1.5 - Lipids and Nucleic Acids Flashcards
What do lipids do?
Lipids are biological molecules which maintain the differences between what is outside and inside a cell
- They are the gatekeepers
How do lipids react to water?
Lipids are insoluble in water (meaning they cannot be dissolved by water)
Why are lipids insoluble?
Lipids are insoluble in water because they are nonpolar molecules. Water is a polar molecule, meaning it has a positive and a negative end. Lipids, being nonpolar, don’t interact well with the polar water molecules, causing them to repel each other. This property makes lipids hydrophobic, or “water-fearing,” and is why they tend to clump together and separate from water.
What are the roles of lipids?
The roles for lipids in organisms include:
- Energy storage (fats and oils)
- Cell membranes (phospholipids)
- Capture of light energy (carotenoids; give colour to vegetables/leaves)
- Chemical messengers
- Hormones and vitamins (steroids and modified fatty acids)
- Thermal insulation
- Electrical insulation of nerves
- Water repellency (waxes and oils).
T/F: Lipids share a common core structure
FALSE: Lipids do not share a common core structure
What is common to lipids is their hydrophobicity (they ALL avoid water)
What are saturated fats?
A saturated fat is a type of fat in which the fatty acid chains have all single bonds
What are unsaturated fats?
Unsaturated fats have at least one double bond between carbon atoms, creating a kink in the chain. This kink prevents the molecules from packing tightly, keeping the fat liquid at room temperature.
Unsaturated fats are usually liquid, come from plants, and are healthier for your heart.
How do the structures of saturated and unsaturated fats differ?
Saturated fats have a straight structure, while unsaturated fats have bends in them
- Unsaturated fats also have double carbon bonds
What is the state of fully saturated fats at room temperature?
At room temperature, fully saturated fats are solid (think butter). They have high-temperature stability (minimal changes to state over wide temperature range, no sudden changes)
What is the state of unsaturated fats at room temperature?
At room temperature, unsaturated fats are liquid (think oil). They have low-temperature fluidity (meaning they are still fluid at low temperatures)
What are triglycerides?
Triglycerides are the most abundant lipids and the most concentrated source of energy
What are triglycerides made of?
The building blocks of triglycerides are glycerol (the same for each fat molecule) and fatty acids (different for each fat, they determine its chemical nature)
What are the types of fatty acids?
- Saturated fatty acid (all available bonds are filled)
- Unsaturated fatty acid (has one or more double bonds)
How are triglycerides formed?
Triglycerides are formed by a dehydration synthesis
Why do fats possess more energy stored per unit mass/volume than carbohydrates?
Fats possess more energy per molecule and less hydration compared with carbohydrates because they have a higher number of CH bonds (LONG chain of molecules)
What are the two kinds of unsaturated fats?
Monounsaturated and polyunsaturated
What are the two kinds of hydrogenated fats?
Cis and trans fats
Where are fats stored in animals?
In animals, fats are stored in adipose cells (connective-tissue cells designed to store fat)
What are phospholipids?
Phospholipids are fat compounds similar to triglyceride
One end of the phospholipid is water-soluble (hydrophilic); the other end is fat-soluble (hydrophobic)
What are phospholipids used for?
Phospholipids are used to join two different chemical environments
What are bilayers?
Bilayers are double layers of phospholipids that make up cell membranes (also called biological membranes)
What are steroids?
Steroids are signaling molecules. Steroids are organic compounds with a series of fused rings
What is the structure of a steroid?
Steroids have a common 4-ring structure
What do steroids do?
Steroids are involved in many structural and functional roles
What is cholesterol?
Cholesterol is a common steroid in animal cell membranes. It is absorbed from food and synthesized in the liver. In addition to being a membrane constituent, it also is an initial substrate (layer) for synthesis of the hormones testosterone and estrogen (which are both also steroids)
What properties do cholesterol have in the cell?
Cholesterol is a membrane temperature fluidity buffer, meaning it helps the cell regulate temperature and avoid extremes (too hot, too cold)
What are vitamins?
Vitamins are small organic molecules essential to health
What is Vitamin A good for?
It is important for normal development, maintenance of cells, and night vision
What is Vitamin D good for?
It is important for absorption of calcium in the intestines.
What is Vitamin E good for?
It is an antioxidant. It protects membranes from disease-causing agents.
What is Vitamin K good for?
Vitamin K is a component required for normal blood clotting.
What are waxes?
Waxes are saturated long fatty acids bonded to long fatty alcohols via an ester linkage (bond between oxygen and carbon atoms)
What are waxes used for?
Waxes protect our hair, birds’ feathers, and insects’ eggs from both the damaging effects of excess water, and the damaging effects of water loss
What are nucleic acids polymers?
Nucleic acid polymers are linearly arranged information molecules. They are composed of nucleotides (A, T, G, C)
What are the two types of nucleic acid polymers? (aka Polynucleic acids)
The two types of nucleic acid polymers are DNA (deoxyribonucleic acid) and RNA (ribonucleic acid)
What do DNA molecules do?
The DNA molecules of humans are enormous polymers that encode hereditary information bound in nucleotides
What do RNA molecules do?
The RNA molecules carry out the instructions encoded in DNA
What is the structure of DNA?
A double helix
What are the 3 nitrogenous bases?
Cytosine, thymine, and uracil
- Uracil is only present in RNA (it replaces thymine in RNA molecules)
What are the 2 purines?
Adenine and guanine
What are the 2 pentose sugars?
Deoxyribose (in DNA)
Ribose (in RNA)
What are the three main structural differences between DNA and RNA?
- RNA has ribose, which has oxygen at carbon 2 of the sugar (two OH instead of one)
- Instead of having thymine, RNA molecules have uracil
- RNA is single stranded (single helix instead of double helix)
When it comes to purine and pyrimidine bases, which is the small structure and which is the large structure?
Purine base = smaller word but BIGGER structure
Pyrimidine base = larger word but SMALLER structure
What are the nucleotide pairings?
A pairs with T (or U), C pairs with G
- Every pairing needs 1 purine and 1 nitrogenous base
