CHAPTER 3Molecules of Life

ORGANIC COMPOUNDS

Compounds with hydrogen and other elements covalently bonded to carbon (hydrocarbons have ONLY hydrogen atoms bonded to carbon like gasoline and fossil fuels)

carbohydrates

lipids

proteins

nucleic acids

CARBON BONDING BEHAVIOR

outer shell has 4 electrons, can hold 8, forming up to 4 covalent bonds

PATTERNS

chains or rings formed, using carbon as the backbone (brown)

AN ORGANIC COMPOUND

different representations of hemoglobin

FUNCTIONAL GROUPS

atoms or groups of atoms covalently bonded to the carbon backbone

responsible for different properties of organic compounds

cells keep pools of organic compounds for building larger molecules or as energy source

SOME FUNCTIONAL GROUPS

hydroxyl group (alcohols, sugars) -OH-

amino group (amines, amino acids) -NH3 -

carboxyl group (fatty acids) -COOH

phosphate group (DNA, RNA, ATP) -PO3 +

sulfhydryl group (protein stabilizers) -SH

AN EXAMPLE

estrogen and testosterone have different positions of functional groups which make differences in male and female wood ducks

TYPES OF REACTIONS

functional group transfer- molecule gives up its functional group, another accepts

electron transfer- one or more electrons given from one molecule to another

rearrangement- changing of internal bonds converts one molecule to another

condensation

cleavage/ hydrolysis

CONDENSATION RXN.

build polymers from subunits (monomers)

enzymes remove -OH from one molecule and H from another, making water as the two bond

HYDROLYSIS RXN.

type of cleavage reaction breaking polymers into subunits

enzyme breaks molecule in two or more sites, exposed sites get -OH and H attached from water

CARBOHYDRATES

monosaccharides are simple sugars with one subunit, used for fuel, structural units (glucose, fructose, ribose, deoxyribose)

disaccharides are two monosaccharides, used as self recognition markers on cells, cell receptors (maltose, lactose, sucrose, table sugar is made from sugar cane and sugar beets)

oligosaccharies are short chain carbohydrates with two or more subunits (include disaccharides like sucrose, table sugar, cell surface flags)

polysaccharides have many subunits and are complex carbohydrates (starch, cellulose, glycogen)

MONOSACCHARIDES

glucose fructose

DISACCHARIDES

condensation reactions

glucose + glucose = maltose

glucose + galactose = lactose

glucose fructose

sucrose

POLYSACCHARIDES

straight or branched chains of many sugar monomers, most common include only glucose

cellulose and starch differ in the bonding patterns producing a tough, indigestible, structural component in plants (cellulose) and an easily digestible, stored starch product in plants

CELLULOSE AND STARCH

GLYCOGEN

storage of sugars in animals

large stores in liver, muscle

low blood sugar makes liver cells break down glycogen and release glucose into blood, used for brief burst of exercise

ANOTHER POLYSACCHARIDE

chitin is structural component of animal exoskeletons and fungal cell walls

nitrogen containing groups attached to glucose monomers

LIPIDS

FATS contain fatty acids: long hydrocarbon chains with terminal carboxyl group

FATS include triglycerides, phospholipids, waxes

STEROLS have no fatty acids

all insoluble in water

FATTY ACIDScarboxyl group at one end -COOH

carbon backbone, up to 36 carbons

saturated fatty acids have only single bonds between carbon atoms, are solid at room temp, ex. butter, lard

artificial saturated fats are hydrogenated oils, made solid at room temp. by putting H atoms on mol., creates “trans” shape that body has trouble dealing with

unsaturated fatty acids contain double bonds, are liquid at room temperature, ex. oil

SATURATED VS. UNSATURATED

straight chain allows saturated fats to pack tightly with other molecules

kinks of unsaturated prevent close packing, normal “cis” bend

FATS: TRIGLYCERIDES

fatty acid chains attached to glycerol

triglycerides

triglycerides are animal storage of fats, stored in adipose tissue

TRIGLYCERIDE INSULATION

FATS: PHOSPHOLIPIDS

main component of cell membranes

2 fatty acid (tails) + glycerol + phosphate + polar alcohol group (head)

