Module 5.1 Cell Membranes Flashcards
What is the difference between cell membrane and plasma membrane?
Plasma membrane is the membrane surrounding a cell; cell membrane includes the plasma membrane and internal membranes.
Plasma membrane
is the membrane surrounding a cell
Cell membrane
the plasma membrane and the internal membranes as well
All cells have a
plasma membrane
What is the major function of the plasma membrane?
To separate outside from inside the cell.
What is the plasma membrane’s permeability?
Semi-permeable/selectively permeable.
What types of molecules can enter the cell through the plasma membrane?
- Glucose
- Water
- Oxygen
What types of waste molecules leave the cell?
- Carbon dioxide
What is the Fluid Mosaic Model?
A model describing membranes as a combination of phospholipids and proteins arranged in a bilayer.
All membranes are a combination of
phospholipids arranged in the bilayer
What components are found in the phospholipid bilayer?
- Hydrophilic heads
- Hydrophobic tails
What do hydrophilic heads and hydrophobic tails represent in phospholipids?
Heads are made of glycerol and phosphate; tails are 2 hydrophobic fatty acids.
How do phospholipids arrange in the bilayer?
Hydrophilic heads face the water outside and inside the cell; hydrophobic tails form an oily middle.
What is the fluid part of the Fluid Mosaic Model?
Phospholipids can move laterally in their own half of the bilayer.
True or False: Phospholipids can flip flop from one half of the bilayer to another.
False.
What is the permeability of the phospholipid bilayer?
Impermeable to most molecules.
What types of molecules can pass through the phospholipid bilayer?
- Small uncharged molecules (e.g., O2, CO2)
- Hydrophobic molecules (e.g., triglycerides)
What role does cholesterol play in animal cell membranes?
Cholesterol stiffens animal membranes and provides strength and flexibility.
Why do plants not require cholesterol in their membranes?
Plants have a rigid cell wall surrounding their plasma membranes.
What function do carbohydrates serve on the surface of cells?
Act as cell ‘nametags’ for immune system recognition.
How does the immune system respond to ‘unfriendly’ cells?
The immune system usually attacks them.
What are blood groups an example of?
Carbohydrate nametags.
What is the role of proteins in membranes?
Proteins serve various functions, including transportation and signaling.
What are transport proteins?
Proteins that allow molecules to enter or exit the cell.
What is the function of channel proteins?
Form a channel for specific molecules to enter the cell.
How do channel proteins ensure specificity?
They have gates that open only at a signal.
What are carrier proteins?
Proteins that transport specific molecules across the membrane.
What happens to carrier proteins when a specific molecule enters?
They change shape to release the molecule on the other side.
What is the role of receptor proteins?
Receive chemical signals that cause changes inside the cell.
