Chapter 7: Membranes

Give two examples of glycolipids...

1. Cerebrosides 2. Gangliosides

Proteins attached to inner surface of plasma membrane are covalently linked to...

1. Fatty acids 2. Prenyl groups (isoprene derivatives)

Membranes contain three classes of proteins. What are they?

1. Integral Membrane proteins 2. Peripheral Proteins 3. Lipid-anchored proteins

Two properties of fatty acids determine membrane fluidity. What are they?

1. Length of fatty acid chains 2. Degree of unsaturated bonds

Prominent lipids in most membranes are:

1. Phospholipids 2. Glycolipids 3. Sterols

Fatty acids range between __ and __ carbons and dictates the usual thickness of membranes which is what?

12 and 20 6-8 nm

Integral membrane proteins are ____________ proteins, possessing one or more hydrophobic regions.

Amphipathic

Some proteins are involved in targeting, sorting, and modifying proteins in the __ and _____ _______?

ER; Golgi complex

______ _____ are components of all membrane lipids. Except for the ________?

Fatty acids; sterols

Name four sugars found in glycoproteins

Galactose (Gal) Mannose (Man) N-acetylglucosamine (GlcNAc) Sialic acid (SiA)

___________: Major lipids on bacterial and fungal cell walls

Glycolipids

___________: prominent in membranes of brain and nerve cells

Glycolipids

Proteins attached to external surface of plasma membrane are covalently linked to...

Glycophosphotidylinositol (GPI), a glycolipid found in external monolayer of plasma membrane

Lipids + Proteins are found in micro domains or _____ _____ which helps with _________?

Lipid Rafts; cell signaling

Sterols are absent in most bacterial cells, except for __________ species?

Mycoplasma

Carbohydrates linked to amino acid side chains do this by...

N of amino group and O of a hydroxyl group

Glycoproteins: _-linked or _-linked glycosylation

N; O

_________ (16 carbons) and ________ (18 carbons) are common saturated fatty acids.

Palmitate; stearate

Most abundant phospholipid found in membranes?

Phosphatidylcholine

Main phospholipid of animal plasma membrane?

Sphingomyelin

__: the temperature when membranes become fluid

TM

Lipid bilayer _______ as a _____ and allows movement of both lipids and proteins.

behaves; fluid

glycoproteins play an important role in ____-____ recognition.

cell cell

Speaking of Sterols; Animal cell membranes have __________? Plant cell membranes have ___________? Fungal cell membranes have _________?

cholesterol; phytosterol; ergosterol

Peripheral Membrane Proteins are bound loosely to membrane surfaces through weak ____________ forces and __________ bonding?

electrostatic; hydrogen

Amphipathic proteins contain hydrophobic regions _______ within membrane? Hydrophilic regions extend out from __________?

embedded; membrane

Some proteins are _________ and particular enzymatic functions are localized to specific __________?

enzymes; membranes

In terms of glycoproteins, attached carbohydrate groups produce on the _________ surface of cell.

external

Membranes also provide attachment to external structures such as ____________ ______ or cell _____?

extracellular matrix; wall

Membranes function properly only in the ______ state?

fluid

Fatty Acids are essential to membrane structure and _________?

function

Peripheral membrane proteins lack discrete ____________ ___________, and do not penetrate into the lipid bilayer

hydrophobic sequences

Some proteins are involved in _____________ communication.

intercellular

The fluid mosaic model is a mosaic of proteins that is embedded in, or at least attached to, a fluid _____ ______?

lipid bilayer

Lipid anchored membrane proteins are present on surface of ______ ________? They're _________ bound to a lipid molecule embedded in the layer.

lipid bilayer; covalently

Membranes are composed of several types of ______?

lipids

The fluid part of the the fluid mosaic model is composed of ______. While the Mosaic part is composed of ________.

lipids; proteins

Most of the glycolipids in the PM are in outer layer and help in establishing ________ ________?

membrane symmetry

An essential feature of every cell is the presence of _________ defining boundaries of cells and internal compartments.

membranes

Sterols are absent in inner membranes of _____________ & ______________?

mitochondria; chloroplasts

______ (one double bond) and ________ (two double bonds) are both 18-carbon unsaturated fatty acids.

oleate; linoleate

However, rotation of _______________ and lateral __________ within the same monolayer are rapid and random.

phospholipids; diffusion

Glycoproteins are most prominent in _______ ___________?

plasma membranes

A fatty acid's long hydrocarbon tail provides a barrier to diffusion of _____ solutes?

polar

Some membrane proteins are ________ proteins and help in signaling across membranes

receptor

Peripheral membrane proteins can be readily ______ from membranes by changing __ or ionic strength.

removed; pH

Some proteins help in stabilizing and _______ the cell membrane.

shaping

Membranes of most eukaryotic cells contain significant amounts of ______?

sterols

Carbohydrate chains attached to glycoproteins are either ______ or ________ chains. Contain _ to __ sugar units.

straight; branched 2 to 60

Membrane fluidity changes with ___________. Every membrane has a specific transition _____________?

temperature

Some membrane proteins are _________ proteins and facilitate movement of nutrients across membranes while others are _______ proteins and provide passage through membranes.

transport; channel

The __________ _________ of lipids from one monolayer to another requires their hydrophilic heads to move all the way through the hydrophobic interior of the bilayer which is rare.

transverse diffusion

Lipids with saturated fatty acids pack together ____? Lipids with unsaturated fatty acids do not pack together ____?

well