Topic 3: Membranes Flashcards

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1
Q

Describe fatty acids

A

Long chain of carbon atoms with a carboxyl group at one end

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2
Q

Average number of carbons in a fatty acid chain

A

12-20

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3
Q

Describe triacylclylcerols

A

3 fatty acids bound to a glycerol anchor

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4
Q

Describe a phospholipid

A

a glycerol head at the top, attached to two fatty acid tails

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5
Q

What are triacylglycerols used for?

A

to store energy

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6
Q

‘Amphipathic’ means…

A

having both hydrophilic (polar) and hydrophobic (non-polar) properties

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7
Q

A micelle is…

A

a formation of phospholipids, like an oil drop in water. Glycerols face outwards.

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8
Q

A liposome is…

A

a formation of phospholipids, used in medicine to deliver needed substances. Hollow ball of phospholipids, with hydrophilic properties facing outwards, but also inwards in a second layer

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9
Q

Which type of proteins go all the way through the membrane?

A

Integral Proteins

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10
Q

Peripheral proteins never touch….

A

the hydrophobic core

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11
Q

Amphipathic proteins are…

A

integral proteins

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12
Q

Four functions of membrane proteins

A

Transport, enzymatic activity, signal transduction, and attachment recognition

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13
Q

Sterols can prevent freezing in the bilayer by…

A

embedding themselves between the phospholipids, preventing them from packing too tightly

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14
Q

Sterols can prevent melting in the bilayer by…

A

embedding themselves between the phospholipids to fill in the gaps.

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15
Q

Four ways to increase membrane fluidity

A

1) short chain fatty acids
2) unsaturated fatty acids
3) sterols
4) higher temperatures

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16
Q

Four ways to decrease membrane fluidity

A

1) long chain fatty acids
2) saturated fatty acids
3) sterols
4) lower temperatures

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17
Q

True or False: Sterols are amphipathic

A

True

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18
Q

Order the following from best to worst for crossing the cell membrane:
Ions, small uncharged polar molecules, large uncharged polar molecules, non-polar molecules

A

1) non-polar molecules
2) small, uncharged polar molecules
3) large uncharged polar molecules
4) ions

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19
Q

True or False: facilitated diffusion is active transport

A

False

20
Q

Aquaporins are…

A

narrow channel proteins that allow the passage of water across the membrane

21
Q

A Gated channel is…

A

a channel protein that can switch between open, closed, and intermediate states to transport most ions across the cell membrane

22
Q

Carrier proteins…

A

passively transport larger molecules across the cell membrane using diffusion and facilitated transport

23
Q

Why do cells need a selective barrier?

A

To maintain homeostasis in dynamic environments

24
Q

How does diffusion work in relation to the concentration gradient of a solute

A

works with the concentration gradient to reach equilibrium, does not require ATP

25
Q

Osmosis vs Diffusion

A

Osmosis is specifically the diffusion of water. If the solute can’t diffuse to reach equal concentrations, water will diffuse to do so

26
Q

Type of diffusion represented with a linear function

A

Simple diffusion (rate of reaction increases steadily with concentration)

27
Q

Type of diffusion represented with a logarithmic function

A

Facilitated diffusion (rate of reaction increases drastically at first, but levels out and reaches a plateau)

28
Q

A 5M liposome placed in a 10M solute, solution is….

A

hypertonic. water diffuses outwards

29
Q

4.2M liposome placed in a 4.2M solute, solution is….

A

isotonic. At equilibrium

30
Q

9.2M liposome placed in 4.2M solute, solution is….

A

hypotonic, water diffuses inwards

31
Q

Secondary Active Symport…

A

a solute is transported against it’s own concentration gradient with the help of a driving ion in the same direction

32
Q

Secondary Active Antiport

A

a solute is transported against its own concentration gradient with the help of a driving ion in the opposite direction

33
Q

Secondary Active Transport…

A

indirectly uses ATP, taking energy released by other reactions

34
Q

Primary Active Transport…

A

requires ATP

35
Q

Which of the following is NOT found in a triglyceride?
Saturated fatty acids, unsaturated fatty acids, charged organic group, or glycerol anchor.

A

Charged organic group

36
Q

A larg epolar molecule moves through a protein against its concentration gradient, and hydrolyzes ATP during the process. What is this?

A

Primary active transport

37
Q

What could a cell do to prevent its membrane from becoming too viscous?

A

Increase sterols, increase unsaturated phospholipids

38
Q

Which of the following can most easily diffuse across a lipid bilayer?
Methane, water, glucose, or H+

A

Methane
(non-polar small molecule)

39
Q

How does preserving olives in brine (20-30% salt solution) help prevent it from spoiling or being contaminated by microorganisms?

A

Bacteria can’t survive in a hypertonic solution because their cytoplasm loses wate

40
Q

Which of the following is NOT a component of a phospholipid?
A 3-carbon glycerol backbone
A phosphate group
A core of four fused carbon rings
Two fatty acid tails

A

A core of four fused carbon rings

41
Q

A cell wanting to move Magnesium ions across a lipid bilayer down its concentration gradient would use…

A

a protein channel

42
Q

Unsaturated fatty acids cause a membrane to be fluid at lower temperatures. Why?

A

The double bonds form a kink in the fatty acid tails, forcing adjacent lipids to be spaced further apart

43
Q

In the fluid mosaic model, what does ‘fluid’ refer to?

A

The movement and exchange of phospholipids and proteins within the two layers of phospholipids

44
Q

What is the difference between simple diffusion and facilitated transport?

A

Facilitated transport requires a transport protein, while simple diffusion does not

45
Q

What 2 terms can refer to the movement of water across a membrane from an area of lower solute concentration to an area of higher solute concentration?

A

Diffusion & Osmosis