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biochemistry and molecular biology > module 4 > Flashcards

module 4 Flashcards

lipids and carbohydrates

1
Q

Describe 3 broad areas for lipid functions and provide examples

A
  • Storage
    • Structure
      Signals
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2
Q

Define the term lipid

A

Lipids are organic molecules characterized by insolubility in water and solubility in nonpolar solvents.
- They serve essential functions including energy storage, membrane structure, and signaling.

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3
Q

what are the essential componets of a storage lipid

A
  • Fatty acids are essential components of other important lipids
    § Waxes
    § Phospholipids
    Triacyclglycerols
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4
Q

what are biological lipids used for

A

□ Energy storage
□ Structural components of biological membranes
Signals and cofactors

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5
Q

Fatty Acid Melting Points trends

A

Melting points increase with chain length and decrease with unsaturation.

Longer, saturated fatty acids have higher melting points due to stronger intermolecular forces. Unsaturated fatty acids with cis double bonds have lower melting points due to kinks in the chain.

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6
Q

Fatty Acid Solubility trends

A

Fatty acids are insoluble in water but soluble in nonpolar solvents. Solubility decreases with increasing chain length.

Longer hydrocarbon chains make fatty acids more hydrophobic, reducing solubility in water. Shorter chains and polar functional groups increase solubility in water to some extent.

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7
Q

Explain trends in melting temperatures of natural fats

A

Influenced by fatty acid composition, chain length, and degree of saturation.
- Saturated fatty acids have higher melting points due to stronger intermolecular forces.
- Longer fatty acid chains generally have higher melting points.
- Unsaturated fats have lower melting points due to double bonds introducing kinks in the chains.
- Natural fats contain a mixture of saturated and unsaturated fatty acids, influencing their melting temperatures.

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8
Q

identify an omega 3 fatty acid

A

Omega-3 Fatty Acids:
- Have a double bond at the third carbon from the methyl (omega) end of the fatty acid chain.
- Examples include α-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA).
- Found in fatty fish (such as salmon, mackerel, and sardines), flaxseeds, chia seeds, walnuts, and algae.

  • 3rd carbon in the opposite direction of the carboxyl group
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9
Q

identify an omega 6 fatty acid

A

6th carbon from the oppoite end of the carboxyl group (COOH)

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10
Q

highlight the structure of triglycerides

A

they have a glycerol molecule with 3 OH groups that attach to 3 fatty acids via an ester link/bond. these can be the same fatty acid or they can be different

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11
Q

are triglycerides storage molecules

A

yes they are storage molecules

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12
Q

what are the biological functions of lipids (there are three)

A

Storage of energy
§ Reduced compounds: lots of available energy through oxidation
§ Hydrophobic nature: good packing

  • Insulation from environment
    § Low thermal conductivity
    § High heat capacity (can adsorb heat)
    § Mechanical protection (can absorb shocks)
  • Water repellent
    § Hydrophobic nature keeps surfaces of the organism dry
    § Prevents excessive wetting
    § Prevents loss of water via evaporation
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13
Q

what are phospholipids

A

are defined by the phosphate group within their polar head

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14
Q

what are the 2 categories of phospholipids

A

1) Glycerophospholipids (based on the glycerol molecule)
2) Sphingolipids (bases on sphingosine)

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15
Q

what is a Glycerophospholipids

A

a Glycerophospholipids is a phospolipid where it has 2 fatty acids attach to a glycerol, however it has a phosphate group an an alochol group attach to where the third fatty acid would be

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16
Q

what is the range of charges on a Glycerophospholipids

A

ranges -4 to 0 in charge

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17
Q

what are Glycerophospholipids mainly used for

A

used in for structure and signalling

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18
Q
A
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19
Q

what is a Sphingolipids

A

a phospholipid where the glycerol is an L shape (where one of the fatty acids would be), one fatty acid attach to the glycerol through an ester bond and a phosphate group and a chlorine group bonded to the phosphate group

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20
Q

what are Sphingolipids used for

A

structure and signalling roles

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21
Q

what is a glycolipid

A

a lipid where it contains a mono or oligosaccahride which is then bonded to a sulphate group (SO4) units in their head groups

22
Q

what is is a sterol

A

a sterol is a molecule that has 4 fused carbon rings where 3 rings are 6C rings and the and the 4th carbon ring is a 5C ring with an alkyl side chain bonded to the 6C ring and a OH group on the first 6C ring

23
Q

why are sterols amphipathic

A

they have both a hydrophobic (alkyl side chain and the Carbon rings and a hydrophilic end (hydrogen bonding with the polar hydroxyl group)

24
Q

What factors impact membrane fluidity?

A

Temperature and composition

25
Q

How does temperature affect membrane fluidity?

A
  • Increased temperature increases fluidity
  • Decreased temperature decreases fluidity
26
Q

How does composition affect membrane fluidity and what is the effect of cholesterol in the lipid membrane

A
  • Saturated fatty acids decrease fluidity
  • Unsaturated fatty acids increase fluidity
  • Cholesterol stabilizes fluidity over a range of temperatures
27
Q

how are proteins embedded into the membrane

A
  • Proteins embedded in the bilayer sheet are held together by hydrophobic interactions
28
Q

what is lateral diffusion and is this process fast or slow (what regions of the membrane

A

In lateral diffusion, molecules move laterally (sideways) along the surface of the membrane.

