CHEM - LIPIDS 2.0

What is a lipid?

• class of naturally occurring organic molecules

• categorized based on similar solubility characteristics:

  • insoluble in water

  • soluble in organic solvents (ie. other lipids)

What is the significant of lipids in saliva?

• contains fatty acids, triglycerides, glycerophospholipids, sphingolipids and cholesterol

• these rations can change during times of disease

What is the significance of lipids in dental calculus (hardened plaque)?

lipids make up 10% of calculus (proteins make up 50)

What is the significance of lipids to caries?

High levels of triglycerides in children’s saliva is correlated to early childhood caries

What are the functions of lipids?

1. Structure of Membranes - separates aqueous cellular environments, binds cells together

2. Storage - storing metabolic fuel → specialized fat storing cells: adipocytes

3. Transport of Metabolic Fuel

4. Insulation - heat loss, injury prevention, nerve impulses

5. Chemical Signalling - steroids/hormones

What are the 4 types of lipids?

1. Fatty Acids -

• long chain carboxylic acid

• free + esterfied

2. Lipids with Glycerol

• mono/di/tri-glycerols

• glycerophospholipids

1. Lipids w/o Glycerol

• sphingolipids - cermides, sphingomyelin

• steroids

• vitamins

1. Lipids attaches to other molecules

• lipoproteins (LDL, HDL, ect)

What functional group is this?

Carboxyl

What functional group is this?

an Ester

What functional group does this image correspond to?

an alcohol

What molecule is this?

Glycerol (prop-1,2,3-triol)

What are simple lipids?

• fatty acids

• fatty acid esters

• triglycerides

What are the 2 categories of complex lipids?

→ Phospholipids - sphingolipids and glycerophospholipids

→ Glycolipids (have glucose/galactose)

What are complex lipids?

• typically amphipathic

• have polar/non-polar groups

• often present in membranes

What are fatty acids?

long chain carboxylic acids

What lipid has the ratio 16:0?

plamic acid

What lipid has the ratio 18:0?

stearic acid

What lipid has the ratio 18:1?

Oelic acid

Saturated vs. Unsaturated

SATURATED -

• has single bonds

• increased saturation = increased BP

• usually solid (can pack tight)

UNSATURATED -

• has double bonds

• lower melting points

• rigid bonds (prevents tight packing)

How does carbon chain length affect solubility?

The longer the carbon chain, the less soluble the molecule becomes

How does saturation affect solubility?

More saturated molecules typically have lower water solubility

What is the optimal temperature for a human being?

37 degrees

What types of fatty acids are animal fats and vegetable oils?

triglycerides (fatty acid tri-esters → have 3 ester bonds)

Why do animals store energy as lipids and plants as carbohydrates?

• Lipids allow animals to store more energy per/g (9kcal/g) than carbohydrates. This allows them to move energy easier without being weighted down

• Plants do not need to move and therefore store energy as carbohydrates. Carbohydrates are also water soluble allowing for easy transport of energy

What type of linkages occur in DNA, RNA and nucleotide molecules (ATP)?

• phosphoester linkages between phosphate groups

• glycosidic linkages between the base and the sugar

(phosphoric anhydride bonds?)

How much ATP does the heart typically use per day?

35kg of ATP/day

What are triglycerides?

• most abundant lipids in human

• 3 fatty acid molecules attached to a glycerol by ester linkage

(aka treaclyglycerols)

Where are triglycerides commonly found?

→ Deposition Lipids (storage) - adipocytes

→ Dietary Lipids - >90% of lipids

→ Transport lipids - chylomicrons

What are oils?

• triglycerides rich in unsaturated fatty acids

• usually liquid at room temp

What are fats?

• triglycerides rich in saturated fatty acids

• usually semi-solid @ room temp

What are lipases?

enzymes that hydrolyze and release fatty acids (hydrolysis)

Where do variation in dietary fatty acids occur (ie. beef tallow vs. olive oil)?

in the saturation and amount of cholesterol

What are phosphoglycerides?

• the second most abundant group of naturally occurring lipids

• contain glycerol and phosphate

What is Lecithin?

