topic 4 Flashcards
explain fluid characteristic of a membrane
1) Phospholipids move independently within/between bilayer
2) Held together through hydrophobic interactions between fatty acid tails
explain mosaic characteristic of a membrane
Mixture of different embedded protein molecules
Phospholipid
Glycerol + 2 fatty acid tails + Phosphate group
Amphipathic
Both hydrophobic and hydrophilic
Characteristics of membrane [5]
1) Fluid
2) Mosaic
3) Phospholipid bilayer
4) Embedded proteins + components
5) Semi-permeable
How does the chemical bonding of FA influences its properties
If FAs are saturated = all single bonds = high density = less fluid
If FAs are unsaturated = same double bonds = low density = more fluid
Functions of embedded proteins [6]
1) Support
2) Transport
3) Receptors for hormones
4) Cell adhesion
5) Antigen markers
6) Enzymes catalyzing reactions in bilayer
Common components in cell membrane [5]
1) Protein
2) Glycoprotein
3) Glycolipid
4) Phospholipid
5) Cholesterol
transmembrane
spans entirely from external to internal
Peripheral
On the sides
Integral
Inside
Active transport [4]
1) From area of lower concentration to higher concentration
2) Against concentration gradient
3) Requires ATP energy
4) Requires typically protein carriers
Why active transport [2]
1) Some raw materials need to be accumulated outside before entering cell
2) Waste products exported out
Ion pumps to maintain membrane potential (K-Na Pumps)
Sodium-potassium pump
Maintaining Membrane potential
A constant flow of Na+ via facilitate diffusion
Need to overcome this excess positive charge
NA/J pumps 3xNa+ out (Against conc grad) and pumps 2xK+ in
exchange create overall negative charge inside cell
Bulk transport
Movement of large quantities of molecules
2 types of bulk transport
Endocytosis
Exocytosis
Endocytosis
Into the cell:
Membrane engulfs
Inward fold
Invaginates
2 types:
Phagocytosis (Solds)
Pinocytosis (Liquid)
Phagocytosis
Form phagocytosed ball (Phagosome)
Combine with lysosome (Phagolysosome)
Enzymes break down foreign substance
