Chemistry (4th Period) / Biology (5th Period)

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"Today, we will begin studying gases and gas laws. One such law is known as Boyle's Law.

"Air is a gas. Gases have various properties which we can observe with our senses, including the gas pressure, temperature, mass, and the volume which contains the gas. Careful, scientific observation has determined that these variables are related to one another, and the values of these properties determine the state of the gas.

"In the mid 1600's, Robert Boyle studied the relationship between the pressure p and the volume V of a confined gas held at a constant temperature. Boyle observed that the product of the pressure and volume are observed to be nearly constant. The product of pressure and volume is exactly a constant for an ideal gas.

p * V = constant

"This relationship between pressure and volume is called Boyle's Law in his honor. For example, suppose we have a theoretical gas confined in a jar with a piston at the top. The initial state of the gas has a volume equal to 4.0 cubic meters and the pressure is 1.0 kilopascal. With the temperature and number of moles held constant, weights are slowly added to the top of the piston to increase the pressure. When the pressure is 1.33 kilopascals the volume decreases to 3.0 cubic meters. The product of pressure and volume remains a constant (4 x 1.0 = 3 x 1.33333 ).

Homework: Look up another gas law and explain its significance with regards to Boyle's Law.




"Now, today we will begin discussing one of the fundamental structures of life: the cell.

"There are two types of cells: eucaryotic and prokaryotic cells.

"Eucaryotic cells are the basic structural motif of multicelled organisms. That is, you, me, anteaters, palm trees, rose bushes, poison ivy, etc. are all multicelled organisms. Because multicelled are highly visible (i.e., they have so damn many cells you can actually see them with unaided eyes) and since we are multicelled organisms, the biology of multicelled organisms is disproportionally represented in introductory biology texts. Nevertheless, the majority of evolutionary diversity is not found among eucaryotes.

"Cells that lack a membrane-bound nucleus are called prokaryotes (from the Greek meaning before nuclei). These cells have few internal structures that are distinguishable under a microscope. Cells in the monera kingdom such as bacteria and cyanobacteria (also known as blue-green algae) are prokaryotes.

"Prokaryotic cells differ significantly from eukaryotic cells. They don't have a membrane-bound nucleus and instead of having chromosomal DNA, their genetic information is in a circular loop called a plasmid. Bacterial cells are very small, roughly the size of an animal mitochondrion (about 1-2µm in diameter and 10 µm long). Prokaryotic cells feature three major shapes: rod shaped, spherical, and spiral. Instead of going through elaborate replication processes like eukaryotes, bacterial cells divide by binary fission."

Lab work: Using the materials I've set out, create either form of a cell.

Quiz: Betcha thought I'd forgotten. Please complete it before you leave.

"And, Isobel, would it be possible for you to switch to the first section of biology, considering that you're the only one enrolled in this one?" Ms. Sidle smiles slightly at this.