BIOEE 1780 Lecture Notes - Lecture 14: Ventral Nerve Cord, Chitin, Blastomere
7 May 2018
School
Department
Course
Professor
Synapomorphies for Choanoflagellates and Animals:
1. Cadherins: cell surface adhesive proteins
2. Tyrosine Kinases: cell surface receptors
Choanoflagellates: collared or funnel flagellates
• "Choano" = funnel
• Aquatic
• Filter feed on bacteria
• Synapomorphy: collar of sticky tentacles (used to capture bacteria to eat via phagocytosis)
• Have a single posterior flagellum
• Unicellular, but can form small colonies
General Characteristics of Animals
1. Multicellularity
2. Heterotrophy (using nutrients produced by other organisms)
3. Single posterior flagellum
4. Lack chitin in the cell wall
5. Internal digestion
6. Motility (independent movement)
Animal Synapomorphies:
• DNA
• Having 7 or more HOX genes (regulatory genes that are important in determining body plans)
• Junctions between cells
• Extracellular matrix molecules contain collagen
Early animal ancestors likely formed multicellular colonies, which were more efficient at capturing their
prey than single cells.
• Certain cells in the colony became specialized (i.e. differentiated)
How do you differentiate animal groups?
1. Cell layers
2. Symmetry
3. Gastrulation
4. Body cavity
5. Segmentation and appendages
Blastula: a hollow ball of cells; one cell thick
• Multiple cell layers form, ultimately giving rise to tissues and organs
• Two types of animals:
o Diploblastic
o Triploblastic
Diploblastic Animals: embryos have two cell layers…
1. Outer ectoderm
2. Inner endoderm
Examples: Ctenophores, Cnidarians
Document Summary
Synapomorphy: collar of sticky tentacles (used to capture bacteria to eat via phagocytosis) Synapomorphies for choanoflagellates and animals: cadherins: cell surface adhesive proteins, tyrosine kinases: cell surface receptors. Choanoflagellates: collared or funnel flagellates: aquatic, have a single posterior flagellum, unicellular, but can form small colonies. General characteristics of animals: multicellularity, heterotrophy (using nutrients produced by other organisms, single posterior flagellum, lack chitin in the cell wall, motility (independent movement) Animal synapomorphies: dna, having 7 or more hox genes (regulatory genes that are important in determining body plans, extracellular matrix molecules contain collagen. Early animal ancestors likely formed multicellular colonies, which were more efficient at capturing their prey than single cells: certain cells in the colony became specialized (i. e. differentiated) How do you differentiate animal groups: cell layers, symmetry, gastrulation, body cavity, segmentation and appendages. Blastula: a hollow ball of cells; one cell thick: multiple cell layers form, ultimately giving rise to tissues and organs.
