The chemical properties of carbon allow it to form the macromolecules found in all living organisms such as: carbohydrates, lipids, proteins and nucleicacids
carbons have fourvalence electrons in its' outer shells allowing them to form fourcovalentbonds with other carbon atoms or non-metal elements
the covalent bonds that carbons form can be single bonds or a combination of single and double bonds
covalent bonds are bonds that form when valenceelectrons are shared between two non-metal elements
there is a wide diversity of carbon compounds, they can be;
unbranchedchains such as fatty acids
branchedchains such as triglycerides
singlerings such as glucose
multiplerings such as cholesterol
monomers are molecules which join to other similar molecules to form polymers
the macromolecules of life are polymers built out of monomers
monomer -> polymer -> macromolecule ->
glucose -> polysaccharide -> amylose and amylopectin in starch or cellulose
aminoacid -> polypeptide -> proteins
nucleotide -> polynucleotide -> DNA and RNA
fattyacids and glycerol -> triglycerides -> fats and oils
condensation reactions include the combining of twomoleculestogether and the release of a watermolecule
many repeated condensationreactions with monomers produce macromoleculepolymers
hydrolysis reactions include the addition of a watermolecule to breakdown a large molecule into smaller molecules
macromolecules are digested (broken down) during hydrolysis to their monomers through a series of hydrolysisreactions
in hydrolysis:
water causes a monomer to break of from a polymer
water separated into -H and -OH
-H attaches to one molecule and -OH attaches to the second molecule
carbohydrates are a large group of organiccompounds present in foods and living tissues and include sugars, starch and cellulose.
carbohydrates contain hydrogen and oxygen in the same ratio as water (2:1) and can be typically broken down to release energy in the animal body
carbohydrates are classified based on the number of sugarmonomers in the molecule:
monosaccharides - 1 sugar molecule i.e. glucose, ribose, fructose
disaccharide - 2 sugar molecules i.e. sucrose, maltose, lactose
polysaccharide - many sugar molecules i.e. starch, glycogen, cellulose, chitin
pentose sugars are monosaccharides that contain 5carbons i.e. ribose and deoxyribose
hexose sugars are monosaccharides that contain 6 carbons i.e. alphaglucose and betaglucose (where bonds usually form between carbon 1 and carbon 4 during the formation of polysaccharides)
glucose is a typical monosaccharide that possess the following properties:
soluble in water - it is a polar molecule which readilydissolves in water
transportability - since it is soluble, it can be transported within bodyfluids, such as the bloodstream in humans
chemicalstability - it is a relatively stable compound so it doesn't degrade as it's being transported
energyyield - it is the primary fuel for respiration in cells. it is repeatedly oxidized to produce net gains of up to 36ATP molecules
polysaccharides are composed of manysugarmolecules combined through a series of condensationreactions
polysaccharides such as starch in plants and glycogen in animals serve as stores of energy and are composed of longchains of glucose molecules
glucose molecules can be added to the polysaccharides (starch or glycogen) by condensation reactions or can be removed by hydrolysis reactions
starch and glycogen are compactpolysaccharides due to the coiling and branching as they are formed and this compactnature of polysaccharides allow the storage of many glucose molecules making them excellent storage compartments
starch is composed of twopolysaccharide molecules:
amylose - long chains of alphaglucose molecules
amylopectin - long chains of alphaglucose with branching chains of alphaglucose
amylose and amylopectin are large polysaccharide molecules and are not very soluble in water. this allows compact storage of starchgrains in plant cells, without impacting osmoticpressure in cells.
amylose consists of long chains of alphaglucose with glycosidicbonds between carbon-1 and carbon-4.
glucosemolecules can be added to amylose by condensation reactions or removed by hydrolysis reactions.
amylopectin consists of long chains of alphaglucose with glycosidicbonds between carbon-1 and carbon-4, however, at every 20th glucose molecule an additional glucosemolecule binds at carbon-6 and this is what results in amylopectin's branched structure
glycogen is a polysaccharide used for short-term energy storage in animals
glycogen, a polysaccharide, is composed of chains of alphaglucose with bonds between carbon-1 and carbon-4
in glycogen, many branches of alphaglucose chains are present with alpha glucose binding to carbon-6
glycogen is an insolublecompactmolecule, due to its many branches and coiling during polymerization
cellulose is an unbranchedpolysaccharide composed of betaglucose molecules - which are found in the cellwalls of plants
cellulose molecules consist of long chains of betaglucose molecules bonded between carbon-1 and carbon-4.
note that every 2nd beta glucose is flipped, resulting in straightchains of cellulose molecules
cellulose molecules form groups known as microfibrils which are held together by hydrogenbonds
cellulose microfibrils have hightensilestrength which allows them to maintain the structuralintegrity of cellwalls in plants
fourcellulose molecules can be held together by hydrogenbonds
glycoproteins are integralproteins located within the phospholipidbilayers of cells
glycoproteins always have a chain of carbohydrates attached and these carbohydrates have a specificshape and can act as an antigen
roles of glycoproteins include:
celltocelladhesion - glycoproteins interact with other glycoproteins allowing the formation of tissues
receptors - for hormones. when a hormone binds to a specific glycoprotein receptor, it changes the metabolism of the cell
celltocellcommunication - neurotransmitters bind to glycoproteins allowing communication between cells
immuneresponse - they act as markers on cells allowing the immunesystem to distinguish between self and non-self
glycoproteins act as antigens if the glycoprotein is not recognized as itself by the immunesystem