Starch: Amylose vs. Amylopectin

Lab Manual 1.Microscopes and Plant Cells Lab

1.25.12

Pre-Lab Quiz1. Say your oculars have a 10x magnification. If you

are looking at a specimen using the 40x objective, what is your total magnification?

2. What is the name of the moveable structure to which the objectives are attached?

3. What do the leucoplasts found in potatoes store? 4. What is the special name for these storage

structures? 5. How do some plants cope with the build up of

toxic substances?

The Compound Microscope

• Always carry microscopes with 2 hands: one at the base, one at the arm

• Demo of microscope parts• Always make sure you’re on the lowest

objective when mounting or removing slides

• Wipe up spills immediately so you don’t destroy the lenses

Outline for today’s lab:• The letter E• Cork cells- cell wall • Onion- cell wall, nucleus, nucleoli, cytoplasm,

vacuoles... Add IKI if necessary• Elodea leaf- cell wall, cytoplasm, nucleus,

chloroplasts, vacuole (tonoplast)... Add NaCl if you want to see plasmolysis.

• Potato tuber- leucoplasts (amyloplasts), intercellular spaces

• Red pepper- chromoplasts• Zebrina- raphides• Begonia- druses

The “e” Exercise: Dissecting vs. Compound Microscope

“Depth of Field”

x

z

y

How thick of a slice can I get in focus at once?

Lower magnification

x

z

y

Higher magnification

Representative Plant Cell

Cork cell walls

100x

Onion and IKI

IKI (Lugol’s solution) should turn black in the presence of starches. It should help you distinguish between some of the different cellular compartments.

Elodea and PlasmolysisWaterweed (Elodea densa) a submersed South American aquarium plant that is naturalized in ponds, streams and lakes throughout North America. The cartoon cell to the left shows a living photosynthetic cell. Because most of the cell is occupied by a water-filled, large central vacuole, the chloroplasts are displaced around the periphery of the cell, just inside the cell wall and membrane. The cell on the right has shrunken away from the cell wall (plasmolysis) due to water loss caused by disruption of its osmotic balance.

Potato tuber

Red Pepper

Different Plastids in PlantsPrecursor of all plastids

Protein-modifying compounds

Site of photosynthesis

Synthesize and store pigments

Starch storage Fat storage

Monoterpenesynthesis; precursor to other plastids

Chloroplasts not yet exposed to light

Zebrina Raphides

Begonia

Begonia Druses

Begin lab exercises!