Experiment 1: Biochemistry Laboratory Experiments on Cells and Solutions

Cell

The fundamental unit of life.

Protoplasm

The substance contained within a cell, subdivided into various components.

Nucleus

An important part of the cell that contains genetic material.

Cytoplasm

The gel-like substance within the cell membrane, excluding the nucleus.

Plasma Membrane

Gives mechanical strength, shape, and some protection to the cell.

Dialysis

A process involving the diffusion of solutes through a semipermeable membrane.

Diffusion

The net movement of a particular substance from a region of higher concentration to a region of lower concentration.

Osmosis

The movement of water from the solution with the free osmotically active particles to the solution with fewer particles.

Osmotic Concentration

The number of osmotically active particles contained per unit volume.

Osmotic Pressure

The pressure required to stop the movement of water through a semipermeable membrane due to osmosis.

Weight Percent Change

Calculated using the formula % change = (Final weight - Initial weight) / Initial weight × 100.

Hypertonic

High concentration outside the cell which causes the cell to shrink due to the solute outside absorbing the solute inside.

Hypotonic

Lower concentration outside the cell, which causes the cell to swell or burst due to overabsorption of the solute.

Surface Tension

The property of the surface of a liquid that allows it to resist an external force.

2% Saline Solution

A solution containing 2% sodium chloride in water.

4% Saline Solution

A solution containing 4% sodium chloride in water.

8% Saline Solution

A solution containing 8% sodium chloride in water.

Distilled Water

Water that has been purified by distillation.

Potassium Permanganate

A chemical compound used in the experiment to observe diffusion.

Cellophane

A thin, transparent film used in the dialysis experiment.

Buret Clamp

A device used to hold the cellophane containing the mixture in place during the dialysis experiment.

Silver Nitrate Solution

A chemical used to test for the presence of chloride ions in the dialysate.

Iodine Solution

A chemical used to test for the presence of starch in the dialysate.

Dialysis

It is the diffusion of solute molecules across a differentially permeable membrane.

Surface Tension

It is the elastic-like force on the surface of a liquid caused by the attraction (cohesion) between the liquid's molecules, especially at the surface.

Plant Cells vs Animal Cells

Animal cells don't have a cell wall, chloroplasts, and vacuoles. Plant cells don't have lysosomes and centrioles.

Dialysate Reaction with Silver Nitrate

Because the Chlorine anion in dialyzate reacts and forms a white precipitate of silver nitrate. This means the chlorine anion is small enough to pass through the dialysis membrane unlike with iodine which either has big or no starch.

Effect of Soaps on Surface Tension

Due to soap's amphiphilic nature it breaks the strong hydrogen bond with water allowing water to mix with oil thus reducing oils surface tension.

Kidney Function

Homeostasis and Filtering.

Hypotonic Environment Effect

Hypotonic = Swells.

Isotonic Environment Effect

Isotonic = As is.

Osmosis

The level of solution liquid inside the thistle tube rose.

Chloroform and Water Mixing Time

119 seconds (Already mixes quickly).

Linseed Oil and Water Mixing Time

80 seconds (Oil remains separate or quickly separates).

Linseed Oil with Soap Mixing Result

Did not separate (Forms stable emulsion, drops take longer to coalesce).

Chloroform with Soap Mixing Result

Chloroform has low surface tension and partial miscibility with water, so soap has minimal effect.

Presence of Starch in Dialysate

No starch is present in the dialyzate, indicating that starch did not pass through the membrane due to its large molecular size.

Color Change with Iodine Solution

No color change indicates that starch did not pass through the membrane.

Amphiphilic Nature of Soap

Hydrophilic part (H2O): Water-loving; Hydrophobic part (Oil): Water-hating.

Trial 1 Diffusion Time

5 minutes 15 seconds.

Trial 2 Diffusion Time

5 minutes and 16 seconds.

Soap as Surfactant

SOAP = SURFACTANT.

Chloroplast Presence in Cells

Plant cells have chloroplasts.

Cell Shape Difference

Plant cells are rectangular; animal cells are round/irregular shaped.