Chapter 14: Genes, Development, and Evolution Flashcards Preview

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Flashcards in Chapter 14: Genes, Development, and Evolution Deck (59):
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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

1

Zygote

Fertilized egg

2

Embryo

Plant or animal in earliest stages of development

3

Determination

The developmental fate of a cell-what type it will become- before characteristics of the cell are apparent

4

Differentiation

The process by which different types of cells arise from less specialized cells, leading to cells with specific structures and functions

6

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 `

7

Growth

the increase in size of the body and it's organs by cell division and cell expansion

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cell fate

the destiny of cells to become part of a certain tissue type

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What is the difference between determination and differentiation?

determination is a commitment; the ginal realization of that commitment is differentiation

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What influences determination?

changes in gene expression and the extracellular environement

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IS determination visible?

nope

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totipotent

cell able to form the entire organism
generally, this belongs to just the zygote

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dedifferentiate

lose differentiated characteristics

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genomic equivalence

of somativ cells
all cells have a complete genome and the info to be any cell in the body

15

enucleated egg

unfertilized egg without a nucleus

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meristems

clusters of undifferentiated, rapidly dividing stem cells at the tips of roots and stems of plants

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true or false: adult mamamals have stem cells in practically all of their tissues

true
they are there so they can replace lost cells

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multipotent

can form a limited repertoire of differentiated cells
differentaites on demand (respond to sepcific signals)

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hematopoietic stem cells

red and white bloof cells

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mesenchymal stem cells

cells that make done and surrounging tissues

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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

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Pluripotent

the abilitiy to form all the cells in the body

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embryonic stem cells

puripotent stem cells from the blastocyst

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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

25

True or false: cell division and cell differentiation are mutually exclusive in many parts of the embryo

true

26

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

27

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

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polarity

the embryo develops a distinct top and bottom that will be opposite ends of a mature organism

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animal pole

top of zygote

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vegetal pole

bottom of zygote

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cytoplasmic segregation

certain materials are distributed unequally in the edd cytoplasm
the amount og these materials determine the cells fate

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cytoplasmic determinants

mateirals in the cell that are distributed in egg cytoplasm and help determine cell fate
embryonic development `

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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

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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

35

true or false: much of development is controlled by molecular switches that allow a cell to proceed down one of two alternative tracks

true

36

pattern formation

the developmental process that results in the spatial organization of a tissue or organism
linked to morphogenesis

37

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

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organ identity genes

encode proteins that act in combination to produce specific whorl features

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homeotic mutation

genes that cause replacement of one organ for another

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positional infromation

spatial sense of cells

41

morphogen

an inducer that provides positional information by diffusing from one group of cells to surrounding cells and setting up a concentration gradient

42

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

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Zone of paralyzinf actvity

sercrete a morphogen which forms a gradient that determines the posterior anterior axis of the developing limg

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maternal effect genes

set up the major axes (anterior-posterior and dorsal-ventral) of the egg
produce cytoplasmic determinants

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segmentation genes

determine the boundary and polarity of each of the segments
and number

46

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

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gap genes

organize broad areas along the anterior-posterior axis
mutations in these result in gaps in the body plan

48

pair rule genes

divide the embryo into units of two segments each
mutations result in embryos missing every other segment

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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

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homeobox

a sequences that encodes an amino acid sequence called the homeodomain
common in different Hox genes

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homeodomain

recognizes and binds to a specific DNA sequence in the promoters of target genes

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evolutionary developmental biology (evo-devo)

interplay between evolutionary and developmental processes

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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

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modularity

the molecular pathways that determine different developmental processes operate independently from one another

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genetic toolkit

developmental mechanisms
modified and reshuffled over evolution

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genetic switches

control how the genetic toolkit is used
involve promoters and transcription factors and enhancers
translate positional info in the embryo

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heterochrony

the genes regulating the development of a module may be expressed at different developmental stages or for different durations in different species

58

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

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parallel phenotypic evoultion

similar traits will evolve repeatedly, expescially among closely related species