FATS: WAXES

long chain fatty acids linked to long chain alcohols or carbon rings

firm consistency, repel water

water proofing applications

honeycombs are beeswax

plant cuticle has cutin

LIPIDS: STEROLS/ STEROIDS

no fatty acids but rigid backbone of carbon rings

cholesterol is most common type in animals

others: vitamin A, cortisol-secreted by adrenal glands, testosterone, vitamin D2-produced in skin from a cholesterol derivative

video

PROTEINS

made of amino acid subunits (few to thousands)

properties of amino acids determined by the reactive R group

amino acids can be nonpolar, polar, positively or negatively charged

peptide bonds (a covalent bond) form through a condensation rxn. to link amino acids together in a chain to form a protein

R

MORE ON PROTEINS

the sequence of amino acids is different for each protein

many amino acids linked together form a polypeptide chain, also known as a protein

proteins can be fibrous (chains arranged as strands or sheets) or globular (chains folded into rounded shapes)

PROTEIN SHAPE

determined by interaction between R groups

shape is essential for protein’s biological activity

uses of proteins: speeding reactions (enzymes), spider webs, feathers, bones, hair, seeds, eggs, cell communication, cell shape and organization, cartilage, skin, and muscles

PROTEIN CELL MARKER

SHAPE TERMS

PRIMARY structure refers to the amino acid sequence of a protein

SECONDARY structure refers to different parts of the chain hydrogen bonding together (R groups) to create a coiled loop, twisted helix, pleated sheet

SECONDARY STRUCTURE

MORE STRUCTURAL TERMS

TERTIARY structure refers to the folding as a result of R group interactions

secondary structures (coils, sheets, loops) fold again, into a DOMAIN, a structurally stable unit

shape of domain and charge distribution around shape determine protein function ex. tunnel shaped proteins are channels in cell

EXAMPLE OF TERTIARY STRUCTURE

part of hemoglobin

red heme group in middle carries oxygen

globular shape

folding due to interaction between R groups

FINAL STRUCTURE

QUATERNARY structure refers to more than one polypeptide chain making up the protein

hemoglobin hasfour polypeptide

chains, top called alpha,bottom called beta

ADDITIONS TO STRUCTURE

proteins can have attached carbohydrates (oligosaccharides), called glycoproteins

ex. found on cell surface

proteins can have attached lipids (triglycerides, cholesterols, phospholipids), called lipoproteins

ex. cholesterol and triglycerides transported by proteins

CONSEQUENCE OF MISTAKE IN PROTEIN SHAPE

normal beginning of hemoglobin AA chain

glutamate

AMINO ACID MISTAKE

mistake caused by two recessive alleles coding for protein

valine

SICKLE CELL ANEMIA

valine results in an improper charge in the protein

this spot is nonpolar, sticky, water repellent

RBC distorts into sickle shape which disrupts circulation

caused by two recessive alleles

DESTROYING A PROTEIN

a protein can be DENATURED, or made to unfold so it cannot function properly due to the disruption of its shape

a change in pH, temperature, or salinity can denature a protein

amino acid mistakes can also make a protein not function properly, ex. sickle cell anemia

NUCLEIC ACIDS

built from nucleotides

pentose sugar (ribose or deoxyribose)

at least one phosphate group

base of carbon and nitrogen (ring shape)

adenine and guanine are purines (double ring)

cytosine, thymine and uracil (in RNA) are

FUNCTIONS OF NUCLEOTIDES

energy carriers (ATP is a nucleotide)

chemical messengers

coenzymes (helpers of enzymes, needed for enzyme function, shuttling of H and electrons, ex. NAD+, FAD)

building blocks for DNA, RNA

DNA VS. RNA

DNA

stores genetic info

has bases A, T, C, G

deoxyribose sugar

double stranded

RNA

expression of genetic info

has bases A, U, C, G

ribose sugar

single stranded

NUCLEIC ACID STRUCTURE

backbone of phosphate and sugar

ATP

can make other molecules reactive by transferring a phosphate group