2.2 – Membrane Structure and Functions

Learning Goals Understand the Fluid Mosaic Model and how it relates to cell membranes Be able to explain how Phospholipid Bilayers form in water Determine the functions of membrane proteins

The Fluid Mosaic Model

_________________________________ – states that membrane proteins float freely throughout the ______________________

Membranes are not rigid with molecules locked into place

Membranes contain a mosaic (wide assortment) of proteins

______________________ – a membrane lipid attached to a carbohydrate group

______________________ - a membrane protein attached to a carbohydrate group

Both are involved in cell recognition/interaction

Role of Phospholipids Make up the

________________________________ __________________________________________

form bilayer in water (forms spontaneously) __________________________________________

help to stop membranes from becoming too rigid in cold temperatures and hold membranes together at higher temperatures

Integral Membrane Proteins

Peripheral Membrane Proteins

Role of Membrane Proteins

_____________________– transport substances across the membrane (ones that cannot simply diffuse)

Ex. May move larger amino acids across the membrane

_________________________ – help with cellular respiration/photosynthesis

Ex. ATP Synthase is used to create ATP

_________________________ – bind to chemicals and cause changes within the cell

Ex. Hormones bind to membrane protein causing chemical changes inside the cell

_______________________ – proteins can help anchor parts of the cytoskeleton

Ex. Proteins attach to microtubules

________________________ – allows cells to recognize one another and invading pathogens (diseases)

Ex. Neighboring cells can recognize one another based on specific proteins

Questions

1. What does the word “mosaic” mean in the Fluid Mosaic Model? What does the term “fluid” mean?

2. What is the difference between Glycoproteins and Glycolipids? Why do they both contain the word Glyco?

3. Explain the role of Cholesterol in cell membranes.

4. Explain the function of Proteins, Carbohydrates and Lipids in the cell membrane.

5. Explain the purpose of each of the 5 categories of membrane proteins. Include pictures.