Macromolecules

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