Lecture 2: Animal Design Principles

Question 1

When body size is small, what is the compartment, SA, transport, and support like?

Answer 1

Compartment: none
SA: High
Transport: Diffusion
Support: Minimal

Question 2

When body size is large, what is the compartment, SA, transport, and support like?

Answer 2

Compartment: many and complex
SA: Low
Transport: Internal flow
Support: complex

Question 3

What are epithelial cells?

Answer 3

Sheets of multuple copies of one particular cell type organizes into a specialized structure

Question 4

Epithelia: Basal Lamina (How is it formed? What is it?)

Answer 4

Basal ends of epithelia secretes ECM (collagen type 4) to form Basal Lamina.

Basal Lamina is the structural support with important physiological activities such as being the barrier to moving extracellular materials from apical epithelium to basal.

Question 5

What staples the basal side to the basal lamina?

Answer 5

Hemidesmosome

Question 6

Epithelium: Microvilli (Purpose?)

Answer 6

Adaptations to increase SA of apical side of epithelial cells, secretes extracellular materials and cilia move fluid/ mucus

Question 7

Junctions between adjacent cells

Answer 7

Belt/adhering junctions
Gap junctions
Septate junctions

Question 8

What are belt/ adhering junctions?

Answer 8

Protonaceous secretions on the outer surface of cell that joins epithelial cells to neighbours.
Makes terminal web to provide mechanical stiffness.

Question 9

Septate Junctions

Answer 9

Extracellular junctions between adjacent cells made of materials that form an extremely fine connecting network that closes the traverse spaces between cells while creating a barrier

Question 10

Gap Junctions

Answer 10

Protein molecules secreted in plasma membrane of one cell and span extracellular space to create a pore between cells, a tunnel for material to move between adjacent cells

Question 11

What molecules do animal eggs have?

Answer 11

Sulphate determinants such as mRNA and proteins

Question 12

What do embryos consume and what happens?

Answer 12

Embryos consume yolk from oocytes in which morphogenetic determinants are not uniformly distributed

Question 13

Vegetal cells become ______

Animal cells become ______

Answer 13

Digestive tract; Epidermis

Question 14

Radial Cleavage

Answer 14

4 cells (blastomeres) divide perpendicular to axis, daughter cells sit on top

Question 15

Spiral Cleavage

Answer 15

Slight angle of third cleavage and subsequently, daughter cells are tilted and nestled in crevices

Question 16

Invagination

Answer 16

Cells at vegetal pole change shape causing vegetal pole to buckle and form an archenteron with blastopore (anus then mouth)

Question 17

Epiboly

Answer 17

Cells at animal pole proliferate and migrate to vegetal pole, forcing vegetal cells inside

Question 18

Ingression

Answer 18

Cells that have morphological determinants to be the gut detach from basal lamina and wiggle out of epithelium moving into blastocoel to form digestive tract

Question 19

Mesoderm, the third embryonic germ layer

Answer 19

Arises as subpopulation of endodermal cells at vegetal pole to make endomesoderm
Early mesodermal cells migrate into blastocoelic space making mesenchyme

Question 20

Hemel system/ BVS

Answer 20

Mesodermal epithelial cells help coelomic animals to force fluid movement by muscle contraction

Cellular lining by basal lamina can be a filter to allow some materials to move from blood into coelomic space

Question 21

Nephridium

Answer 21

Filtered material passes through mesodermally derived tubule creating passage to exterior medium

Question 22

Podocytes

Answer 22

Broad cells with fingle like extensions, interdigitate with each other to form a filtration barrier to pressurize fluid through basal lamina into coelomic space