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Flashcards in Introduction: Cell Membranes Deck (16):

What are the functions of membranes

Highly selective permeability Barriers which embody carriers and transporters etc

Maintain differences in ion concentrations inside and outside of the cell

Contain receptors for stimuli external and internal to the cell

Cen generate electrical and chemical signals

Are essential for energy conv

Cell cell adhesion


What does the lipid bilayer consist of

Lipids (phospholipids, glycolioids, cholesterol) and proteins
Bilateral with a trilaminar appearance


What is the structure of a phospholipid


( hydrophillic head and hydrophobic head)


What are lipid bilayers

Non covalent assemblies


What su the fluidity of the lipid bilayer like

Phospholipids in constant motion where they rotat,vibrate


How does cholesterol effect the membranes

Cholesterol is s rigid steroid
Intercalated between phospholipids
Decreases fluidity of mem at warm temp
Maintains fluidity at cold temps prevent crystallisation of phospholipids
Reduces mem perm to hydrophillic molecules


What are the different kind of membrane proteins

Integral proteins embedded
Transmem proteins span mem
Peripheral proteins don't penetrate mem
Lipid anchored protiens possess lipid modificicatins that hold them in association with the mem


What is membrane carbohydrate

A small amount of mem carb located on outer surface of cells
Short carb chains found bound to mem proteins and to a lesser extent lipids
- glycoproteins and glycolioids
- together form layer - glycocalyx


What is the overall structure phrased as for a lipid bilayer

Fluid mosaic model structure


What are some of the functions of the lipid bilayer

Forms basic structure of mem
Hydrophobic interior serves as a barrier to polar and charged subs
Responsible for fluidity of mem
Enable cell to change shape
Certain of phospholipids are precursors for signalling mols


What are ion channels

Some transmem proteins form water filled highly selective ion channels regulated by chemicals (neurotransmitters) transmem voltage or physical stimuli

Some drugs target sodium channels to block and give anaesthesia

Some ion channels may be abnormal


What are carrier transport proteins

Spam mem
Exhibit substrate selectivity
Diff cell types express diff kinds of carriers
Docking marker acceptors- located inner surface and interact with sec vesicle leading to exocytosis


What are some other types of mem proteins

Mem bound enzymes - either side of mem such as phospholipase C

Receptors - most transmem with binding site bind specific mols

Call adhesion molecules (CAMS) - cadherins which help hold cells in tissues together or integrins which span plasma mem acting as a link between extra and intra cellular enviro


How do some carbs serve as self identifying markers

Short carb chains on outer mem surface serve as self identifying markers

Diff cell types have diff markers
Imp for cell - cell interactions

Role in tissue growth - so cells do not overgrow


What are some examples of specialised cell junctions

Link cells directly

Tight junctions - join lateral edges of epi near luminal surface LEAKY

Desmosomes - adhering junctions that anchor cells together especially in tissues subject to stretching

Gap junctions - communicating junctions, allow move of ions and small mols between cells in heart as eg


What are membranes

Boundaries between
Extracellular and intracellular environments
Intracellular organelles such as ER, mito, golgi, lysosomes