Chapter 11 Flashcards
Gene expression
overall process which genetic info flows from genes to proteins
Gene regulation
controlling gene expression by turning genes on or off
Gene regulation in prokaryotic cells
response to signals from environment
Operon
segments of chromosome with genes and adjacent control sequences (promotor/operator)
Operator in operon controls
gene expression, on/off switch
Repressors
turn off operons by binding to operator (block RNA polymerase binding to promotor)
Activators
turn on operons by binding to DNA (make it easier for RNA polymerase to bind to promotor)
Gene regulation in eukaryotes
-response to single from internal and external environment
Cell differentiation in multicellular organisms is due to
control of gene expression
Cell differenention
cells are specialized in structure and function for specific role in body
Selective gene expression
subset of genes expressed in each cells type is unique
Strucural and chemical modification to DNA and associated proteins may lead to long term..
inactivation of genes
Multiple ______ regulate gene expression in eukaryotes
mechanisms
_______ and ______ regulation control gene expression
transcription and translation
Tightly packed DNA can..
block gene expression by preventing RNA polymerase from binding
Chemical modification to eukaryotic chromosomes block
gene expression
Addition/removal of chemical group to histones causes them to..
bind DNA more tight/loose
Chemical modifications to eukayortic chromosomes can be
inheited
Add chemical group to DNA bases which..
turns off genes (=methylation)
X chromosome is
chemically modified and highly compact
Inactivated compacted chromosome=
Barr Body
Which X chromosome inactivated is
random
Epigenetic
cheimcal modification to genome, important in gene regulation
Epigenetic explains
some of differences in identical twins as they age
Epigenetic inheritance
inheritance of traits transmitted by mechanisms not directly involving nucleotide sequence
Multicellular organisms cells are differentiated for
specilizaed roles
Differentiated cells only express ___ ____ of total genes
small percentage
“Housekeeping genes”
continually “on” in most cells for routine activities
Regulation of transcription at initiation
- activators help turn on transcription
- transcription factors bind to enhancer sequences
- repressors bind to silencers to inhibit transcription
Transcription factors are ____ proteins
activator
Transcription factors create
complex with RNA polymerase at promotor, turn gene on
RNA processing controls
gene expression and flow of mRNA
Alternative RNA splicing
produces multiples types of polypeptide from a single gene
MicroRNA (miRNA)
control gene expression
miRNA bind to
complementary mRNA
RNA interference (RNAi)
turns genes off
After mRNA is fully processed and transported to the cytoplasm, gene expression can still be regulated by
- breakdown of mRNA
- initiation of translation
- post-translational modification
Post translation modifications include
protein activation and protein breakdown
Cell to cell signalling often
initiates a signal transduction pathway
Binding of signalling molecule activates ..
series of relay proteins
Signalling cell may secrete ___ ____ to initiate pathway on other call
signalling molecules
Signal transduction pathway
last rely protein activates transcription factors, turns gene on
Cell signalling in gene expression is important in
animal development
Cell-to-cell signalling may initiate gene expression in..
early embryo development
Cell signalling triggers gene expression of
homeotic genes
Homeotic genes
master control genes that regulate other genes
Protein products of one set of ___ cause cascades of gene expression to develop __ ___
genes; body parts
Mutation in a homeotic gene can cause..
body parts in wrong places
Most differentiated cells retain..
a full set of genes, even though only a subset may be expressed
Plant cloning
a root cell can divide to form an adult plant
Animal cloning achieved by..
nuclear transplantation
Reproductive cloning is used to produce animals with desirable traits to produce..
- better agricultural products
- therapeutic agents
- to restock populations of endangered animals
Another way to clone uses..
embryonic stem cells
Embryonic stem cells are harvested from a
blastocyst
Embryonic stem cell cloning can be used to produce
cell cultures for research or stem cells for therapeutic treatments
Therapeutic cloning produces
embryonic stem cells (ES cells)
Adult stem cells
give rise to many but not all cell types
Certain conditions induce __ _____ in stem cells causing ____
gene expression; differentiation
ES cells have more ____ _____ than adult stem cells
developmental potential
Therapeutic cloning aims to supply cells for the…
repair of damaged or diseased organs
Cancer cells do not respond to
normal regulation signals
Cancer cells are due to
changes in gene expression
Oncogene
gene which can cause cancer when present in single copy
A cell can acquire oncogenes by
virus or mutation of own genes
Proto-oncogene
normal gene that has potential to become an oncogene
Proto-oncogene code for..
growth factors or proteins that affect growth factors or some aspect of cell cycle
Growth factors
proteins that stimulate cell division
Tumour supressor gene
normal gene whose products inhibit ell division, protein products prevent uncontrolled cell growth
Mutations of tutor suppressor genes may contribute to
onset of cancer
Carcinogens
cancer causing agents that alter DNA and make cells cancerous
Majority of cancers arise from
mutations caused by environmental factors
