Module 5.1 Cell Membranes Flashcards
Every cell has a
cell membrane
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 (bacteria, plant, animal, ancient cells) have a
plasma membrane
Human/animal cells typically only have a cell membrane and not a
cell wall
What is the major function of the plasma membrane?
To separate outside from inside the cell.
The plasma membrane is a protective
wall or fence that goes around the entire cell
Plasma membranes regulate
Plasma membranes regulate
Plasma membranes are an important part of the definition of the
Cell Theory
What is the plasma membrane’s permeability?
Semi-permeable/selectively permeable.
What types of molecules can enter the cell through the plasma membrane?
- Glucose (needs active transport)
- Water
- Oxygen
What types of waste molecules leave the cell?
- Carbon dioxide
What is the Fluid Mosaic Model?
The structure of a cell membranes as a mosaic (art) of compounds. A combination of phospholipids and proteins (and others) arranged in a bilayer that gives it a fluid character.
All membranes are a combination of
phospholipids arranged in the bilayer
What components are found in the phospholipid bilayer?
- Hydrophilic heads
- Hydrophobic tails
What are phospholipid heads made of?
The hydrophilic heads are made of glycerol and phosphate
What are phospholipid tails made of?
2 hydrophobic fatty acids that may be saturated or unsaturated
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. They can go side to side
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. They are semipermeable
What types of molecules can pass through the phospholipid bilayer? ***** slide 15
- Small uncharged polar molecules (O2, CO2, n2, h20, glycerol, ethanol, urea)
- Small hydrophobic molecules (O2, CO2, N2, triglycerides)
What needs help passing through the bilayer? What needs active transport?
- Large polar molecules (glucose, sucrose)
- Hydrophilic ions
- Ions (charged molecules)
Animal cells also have what in the bilayer of the plasma membrane?
Cholesterol.
Cholesterol helps with what
It helps with the cell rigidity, flexibility, stiffness and strength of that cell membrane.
Human cells also have what associated with the outside of the plasma membranes?
Carbohydrates
What role does cholesterol play in animal cell membranes?
Cholesterol stiffens animal membranes (especially at temperature extremes) and provides strength and flexibility.
Cholesterol is about the size of the
fatty acid tail. (remember 4 fused rings)
Being a lipid, cholesterol will insert into the what?
Middle of the membrane
Why do plants not require cholesterol in their membranes?
Plants have a rigid cell wall surrounding their plasma membranes and so they don’t need the strengthening of cholesterol
If a package is labeled “No cholesterol”, it is less likely to contain
Animal matter
Carbohydrates stick out of the
phospholipid bilayer
What function do carbohydrates serve on the surface of cells?
Act as cell ‘nametags’ for immune system recognition.
True or false: Every cell in your body has a name tag
True
Carbohydrates recognize whether a cell is
friendly or foe
If the cell is “friendly”, the immune system will
leave alone
How does the immune system respond to ‘unfriendly’ cells?
The immune system usually attacks them.
If you cut your finger and introduce bacteria, the body will recognize the bacteria
unfriendly. It will attack and destroy
Sometimes the body gets too vigilant and will think the pollen we breathe in is
unfriendly and vigorously attacks it
What are the 4 blood groups
Group A, Group B, Group AB, Group O
Our red blood cells have
Antigens and antibodies in plasma
Antigens are
carbohydrate markers
Group A has which antigen
A antigen
Group A has which antibodies in plasma?
Anti-B
Group O has which antibodies in plasma?
Anti-A and Anti-B
Which blood group has no antigens
Group O
Which blood group does no have antibodies in plasma?
Group AB
What are blood groups an example of?
Carbohydrate nametags.
Where are proteins found on a membrane?
In the membrane or attached to them
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. They are like the doorway to the building
What is the function of channel proteins?
Form a channel for specific molecules to enter the cell.
Channel proteins have
They have gates that open only at a signal.
Channel proteins will only accept molecules of a given
size/proper fit/shape
The channel is protected by
a gate that will 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.
Some carrier proteins require what to transport?
ATP
What is the role of receptor proteins?
Receive chemical signals that cause changes inside the cell.
Receptor proteins receive a
chemical signal from outside that will cause a shape-change in the membrane protein
A shape change in the membrane protein causes
other changes inside the cell
9 times out of 10 receptor based transport is mostely
hormones coming in or out
Many hormones work by binding to
receptor proteins on target cells
