Cells Flashcards
What is the typical thickness of the cell membrane?
7-10 nanometers
List some key functions of the cell membrane.
*A selective barrier to the passage of substances
* Detect chemical signals from other cells
* Make intercellular communication
What is the general composition of the cell membrane?
55% proteins
25% phospholipids
13% cholesterol
4% other lipids
3% carbohydrate
What does “More active, more protein” refer to in the context of the cell membrane?
Membranes with higher levels of activity tend to have a higher percentage of protein
What is the fundamental structure of the cell membrane?
Lipid bilayer
What model describes the arrangement of components in the cell membrane?
Fluid mosaic model
What are the main components of the lipid bilayer?
Phospholipids (forming the bilayer), proteins (integral and peripheral), and carbohydrates (attached to lipids and proteins on the extracellular side).
What are the two main types of membrane proteins?
Integral and Peripheral proteins
Describe Integral membrane proteins
Amphipathic which means they have both hydrophobic and hydrophilic regions.
Describe peripheral membrane proteins
Not amphipathic
Functions of integral proteins?
function as carriers, channels, or ion pumps.
Functions of peripheral membrane proteins
function as enzymes or controllers of intracellular function
What are membrane carbohydrates and what does it form?
They are carbohydrates associated with the cell membrane.
They form Glycoproteins (carbohydrates attached to proteins) and Glycolipids (carbohydrates attached to lipids)
Which together make up the glycocalyx
What is the function of glycocalyx?
Enables cells to identify and interact with each other.
What are the types of transport for small molecules?
Simple diffusion and protein-mediated transport (facilitated diffusion via ion channels or carriers).
What are the types of transport for big molecules?
Endocytosis and exocytosis.
These processes require ATP
What is simple diffusion?
Movement of lipid and water soluble molecules from high to low concentration without energy or chemical transport mechanisms.
What molecules move by simple diffusion?
Oxygen,CO₂, fatty acids, water, alcohol, urea, glycerine , steroid hormones.
What factors increase the rate of simple diffusion? Or
What are the factors that affect flux?
•Increased concentration difference
• Increased temperature
• Increased surface area
• Increased lipid solubility (nonpolar molecules)
What factor decreases the rate of simple diffusion?
Increased mass of the molecule
What type of molecules and ions use protein-mediated transport?
Slightly large polar molecules like amino acids & electrical charged ions
Name two types of passive transport that utilize protein-mediated transport.
Facilitated diffusion (via ion channel)
Facilitated diffusion (via carrier)
What is the energy requirement for facilitated diffusion?
Energy is required
concentration gradient of the transported substance is the energy source.
What assists in the movement of substances during facilitated diffusion?
specific membrane protein: carrier or channel.
