Chapter 6a Lipids Flashcards
List the three elements that are most commonly found in lipids
Hydrogen, Carbon, Oxygen
What is the main difference between carbohydrates and lipids in terms of elements?
Lipids have significantly less oxygen than carbohydrates
Do lipids form polymers?
No , they are the only class of large molecules to not form polymers
What is the unifying feature of lipids?
They have little to no affinity for water. (Lipids are hydrophobic because they consist mostly of carbon-hydrogen bonds)
Why are hydrocarbons hydrophobic?
Hydrocarbons like lipids are non-polar, while water is polar. They do not interact with each others (“like dissolves like”). Carbon-Hydrogen bonds are non polar.
What are fatty acids?
Fatty acids are long chains of carbon attached to a carboxyl group at one end
What is the difference between saturated and unsaturated fatty acids?
Saturated fatty acids contain NO c=c bonds, so the amount of carbons to hydrogens ratio are 1:1 (saturated)
Unsaturated fatty acids contain c=c bonds, so the amount of carbons to hydrogens are not 1:1. These c=c bonds are called kinks
Unsaturated has less hydrogens than saturated and thus are “less saturated”.
What are glycerol?
Glycerol is a three-carbon alcohol with hydroxyl groups attached to each carbon
How are triacylglycerols created?
Constructed from two types of molecules: fatty acids and glycerol
Three fatty acids are joined to glycerol by an ester linkage
This ester linkage is formed from dehydration reactions (syntheses)
What is the physical difference between saturated fats and unsaturated fats (oils)
Fats made from saturated fatty acids are saturated fats and are solid at room temperature (most animal fats are saturated)
Fats made from unsaturated fatty acids are called unsaturated fats or oils and are liquid at room temperature
Saturated fats tend to be solid at room temperature due to their fatty acids being saturated. Less space between each other allows for hydrophobic interactions between these saturated fatty acid chains. They become more stable as well as packed.
Unsaturated fats tend to be liquid at room temperature due to their fatty acids being unsaturated and creating space between the fatty acids chains. The unsaturated fatty acids have kinks to their structure which has a less likely chance for hydrophobic interactions to occur. Less dense due to the physical shape of the fatty acids
What are the three functions of fat in an animal’s body
Insulation
Cushioning and protection of organs
Energy storage
- A gram of fat stores more than twice as much energy as a gram of polysaccharide
What are phospholipids?
In most cases, two fatty acids and a phosphate group attach to a glycerol.
Phospholipids usually have one saturated acid tail and one unsaturated.
The phosphate group has a negative charge, so additional small molecules which are usually charged or polar often bond to the phosphate group.
Creating a polar/charged head which is hydrophilic and a nonpolar (hydrophobic) tail
What is the function of phospholipids
When phospholipids are added to water, they self-assemble into a phospholipid bilayer, where the hydrophobic tails point towards the interior, while the hydrophilic heads face out.
This bilayer arrangement is found in cell membranes and is the major component of all cell membranes. (Chpt 6b-f)
What are steroids and what is their main function?
Steroids are lipids characterized by a carbon chain consisting of four fused rings.
Used for signalling in the human body, travels in the circulatory system
Cholesterol (one of the most important steroids) is a component in animal cell membranes and is a precursor for some steroid hormones