• the most abundant glycerophospolipid

• a natural supplement found in eggs and soy beans

• rich in choline

What is the most abundant lipid in cell membranes?

phospatidylcholine (phosphoric acid + choline w/ flexible HC chains)

What molecule is this?

Lecithin

What functional group is this?

Phosphate

What functional group is this?

Choline

What is the physiological pH of the body?

What are Sphingolipids?

• long chain amino alcohols → sphingosine

• may be found in the coating of nerve axons (myelin sheath)

What is this molecule?

Sphingosine

What are glycolipids?

• complex lipids that contain a carbohydrate (glucose/galactose) and a sphingosine

• ex. Cerebrosides

What are cerebrosides?

• glycolipids commonly found in brain cell membranes and myelin of oligodendrocytes

• accounts for 7% of dry brain mass

• ceramide monosaccharides

What is the function of Sphingomylein, cerebrosides and cholesterol?

Increase electrical resistance across the bilayer (ie. increase insulation)

What is white matter?

• region of the CNS that contains myeline sheath (insulating coating)

• majority of the coating is sphingomyelin

What do Shwann cells do?

produce myelin

What is MS?

The demyelination of white matter, causing decreased nerve transmission

What are steroids?

• lipid

• derivative of perhydrocyclopentaphenanthrene (tetracyclic ring structure)

• most are biological regulator compounds, especially hormones

ex. testosterone, cholesterol, dianabol, estrogen

What are hormones?

substance produces by a cells system and is delivered by the bloodstream to a remote target system

What are androgens?

• male sex hormone

• matures 2nd male sex characteristics

What are Estrogens?

• female sex hormones

• matures 2nd sex characteristics

• controls the menstrual cycle

What are Adrenocorticoid Hormones?

• glucocorticoids

  • regulation of carbohydrate metabolism

  • synthesized in the adrenal cortex

• mineralocorticoid - K+, Na+ regulation

What is signal transduction?

a set of biochemical mechanisms which transmit extracellular signals inside the cell and target the proteins which control either metabolic or gene expression

What does the Agonist do in Signal Transduction?

binds to receptors to activate:

→ Endogenous (hormones)

→ Exogenous (drugs)

What does the Antagonist do in Signal Transduction?

binds to a receptor to block agonist and reactive the receptor

What is the purpose of second messengers?

• relay signals between receptor proteins and target proteins

• produced by hydrolysis of glycerophospholipids

• amplifies messages

What is Catabolism?

Breakdown of macromolecules

What is anabolism?

Buildup of macromolecules

What are nutrients?

Set components in an organisms diet required for growth, replacement and energy

What are macronutrients?

molecules necessary for energy

ex. carbohydrates, fats (oils), proteins

What are micronutrients?

essential minor dietary compounds

ex. Vitamins (organic compound)

Minerals (inorganic compounds)

Which Vitamins are lipids soluble?

→ Vitamin A - for vision

→ Vitamin D3 - regulates calcium and phosphorous metabolism

→ Vitamin E - serves as an antioxidant, aids in reproduction

Which vitamins are water soluble?

→ Vitamin C

→ Vitamin B3

What is Vitamin A?

• unsaturated hydrocarbon with a polyene

• lipid soluble

• forced from beta-carotene

• retinal is an aldehyde derivative of Vitamin A bound to a protein opsin in the rod cell of the eye

• deficiency = night blindness (enamel hypoplasia)

rec 1mg/day otherwise toxic

What is Vitamin D3?

• steroid derived molecule

• lipid soluble

• formed from cholesterol + UV from the sun

• presence of D3 increase synthesis of Ca2+ binding protein = increase absorption of dietary calcium (increased calcium uptake by the teeth)

• deficiency = softening of the bones → Rickets and Enamel Defects

rec. 5ug/day

What are Low Density Lipoproteins (LDL)?

• remains in the plasma for 2-3 days and carries cholesterol to the cells

• most of the cholesterol in the blood is carried by LDL - has about 175mg cholesterol/ 100ml of blood

APOLIPOPROTEIN (APOB-100)

• LDL

• single peptide chain

• core = hydrophobic

• surface = hydrophilic

• peripheral proteins allow LDL to be recognized by the cells

• allows cells to obtain cholesterol