membrane structure - lecture 1/28

Cell __________ define the boundaries of a cell and __________ internal compartments such as ___________.

Membranes, enclose, organelles.

Cell membranes function as a selectively ___________ barrier, maintaing ___________, ____________ between cells by ______ detection.

Permeable, homeostasis, communication, signal.

Cell membranes function in cell ___________ to other cells, the imort and export of __________, and allows for ___________ and ___________.

Attachment, molecules, movement, expansion.

Cell membranes consists of a _____ bilayer with _________embedded in it. This is also known as the _____ ________ model.

Lipid, proteins, fluid mosaic

_____ and __________ composition differ depending on where the membrane is _________.

Lipid, protein, found

cell membranes are _____-________, which allows for expansion or contraction, ____________ of the cell, fusion with other ___________ or ___________ of the cell.

Self-sealing, deformation, membranes, movement

membranes contain a great diversity of _______, because the lipids can form ________ in _______.

Lipids, bilayers, water

The main classes of membrane lipids are __________lipids, ______lipids, and ________.

Phospho, gluco, sterold

All of the main classes of membrane lipids are ______________, which mean they contain both _____________ and _____________ components.

amphipathic, hydrophilic, hydrophobic

_______lipids are the most abundant lipid in ___________.

Phospho, membranes

_____________ membrane lipids drives lipid molecules to assemble into ________, in an _________ environment.

Amphipathic, bilayers, aqueous

Turning into bilayers forces hydro________ molecules to cluster and exclude water, which creates an energetically __________ structure.

Phobic, favorable

_____________ form lipid droplets, which are clumps of fat that _____ be transported. If you needed to move this fat cell it would beed ______________ around it.

Triglycerides, can’t, phospholipids

Being amphipathic makes ___________ self-sealing and fold into _______ compartment/spheres.

Membranes, closed

A _____ in the bilayer creates a free edge exposed to the ______. This is bad because the hydro ______ parts want to away from water.

Tear, water, hydrophobic

To avoid contact with ______ phospholipids arrange into closed, ____-_________ compartments to eliminate any ____ _______.

Water, self-sealing, free edges

The lipid _______ behaves as a ____-dimensional fluid.

Bilayer, two

Random ________ motion causes lipids to _______, freely within a _________. This motion can be constrained by _________ in the membrane.

Thermal, diffuse, monolayer, proteins

The movement of lipids from one _________ to another is ________ diffusion. This flip-flop is relatively _____.

Monolayer, transverse, rare.

for a lipid to flip-flop, its _______ head must cross the hydrophobic core of the _________, which is an energetically ____________ process.

Polar, bilayer, unfavorable

___________ diffusion requires _________ that ________ this reaction, and they act only on specific _______.

Transverse, enzymes, catalyze, lipids

membrane _______ allows some membrane proteins to move ________, which is required for cell __________.

Fluidity, rapidly, signaling

___________ fluidity allows the ______ of membranes, organelles, and vesicales, (consist of endo and exocytosis) and cell _________.

Membrane, fusion, division

If ____ protiens that recieve a _______ (substrate) get stuck it can cause _________ in cells, because this causes the cell to _______ when it shouldn’t.

Two, ligand, cancer, divide

The ________ of the membrane at a ____________ depends on its ______________ composition.

Fluidly, temperature, phospholipid

________ tailed lipids have an __________ strength of interaction which causes a __________ in fluidity, and becomes more _______.

Longer, increased, decrease, solid

The longer the ____ of a lipid is the more _______ to becomes.

Tail, solid

at a given ____________, a short-tailed lipid will be more _______ than a long-tailed lipid.

Temperature, fluid

The optimal membrane ______ ______ size is 12 - 20 __________ long.

Fatty acid, carbons

Fewer or more _________ form less stable ___________, this determines the _________ of the membranes, (usually 6-8 nm).

Carbons, membranes, thickness

degree of ______________, is where an unstaturated _______ creates extra space in the ___________ which _________ fluidity.

Unstaturation, lipid, membrane, increases

The _____ shape of ____________ lipids causes gapes which make the membrane _____ fluid.

Bent, unsaturated, more

the membranes of most ___________ contain ______, which is a 4 ring structure. _____ size depends on the ______ of sterol you have.

Eukaryotes, sterols, tail, type

the main sterol in animal cell membranes is ___________.

Cholesterol

_____ cell membranes have small amounts of ____________, which function similar to ________ in animals.

Plant, phytosterols, sterols

________ cell membranes contain ____________, which is similar to cholesterol.

Fungal, ergosterol

since ergosterol is present in ______, but not in animals, it is a useful target for __________ drugs.

Fungi, antifungal

ergosterol is one reason why we can get ________ infections.

Fungal

monistat is an ___________ medication used to treat ringworm, putyriasis versicolor, and yeast infections of the skin or vagina, because it ________ the synthesis of ergosterol.

Antifungal, inhibits

__________ has an important influence on lipid ________.

Cholesterol, bilayers

sterols are slightly ____________ and can H-bond with _______lipids via the terminal _________ group.

Amphipathic, phospho, hydroxyl

The intercalation of rigid ____________ molecules into a membrane ___________ its fluidity. it also prevents _____________ chains from packing together _________. This stops it from becoming solid at ____ temps.

cholesterol, decreases, hydrocarbon, tightly, low.

cholesterol is a _________ ______, maintinaing the correct amount of _____. A lot of other _________ in other organisms may function similarly.

Fluidity buffer, fluid, sterols

sterols _________ the _____________ of membranes to ions and small polar molecules. This is becuase they fill spaces between the ______________ chains of _________lipids.

Decrease, permeability, hydrocarbon, phospho

When sterols fill _______, this blocks the ________ that ions and small molecules would take through the ___________.

Gaps, routes, membrane

most organisms can __________ membrane fluidity by varying the _______ composiion in the membranes. This is important in ______________, (organism that cannot regulate their own body temp).

Regulate, lipid, poikilotherms

poikilotherms use homeoviscous ____________, which helps with changes in temp by __________ the length and degree of ____________ of fatty acids, or proportion of ____________ in their membranes.

adaptation, altering, staturation, chelesterol

hibernating __________ use homeoviscous adaptation, to adpat to changes in body ______, by adding a greater proportion of ____________, fatty acids into their membrane _________lipids.

mammals, temp, unsaturated, phospho

An exampe of a ___________ in permeability is the removal of ___________ from sperm membrane which allows ____ influx, and causes ___________, (the process sperm must undergo to be able to fertilize an egg).

Decrease, cholesterol, ion, capacitation