BSCI330 plasma membrane and plant cell wall Flashcards
what is the plasma membrane composed of
phospholipids and sterols
what is the basic structure of cellular membranes
bilayers, which are spontaneously formed by phospholipids
what are lipid bilayers
2D fluids that allow the lateral diffusion of molecules within bounds of membrane
what is the polarity of the plasma membrane
amphipathic (polar head group interacts with water, hydrocarbon tail doesn’t)
what are the two major sterols
in animal cells - cholesterol
in plant cells - phytosterols
in fungi - ergosterol
what orients a sterol molecule
polar head group
which sterol is used for antifungal drugs
ergosterol (the pores allow ions and water to move across and kill the bad cell or block fungal cell growth, causing them to die)
why can phospholipids self-assemble into lipid bilayer membranes
amphipathic nature - polar heads on outside, hydrocarbon tails on inside
what does the fluid mosaic model of cell membrane mean
molecules of substance can diffuse past each other
+
not a continuous surface - has various neighborhoods (microdomains) of different compositions
what is the charge gradient in the cell membrane
inside the cell is more negatively charged than outside surface (this is asymmetry of leaflets)
what are some functions of the membrane
ability to move molecules, to transmit signals, to connect plasma membrane to interior cytoskeleton, to interact with extracellular matrix
what does integral vs peripheral proteins mean
integral is inserted into membrane interior
peripheral is bound to surface of membrane but doesn’t insert into membrane
what is the plant cell wall
a carbohydrate matrix surrounding the plant cell, distinct from the plasma membrane
what is a major component of the plant cell wall
cellulose, which provides tensile strength (resistance to stretching)
how is cellulose resistant to compression
cellulose microfibrils are interwoven with pectin that provides resistance to compression
