FGCU Palmtag Bio 1 Chapter 7 Study Guide
What is a plasma membrane? Name and describe the components of a phospholipid bilayer. How do phospholipids form the bilayer? In what kind of solvent does this occur, and why?
2 layers- head: choline, phosphate, glycerol (hydrophilic-loves water) tail: fatty acid (hydrophobic-hates water) Heads are pointed out and tails pointed in.
What is a phospholipid? What chemical properties of the phospholipid are important to a cell membrane (plasma membrane)? Why are they called amphipathic?
A lipid made up of glycerol joined to two fatty acids and a phosphate group. The hydrocarbon chains of the fatty acids act as nonpolar, hydrophobic tails while the rest of the molecule acts as a polar, hydrophilic head. Phospholipids form bilayers that function as biological membranes, such as the cellular membrane.
What is a glycolipid and a glycoprotein? What purpose do they serve on a cell membrane?
Glycolipid- Lipid with carbohydrates covalently attached Glycoprotein- Protein with carbohydrates covalently attached Contributes energy and acts as a marker for cellular recognition.
Compare and contrast how a hyper-, hypo-, and isotonic solution affect an animal and plant cell.
Hypertonic (saltwater): Plant- shrivel (plasmolysized) Animal- Burst Hypotonic (freshwater): Plant- swell (turgid) Animal- Shrivel Isotonic: Plant- flaccid Animal- Normal
What is the purpose of a paramecium's contractile vacuole?
It constantly expels water to combat the constant diffusion of water into the paramecium's cells.
What is meant by selective (differential) permeability? What types of solutes pass easily across the lipid bilayer? Which cross only to a limited extent? Which cannot cross the lipid bilayer at all? Can such solutes enter a cell? If so, how?
Only allows certain materials to pass through, such as nonpolar solutes. Ions are not permeable.
How is an integral protein different than a peripheral protein?
Peripheral proteins are under the phospholipid bilayer, while integral proteins are inscribed in the bilayer. Integral proteins pass entirely through the lipid bilayer of the plasma membrane and have domains that go from the outside of the cell to the cytoplasm inside the cell. While peripheral proteins are only on the one side of the lipid bilayer, either the outside of the cell or the cytoplasmic side inside the cell, but not both.
How are proteins arranged in the cell membrane? What aspect of their structure allows them to be positioned in both hydrophobic and hydrophilic environments? What function do they provide for the cell? Identify the different types of membrane proteins and the function they provide for the cell.
Proteins in the phospholipid bilayer. Head and tail. Import and export cell materials. Passive and active transport
What's the difference between a saturated and an unsaturated lipid? How does this affect bilayer permeability? How does it affect the membrane's fluidity? In what way is the phospholipid bilayer "fluid" ? What is cholesterol and what affect does it have on a membrane?
Saturated lipids are solid at room temp and have at least one double bond creating a 120 degree kink, unlike unsaturated lipids. Cholesterol is a lipid that fills in the spaces left by kinks in the unsaturated hydrocarbon tails of neighboring phospholipids.
State the principle that determines how a substance diffuses. What is osmosis? How is osmosis different from diffusion, how is it similar? Describe the terms: diffusion, osmosis, concentration gradient, and equilibrium. In what direction does net movement of water occur when a cell is placed in a hypertonic, isotonic, or hypotonic solution?
Substances diffuse from high to low concentration. Osmosis is exclusively the movement of water, diffusion includes all other substances. Hypertonic- cell loses water Hypotonic- takes up water Isotonic- No effect
Why do cells need to move substances through their membrane?
Their existence relies on the removal of waste.
