Membrane Fluidity And Membrane Protiens

Question 1

What is the maximum number of double bonds in a fatty acid

Answer 1

6

Question 2

Why are cis double bonds better than trans in fatty acid tails?

Answer 2

Cis bonds are more reactive, and allow more reaction in the cell for metabolism and cell signalling

They give more bend which increases fluidity of the tails

Question 3

What determines the physical state of the membrane and what is it influenced by

Answer 3

Fluidity/ viscosity

Influenced by temp

Question 4

What is transition temperature

Answer 4

The melting temp

When it turns from solid to liquid

Question 5

If you’re below transition temp what happens to the membrane

If above

Answer 5

More rigid and tightly packed

More fluid and movement

Question 6

What is transition temperature (fluidity) affected by?

Answer 6

Fatty acid chain saturation

Cholesterol content

Fatty acid chain length

Question 7

Interactions in membrane phospholipids are held together by

Answer 7

Van der waals

Question 8

If you have less van der waals interactions what does this mean

Answer 8

Tails further apart, more fluid

Question 9

What does fatty acid chain saturation do to fluidity

Answer 9

If saturated, the fatty acids are less fluid, and straight flexible rods

In cis unsaturated, the fatty acids bend at the double bond so they’re more fluid

Question 10

What does cholesterol content do to fluidity

Answer 10

Cholesterol has rigid hydrophobic rings that impair the movement of the fatty acid tails at lower temp
DONT JNDERSTAND

Question 11

What does fatty acid chain length do to membrane fluidity

Answer 11

Shorter chains less van der wall interaction, so more fluid because less energy needed to break them apart

If longer more interactions, more rigid

Question 12

Why is a balance of membrane fluidity and rigidity important

Answer 12

It helps keep structural organization and support

Is enables interactions (clusters of protiens

Is helps with membrane assembly, cell growth, cell division

Helps in cell movement, secretion, and endocytosis

Question 13

What do cells do to respond to changing environmental conditions?

Answer 13

That alter third lipid compositions to maintain membrane fluidity

Question 14

How do cells respond to cold temps to maintain membrane fluidity

What is hot temp?

Answer 14

Temp is cold so they want to become more fluid

They desaturate single bonds in the fatty acid chains (make double bonds)

They reshuffle their chains between other phospholipids to make two unsaturated fatty acids

They change the type of phospholipids they synthesize, so they make more fatty acids with unsaturated (double) bonds and shorten fatty acid chain lengths

If hot they do the opposites

Question 15

What enzyme desaturates single bonds

Answer 15

Desaturase

Question 16

What happens to the transition temp if saturated fatty acids are increased

Answer 16

More saturated (more single bonds) more rigid.

Transitions temp increase cause it take more energy to go from rigid to fluid

Question 17

Is you have more double bonds what happens to transition temp

Answer 17

More fluid so lower transition temp

More likely to be fluid (melt) at lower temp

Question 18

How are protiens distributed across the two leaflets of the membrane bilayer

Answer 18

Asymmetrically

Question 19

What are the three classes of membrane protiens

Answer 19

Intergral Protiens

Peripheral proteins

Lipid anchored proteins

Question 20

What are integral membrane protiens

Answer 20

They are protein that are permanently anchored to or are part of the membrane

Include mono topic, bitopic and poly topic proteins

Question 21

What are mono topic, bitopic and poly topic proteins

Answer 21

mono topic: spans only one of the membrane leaflets

Bitopic: spans the whole leaflet

poly topic: spans the whole leaflet multiple times

Question 22

What are transmembrane protiens

Answer 22

Proteins that pass through the lipid bilayer and have one or more transmembrane domains

Act as receptors channels or have roles in electron transport

Amphipathic

Question 23

What integral membrane protiens are also Transmembrane protiens

Answer 23

Bitopic

And

Polytopic

Question 24

Transmembrane domain of transmembrane protiens are generally

The surface of the transmembrane proteins are

Channels in the membrane may also be

Answer 24

Hydrophobic (do vanderwal with fatty acids in the bilayer)

Hydrophilic

Hydrophilic

Question 25

Stuff about glycoprotein A slide 15

Answer 25

Idk

Question 26

What is a way to identify the transmembrane domains

Answer 26

By doing computational analysis of amino acid sequence in the membrane to find the transmembrane domains

It’s usually a string of 20 nonpolar amino acids to span both top and bottom layer of the membrane

Question 27

Lost the major membrane functions

Answer 27

Compartmentalization

Scaffold for biochemical activities (enzymes there to make sure inter actions occur)

Selectively permeable barrier

Solute transport

Response to external stimuli

Cell-cell communication

Energy transduction (mitochondria turns carbohydrate energy to atp)