CellStructureandorganellespart2.pptx (1)

(Chapter 7- Section 2)
(part 2)
-When thinking about how cells move materials in and out, it
can be helpful to think of a cell as a country. The boundaries of
a country are its borders, and nearly every country tries to
regulate and control the goods that move across those
Cells have their own borders, which separate the cell from its
surroundings and also determine what comes in and what
goes out.
How can a cell separate itself from its environment and still
allow material to enter and leave? By the cell membrane
Cell Membrane
• Regulates what enters and leaves the cell (cell membrane is
selectively permeable or semipermeable, this meaning
some substances can pass across them and others cannot)
• Provides protection and support
Structure: Fluid Mosaic Model. It consists of:
1. Phospholipid bilayer – two layers of phospholipids (having
hydrophilic phosphate heads and hydrophobic lipid tails)
2. Proteins run through the layers (Some proteins form
channels and pumps that move material across the cell
3. Carbohydrates are attached to some of the proteins
(carbohydrates act like I.d. cards, allowing cells to identify
one another)
The Cell Theory:
Cell theory has three parts:
1. All living things are made of one or more cells.
2. Cells are the basic units of structure and function in
3. All cells arise from existing cells.