Biochem #5 Flashcards
lipids
characterized by insolubility in water and solubility in nonpolar organic solvents.
o Serve roles in structural, signaling, and energy storage.
each of the membrane components of lipids is an _____ molecule, meaning it has both hydrophilic and hydrophobic regions.
amphipathic
phospholipids
contain the following elements: a phosphate and alcohol that comprise the polar head group, joined to a hydrophobic fatty acid tail by phosphodiester linkages.
o Can be classified based on their backbone
Ex: glycerol forms phosphoglycerides.
phosphodiester linkage
phosphate group in between two oxygens.
all lipids share the _____
long chain fatty acid tail
saturated fatty acid
fully single bonds, greater Van der Waals, and more stable, form solids at room temperature (butter), straight down
unsaturated fatty acid
includes one or more double bonds, which introduce kinks and make them hard to stack and solidify, liquids at room temperature (olive oil)
what are the two properties that determine lipid properties?
determined by the degree of saturation in fatty acid chains and the functional groups to which the fatty acid chains are bonded.
glycerophospholipids/phosphoglycerides
specifically, those phospholipids that contain a glycerol backbone bonded by ester linkages to two fatty acids and by a phosphodiester linkage to a highly polar head group.
o Head groups differ and glycerophospholipids are named based on their head group.
Head can be positive, negative, or neutral.
Ex: phosphatidylcholine (with a choline head group)
sphingolipid
o Sphingolipids have a sphingosine ORRRRR sphingoid (sphingosine-like) backbone, as opposed to the glycerol backbone of glycerophospholipids.
o Also have long-chain nonpolar fatty acid tails and polar head groups
o Can be both phospholipids or glycolipids (contain glycosidic linkages to sugars)
o Divided into four major subclasses, differing by their head groups
1. ceramide
2. sphingomyelins
3. glycosphingolipids (glycolipids)
4. ganglioside
ceramide
sphingolipid
the simplest, which has a single hydrogen atom as its head group.
Sphingomyelins
sphingolipid
major class of sphingolipids that are also phospholipids.
• Have a phosphodiester bond and the head has no net charge.
• Major components of the plasma membranes of cells producing myelin.
glycosphospholipids
sphingolipid head groups composed of sugars bonded by glycosidic linkages. Glycolipid. • NOT phospholipids. • Broken down further o 1. Cerebrosides: have a single sugar o 2. Globosides: have two or more sugars. • no net charge at physiological pH found on the outside of plasma membrane
gangliosides
sphingolipid
most complex sphingolipid. Also a glycolipid.
• Have polar head groups composed of oligosaccharides with one or more NANA (sialic acid) molecules and a negative charge.
waxes
esters of long chain fatty acids with long chain alcohols.
o Pliable solids at room temperature.
o Function as protection for both plants and animals. Also in animals they prevent dehydration, act as lubricant and water repellent
o Structure building: bee hives.
what are the precursors to steroids and other lipid signaling molecules and have varied independent function
terpenes and terpenoids
terpenes
: class of lipids built from isoprene moieties and share a common structural pattern with carbons grouped in multiples of five. (C5H8).
Produced mainly by plants and insects (insect’s protective mechanism)
Can be good smelling or bad smelling, contribute to many scents.
Grouped according to the number of isoprene units present (with a single terpene unit containing two isoprene units):
• Monoterpene (C10H16): found in essential oils and turpentine
• Sesquiterpenes: contain three isoprene units.
• Diterpenes: contain four isoprene units
• Triterpenes: contain six isoprene units, can be converted to cholesterol and various steroids.
• Tetraterpenes: have eight isoprene units.
o Ex: carotenoids, like beta-carotene
diterpene has how many terprene units and how many carbons
2 terpene units and 4 isoprene units (20 carbons)
terpenoids
(isoprenoids): derivatives of terpenes that have undergone oxygenation or rearrangement of the carbon skeleton.
Named similar to terpenes.
Contribute to steroid biosynthesis and many scents.
steroids
structurally, are metabolic derivatives of terpenes and are very different from phospholipids.
Have 4 cycloalkane rings fused together (3 cyclohexane and 1 cyclopentane)
Nonpolar
Functionality is determined based on oxidation status of the rings and functional groups that they carry.
steroid vs. phospholipid structure
steroid has the many ring structure
steroid hormones
steroids that act as hormones, secreted by the endocrine glands into the bloodstream and then travel on protein carriers to distant sites, where they can bind to specific high-affinity receptors and alter gene expression.
Ex: testosterone, various estrogens, cortisol, and aldosterone.
cholesterol
a steroid of primary importance.
Part of the phospholipid bilayer and mediates membrane fluidity.
Is amphipathic
Adjusts membrane/keeps it intact at high and low temperatures.
Precursor for steroid hormones, bile acids, and vitamin D
prostaglandins
unsaturated carboxylic acids derived from arachidonic acid and contain one five-carbon ring.
Signaling molecule, can act as paracrine or autocrine signaling molecules
Regulate the synthesis of cAMP (involved in the pathway that causes pain, as well as other pathways)
• Have powerful effects on smooth muscle contraction, body temperature, the sleep-wake cycle, fever, and pain.
vitamin
an essential nutrient that cannot be adequately synthesized by the body and therefore must be consume in the diet.
what are the fat soluble vitamins
ADEK
vitamin A
A (carotene): important in vision, growth and development, and immune function
• Retinal: component of light-sending molecular system in the human eye
• Retinol: the storage form of vitamin A
• Retinoic acid: a hormone that regulates gene expression
Vitamin D
(cholecalciferol): can be consumed or formed in UV light-driven reaction in the skin
• In the liver and kidneys, it is converted to calcitriol, biologically active Vitamin D.
• Calcitriol increases calcium and phosphate uptake in the intestines, which promotes bone production.
• Rickets: a condition seen in children and characterized by underdeveloped, curved long bones as well as impeded growth.
Vitamin E
characterizes tocopherols and tocotrienols.
• Antioxidant, destroys free radicals and prevents oxidative damage.
Vitamin K
includes phylloquinone (K1) and menaquinones (K2). • Important for blood clotting. • Also introduces calcium binding sites on several calcium-dependent proteins
triacylglycerols (triglycerol)
class of lipids specifically used for energy storage. 1. The carbon atoms of fatty acids are more reduced than those of sugars, and therefore oxidation of triacylglycerols yields 2x the energy. 2. They are hydrophobic which helps decrease their weight because they do not need hydration for stability like hydrophilic polysaccharides.
o Composed of three fatty acids bonded by ester linkages to glycerol
Rare for all 3 fatty acids to be the same.
o Adipocytes: store large amounts of fat and are found primarily under the skin, around mammary glands, and in the abdominal cavity.
o Storage of triacylglycerols in adipose tissue.
adipocytes
cells in animals that store large amounts of fat and are found primarily under the skin, around mammary glands, and in the abdominal cavity.
o Storage of triacylglycerols in adipose tissue.
