Lab: Cells and Tissues

Would you ever find functional plastids inside the vacuole?

no, bc

1) the vacuole only stores sugars, proteins, ions, and anthocyanins

2) digests and recycles old organelles

What are the two other organelles that are cytoplasmically streaming, but too small to see with a microscrope?

mitochrondia and golgi apparatus

What organelles are stationary?

nucleus and ER

Viruses are larger than plasmodesmata. How do they get through?

Viruses produces viral movement protein that dilates the PD and mimics the cell’s regulators of PD

Why does it make sense that organelles can’t fit through the PD?

PD channels are smaller in size than the organelles. Only specific, smaller molecules can pass btwn adjacent plant cells.

What is cytoplasmic streaming?

the rapid movement of the cytoplasm around the cell

Why is cytoplasmic streaming essential in plant cells?

plant cells are larger than animals cells —> diffusion is not effective in plant cells —> the cells are too large —> cytoplasmic streaming is effective

How does the cytoplasm move in cytoplasmic streaming?

myosin on the chloroplasts binds to the actin filaments in the PD —> myosin slides along the actin filaments —> contracts and releases using ATP —> the force of the organelles movement pulls the cytoplasm along with it

What is plasmolysis?

the shrinking of the vacuole and the pulling of the plasma membrane from the cell wall

What was responsible for plasmolysis of the cell in NaCl?

solutes are higher in the NaCl soln —> water potential is low outside the eloda cell —> water flows out from the vacuole into the NaCl soln

Which elodea cells had the greatest turgor pressure, tap-water, plasmolyzed, distilled water or deplasmolyzed?

• DI water

  • Why? elodea cell had more solutes than the DI water —> water potential in the elodea cell was low —> water flows into the elodea cell —> vacuole fills w/ water —> the vacuole press against the cell wall

In the vascular bundles, xylem is towards the inside. Why?

it stores water —> prevents freezing

In the cross section of a celery, what are the cells clustered just below the epidermis? Why do you find these cells here instead of fibers?

collenchyma —> provides flexibility which prevents damage while the plant is growing

Why is hemp better ecologically to use than synthetic ropes?

1) absorbs and stores lots of CO₂

2) biodegradable

What are the gritty cells in pears? Function?

• stone cells

  • func:

    • anti-predation by breaking the probosci of the insects