chapter 8

CHAPTER 8

I. Diffusion and OsmosisA. Process by which molecules spread from areas of high concentration to areas of low concentration

1.When molecules are even throughout a space it’s called equilibrium2. Concentration gradient- a difference

between concentrations in a space

B. OSMOSIS

1. The movement of water2. Membrane is selectively permeable, meaning it allows some things in and out3. Water and oxygen can move freely across the cell membrane by diffusion4. Water will move in the direction of more solute (or low water concentration)

C. SALT SUCKS!

1. Salt is a solute, when concentrated inside or outside the cell, water will go (be sucked) in the direction of the high salt concentration2. Types of solutions:

a. Isotonic: means same. Concentration of solute is equal on both sides. Water will move back and forth but won’t have a result on either side

b. Hypotonic- means less, less solute outside the cell, salt sucks so water moves into the cell

• Cell gains water & grows larger• In plant cells, central vacuoles fill, cell

becomes stiff & rigid- cell wall keeps cell from bursting• In animal cells, cell may be in danger of

bursting, so contractile vacuoles pump water of the cell

c. Hypertonic means more- more salt molecules outside the cell- water leaves the cell

• In plant cells, the vacuole loses water and the cells shrink, causing wilting• In animal cells, cells shrink• In both cases, cells could die• Dangerous to drink sea water- causes more

dehydration. Salting fields used as war tactic to reduce food supply of enemy

D. ACTIVE TRANSPORT

1. When cells must move materials in an opposite direction - against a concentration gradient.

a. Active transport requires Energy.b. Proteins or Pumps are found in the cell membrane transport molecules across the

membrane. Proteins are used to move sma ll molecules such as calcium, potassium, and sodium ions across the membrane

2. Endocytosis - cell takes in large particles by engulfing them

3.Phagocytosis - "cell eating" - extensions of cytoplasm surround a particle and then the cell engulfs it.

4. Pinocytosis - the process of taking up liquid from the surrounding environment.

5. Exocytosis - cell gets rid of particles, opposite of endocytosis

II. CELL GROWTH

A. Limits to Cell Growth1. Exchanging Materials- hard to get waste out2. Cells are limited in size by their SURFACE AREA and VOLUME ratio

B. CELL DIVISION - Process where a cell splits into two identical daughter cells

1. Mitosis - division of the nucleus2. Cytokinesis - division of the cytoplasm

C. CHROMOSOMES1. Made of DNA a. twisted ladder shape called double helixb. carries the code to make the proteins for specific cell functionsc. base order carries the code -adenine, guanine, cytosine, thymine2. Found in Nucleus3. Number depends on organism

D. CELL CYCLE - events cells go through as they grow and divide

START HERE!

1. Interphase- growth and development phase performing cell functions

a. DNA replicates (copies)b. Organelles double in number, to prepare for division

2. Mitosis- phase of cell cycle where cells divide (reproduce)a. four phases-prophase: chromosomes wind up and become visible-metaphase: chromosomes line up in the middle of the cell (at the equator)-anaphase- spindle fibers pull chromosomes away from middle, to opposite poles

-telophase- two nuclei are visible, nuclear membrane forms around each group of chromosomes, chromosomes unwind- during this phase, cytokinesis takes place: the cytoplasm is “cut” or separated to form two new cells

prophase metaphase

anaphase telophase

3. Cells divide at different rates, depending on the cell typea. Nerve and muscle cells usually stop dividing once developed

b. Skin cells divide frequently as skin is being replaced constantly

4. What Controls Cell Division?a. Cell cycle regulators Internal regulatorsExternal regulators5. When control of the cell cycle fails, cells begin to divide uncontrollably, resulting in masses and failure of the cells to perform their normal functions. This condition is called cancer.

6. Cancer = uncontrolled cell growth• Takes over the cell cycle• Causes can be environmental, genetic, viruses

7. Vaccines against cancer?• Gardasil is a vaccine that protects against HPV and can therefore

protect females from certain kinds of cervical cancer.

Your Opinion: Answer in your notebook• This vaccine must be administered at a young age before sexual

activity. Some states want to require this vaccine for all young girls.

*Do you think the government should require this vaccine?

CANCER RESEARCH ASSIGNMENT

Working in groups of 2 or 3, select one type of cancer you are interested in researching online.

In your science notebooks, tell me the symptoms associated with the type of cancer you selected, how it impacts the body, how it is diagnosed, how it is treated, and whether it is considered life threatening. Each person in the group should write this information in their notebook to receive credit for completing the assignment.