CHEMISTRY!

estrogens

group of female sex hormones, direct the development of female sexual characteristics: the uterus increases in size, fat is deposited in the breasts, and the pelvis broadens.

Omega 6 Fatty Acids

in which the first double bond occurs at carbon 6 counting from the methyl end of the carbon chain.

Cortisone

increases the blood glucose level and stimulates the synthesis of glycogen in the liver.

Cortisol

is released under stress to increase blood sugar and regulate carbohydrate, fat, and protein metabolism.

Aldosterone

is responsible for the regulation of electrolytes and water balance by the kidneys.

Progesterone

prepares the uterus for the implantation of a fertilized egg. If an egg is not fertilized, the levels of progesterone and estrogen drop sharply, and menstruation follows.

Male sex hormones - Testosterone and androsterone

promote the growth of muscle and facial hair, and the maturation of the male sex organs and of sperm.

omega-3 fatty acids

the fatty acids in fish oils are mostly the omega-3 type, in which the first double bond occurs at the third carbon counting from the methyl group.Three common omega-3 fatty acids (or ω-3ω-3 fatty acids) in fish are linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA).

Steroid Hormones

which include the sex hormones and the adrenocortical hormones, are closely related in structure to cholesterol and depend on cholesterol for their synthesis

Cholesterol

which is one of the most important and abundant steroids in the body, is a sterol because it contains an oxygen atom as a hydroxyl group (—OH)(—OH) on carbon 3.

Lipoproteins

They are made more soluble by combining them with phospholipids and proteins to form water-soluble complexes called

Steroids

are compounds containing the steroid nucleus, which consists of three cyclo-hexane rings and one cyclopentane ring fused together. The four rings in the steroid nucleus are designated A, B, C, and D.

Waxes and Triacylglycerols

A wax is an ester of a long-chain fatty acid and a long-chain alcohol. The triacylglycerols are esters of glycerol with three long-chain fatty acids. Fats contain more saturated fatty acids and have higher melting points than most vegetable oils.

Cell Mebranes

All animal cells are surrounded by a semipermeable membrane that separates the cellular contents from the external fluids. The membrane is composed of two rows of phospholipids in a lipid bilayer. Proteins and cholesterol are embedded in the lipid bilayer, and carbohydrates are attached to its surface. Nutrients and waste products move through the cell membrane using passive transport (diffusion), facilitated transport, or active transport.

What is the function of cholesterol in the cell membrane?

Cholesterol adds strength and rigidity to the cell membrane.

Why is cholesterol in the lipid family?

Cholesterol is not soluble in water; it is classified with the lipid family.

Fatty Acids

Fatty acids are unbranched carboxylic acids that typically contain an even number (12 to 20) of carbon atoms. Fatty acids may be saturated, monounsaturated with one double bond, or polyunsaturated with two or more double bonds. The double bonds in unsaturated fatty acids are almost always cis.

Phospholipids

Glycerophospholipids are esters of glycerol with two fatty acids and a phosphate group attached to an ionized amino alcohol. In a sphingomyelin, the amino alcohol sphingosine forms an amide bond with a fatty acid, and phosphoester bonds to phosphate and an ionized amino alcohol.

Cholestorol

If a diet is high in cholesterol, the liver produces less cholesterol. A typical daily American diet includes 400 to 500 mg of cholesterol. Should not eat more than 300g

Lipid Bilayer

In a cell (plasma) membrane, two layers of phospholipids are arranged with their hydrophilic heads at the outer and inner surfaces of the membrane, and their hydrophobic tails in the center. This double layer arrangement of phospholipids. The outer layer of phospholipids is in contact with the external fluids, and the inner layer is in contact with the internal contents of the cell.

Describe the role of phospholipids in the lipid bilayer.

Phospholipids consist of polar and nonpolar parts. In a cell membrane, an alignment of the nonpolar sections toward the center with the polar sections on the outside produces a barrier that prevents the contents of a cell from mixing with the fluids on the outside of the cell.

Cell Membrane

Semipermeable so that nutrients can enter the cell and waste products can leave.The main components of a cell membrane are the glycerophospholipids and sphingolipids.

17.6 Steroids: Cholesterol, Bile Salts, and Steroid Hormones

Steroids are lipids containing the steroid nucleus, which is a fused structure of four rings. Steroids include cholesterol, bile salts, and steroid hormones. Lipids, which are nonpolar, are transported through the aqueous environment of the blood by forming lipoproteins. Bile salts, synthesized from cholesterol, mix with water-insoluble fats and break them apart during digestion. Lipoproteins, such as chylomicrons and LDL, transport triacylglycerols from the intestines and the liver to fat cells and muscles for storage and energy. HDL transports cholesterol from the tissues to the liver for elimination. The steroid hormones are closely related in structure to cholesterol and depend on cholesterol for their synthesis. The sex hormones, such as estrogen and testosterone, are responsible for sexual characteristics and reproduction. The adrenal corticosteroids, such as aldosterone and cortisone, regulate water balance and glucose levels in the cells, respectively.

corticosteroids

The adrenal glands, located on the top of each kidney, produce a large number of compounds

Bile Salts

The bile salts in the body are synthesized from cholesterol in the liver and stored in the gallbladder. The bile salts with their nonpolar and polar regions act much like soaps, breaking down large globules of fat into smaller droplets. When large amounts of cholesterol accumulate in the gallbladder, cholesterol can become solid, which forms gallstones

What features have been added to the steroid nucleus in cholesterol?

The cholesterol molecule contains a hydroxyl group (—OH)(—OH) on the first ring, one double bond in the second ring, methyl groups (—CH3)(—CH3) at carbons 10 and 13, and a branched carbon chain.

What part of cholesterol is the steroid nucleus?

The four fused rings form the steroid nucleus.

Chemical Properties of Triacylglycerols

The hydrogenation of unsaturated fatty acids of a triacylglycerol converts double bonds to single bonds. The hydrolysis of the ester bonds in triacylglycerols in the presence of a strong acid produces glycerol and fatty acids. In saponification, a triacylglycerol heated with a strong base produces glycerol and the salts of the fatty acids (soap).

What classifies cholesterol as a sterol?

The hydroxyl group determines the sterol classification.