Review Material for Chemistry and Biology


Ions

Are elements/molecules with an a different number of electrons than protons. This imbalance in charge results in the element/molecule having an electrical charge.

Similar electrical charges (2 positive (+) charges for example) repel each other.

Different electrical charges (a positive (+) and a negative (-) charge) attract each other.

Ions are important because the allow the nervous system and the muscular system to function.
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Isotopes

Are elements with differing numbers of neutrons. This will change the atomic mass of the element but not its chemical function.

Isotopes are frequently used in medicine to help visualize the inside of the body (during CAT scans, and X-Rays).
3 Isotopes of Hydrogen - the only change is the different amounts of neutrons (black circles)
3 Isotopes of Hydrogen - the only change is the different amounts of neutrons (black circles)


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Passive Transport

is the tendency for substances to move down their concentration gradients. This means a salt cube placed in water will dissolve. This occurs because the salt molecules move from where they have a high concentration, in the salt cube to where they have a low concentration, in the water.

A Demonstration of Diffusion

Passive Transport allows substances like water, sugar and oxygen to move in and out of cells in the body.

When you compare the solute concentration of two different solvents there are three situation that arise:

Isotonic

Two solutions having the same solute concentration are said to be isotonic (iso = same). There is no net passive transport in this situation because there is no difference in solute concentration.

Isotonic Solutions
Isotonic Solutions

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Hypertonic

One solution has a greater solute concentration than the other.In the picture below there is more solute (green circles) outside the orange cell than inside. The outside solution is hypertonic to the inside solution. Due to this the water concentration inside the cell is greater than outside and the water tends to passively transport out of the cell.

This orange cell is in a hypertonic solution
This orange cell is in a hypertonic solution


http://www.phschool.com/science/biology_place/biocoach/images/biomembrane1/Hyper.gif

Hypotonic

One solution has a lesser solute concentration than the other.In the picture below there is less solute molecules outside the orange cell than inside. The outside solution is hypotonic to the inside solution. Due to this the water concentration outside the cell is greater than the inside and the water tends to passively transport into the cell.

There are few solute molecules outside the cell. The cell is said to be in a hypotonic solution
There are few solute molecules outside the cell. The cell is said to be in a hypotonic solution

http://www.phschool.com/science/biology_place/biocoach/images/biomembrane1/Hypot.gif

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Cell Parts

Cell Membrane: Outside flexible covering of a cell. Its primary function is to control which substances move in and out of the cell.

Nucleus: Found in many cells of the body (although mature Red Blood Cells have no nucleus and striated muscle cells have dozens of nuclei). Contains chromosomes made up of DNA.

DNA: Instructions for building proteins are found in DNA. Proteins will be the structure for cell and tissue parts (like collagen in skin). Proteins can also speed up chemical reactions. These proteins are known as enzymes.

Chromosomes: Huge structures that contain the DNA of the cell.

Cytosol: All the liquid inside of the cell. The majority of chemical reactions occur here, and most of the 'decisions' of the cell occur in the cytoplasm.

Mitosis and Cancer

Mitosis is asexual cell division. Your body undergoes mitosis for both growth and to repair/maintain tissues.

Cancer is a malfunction of mitosis and the cell cycle where the cancerous cells continue to undergo mitosis repeatedly when they should not. In malignant cancer, this growth consumes energy and crowds out healthy cells. If left long enough without treatment, a malignant cancer will seed new cancer tumors in different areas of the body, eventually the damage will lead to an inability to maintain homeostasis and death will occur.