This process is relatively fast and occurs spontaneously as molecules move from regions of higher concentration to regions of lower concentration.

29
Q

what is translocation movement of phospholipids

A

Transbilayer translocation, also known as flip-flop or transverse diffusion, involves the movement of molecules across the lipid bilayer from one leaflet to the other.

Unlike lateral diffusion, transbilayer translocation requires molecules to cross the hydrophobic core of the lipid bilayer.

Transbilayer translocation is generally slower and less frequent than lateral diffusion due to the energy barrier presented by the hydrophobic interior of the membrane.

30
Q

what is the importance of translocation (also known as flip-flop)

A

This process is essential for maintaining lipid asymmetry in biological membranes and for the redistribution of certain molecules between membrane leaflets.

31
Q

Differences Between Lateral Diffusion and Transbilayer Translocation

A

Lateral Diffusion: Movement within the plane of the lipid bilayer.
Transbilayer Translocation: Movement across the lipid bilayer from one leaflet to the other.
Lateral diffusion is fast and occurs laterally along the membrane surface.
Transbilayer translocation is slower and involves crossing the hydrophobic core of the membrane.

32
Q

what is the impact of tempreature on Membrane Fluidity

A
  • Higher temperatures increase membrane fluidity by increasing lipid mobility.
  • Lower temperatures decrease fluidity by reducing lipid mobility.
  • Extremely high temperatures can disrupt membrane integrity.due to the heat breaking the intramolecular bonds within the phospholipid membrane
33
Q

what is the impact on composition on the membrane fluidity

A

Saturated fatty acids decrease fluidity by packing tightly.
- Unsaturated fatty acids increase fluidity by introducing kinks.
- Cholesterol modulates fluidity: reduces at moderate temps, prevents solidification at low temps.

34
Q

explain Asymmetry of Biological Membranes

A

Lipid Asymmetry: Different lipid compositions in inner and outer leaflets
- Protein Asymmetry: Some membrane proteins asymmetrically distributed or oriented.
- Essential for selective permeability, cellular organization, and signaling.
- Actively maintained by flippases, floppases, and scramblases.

35
Q

are membranes asymmetric

A

yes

36
Q

what are the 3 roles of membrane proteins

A

· Permit selective entry and exit of molecules from cell via transport
· Provide recognition signals via receptors
Provide structural support to the cell

1) selective entry
2) recognition for receptor
3) structure and support

37
Q

what are peripheral membranes proteins

A

proteins that are firmly attached to the membrane via hydrogen bonding and ionic interaction with polar groups of lipids

38
Q

how are peripheral membrane proteins disrupted

A

1) High salt
2) Change pH
Chelating agent

39
Q

what are integral membrane proteins

A

associate with outside surfaces that interact with hydrophobic interaction with acyl chains of membrane lipidsho

40
Q

how are intergral membranes proteins released

A

via the disruption of hydrophobic interactions

41
Q

what are 2 molecules that are permeable through the plasma membrane

A

O2 CO2 `

42
Q

can large uncharged polar molecules go through the plasma membrane

A

No they cannot

43
Q

what are transport proteins

A

proteins that transfer small water soluble across the lipid bilayer

44
Q

are transport proteins specific

A

yes

45
Q

Active vs. Passive Transport

A

Active Transport:
- Requires energy input (ATP or electrochemical gradient).
- Moves substances against their concentration gradient.
- Examples: Sodium-potassium pump, proton pump.
- Can be regulated to maintain specific concentrations.
- Energy source: ATP hydrolysis or electrochemical gradients.

Passive Transport:
- Does not require energy input; relies on concentration gradients.
- Moves substances along their concentration gradient.
- Examples: Simple diffusion, facilitated diffusion, osmosis.
- Generally not regulated; follows concentration gradients.
- Energy source: Potential energy stored in concentration gradients.

Similarities:
- Both involve movement across biological membranes.
- Both can involve ions, small molecules, or larger molecules.
- Both are essential for maintaining cellular homeostasis.

46
Q

what are the 3 different roles of sugars

A

1) source of energy -glycogen
2) structure - cellulose
3) cell communication- used in specific recognition interactions

47
Q

what is a monosaccharide

A

Basic unit of carbohydrates

48
Q

what is an aldose carbohydrate, what are the 2 forms and what is the naturally occuring one

A

-a carbohydrate that has an aldehyde group
- there are 2 isomers
1) D and L glyceraldehyde
and D is the most common

49
Q

what is a ketose carbohydrate

A

a carbohydrate with a ketone in it

50
Q

draw D and L glyceraldehydes

A
51
Q

what is the difference between alpha and beta carbohydrates

A

alphas point both down (alphas are always bottoms

betas have point pointing up and 1 pointing down

52
Q
A

biochemistry and molecular biology (4 decks)

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