lecture 6 - Development of a Body Pattern I

Question 1

Darwin’s theory on similarity among early embryos

Answer 1

the common ancestor of all vertebrates also looked similar and diverse physical traits arise later in development (adaptive)

Question 2

establishing polarity

Answer 2

hierarchy of transcriptional factors interact with one another to map every detail of cellular differentiation

Question 3

oskar & nanos

Answer 3

mRNA asymmetrically localized to the posterior of egg

Question 4

bicoid

Answer 4

mRNA is asymmetrically localized to the anterior of the egg

Question 5

maternal polarity genes

Answer 5

class of genes provided by the mother such that their protein products are unevenly distributed in the zygote and specify the body axis

Question 6

cytoplasm is …

Answer 6

continuous but not homogenous

Question 7

bicoid and hunchback mRNAs protein products critical for…

Answer 7

head and thorax formation

Question 8

nanos and caudal mRNAs protein products critical for …..

Answer 8

formation of abdominal segments

Question 9

syncytium

Answer 9

a single cells containing several nuclei with one continuous cytoplasm (nucleus divides repeatedly until the egg consists of multiple nuclei)

Question 10

morphogen

Answer 10

a molecule that signals in a concentration-dependent manner

Question 11

bicoid protein

Answer 11

TF that is concentrated in the anterior of the embryo

Question 12

nanos protein

Answer 12

concentrated in the posterior of the embryo; a translational repressor

Question 13

position of nucleus in syncytium

Answer 13

determines the mixture of proteins it’s exposed to and the genes it will express (different TF distributed along the syncytium)

Question 14

bicoid & nanos

Answer 14

antagonistic effect

Question 15

testing the role of Bcd in polarity

Answer 15

injected bcd mRNA into other regions of syncytium, head structure developed when at the middle of end of the embryo if injected in those regions

Question 16

role of bcd conclusion

Answer 16

bicoid alone is sufficient to induce formation of the head; mutant = no head