Chem 120 Exam 5

glycerides (type of lipid)

glycerol-containing lipids

nonglyceride lipids (type of lipid)

sphingolipids, steroids, and waxes

complex lipids (type of lipid)

lipoproteins

the 7 lipid functions

1) energy source

2) energy storage

3) cell membrane structural components

4) hormones

5) vitamins and vitamin absorption

6) protection

7) insulation

energy currency for lipid function

ATP (Adenosine triphosphate)

Energy storage of lipids

in the form of triglycerides and stored in adipocyte cell

lipid function: energy source

good energy source

(more than 2x the energy is produced than the same amount of carbohydrates)

lipid function: cell membrane structural components

phosphoglycerides, sphingolipids, and steroids are basic structural components of all cell membranes.

lipid function: hormones

critical chemical messengers that allow body tissue to communicate with each other

lipid function: vitamins and vitamin absorption

lipid-soluble vitamine A,D,E, and K

Vitamin carrier transport to small intestines

lipid function: protection

fat serves as a shock absorber for vital organs

4% of total body fat is reserved for this critical function

lipid function insulation

fat stored under skin for cold temperatures

saturated fatty acids

has no double bonds

higher MP and BP because of packing

solid at room temperature

unsaturated fatty acids

do have a double bond

the double bond is normally in a cis configuration

double bonds lower the melting temperature

(the cis configuration doesn’t allow fatty acids to pack as close together)

liquid at room temperature

eicosapentaenoic acid (EPA) and docsahexenoic acid (DHA) where are they found?

Omega-3 Fatty acid

found in salmon, albacore tuna, sardines, lake trout and mackerel

a-linolenic acid where is this found?

Omega-3 Fatty Acid

* found in flax seed, soybean, canola
* is essential fatty acid- must be acquired through diet

Omega-3 structure

draw it out

prostaglandins (describe and draw) (Eicosanoids)

Eicosanoids: Omega-3 Fatty acid

* act like hormones in controlling the body’s processes
* made in most tissues
* exert their effects on cells that produce them and cells in the immediate vicinity

6 Biological Processes Regulated by Eicosanoids (and structure)

blood clotting

inflammatory response

reproductive system

gastrointestinal tract

kidneys

respiratory tract

thromboxane

lipid

draw it out roughly

Leukotriene

lipid

draw it out roughly

aspirin

lipid

inhibits prostaglandin (stimulates inflammation response) synthesis and helps alleviate the pain

glycerides and what you can make out of it.

lipid esters

esterification may occur at one, two, or all three alcohol positions producing

* monoglyceride
* diglycerides
* triglyceride

monoglyceride

lipid ester

has a fatty acid chain at one alcohol group of the glycerol

triglycerides

fatty acid chain at each alcohol group of the glycerol

Fats

come from animals, unless from fish, and are solid (higher MP) at room temp

have saturated fatty acid tails- pack closely together

oils

come from plants, and are liquid (lower MP) at room temp

contain unsaturated fatty acid tails that are kinked- can’t pack as closely together

esterification

reaction between the carboxyl of the fatty acid and the hydroxyl of an alcohol

hydogenation

addition reaction of H2 converts unsaturated to saturated fat, food industry

acid hydrolysis

produces the fatty acids and glycerol, a reverse of esterification

saponification

produces the fatty acid salts and glycerol; makes soap

what is phospholipid

any lipid containing phosphorus

what do phospholipids contain

* glycerol
* fatty acid
* phosphoric acid with an amino alcohol

what is amphipathic

are phospholipids amphipathic?

have hydrophobic and hydrophilic domains

yes they are…

* head is hydrophilic, tail is hydrophobic

structure of phospholipids

replace an end fatty acid of a triglyceride with a phosphoric acid linked to an amino alcohol

phosphoglycerides in cells

structural component of cell membranes

suspended in water, they spontaneously rearrange into ordered structures

* hydrophobic group to center
* hydrophilic groups to water
* basis of membrane structure

sphingosine (sphingolipids) and it’s categories

* nitrogen-containing
* amphipathic, like phospholipids
* polar head group
* two nonpolar fatty acid tails (1 being sphingosine)
* structural component of cellular membranes
* two major categories
* sphingomyelins
* glycosphingolipids

sphingomyelins

phospholipids

* structural lipid of nerve cell membranes
* myelin sheath feature

glycosphingolipids

phospholipid

* built on a ceramide
* cerebrosides have a single monosaccharide head group

2 Examples of glycosphingolipids and structures

glucocerebroside

galactocerebroside

glucocerebroside- in membranes of macrophages

galactocerebroside- in membranes of brain cells

steroid

are synthesized from the five-carbon isoprene unit

part of a diverse collection of lipids called isoprenoids

* terpenes

contain the steroid carbon skeleton

* a collection of 4 fused carbon rings

LDL

“bad cholesterol”

carry cholesterol from liver to peripheral tissue

helps regulate cholesterol levels in those tissues

frequently 40% of the plasma cholesterol

HDL

“Good cholesterol”

picks up cholesterol for removal for recycling

made in liver

lipoprotein structure

contain:

neutral lipid core (cholesterol ester or triacylglycerol)

surrounded by a layer of

* phospholipid
* cholesterol
* protein

structure of a soap micelle and a lipoprotein are very similar

chylomieron

transport triglycerides from intestines to other tissue

VLDL

bind triglycerides synthesized in liver and carry to adipose tissue and other tissue for storage

