lecture 4 - the origin of animals

Question 1

What is the purpose of the nuclear membrane in eukaryotes?

Answer 1

separates transcription and translation

Question 2

What systems need to develop to overcome the issues arising from complex multicellularity?

Answer 2

molecular mechanisms of cell adhesion
communication between cells
complex patterns of cells and tissues
regulatory gene networks
reproduction
internal and external environment

Question 3

What were the first group of true animals?

Answer 3

sponges

Question 4

What features did sponges develop?

Answer 4

flagellated cells called choanoctyes set up currents that draw water into the cavity and ingest and process food

gel-like mesohyl supports cells that form spicules and generate reproductive cells

cells that line the exterior sense and respond to the external environment

Question 5

What were the first organisms to evolve with a clear distinction of two cell layers?

Answer 5

cnidarians - (jellyfish and sea anemone) have two cell layers separated by a gel-like matrix

Question 6

What were the key steps in the evolution of complex multicellular organisms?

Answer 6

cell adhesion and cell signalling
cell-to-cell communication (gap junctions in animals and plasmodesmata in plants)
bulk transport

Question 7

What does bilateral symmetry allow?

Answer 7

the development of complex organs

Question 8

What is the structure of an insect wing?

Answer 8

insect wings develop from imaginal discs and consist of two epithelial sheets
they show complex patterns and colouration
this is determined by complex gene expression patterns
many of the genes that pattern the wing are shared among all animals