Cell Organisation And Communication

Question 1

Gap junction

Answer 1

A type of intercellular junction in animal cells, consisting of proteins surrounding a pore that allows the passage of material between cells

Question 2

Intermediate filament

Answer 2

Fibrous proteins supercoiled into thicker cables
8-12 nm
Made up of one of several different proteins (such as keratins), depending on cell type
Functions:
Maintenance of cell shape (tension-bearing elements)
Anchorage of nucleus and certain other organelles
Formation of nuclear lamina

Question 3

Microfilament

Answer 3

Two intertwined strands of actin, each a polymer of actin subunits
7 nm
Functions:
Maintenance of cell shape (tension-bearing elements)
Changes in cell shape
Muscle contraction
Cytoplasmic streaming
Cell motility (as in pseudopodia)
Cell division (cleavage furrow formation)

Question 4

Microtubules

Answer 4

A hollow rod composed of tubulin proteins.
Tubulin is a dimer consisting of α-tubulin and β-tubulin
25 nm with 15 nm lumen
Functions:
Maintenance of cell shape (compression-resisting “girders”)
Cell motility - found in cilla and flagella
Chromosome movements in cell division
Organelle movements

Question 5

Plasmodesma

Answer 5

An open channel through the cell wall that connects the cytoplasm of adjacent plant cells, allowing water, small solutes, and some larger molecules to pass between the cells

Question 6

Signal transduction

Answer 6

The linkage of a mechanical, chemical, or electromagnetic stimulus to a specific cellular response

Question 7

Signal transduction pathway

Answer 7

A series of steps linking a mechanical, electrical, or chemical stimulus to a specific cellular response