Multicellularity and Signalling Flashcards
Advantages of size (multicellularity)
Mobility
Strength/power
Challenges of size (multicellularity)
Instability
Absorption and excretion more difficult
Greater energy and space needs
Advantages of multicellularity
- Size
- Specialization of cell/organ/tissue function: division of labor
Challenges of multicellularity
- Size
- Compartmentalization at organism’s level
- Organization of cells/organs/tissues
- Communication between cells/tissues
- Complex reproduction
- Generation times longer
- Slower adaptation/evolution
- CANCER
Aplysia
Famous model system for study of learning and memory
Exhibits learning behaviors similar to humans despite lack of brain
Evidence that learning and memory are , to some extent, mediated on a cellular level
Adaptations of multicellularity
- Stability and cellular organization (cell adhesion and extracellular matrix)
- Compartmentalization/protection from environment (mostly cell adhesion; ECM to some degree)
- Enhanced intercellular communication (mostly cell signaling)
- Mechanisms to absorb nutrients, H20, O2, etc. and to excrete waste (Physiology)
- Differentiation of cells (developmental biology)
- Reproduction (physiology and developmental biology)
Stability and cellular organization (multicellular adaptation)
Cell adhesion and extracellular matrix
Compartmentalization/protection from environment (multicellular adaptation)
Mostly cell adhesion; ECM to some degree
Enhanced intercellular communication (multicellular adaptation)
Mostly cell signaling
Cell adhesion molecule (CAM)
Integral membrane proteins
Bind to CAMs on adjacent cells
Stabilize the organism
Homophilic cell adhesion
CAMs bind to same molecule on adjacent cell
Helps cells of organs stay together in same place
All cells of one type express same CAM so they know to associate with each other
Epithelial cells
Polarized cells that form epithelia
Held together by tight junctions
Every point of contact made of tight junctions/CAMs
Epithelia
Boundary between organism and outside world
Tight junctions
Continuous intercellular barrier between epithelial cells
Made up of multitudes of cell adhesion molecules
Extracellular matrix (ECM)
Dense thicket of proteins that fill virtually all space between cells in animals
Lots of glycosylation
Anchors cells
Structural support/cusioning
Filtering of substances (eg kidney
Signaling and communication