Cell Transport 3.4, 3.5 29 September 2014

Homeostasis: maintaining a constant internal environment despite changes in the external environment by compensating for disruptions. An organism is homeostasis is in proper balance.

When you are “out of balance” your cells do things to compensate for the imbalance. Example: You are dehydrated because you haven’t consumed water in over 24 hours.

You’re kidneys respond by retaining MORE water (you urinate less) You’re kidneys respond by retaining MORE water (you urinate less). His helps to restore balance.

Example: However, when you have too much water such as after drinking lots of water, your kidneys retain LESS water to maintain balance.

Passive transport: when molecules move across cell membrane without needing cell energy (ATP). Diffusion and osmosis are passive transport types.

Diffusion –molecules move from areas of high concentration to areas of low concentration. Concentration is amount of “stuff” per volume.

Concentration gradient is the difference in concentration from one area to another. Things spontaneously move DOWN a concentration gradient.

Osmosis : the diffusion of water across the cell membrane.

Which has the higher concentration of water? 10 grams of sugar in 50 mL of water. 20 grams of sugar in 50 mL of water.

Hyper means “above”. Hyperactive Hyperdrive

Hypo means “below”. Hypothermia Therma means “heat”.

Iso means “equal”. Isosceles Triangle

A hypertonic solution – higher solute concentration than cell A hypertonic solution – higher solute concentration than cell. Water leaves cell.

A hypotonic solution – lower solute concentration than cell A hypotonic solution – lower solute concentration than cell. Water enters cell.

A isotonic solution – same solute concentration than cell A isotonic solution – same solute concentration than cell. No significant flow of water across cell membrane.

facilitated diffusion – diffusion of molecules across the cell membrane through transport proteins. Facilitate means “to support” or “make easier”

Active transport– molecule movement from low to high concentration Active transport– molecule movement from low to high concentration. Requires energy ATP. ATP = Adenosine TriPhosphate (Ahdin-O-seen Tryfossfate)

Endocytosis – taking things into the cell by engulfing them into a membrane. Endo means “within”.

Phagocytosis – taking large materials into the cell by engulfing them into a membrane. Destroys foreign pathogens. Involved in cell immunity. Phago means “to eat”. Cyto means “cell”.

Exocytosis – fusion of a vesicle with cell membrane to carry materials out of cell. Exo means “outside”, i.e. EXIT, EXTERNAL, etc.