THANATOCHEMISTRY

CRYOGENY

Cryogenics: A How-To Manual

• 1) Remove head• 2) Immerse head in

hypertonic glycerol bath

• 3) Place head in liquid nitrogen until ???

• 4) Place head in distilled water

• 5) Enjoy!

Why doesn’t cryogenics work?

TONICITY

• Def: Relative measure of dissolved particles (solute) in the solution surrounding the cell membrane

• Measurement is always compared to interior/cytoplasm of cell

• Water does not have a tonic classification as it is invariably the solvent

PLASMOLYSIS

• DEF: Loss of water and turgor due to placement of cell in HYPERTONIC environment

• Water leaves cell via osmosis, causing vacuole to shrink, or cytoplasm to lose volume (crenation)

CYTOLYSIS

• Def: Cells placed in HYPOTONIC environments may undergo cytolysis/cell rupture as water enters the cell

• Loss of the lipid bilayer ultimate causes cell death

TURGOR

• In plants, the cell wall resists cytolysis in hypotonic environments

• This turgor pressure allows the plant to resist gravity

Lab: Semipermeable Membranes and Osmosis

• Purpose: To analyze the movement of solutes and water across a selectively permeable membrane

• Method: Tracking movement of solutes and water achieved by use of organic indicators and qualitative description of turgor (rigidity of fluid filled container)

Dialysis

• Loss of kidney membrane permeability due to disease or damage requires dialysis

• Wastes are removed from body by passing blood through an artificial cell membrane

Protocol #1

• Fill beaker 2/3rds full with tap water• Add Lugol’s solution until mixture is amber

Protocol #2

• Open wet dialysis tube using fingers and glass rod. Tie one end off with string

• Using seral pipettes fill tube with starch and glucose solutions

• Tie off open end. Do NOT leave space for air• Trim the strings and excess tubing

Protocol #3

• Immerse “cell” in iodine-water bath• Allow to sit for 20 minutes while doing

Protocol #4• After 20 minutes, qualitatively assess color

of bath, cell and turgidity of cell• Retest water with Tes-Tape to check for

presence of Glucose

Protocol #4

• Observe Elodea cells in fresh water (pre-made slide) and sketch

• Make a 2nd slide using one Elodea leaf and a drop of 6% NaCl solution

• Sketch the 2nd slide, noting any changes between the fresh water and salt water

Lab: Semipermeable Membranes and Osmosis

• Purpose: To analyze the movement of solutes and water across a selectively permeable membrane

• Method: Tracking movement of solutes and water achieved by use of organic indicators and qualitative description of turgor (rigidity of fluid filled container)

Protocol #1

• Fill beaker 2/3rds full with tap water• Add Lugol’s solution until mixture is amber• Test water with Tes-Tape to determine if glucose

is present in the bath

Protocol #2

• Open wet dialysis tube using fingers and glass rod. Tie one end off with string

• Using seral pipettes fill tube with starch and glucose solutions

• Tie off open end. Do NOT leave space for air• Trim the strings and excess tubing

Protocol #3

• Immerse “cell” in iodine-water bath• Allow to sit for 20 minutes while doing

Protocol #4• After 20 minutes, qualitatively assess color

of bath, cell and turgidity of cell• Retest water with Tes-Tape to check for

presence of Glucose