lecture 3 Flashcards
Define de novo synthesis
The formation of complex molecules from simpler molecules or precursors through a certain biochemical pathaway. De novo means from the beginning so basically you are syntheizing molecules from scratch
Define stereoisomers
are molecules that have the same chemical formula and the same order of atoms (connectivity) but differ in how the atoms are arranged in 3D space.
define Geometrical Isomers (Cis/Trans):
Atoms differ in arrangement around a double bond or ring
define structural isomers
are compounds that have the same molecular formula but differ in the connectivity of their atoms
define positional isomers
The functional group is attached at different positions on the main chain.
what makes something chiral
It has 4 different atoms attached to the carbon, it has no plane of symmetry (non superimposible mirror image)
differentiate between in vivo and in vitro
The difference lies in where the study/experiment takes place. In vivo (within the living) is when testing is done in living organim or cell like in a human, animal or plants. In vitro is done (within the glass) outside the living organims so like in a test tube, using a dead organims or a tissue extract
define geometrical isomerization
modification of the configuration of the ethylenic double bond
what are the categories of classification of lipids
- physical state at room temperature (solid or liquid)
- polarity (polar or neutral)
- essentiality for humans (essential or non essential)
- structure (simple, derivived, complex)
classify lipids based on polarity
polar= glycerophospholipids, glycerolglycolipids
neutral (most lipids)= fatty acids, alcohols, glycerides, sterols
why do VSCFA exhbit polarity?
The hydrophilic carboxyl group dominates due to the lack of a long hydrophobic chain
classify fatty acids based on their chain length
- less than 4= very short chain fatty acids
- 4-10= short chain fatty acids
- 12-14= medium chain fatty acids
- 16-18= long chain fatty acids
- more than 20= very long chain fatty acids
what are the 3 ways in which trans fatty acids can originate?
- from bacteria due to biohydrogenation
- from the deodirzation of oils
- partial hydrogenation
describe biohydrogenation and why it happens
Biohydrogenation is a metabolic adaptation by bacteria to convert unsaturated fatty acids into saturated forms. This occurs in the rumen of the animal which has aneorbic conditions. And during this process trans fatty acids are formed and will accumulate in the animals resulting in trans fat in dairy products and meat. This is done as an adaptation response as saturated fats are more stable and is better for the bacteria in the rumen.
describe deodirization of oils and why its done and how it forms trans fatty acids
It is a refining process done to remove odors, flavors etc. This process is typically done under heat which can result in cis unsaturated fatty acids to isomerize into trans ones. This is especially seen in oils rich in polyunsaturated fatty acids like soybean and sunflower oils.
define partial hydrogenation
Partial hydrogenation is a chemical process in which hydrogen is added to some, but not all, of the double bonds in unsaturated fatty acids, often converting them into trans fats as intermediates.
Why can plants and not humans synthesize omega 3 and 6?
Because plants can synthesize via de novo pathaway and have the needed desaturase enzymes, which humans do not.
can animals synstheize omega 3 and 6
- No animals can make omega-3 and omega-6 fatty acids de novo—they must get them from their diet.
- Some animals can convert and elongate essential fatty acids to form other biologically important compounds (e.g., EPA, DHA, AA), but they still rely on dietary precursors
cholesterol can oxidize in?
in vivo and during food processing
what is it called when a phospholipid has a fatty acid removed in the sn-2 posiition
lysophospholipids
how is fluidity mainatined in relation to phospholipifs
the fatty acid at the Sn-2 position is typically more saturated than at the sn-1 position
hiw is cis form of vitamin A formed?
via light induced isomerization
what is the DV of vitamin A and what is a toxic amount?
DV= 1000 retinol equivalents, but exceed 15000 and ur cooked
how is vitamin D3 synthesized in humans?
using 7-dehydrocholesterol, occurring
naturally in the skin via light irradiation