Biological Membranes Flashcards by Ines T

Name 7 structures found in the fluid mosaic model

-Glycoprotein
-Glycolipid
-Channel proteins & carrier proteins (intrinsic)
-Extrinsic proteins
-Cholesterol
-Phospholipid bilayer

How well did you know this?

Not at all

Perfectly

What are transmembrane/intrinsic proteins?

Embedded through entire bilayer

How well did you know this?

Not at all

Perfectly

What are extrinsic proteins?

Present in 1 side of bilayer

How well did you know this?

Not at all

Perfectly

State 1 difference in function and 1 difference in structure between a channel and carrier protein

Function
-Channel: Facilitating diffusion only
-Carrier: Facilitating diffusion + Active transport

Structure
-Channel: Open on both ends
-Carrier: Only open on 1 end

How well did you know this?

Not at all

Perfectly

State the function of the phospholipid bilayer

Acts as barrier for water-soluble substances

How well did you know this?

Not at all

Perfectly

State 1 structural similarity and difference between glycolipids and glycoproteins

-Both contain polysaccharides

-Glycolipids attached to lipids, glycoproteins attached to proteins

How well did you know this?

Not at all

Perfectly

State the function of glycoproteins in the cell surface membrane

-Antigens -> cell recognition
-Receptors -> chemical signalling
-Adhesion (can bind to molecules)

How well did you know this?

Not at all

Perfectly

State the function of glycolipids in the cell surface membrane

-Antigens -> cell recognition
-Receptors -> chemical signalling

How well did you know this?

Not at all

Perfectly

State the function of cholesterol in the cell surface membrane

-At ↓ temp, ↑ fluidity of membrane
-At ↑ temp, ↑ stability
(Regulate fluidity)

How well did you know this?

Not at all

Perfectly

State 2 roles of cholesterol in living organisms

-Regulates fluidity of phospholipid bilayer
-Makes vitamin D

How well did you know this?

Not at all

Perfectly

Explain why phospholipids form a bilayer in the plasma membrane [3 marks]

-Polar hydrophilic phosphate group attracted to aqueous solution
-Non-polar hydrophobic fatty acid tails repelled from aqueous solution
-Both tissue fluid & cytoplasm = aq -> phospholipds form 2 layers w/ hydrophobic tails facing in & hydrophilic phosphate groups out

How well did you know this?

Not at all

Perfectly

State 5 factors affecting the rate of diffusion

-Temp
-Particle size
-Diffusion distance
-SA
-Diff in conc gradient

How well did you know this?

Not at all

Perfectly

State Fick’s law

Rate of diffusion ∝ SA × diff in conc / diffusion d

How well did you know this?

Not at all

Perfectly

Describe and explain the relationship between molecule size and diffusion

-As molecule size ↑ rate of diffusion ↓
-Larger molecule = ↑ mass -> ↑ KE to move
-Also ↑ likely to collide w/ other molecules -> further slows diffusion

How well did you know this?

Not at all

Perfectly

Define the term facilitated diffusion

Diffusion across plasma membrane through carrier/channel protein

How well did you know this?

Not at all

Perfectly

State what type of molecules require simple diffusion vs facilitated diffusion

Simple
-Small
-Non-polar
-Lipid-soluble
-Not charged

Facilitated
-Large
-Polar
-Water-soluble
-Charged

What is a hypertonic water solution?

-↑ ψ in cell
-Water moves out of cell BY OSMOSIS
-Animals: Shrivel (crenated)
-Plants: Plasma membrane detaches from cell wall

What is a hypotonic water solution?

-↓ ψ in cell
-Water moves into cell BY OSMOSIS
-Animals: Cell may burst (cytolysis)
-Plants: Pressure exerted onto cell wall -> plasma membrane pushes against cell wall

What is an isotonic solution?

-System is in dynamic equilibrium

Name 5 factors affecting membrane permeability

-Temp
-Solvent
-pH
-Cholesterol
-Whether fatty acid chains are saturated or unsaturated

How does temperature affect membrane permeability?

-↑ temp = ↑ fluid = ↑ permeable

How do solvents affect membrane permeability?

-Water, ethanol & benzine all dissolve membranes

How does cholesterol affect membrane permeability?

-↑ cholesterol = ↓ fluid = ↓ permeable

How do fatty acids affect membrane permeability?

-Unsaturated fatty acids have kinks (caused by C=C) -> ↑ permeability

Define the term active transport

-Net movement of particles -From area of lower conc to higher conc -Against conc gradient -Using E from hydrolysis of ATP -Requires carrier proteins

What kind of molecules move by active transport?

-Polar -Non-polar -Charged -Lipids -Water-soluble

Which reaction releases energy?

Hydrolysis of ATP

What are the two types of bulk transport?

-Endocytosis -Exocytosis

Name the 2 types of endocytosis

-Phagocytosis -Pinocytosis

Describe the 3 stages of endocytosis

1.Plasma membrane invaginates pathogen 2.Vesicle pinches off from plasma membrane 3.Transport vesicle forms

Describe the 3 stages of exocytosis

1. Move- Along cytoskeleton w/ motor proteins 2. Fuse- Vesicle fuses w/ cell surface membrane 3. Secrete- Contents of vesicle released into extracellular environ

State the role of membrane-bound receptors

Sites where hormones & drugs bind

a) Name 2 passive methods of transport of molecules b) Name 3 active methods of transport of molecules which require ATP as an immediate source of energy

a) Simple & facilitated diffusion b) Active transport, endocytosis, exocytosis

What does ATP stand for?

Adenosine triphosphate

Define the term osmosis

-Net movement of water molecules -Across partially permeable membrane -Across water potential gradient

Why does the fluid mosaic model have its name?

-Fluid: Lateral movement of phospholipids -Mosaic: Proteins/glycolipids/glycoproteins scattered throughout phospholipid bilayer -Model: Representation as no photograph available

State functions of cell surface membranes

-Compartmentalisation -Site of chemical reactions -Sites of cell communication -Barrier (partially permeable, only allows small, lipid-soluble/non-polar substances to diffuse across)

Why are polar molecules not able to diffuse across the phospholipid bilayer

Fatty acid tails are hydrophobic