Chapter 8

Question 1

After the egg has been fertilized and metabolism activated,_______ and _______ begin

Answer 1

cleavage and gastrulation

Question 2

_______ begin to form during gastrulation

Answer 2

body axis

Question 3

Model invertebrates display type I embryogenesis:
- immediate activation of _______ genes
- rapid specification of _______
- relatively small number of cells at the start of _______

Answer 3

1) zygotic
2) blastomeres
3) gastrulation

Question 4

What are the 4 model invertebrates?

Answer 4

1) snails (gastropod mollusks, protostome)
2) C. elegans (nematode, protostome)
3) Sea Urchins (echinoderms, dueterostome)
4) ascidians (tunicates, dueterostome)

Question 5

Model invertebrates are:
1) easy to maintain in _______
2) short _______ time
3) Large numbers of _______ in each generation
4) easy genetic and surgical _______

Answer 5

1) lab
2) generation
3) offspring
4) modification

Question 6

______: animals that gastrulate

Answer 6

metazoan

Question 7

_______: basal phyla that have only 2 germ layers

Answer 7

diploblasts

Question 8

_______: have mesoderm, third germ layer

Answer 8

triploblasts

Question 9

diploblasts lack a true _______ and have ectoderm and endoderm

Answer 9

mesoderm

Question 10

Triploblastst are _______ meaning they show bilateral symmetry

Answer 10

bilaterians

Question 11

In protostomes, the blastopore becomes the _______

Answer 11

mouth

Question 12

In protostomes, coelom forms through _______

Answer 12

schizocoely

Question 13

Describe the process of schizocoely?

Answer 13

hollowing out solid core cells (mesoderm) to form coelom

Question 14

_______: organisms that molt their external skeleton

Answer 14

ecdysozoans
- protostome

Question 15

_______: display spiral cleavage and common trochophore larval pattern

Answer 15

lophotrochozoans
- protostome

Question 16

What are the 4 groups of animal phylums that represent protostomes?

Answer 16

1) Mollusks
2) annelids
3) nematodes
4) arthropods

Question 17

In deuterostomes, the blastopore becomes the _______

Answer 17

anus

Question 18

In deuterostomes, coelom forms through _______

Answer 18

enterocoely

Question 19

Describe the process of enterocoely

Answer 19

extending mesodermal pouches from the gut form coelom

Question 20

Lancelots and tunicates do not have a backbone, but their larvae have _______

Answer 20

notochords and pharyngeal pouches

Question 21

What are the 5 “phylums” that represent deuterostomes?

Answer 21

1) echinoderms
2) hemichordates
3) cephalochordates
4) tunicates
5) vertebrates
- 3,4,5 are chordates

Question 22

Snails undergo _______, _______ cleavage

Answer 22

spiral holoblastic
- protostome

Question 23

In spiral cleavage, blastomeres touch one another more closely. They sit in _______ of the nearby cells

Answer 23

grooves
- most thermodynamically stable arrangement

Question 24

_______: blastula with very small blastocoel or no blastocoel

Answer 24

stereoblastulae
- snails has fewer cells than sea urchins

Question 25

In snails, R/L axis is determined by the expression of _______ family paracrine factors

Answer 25

nodal

Question 26

In snails, the first two cleavage planes are nearly _______ producing 4 large blastomeres

Answer 26

meridional - down the middle

Question 27

In snails, subsequent divisions after the first 2, are unequal, producing _______ (towards the animal pole) and _______

Answer 27

micromeres macromeres

Question 28

In snails, the angle of cleavage planes in mitotic apparatus is determined by cytoplasmic mRNA provided to the oocyte from the _______ cells

Answer 28

mother's - maternal affect

Question 29

In Lymnaea peregra, this direction of coiling (LvR spiral) is controlled by alleles of the _______ gene

Answer 29

formin

Question 30

Formin mRNA encodes a protein that binds to _______ and helps align the cytoskeleton

Answer 30

actin

Question 31

Formin mRNA is _______ positioned as early as the 2-cell stage

Answer 31

asymmetrically

Question 32

In snails, mothers with dd carry a homozygous frameshift, the mRNA for Formin is rapidly _______ and can't be donated to the egg cytoplasm

Answer 32

degraded

Question 33

_______ coiling: opening to the right It is caused by what allele?

Answer 33

Dextral - (D = dominant allele)

Question 34

_______ coiling: opening to the left It is caused by what allele?

Answer 34

Sinistral - (d = recessive allele)

Question 35

In order to construct a fate map for snails, scientists: 1) injected large _______ conjugated to _______ dyes into specific micromeres then monitored them 2) _______ of developing embryos

Answer 35

polymers; fluorescent live imaging - confirmed that protostome

Question 36

the morphogenic determinants in snails all initiate gastrulation at the _______ pole very early, when only a few dozen cells have formed

Answer 36

vegetal - autonomous specification

Question 37

In snails, mRNA's for some TF's and paracrine factors partitioned by their association with certain _______ What mechanism allows this?

Answer 37

centrosomes - allows for mRNA to be partitioned - shape formed by **3'UTR**

Question 38

In spirally-cleaving embryos, a unique mechanism of positioning _______ determinants during cell divisions occurs

Answer 38

endomesodermal

Question 39

Spirally cleaving embryos extend a bulb of _______ from one cell prior to and during division and then reabsorb it after division

Answer 39

cytoplasm

Question 40

Extension of a bulb of cytoplasm creates a _______

Answer 40

tre-foil stage embryo

Question 41

A tre-foil stage embryo contains: 1) cleavage orientation in _______ 2) _______ and _______ formation 3) specifying _______ axis 4) guiding _______ gland and _______ inductive interactions

Answer 41

1) D blastomeres 2) mesodermal and intestinal 3) dorsal/ventral 4) shell; eye

Question 42

The bulb of cytoplasm in a Tre-foil stage embryo is called a _______

Answer 42

Polar-lobe

Question 43

in snails, the _______ is required for heart and gut formation

Answer 43

mesentoblast - (4d blastomere) - connected to polar lobe

Question 44

What are the 3 major determinants acting in the process of polar-lobe creation? 1) TF 2) translation 3) signaling pathway

Answer 44

1) b-catenin 2) nanos 3) Notch

Question 45

All cell fates have been largely determined by inductions from the _____ series of blastomeres

Answer 45

D - the organizer

Question 46

in snails, the _______ forms @ ___-days post fertilization as a separate hole not associated with the blastopore

Answer 46

anus 12

Question 47

In snails, gastrulation occurs through what two gastrulation mechanisms

Answer 47

1) epiboly 2) invagination