Chapter 14: Genes, Development, and Evolution Flashcards
Zygote
Fertilized egg
Development
The process by which a multicellular organism, starting with a single cell, goes through a series of changes, taking in the successive forms that characterize its life cycle
Embryo
Plant or animal in earliest stages of development
Determination
The developmental fate of a cell-what type it will become- before characteristics of the cell are apparent
Differentiation
The process by which different types of cells arise from less specialized cells, leading to cells with specific structures and functions
Morphogenesis
The organization and spatial distribution of differentiated cells into the multicellular body and its organs
can occur by cell division, cell expansions, cell movements and apoptosis `
Growth
the increase in size of the body and it’s organs by cell division and cell expansion
cell fate
the destiny of cells to become part of a certain tissue type
What is the difference between determination and differentiation?
determination is a commitment; the ginal realization of that commitment is differentiation
What influences determination?
changes in gene expression and the extracellular environement
IS determination visible?
nope
totipotent
cell able to form the entire organism
generally, this belongs to just the zygote
dedifferentiate
lose differentiated characteristics
genomic equivalence
of somativ cells
all cells have a complete genome and the info to be any cell in the body
enucleated egg
unfertilized egg without a nucleus
meristems
clusters of undifferentiated, rapidly dividing stem cells at the tips of roots and stems of plants
true or false: adult mamamals have stem cells in practically all of their tissues
true
they are there so they can replace lost cells
multipotent
can form a limited repertoire of differentiated cells
differentaites on demand (respond to sepcific signals)
hematopoietic stem cells
red and white bloof cells
mesenchymal stem cells
cells that make done and surrounging tissues
HSSCT
hematopoietic stem cell transplantation
cancer treatment
stem cells removed from blood before treatment and are given signals to increase number in the lab and then stored and then added back
Pluripotent
the abilitiy to form all the cells in the body
embryonic stem cells
puripotent stem cells from the blastocyst
inducedd pluripotent stem cells
made from skin cells (pluripotent stem cells)
use microarrays to compare the genes expressed in ESCs with non stem cells
2. they isolated these genes and made them into a vector for transformation
3. showed that these could be made to differentiate
True or false: cell division and cell differentiation are mutually exclusive in many parts of the embryo
true
MyoD
a trenascription factor activated by cell signaling
activates the gene for p21, an inhibitor of cyclin-dependent kinases, causing the cell cycle to stop
What are the two ways a cell can be made to transcribe a different set of genes than another cell?
asymtmetical distribution of a cytoplasmic factor inside the cell so that its two progent cells receive unequal amounts of the factor
differential exposure of the two cells to an external inducer
polarity
the embryo develops a distinct top and bottom that will be opposite ends of a mature organism
animal pole
top of zygote
vegetal pole
bottom of zygote
cytoplasmic segregation
certain materials are distributed unequally in the edd cytoplasm
the amount og these materials determine the cells fate
cytoplasmic determinants
mateirals in the cell that are distributed in egg cytoplasm and help determine cell fate
embryonic development `
What properties help the mivrotubules and microfilaments move around the cytoplasmic determinants?
they have polarity
cytoskeletal elements can bind specific proteins, which can be used in the transport of mRNA
induction
the signaling events by which cells in a developing embryo communicate and influence one another’s developmental fate
inactivation or activation of specific sets of genes through signal transduction cascades in the responding cells
true or false: much of development is controlled by molecular switches that allow a cell to proceed down one of two alternative tracks
true
pattern formation
the developmental process that results in the spatial organization of a tissue or organism
linked to morphogenesis
What do the spatial differences in gene expression depend on?
the cells in th tissue must know where they are in relation to the body
the cells must activate the pattern of gene expression that is appropriate for their location
organ identity genes
encode proteins that act in combination to produce specific whorl features
homeotic mutation
genes that cause replacement of one organ for another
positional infromation
spatial sense of cells
morphogen
an inducer that provides positional information by diffusing from one group of cells to surrounding cells and setting up a concentration gradient
What are the requirements for a signal to be considered a morphogen?
must specifcally affect target cells
different concentrations of the signal must cause different effects
Zone of paralyzinf actvity
sercrete a morphogen which forms a gradient that determines the posterior anterior axis of the developing limg
maternal effect genes
set up the major axes (anterior-posterior and dorsal-ventral) of the egg
produce cytoplasmic determinants
segmentation genes
determine the boundary and polarity of each of the segments
and number
Hox genes
determine what organ will be made at a given location
encode a family of transcription factors that are expressed in different combinations along the length of the embryo, and help determine cell fates within each segment
gap genes
organize broad areas along the anterior-posterior axis
mutations in these result in gaps in the body plan
pair rule genes
divide the embryo into units of two segments each
mutations result in embryos missing every other segment
segment polarity genes
determine the boundaries and anterior-posterior organization of the individual segments
mutations in segment polarity genes result in segments where posterior structures are replaced by reverse anterior ones
homeobox
a sequences that encodes an amino acid sequence called the homeodomain
common in different Hox genes
homeodomain
recognizes and binds to a specific DNA sequence in the promoters of target genes
evolutionary developmental biology (evo-devo)
interplay between evolutionary and developmental processes
Major ideas of evo devo
many groups of plants and animals, even distantly related ones, share similar molevular mechanisms for development (same toolkits)
modularity
changes in the location and timing of the expression of key genes are important in the evolution of new things
development produces morphology and much of morphological evolution occurs by modification of the existing genes and pathways, not the creation of new ones
modularity
the molecular pathways that determine different developmental processes operate independently from one another
genetic toolkit
developmental mechanisms
modified and reshuffled over evolution
genetic switches
control how the genetic toolkit is used
involve promoters and transcription factors and enhancers
translate positional info in the embryo
heterochrony
the genes regulating the development of a module may be expressed at different developmental stages or for different durations in different species
What are the two major ways that developmental genes and expression constrain evolution?
nearly all evolutionary innovations are modifications of previously existing structures
the genes that control development are highly conserved’ that is, the regulatory genes themselves change slowly over the course of evolution
parallel phenotypic evoultion
similar traits will evolve repeatedly, expescially among closely related species
