Unit 13 - Phospholipid Bilayer

Pen and paper

Take notes and write down any questions.

Cilia surround the outside of the cell

Pairs of microtubule structures

They controls the separation of the chromosome to form two new cells 

Because of the different roles they have

Ribosomes are key to synthesis and packaging of proteins

Waste products are also dissolved before they are taken in by vacuoles or sent out of the cell.

Excellent question and we will cover this over the next few weeks

Cell Membranes (The Phospholipid Bilayer)

•Structure

•Function

•Movement of materials

•Protein channels 

The lipid bilayer acts as a barrier to the passage of molecules and ions into and out of the cell.

However, an important function of the cell membrane is to allow selective passage of certain substances into and out of cells.

Nuclear membranes act as a selective barrier to substances entering and leaving the nucleus

Defines the boundaries for genetic material within the nucleus 

Membranes have the same bio chemical structure

Composed of a double layer of phospholipid molecules, protein, cholesterol and sometimes sugars

The double layer is often called a bilayer due to the arrangement of the molecules

Phospholipids are not bonded to each other, which makes the double layer fluid

Hydrogen bonding of water holds the 2 layers together

Cholesterol embedded in the membrane makes it stronger, more stable and less fluid

(not part of the phospholipids, just next to them!)

The Phospholipid Bilayer is both dynamic and flexible

Also present are protein molecules on both the inner and outer surfaces

Some pass all the way through the membrane and act as channels for substances moving in and out of cells or passing on messages

Sometimes sugar chains attach (Glycolipids & Glycoproteins) and are also present with proteins to enable cells to stick together and form tissues 

Watch the video sent in the chat (0 to 4 minutes 38 seconds)

Describe in your own words how the bilayer works include the following 

•Polar Heads

•Fatty acid tails

•Hydrophobic & Hydrophilic Labels

•Cholesterol

•Protein Channels 

https://www.khanacademy.org/science/high-school-biology/hs-cells/hs-the-cell-membrane/a/structure-of-the-plasma-membrane

https://chem.libretexts.org/Courses/University_of_Kentucky/UK%3A_CHE_103_-_Chemistry_for_Allied_Health_(Soult)/Chapters/Chapter_14%3A_Biological_Molecules/14.3%3A_Phospholipids_in_Cell_Membranes#:~:text=Phospholipid%20bilayers%20are%20critical%20components,into%20and%20out%20of%20cells.

https://www.khanacademy.org/test-prep/mcat/cells/cell-membrane-overview/a/fluid-mosaic-model-cell-membranes-article