Macromolecules

Nucleic acid

Nucleic acid

• Built from nucleotides

• Two types:

1. Deoxyribonucleic acid (DNA): cellular database

2. Ribonucleic Acid (RNA): needed to convert DNA info into polypeptide sequences

• Have one, two or three phosphate groups

Condesnsation reaction

• Involves the release of water (H2O)

• Joining together of two monomers by a covalent bond to form a polymer. Occurs in biosynthesis

• A-OH + B-H → A-B + H2O

Hydrolysis reaction

• Reverse of condensation

• Involves adding water to split a covalent bond, the release of two smaller molecules

• Occurs in digestion

• A-B + H2O → A-OH + B-H

Building block of carbohydrates

monosaccharides

Functional group of carbs

• every carbon atom has H-C-OH, except one carbon atom that has a carbonyl group (C=O)

• Some sugars have an aldehyde group = aldose sugars (glucose), other sugars have keto group = ketose sugars (fructose)

Importance of carbs

• Short-term energy source

• important substrate for building other needed molecules

Glycoproteins

• proteins with sugar tags

• Molecular “tags” on membrane proteins face outside of a cell, used for recognition of specific cells and molecules

Monosaccharide

• simplest form (single sugar)

• most abundant sugars are the hexoses

• usually exist as ring structures when they dissolve in water

Common monosaccharides

Glucose, galactose, fructose, ribose (RNA), deoxyribose (DNA)

Glucose

• the most abundant sugar

• basis for polysaccharides

• produced in photosynthesis

Galactose

• found in lactose with glucose

• found in many plant polysaccharides

Fructose

• found in fruits and vegetables

Disaccharides

• two monosaccharides joined together

• condensation reaction when created

Glycosidic bond

the link between monosaccharide rings

Common disaccharides

sucrose, lactose, maltose

Sucrose

glucose + fructose

Lactose

glucose +galactose

Maltose

glucose + glucose

Polysaccharide

• long chains held togetehr by glycosidic bonds

• condensation reaction between each monosaccharide unit

Common polysaccharides

starch, glycogen, cellulose

Starch

• storage carb used by plants

• insoluble in water

• ex: potatoes

• polymer of glucose

Glycogen

• storage crab used by animals

• ex: liver and skeletal muscle

Cellulose

• usd in plant cell walls to maintain their structure

• indigestible to all organisms except some bacteria

• polymer of glucose

Building block of lipids

glycerol + 3 fatty acids

Functional groups in lipids

carboxyl and phosphate

Importance of lipids

• assebled through condensation

• structiral comonents of cell membranes

• long term energy

• vitamins and hormones

• insolation

• cushioning of organs

Saturated fats

all carbon bonds are singel bonds (more H = stiffer)

Unsatirated fats

some single, some double bonds

Omega-3

double bond between 3rd and 4th carbon

Cis fats

same side (most common fatty acids)

Trans fats

across or other side (toxic

Trans fatty acids

• double bonds are converted into single bonds

• Both these effects straighten out the molecules so they can lie closer together and mecome solid rather than liquid

Tryglyceride

• Formed as a result of three condensation reactions involving the OH groups of the glycerol and the COOH groups of each fatty acid

• For each condensation reaction, an ester bond is formed

Phospholipid

• similar to tryglycerides but one of the fatty acid molecules is replaced by a phosphate group

• lipid part is non-polar and hydrophobic (hates water)

• The phosphate part is polar and hydrophilic (loves water)

• If shaken up the phospholipids would form tiny spherical structures called micelles (like a circle). The hydrophobic tails turn inwards and become protected from the water by the hydrophilic heads

Steroids

• Insoluble in water

• 4 ring structure with various side chains

• Human steroids are synthesized from cholesterol

Hydrogenation

• process which combines gaseous H and oil

• destroys essential fatty acids and replaces them with trans fatty acids

Building block of proteins

amino acids

Functional gorups in protein

• each amino acid has an amino group and a carboxyl group joined by a single carbon atom

• Also has a side chain (R group) that differentiates them

Main functions of proteins

Structurally: muscle tissue, connective tissue, skin, hair, and nails, plus many others

Functionally: enzymes that catalyze biochemical reactions (used in all biochemical reactions)

Peptide bond

• strongest of covalent bonds

• betweeen the amino group of one amino acid and the carboxyl hroup of another

• condensation reaction

Primary structure

the sequence of amino acids in the chain

Secondary structure

• how r groups interact with each other

• the first level of folding of polypeptides

• alpha helix and beta-pleated helix held together by hydorgen bonds

tertiary structure

• becomes active proteins

• the shape the molecule takes when the helix twists and folds around itslef

quaternary structure

• The linking together of a number of polypeptide chains Ex: hemaglobin (has 4 subunits)

Denatiration

when bonds are disrupted and the protein unfolds

renaturation

the reverse of denaturation

Globular proteins

• Compact molecules

• Polypeptide chains “roll up” into spherical shape

• Water soluble (amino acids around R group), unstable

• Metabolic fucntion

• Ex: hemoglobin, enzymes

Fiborous proteins

• Polypeptide chains form long strands

• Stable, insoluble and strong

• Ex: collagen in bone or keratin in hair