module 4 Flashcards
lipids and carbohydrates
Describe 3 broad areas for lipid functions and provide examples
- Storage
- Structure
Signals
- Structure
Define the term lipid
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.
what are the essential componets of a storage lipid
- Fatty acids are essential components of other important lipids
§ Waxes
§ Phospholipids
Triacyclglycerols
what are biological lipids used for
□ Energy storage
□ Structural components of biological membranes
Signals and cofactors
Fatty Acid Melting Points trends
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.
Fatty Acid Solubility trends
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.
Explain trends in melting temperatures of natural fats
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.
identify an omega 3 fatty acid
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
identify an omega 6 fatty acid
6th carbon from the oppoite end of the carboxyl group (COOH)
highlight the structure of triglycerides
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
are triglycerides storage molecules
yes they are storage molecules
what are the biological functions of lipids (there are three)
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
what are phospholipids
are defined by the phosphate group within their polar head
what are the 2 categories of phospholipids
1) Glycerophospholipids (based on the glycerol molecule)
2) Sphingolipids (bases on sphingosine)
what is a Glycerophospholipids
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
what is the range of charges on a Glycerophospholipids
ranges -4 to 0 in charge
what are Glycerophospholipids mainly used for
used in for structure and signalling
what is a Sphingolipids
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
what are Sphingolipids used for
structure and signalling roles
what is a glycolipid
a lipid where it contains a mono or oligosaccahride which is then bonded to a sulphate group (SO4) units in their head groups
what is is a sterol
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
why are sterols amphipathic
they have both a hydrophobic (alkyl side chain and the Carbon rings and a hydrophilic end (hydrogen bonding with the polar hydroxyl group)
What factors impact membrane fluidity?
Temperature and composition
How does temperature affect membrane fluidity?
- Increased temperature increases fluidity
- Decreased temperature decreases fluidity
How does composition affect membrane fluidity and what is the effect of cholesterol in the lipid membrane
- Saturated fatty acids decrease fluidity
- Unsaturated fatty acids increase fluidity
- Cholesterol stabilizes fluidity over a range of temperatures
how are proteins embedded into the membrane
- Proteins embedded in the bilayer sheet are held together by hydrophobic interactions
what is lateral diffusion and is this process fast or slow (what regions of the membrane
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.
what is translocation movement of phospholipids
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.
what is the importance of translocation (also known as flip-flop)
This process is essential for maintaining lipid asymmetry in biological membranes and for the redistribution of certain molecules between membrane leaflets.
Differences Between Lateral Diffusion and Transbilayer Translocation
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.
what is the impact of tempreature on Membrane Fluidity
- 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
what is the impact on composition on the membrane fluidity
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.
explain Asymmetry of Biological Membranes
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.
are membranes asymmetric
yes
what are the 3 roles of membrane proteins
· 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
what are peripheral membranes proteins
proteins that are firmly attached to the membrane via hydrogen bonding and ionic interaction with polar groups of lipids
how are peripheral membrane proteins disrupted
1) High salt
2) Change pH
Chelating agent
what are integral membrane proteins
associate with outside surfaces that interact with hydrophobic interaction with acyl chains of membrane lipidsho
how are intergral membranes proteins released
via the disruption of hydrophobic interactions
what are 2 molecules that are permeable through the plasma membrane
O2 CO2 `
can large uncharged polar molecules go through the plasma membrane
No they cannot
what are transport proteins
proteins that transfer small water soluble across the lipid bilayer
are transport proteins specific
yes
Active vs. Passive Transport
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.
what are the 3 different roles of sugars
1) source of energy -glycogen
2) structure - cellulose
3) cell communication- used in specific recognition interactions
what is a monosaccharide
Basic unit of carbohydrates
what is an aldose carbohydrate, what are the 2 forms and what is the naturally occuring one
-a carbohydrate that has an aldehyde group
- there are 2 isomers
1) D and L glyceraldehyde
and D is the most common
what is a ketose carbohydrate
a carbohydrate with a ketone in it
draw D and L glyceraldehydes
what is the difference between alpha and beta carbohydrates
alphas point both down (alphas are always bottoms
betas have point pointing up and 1 pointing down