Familial hypercholesterolemia

LDL receptor was discovered during an investigation of this genetic disease

* when a cell needs cholesterol, it synthesizes the receptor, which migrates to a coated region of the membrane


* the “captured” cholesterol is absorbed by endocytosis


* failure to make the receptor or a defective receptor is the most common problem encountered for familial hypercholesterolemia.

receptor-mediated Endocytosis drawn out

draw out

lipitor

synthesis of cholesterol by interfering with the enzyme HMG-CoA reductase

* blocks synthesis of Cholesterol inside cells
* stimulates synthesis of LDL-receptor proteins
* more LDL can then enter cells lowering cholesterol levels in plasma

each type of cell has a unique membrane composition with varying percentages of…

lipids, proteins, and some carbohydrates

fluid mosaic model

of a lipid bilayer- lipids are can move (are “fluid”) and are interspersed with proteins much like a mosaic

what does the degree of saturated vs. unsaturated fatty acids and amount of cholesterol effect

rigidity/fluidity of membrane

peripheral membrane proteins

are bound to membranes primarily through interactions with integral protiens

transmembrane proteins (integral membrane proteins)

embedded in and extend through the membrane

drawn out membrane layer with peripheral and integral proteins

drawn out

Fluid Mosaic Model of Membrane Structure drawn out

drawn out

essential fatty acid

any fatty acid that cannot be synthesized by the body

Protein meaning

“of first importance”

most abundant macromolecule in the cell

polymers of proteins

amino acid → folded protein

8 functions of Proteins and a brief description

structure

* coverings and structure (collagen)

catalyst

* enzymes (accelerate chemical reactions)

movement

* muscles, flagella

regulation

* regulate metabolism, gene expression

transport

* move material around in the body

hormones

* chemical messengers

protection

* antibodies, blood clotting

storage

* storage of materials

draw amino acid molecule

out of 20 how many amino acids are stereoisomers

19/20

Zwitterion

a molecule that contains positive and negative charges in equal amounts to have a net zero charge

amino acid Zwitterion pH

At physiological pH (7.0)

are amino acids soluble

Amino acids are all soluble in water because of zwitterion formation.

what will happen to the charges of amino acids at extremely acidic and basic conditions

\+=acid

\-=basic

isoelectric point

pH at which a sample of amino acids or proteins has an equal number of positive and negative charges

D and L isomers drawn out

L is the naturally occurring one

hydrophobic

water fearing

non-polar neutral-- no charge

hydrophillic

water loving

polar

acidic → negatively charged side chains (-)

basic → positively charged side chain (+)

peptide bond

an amide bond between the a-amino group of one amino acid and the carboxylic acid of another amino acid eliminating a molecule of water

peptides

shorter chains of amino acids

dipeptide

when 2 amino acids are condensed or dehydrated

polypeptides

longer chains are of amino acids

N-terminus

the end containing the amino acid with a free -NH3+ group/amino group

C-terminus

the end containing the amino acid with a free -COO- group/carboxyl group

primary structure

amino acid sequence of the polypeptide chain “beads on a string”

second structure

the primary sequence of the polypeptide folds into regularly repeating structures called the secondary structure

* a-helix (most common)
* B- pleated sheet

tertiary structure

three-dimensional folding pattern of a protein due to side chain interactions

* fibrous- insoluble
* globular- soluble

in 3\* *and 4*\* conformations are stabilized in four ways

1. covalent bonds: disulfide bonds (S-S)
2. hydrogen bonds
3. salt bridges: the attraction between ions of opposite charge. + attracted to -
4. hydrophobic interactions: polar groups outward towards water; non-polar groups inward away from water-- London dispersion

quaternary protein structure

2 or more polypeptide chains held together

4 subunits

Fibrous proteins

proteins arranged in fibers or sheets, insoluble in water. Exp: hair, nails, horns, collagen

* mechanical strength
* structural components
* movement

Globular proteins

protein with a generally spherical shape, soluble in water Exp: myoglobin, hemoglobin, immunoglobins

* transport
* regulatory
* enzymes

hemoglobin

is the oxygen-transport protein of higher animalsm

myoglobin

is the oxygen storage protein of skeletal muscle

prosthetic group

a nonprotein molecule that binds to a protein

Heme

oxygen binds to it, it is a prosthetic group

it has iron (Fe2+) in it

protein denaturation

when the protein unfolds, i.e. the secondary, tertiary, and quaternary structure is disrupted, and the protein loses its 3-D shape

coaguation

proteins are unfolded and entangled

6 causes of protein denaturation

\-temp (coagulation)

\-pH (Acids and Bases)

\-organic solvents like alcohol

\-detergents

\-heavy metals

\-mechanical stress (stirring,whipping, and shaking)

catalyst

chemical that increases the rate of a chemical reaction

\-metals

\-polymers

\-proteins

enzyme and naming of one

a biological catalyst, typically a protein

add -ase to end of name

oxidoreductase definition

catalyzes an oxidation/reduction reaction(transfers electron)

transferase definition

transfers a functional group

hydrolase definition

causes hydrolysis reaction (addition of H2O to break a bond)

ligase definition

typically joins pieces together and often breaks/makes C-O, C-C, or C-N bonds(DNA ligase in DNA replication)

Isomerase definition

rearranges functional groups(change shape)

lyase definition

forms/breaks double bonds by removing/adding groups other than by hydrolysis(look for double bonds)

oxidoreductase reaction

transferase reaction