lecture 17- evo devo

Question 1

deep homology

Answer 1

the exchangeability of the pox-6 mouse and eyeless (drosophila) genes between insects and vertebrates, implying conservation of ancient ancestral function

Question 2

when is diversity established?:

Answer 2

during embryogenesis (in early embryogenesis, most vertebrates look very similar

Question 3

totipotent

Answer 3

has the potential to develop into any cell type

Question 4

determination

Answer 4

cell cannot determine it’s fate

Question 5

how many different cell types are there

Answer 5

200

Question 6

is determination reprogramming possible

Answer 6

yes

Question 7

life cycle of a fruit fly

Answer 7

Question 8

genetic control of development

Question 9

complementation test

Answer 9

complementation test, also called cis-trans test, in genetics, test for determining whether two mutations associated with a specific phenotype represent two different forms of the same gene (alleles) or are variations of two different genes. The complementation test is relevant for recessive traits (traits normally not present in the phenotype due to masking by a dominant allele). In instances when two parent organisms each carry two mutant genes in a homozygous recessive state, causing the recessive trait to be expressed, the complementation test can determine whether the recessive trait will be expressed in the next generation

Question 10

egg polarity genes

Answer 10

establishment of main body axes (dorsal, ventral, rostral, caudal)

Question 11

segmentation genes

Answer 11

control the differentiation of the embryo into individual segments (determines the number and polarity of segments)

Question 12

segment identity

Answer 12

establish the identity of each segment (like this part needs, wings, this part needs legs, this part needs genitals)

Question 13

morphogens

Answer 13

proteins that vary in concentration and elicit different developmental responses at different concentrations

Question 14

egg polarity genes: dorsal ventral axis

Answer 14

Question 15

egg polarity genes: anterior-posterior

Answer 15

Question 16

gradients

Answer 16

differential levels of these protein results in differential activation of downstream genes (like hunchback), important for anterior-posterior ends of the embryo

Question 17

segmentation genes 1: gap genes

Answer 17

The gap genes are
responsible for defining the general regions of the embryo – specific gap
genes will be expressed in different sets of segments to differentiate the
thoracic segments from the abdominal segments, etc

Question 18

segmentation genes 1: pair-rule genes

Answer 18

Each pair-rule gene is expressed in every other segment of the body, and together they control development of pairs of segments. Finally, within each segment

Question 19

segmentation genes 1: segment polarity genes

Answer 19

guide the development of
individual segments, and ensure that they are organized appropriately

Question 20

homeotic mutation

Answer 20

one part of the body is transformed to resemble another

Question 21

hox genes are?

Answer 21

segment identity gene; mutations in these cause homeotic transformations

hox genes are transcription factors that control the expression of other genes to determine anterior-posterior segment identity, corresponding to their order on chromosomes

show similarity among very divergent organisms so they must be ancient

Question 22

genetics of pelvic spine: qtl mapping

Answer 22

Question 23

genetics of pelvic spine: pitx 1

Answer 23

Question 24

reporter assays

Answer 24

used to identify activator/repressor binding sites upstream or downstream of the gene of interest, determines where and when and how much the regulatory element drives gfp expression

Question 25

convergent evolution

Answer 25

similar traits evolving independently in different species

Question 25

convergent evolution

Answer 25

similar traits evolving independently in different species

Question 26

embryogenesis

Answer 26

process in which the foundation of an animal’s form is established

Question 27

saturation mutagenesis

Answer 27

by exposing males to a mutagenic chemical that resulted in their sperm acquiring mutations

Question 28

syncytium

Answer 28

In Drosophila, early development is characterized by very rapid division of the nuclei, without division of the cytoplasm. In a very short period of time, the egg becomes a syncytium, essentially a bag containing hundreds of nuclei that share a common cytoplasm. Those nuclei move out to the periphery of the embryo so that they are aligned along the surface of the embryo, at which point they become enclosed by cell membrane. The cells then begin to express different genes, depending on where they are in the embryo. In other words, they begin to differentiate themselves from one another. From this point forward, these cells are no longer all the same.

Question 29

maternal effect genes

Answer 29

The mRNA for the genes that regulate the initial steps of differentiation are actually provided by the mother via the egg (i.e., maternal effect genes from Lecture 10). These are known as egg polarity genes, and they establish the major body axes of the animal – distinguishing anterior (head) from posterior (tail), and dorsal (back) from ventral (belly). Some of these genes encode morphogens. Morphogens are found at different concentrations along one of the body axes, and act on cell differentiation in a concentration-dependent manner. For example, a morphogen might activate expression of certain genes when it is found at high concentrations, while activating other genes when it is found at intermediate or low concentrations

Question 30

Bicoid

Answer 30

egg polarity gene; Bicoid mRNA is found only in the very anterior-most tip of the embryo, where its mRNA is anchored in the cell membrane. When bicoid mRNA is translated, it forms a gradient of Bicoid protein, which is highest at the anterior end (where the mRNA is localized). Bicoid protein activates expression of a second gene, hunchback, which is important for head development

Question 31

Nanos

Answer 31

egg polarity gene; Nanos mRNA is found only in the posterior of the embryo, and when it is translated it forms a gradient of Nanos protein, with the highest concentration at the posterior end. Nanos represses translation of hunchback, contributing to its expression only in the anterior of the embryo and helping to establish the head position. At the same time, Nanos promotes tail-making in the posterior. Between Dorsal, Bicoid, Nanos, and related proteins, the egg polarity genes use multiple morphogen gradients to establish the embryonic body axes, and generate a 3-D map of the embryo

Question 32

transcription factors

Answer 32

a type of protein that binds DNA and thereby regulates the expression of many downstream genes, turning expression up or down

Question 33

cis-regulatory elements

Answer 33

transcription-factor binding sites

Question 34

The plant “toolkit” genes that are responsible for floral patterning are referred to as

Answer 34

ABC genes In Arabidopsis flowers, the structures are organized into four concentric rings, or whorls. Moving out from the middle of the flower are whorls where different floral organs – carpels, stamens, petals, and sepals – form. Overlapping expression of three sets of genes (simply named: A, B, and C genes) determines which organ will form in each whorl. A-genes are expressed in the two outermost whorls; C-genes are expressed in the two innermost whorls; B-genes are expressed in the two intermediate whorls. Thus, each whorl expresses a unique combination of ABC gene expression, which determines which type of organ is produced. In the outermost whorl, only A-genes are expressed, and sepals form. In the second whorl in, both A- and B-genes are expressed, causing petal formation. In the third whorl, B- and C-genes are expressed, causing stamens to form, and in the innermost whorl only C-genes are expressed, and carpels form there. Like with Hox genes, flower structures (in this case whorl identity rather than body segment identity) are determined by the combinatorial expression patterns of ABC genes, and mutations in the ABC genes cause homeotic transformations in flowers. For example, plants that have a mutation in a B-class gene will produce only sepals in the two outermost whorls, and only carpels in the two innermost whorls, because each whorl will express only A- or C-class genes