Module 7 Applied

Question 1

Cytoplasmic Streaming [def]

Answer 1

[def] the directed flow of cytosol and organelles around cells

a) prevalent in plant cells
b) aids in delivery of nutrients and other materials to all parts of the cell

Question 2

What structural entity is involved with cytoplasmic streaming?

Answer 2

Actin filament bundles in longitudinal sections

Question 3

What did the study involving DMSO and Cytochalasin demonstrate? How was it conducted?

Answer 3

a) Fluorescence microscopy
b) Control Group - DMSO
c) Experiment - Cytochalasin (can bind to actin filaments and block polymerization)
d) Result - when cytochalasin was present, cytoplasmic streaming is reduced, demonstrating the importance of actin filaments

Question 4

How are myosin motor proteins involved in cytoplasmic streaming?

Answer 4

They actively move along actin filaments using the hydrolysis of ATP, streaming the cytoplasm

Question 5

T or F: Myosin XI and V have similar morphology

Answer 5

True - they both have a head (motor) domain, neck region, rod region, and globular tail domain

Question 6

Rank the velocity of human myosin V, algae myosin XI, and higher plant order myosin XI

Answer 6

FASTEST: Myosin XI (algae)
MEDIUM: Myosin XI (higher)
SLOWEST: Myosin V (humans)

Question 7

T or F: In most plants, cytoplasmic streaming is always observed

Answer 7

True

Question 8

What factors can influence cytoplasmic streaming?

Answer 8

a) Irradiation with visible light or chemicals to induce streaming in aquatic plants
b) Light changes ATP availability in plants
c) ATP hydrolysis fuels myosin motors which then reposition chloroplasts (cytoplasmic streaming)