause cascade producing different transcription factors (Grape study - 6 different TF for ripening - found that exposure to sun, no damage to the plant = highest production of TF

General transcription factors

Basic cellular processes (regulate)

Basal Transcription Apparatus

minimum set of proteins needed for transcription

TFIID

bind to the promoter (causes a shape change)

TFIIB

binds to promoter and lines up BTA

TFIIF

line up polymerase to optimally transcribe

TFIIE

help polymerase do its job (unwind DNA, etc.)

Specific Transcription Factors

regulate specialized processes in the cell

mediator protein

bridges the gap between BTA and specific TF (brings gene and distal elements together)

enhancer - allows for activator binding (is not a protein)

switch= activate transcription knob= up regulate transcription

silencer - allows for repressor binding

switch= prevent BTA knob= down regulate transcription

Enhancers + Silencers (mutation effects)

have weak binding affinity(no lock and key fit) - single bp mutation can have drastic effects (mice + polydactyly - single bp mutation to ATCC leads to higher percentage of bonds forming —> more expression of polydactyly)

Structural motifs

patterns/themes of structural elements - helix turn helix (alpha helix, turn, alpha helix - fits into major groove) + zinc finger (helix, turn stabilized by zinc, beta sheet - fits into major groove)

Post transcriptional control - alternative splicing

getting many different proteins/functions from the same gene

Post transcriptional control - miRNAs

RISC directs miRNA to mRNA to bind and prevent translation (plant leaves - create their own microbiome)

Post transcriptional control - siRNA

RISC allows for siRNA to degrade mRNA (immune system)

Post translational control - ubiquitinization

ubiquitin binds to lysine, creates more ubiquitin (ubiquitinizing protein) triggers for the protein to unfold and recycle the amino acids