Vertebrate Origins 1

Question 1

Bilateral is defined by the split between

Answer 1

Protostomata and Deuterostomata

Question 2

Ambulacraria is defined by the split between

Answer 2

Echinodermata and hemichordates

Question 3

Deuterostomata is defined by the split between

Answer 3

Ambulacraria and Chordata

Question 4

Chordata is defied by the split between

Answer 4

Cephalochordata and olfactores (urochordates)

Question 5

What are the characteristics of Echinodermata?

Answer 5

7330 extant species, marine, radial symmetry, no head, endoskeleton of calcareous plate, water vasculature system, nerve ring around mouth, nerve cord (arms), no brain, through gut tube, indirect development (larvae)

Question 6

What are the characteristics of Hemichordata?

Answer 6

118 extant species, marine, enteropneusts are diverse and well studied, similar larvae to echinoderms, filter feeding, pharyngeal slits, enterocoelic coelom, stomochord (made of collagen & short), double nerve chord (dorsal and ventral)

Question 7

What are the characteristics of Cephalochordata

Answer 7

Have a notochordm neural plate, myomeres, specifies neural plate, somite derived, sclerotome, post-anal fin with tail, dorsal hollow nerve cord, paired nerves, hindbrain, midbrain, diencephalon, no eyes

Question 8

What is a notochord

Answer 8

It is made of collagen and provides structural integrity and is important in signaling

Question 9

What are myomeres

Answer 9

Segmented muscle blocks

Question 10

What are somites

Answer 10

Building blocks of the vertebrate body plan

Question 11

What is sclerotome

Answer 11

The ventral and medial portion of somite that proliferates mesenchyme, which migrates about the notochord to form the axial skeleton and ribs

Question 12

What are characteristics of Urochordata

Answer 12

3020 extant, indirect development (larvae), sessile, filter feeding, expels water in “sea squirts”, hermaphrodite.

Has a notochord, but degenerates @ adult, reabsorb tail and hind gut as adults, 2 pharyngeal slits. So, notochord, coelom, and post-anal tail were lost, nerve cord reduced, deals with currents, and feces/gametes exit through atriopore

Question 13

What are the general statements on Bilaterian Evo-Devi

Answer 13

Relatively linear genotype-phenotype relationship & C-value enigma

Question 14

What is meant by “linear genotype-phenotype” relationship?

Answer 14

There is a direct connection between genetic instructions and physical features

Question 15

What is the C-value enigma?

Answer 15

Genome size doesn’t positively correlate with structural complexity

Question 16

What are some Genetic Variations that may occur?

Answer 16

Mutation, genome rearrangements, and recombination

Question 17

What is the Regulatory Genome?

Answer 17

The ability to use the same genes over and over again for different reasons for different physiological tasks

Question 18

How can the Regulatory Genome be affected by Variation?

Answer 18

impacting..
- genes whose products regulate the expression of structural genes
- cis-regulatory mechanisms (transcription)
- RNA regulation (translation)
- post-translational regulation (protein activity)

Question 19

New regulation can cause pattern changes. What are the 3 different kind of pattern changes?

Answer 19

Heterchrony - timing of expression
Heterotopy - position of expression
Heterometry - intensity/amount of expression

Question 20

How is WNT important for A-P positioning?

Answer 20

WNT curve. More WNT = more posteriorizing (tails and whatnot) signal across all germ layers

Question 21

What are the three germ layers

Answer 21

Ectoderm, mesodermal, and endoderm

Question 22

What are some characteristics/information about the Dorsal-Ventral (DV) Axis Specification?

Answer 22

Bilaterian stem lineage, bilateral ymmetry. Think of BMP gradient; a WNT antagonist!
Along stem-chordata, inversion occurred

Question 23

When did the DHNC show up in the Deuterostomata crown?

Answer 23

Along the Chordata stem, where the paraxial tail, hindbrain, midbrain, notochord, and somites/myomeres showed up