Cell Membrane Flashcards
Lipid-based structure that separates aqueous
interior of a cell from the aqueous environment surrounding the cell
Cell Membrane
Fatty acids = ____; Phosphate or sugar group = ____
tails; head
Up to ___ of plasma membrane is lipid material
80%
The membranes are lipid ____ made up of
phospholipids
bilayers
Lipid bilayer: Nonpolar tails of phospholipids are in the middle and polar heads are on the surface
■ ____ nanometers thick
■ Contains at least ___ unsaturated fatty acid
6 to 9
one
Cholesterol molecules are also components of plasma membranes. Cholesterol helps regulate membrane ____ –the
fused-ring system does not allow rotation of fatty acid tails in the vicinity and it fits between _____ of the lipid bilayer
fluidity; fatty acid chain
Lipid bilayers also contain proteins
○ Responsible for moving substances such as nutrients and electrolytes across the membrane
○ Act as receptors that bind hormones and neurotransmitters
The membrane proteins and some lipids further react with carbohydrate molecules
Act as markers, substances that play roles in processes by which different cells recognize each other
Membrane proteins can be differentiated into two types of protein
Integral Protein
Peripheral Protein
Penetrates in the lipid bilayer structure, can be complete penetration or partial penetration.
Integral membrane proteins
Integral membrane protein extends across the lipid bilayer
Complete Penetration
Integral membrane protein embedded in one side of the lipid bilayer
Partial penetration
Proteins only found on the surface of lipid bilayer structure
Peripheral Proteins
Proteins embedded with carbohydrate markers
Glycoproteins
Three types of transport
Passive transport
Facilitated transport
Active transport
Process in which a substance moves across a cell membrane by diffusion from a region of higher concentration to a region of lower concentration
Passive Transport
additional info - No cellular energy expenditure
Only a few types of molecules, including O2, N2, urea, and ethanol, can cross membranes by this process
Process in which a substance moves across a cell membrane, with the aid of a membrane protein, from a region of higher concentration to a region of lower concentration
Facilitated Transport
Additional info - No cellular energy expenditure
Specific protein carriers or transporters are involved in the process
Driving Force in Passive Transport
Concentration gradient - movement is from high concentration to low concentration
What type of molecules undergo passive transport
Small organic molecules
Some relatively large molecules can pass if they are lipid soluble
Transport used for polar molecules; Also follows concentration gradient but protein channel is used.
Facilitated Transport
Process in which a substance moves across a cell membrane, with the aid of membrane proteins, against a concentration gradient
Active Transport
additional info - ○ Involves expenditure of cellular energy (Supplied by ATP molecules)
Proteins involved in active transport are called “pumps”
Carrier in active transport can be called as ___
Pumps
