Chapter 18 - Gene Regulation Flashcards
Genes can be activated by _____ ______, or they can be inhibited by the presence of a _______ as they interact with _______ _______ or
________.
Inducer molecules, repressor, regulatory proteins, sequences
Sequence of DNA that codes for a regulatory protein
such as a repressor protein.
Regulatory gene
How the components of an operon function to regulate gene expression in
both repressible and inducible operons.
How positive and negative control function in gene expression.
Impact of DNA methylation and histone acetylation on gene expression.
How timing and coordination of specific events are regulated in normal
development, including pattern formation and induction.
Role of miRNAs in control of cellular functions.
Role of gene regulation in embryonic development and cancer.
Operon
Cluster of related genes with on/off switch
Three parts of operon
Promoter, operator, genes
Promoter
where RNA polymerase attaches
Operator
“on/off”, controls access of RNA poly
Genes
code for related enzymes in a pathway
Repressible Operon
ON –> OFF
Inducible Operon
OFF –> ON
Repressible Operon is ____abolic
Anabolic (build organic molecules)
In a repressible operon, the organic molecule product as as ________ –> bind to _____ to activate it
corepressor, repressor
Trp operon is a(n) _______ operon
Repressible Operon
Inducible Operon is ___abolic
Catabolic (break down food for energy)
In an Inducible Operon, repressor is active –> ______ binds to and inactivates repressor
inducer
Lac operon is a(n) ______ operon
Inducible
Negative control
operons are switched off by active form of repressor protein
◦ Eg. trp operon, lac operon
Positive control
regulatory protein interacts directly with genome to increase transcription
◦ Eg. cAMP & CAP
cAMP ________ when ______ is scarce
accumulates, glucose
cAMP binds to ____
CAP
Differences between cell types is due to _________
differential gene expression
Different cell types (with identical genomes) ____________ to carry out specific functions
turn on different genes
Chromatin Structure
Tightly bound DNA –> less
accessible for transcription
DNA methylation
methyl groups added to DNA; tightly packed; ↓ transcription
Histone acetylation
acetyl groups added to histones; loosened; ↑ transcription
Epigenetic Inheritance
Modifications on chromatin can be passed on to
future generations
Unlike DNA mutations, epigenetic inheritance changes to chromatin ________ (________)
Can be reversed, de-methylation of
DNA
Reason for identical twins
Epigenetic Inheritance
Transcription Initiation
Specific transcription factors (activators or repressors) bind to control elements (enhancer region)
Activators
increase transcription
Repressors
decrease transcription
Activators ______ transcription, repressors _______ transcription
increase, decrease
Transcription Initiation Complex
Activators bind to enhancer regions + other proteins+ RNA polymerase
Regulation of mRNA:
micro RNAs (miRNAs) and small interfering RNAs (siRNAs) can bind to mRNA and degrade it or block translation
Embryonic Development
Zygote –> Organism
Cell Differentiation
cells become specialized in
structure & function
Morphogenesis
“creation of form” – organism’s shape
Determination
irreversible series of
events that lead to cell differentiation
Cytoplasmic determinants
maternal substances in egg distributed unevenly in early cells of embryo
Induction
cells triggered to differentiate
Cell-Cell Signals
molecules produced by one cell influences neighboring cells
eg. growth factors
Pattern formation
setting up the body plan (head, tail, L/R, back, front)
Morphogens
substances that establish an embryo’s axes
Homeotic genes
master control genes that control pattern formation (eg. Hox genes)
Role of Apoptosis
(programmed cell death) to sculpture organs and tissues (because most embryonic cells produced in excess)
Apoptosis carried out by
caspase proteins
Proto-oncogene
stimulates cell division
Tumor-suppressor gene
inhibits cell division
