macromolecules Flashcards
what are organic molecules / hydrocarbons / functional groups
- compounds containing C, H, N, O, P and S
- often small
- organic molecules with C and H, non-polar, energy rich
- component of a molecule that retains distinctive chemical properties, chemical reactions results from transfer of functional group
what are macromolecules
- large molecules (polymers) made up of repeating units (monomers)
- proteins, carbohydrates, lipids and nucleic acids
- built by covalently bonding two or more subunits
- condensation / dehydration: release molecule of water
- hydrolysis: releases energy, molecule of water added, to break apart polymer
what do proteins do
- enzyme catalyst: chemical reactions
- defence: antibodies
- transport: membrane transport and blood cells
- support: cytoskeleton and collagen
- motion: muscle fibre contraction and cilia
- regulation: hormones
what are amino acids
- comprised of central C atom bonded to an amino group (NH2), carboxyl group (COOH), H atom and R side chain (unique for each AA)
- R group: 20 amino acids, classified by shape, size, hydrophobicity, charge and chemical reactivity
- neutral / non-polar: hydrophobic AA, non-polar R groups inside
- neutral / polar: hydrophilic AA
- charged: acidic / basic
describe the different structures of proteins
secondary: backbone folds, stabilised by h-bonds between ‘common’ AA components
- alpha helices or beta pleated sheets
tertiary: folded 3D shape, extended rigid rods or globular mass
- folds non-polar R groups into the interior (hydrophobic), polar face exterior (hydrophilic)
- stability determined by fit of internal portions (H, ionic, van der waals, disulphide)
quaternary: a proteins subunit arrangement, subunit (same or different polypeptide structure)
what happens when unfolding / abnormal proteins occur
- unfolding: alteration of proteins environment (temp, pH, conc.), denaturation / loss of function, renders protein biologically inactive
- abnormal: denatured / mis-folded, marked for degradation, if elimination fails = aggregation (parkinsons, alzheimers)
what are proteins
- polymers of amino acids in specific sequence
- peptide bonds link two or more amino acids
- polypeptide chain
- long AA chains folded into complex shapes
what are protein chaperones
- help proteins fold, refold or disassemble proteins
- molecular: binds to unfolded proteins and prevents aggregation
- chaperonins: form ‘chambers’ which provide suitable environment and time to allow correct folding, deficiency = cystic fibrosis
what is a carbohydrate
- fuels and building materials, contain energy rich C-H bonds (covalent), simple sugars and their monomers
- 1:2:1 - C:H:O (Cn(H2O)n)
- contain multiple OH and =C
- monomers joined together via glycosidic linkages (dehydration), covalent bond, to form polymers
how are carbohydrates classified
- monosaccharide: simple sugar, ring in (aq), 3-7 C atoms, glucose / fructose (6)
- disaccharides: two monosaccharides joined, lactose (glucose + galactose)
- oligosaccharides: in-between di and poly, glycoprotein / glycolipid, raffinose
- polysaccharide: many monosaccharide units (100-1000’s), connective tissue, exoskeleton, cell wall, energy reserve (glucose as glycogen)
what are isomers of monosaccharides
- isomer: two molecules with same chemical formula
- stereo: identical chemical groups bonded to same C atom, different arrangement
- structural: same chemical groups bonded to different C atoms
what is cellulose
- carbohydrate of plants
- glucose can form two rings OH below (alpha, starch) or above (beta, cellulose)
- both produced by plants, chains of glucose
- cellulose cannot be digested by humans (unable to break beta linkages), passes through digestive tract untouched
what are levo / dextro sugars and chirality
- levo: left handed, rare, mirror image of normal sugars (no energy value, tastes same, no calories)
- dextro: majority of sugars `
what are nucleic acids
- amino acid sequence programmed by unit of inheritance (gene)
- gene: DNA = polymer of nucleic acid monomers
- information storage molecules
- ‘blueprint’ for proteins, act as template for copies of themselves
- DNA: hereditary material
- RNA: ‘read’ info encoded in DNA, direct protein synthesis
what is the structure of nucleic acids
- nucleotide (monomers)
- pentose: 5 carbon sugar, DNA (deoxyribose), RNA (ribose), numbered 1-5 (5= hanging off), backbone (C2 bonded to H)
- P group: part of sugar phosphate backbone
- nitrogenous base: protrude from backbone, purines (5C, adenine, guanine) and pyrimidines (6C, cytosine, uracil, thymine)
- 3’ to 5’ prime directionality
- double helix ladder
describe DNA structure (forces / bonds / joining nucleotides)
- P group binds to OH group of adjacent sugar (phosphodiestar bond)
- H bonds: hold two chains together (between bases)
- van der waals forces: between adjacent atoms, stability of entire molecule
what is the function of DNA
- gene codes: nucleotide sequence of DNA = code
- genes: sections code for particular polypeptides
- order: of nucleotides = specifies AA order in protein, primary structure dictates 3D conformation / function of proteins
what is RNA
- ribose sugar (C2 bonded to OH)
- uracil replaces thymine
- single stranded
- involved in protein synthesis
- mRNA = carries message from DNA
- rRNA = part of ribosomes, read mRNA
- tRNA = positions amino acids / complementary bases
what are lipids
- highly vary in form and function
- little / no affinity for water (insoluble, hydrophobic)
- does not fold up like proteins (cluster - cell membrane)
- does not include polymers, common subunits
- triglycerides (3 fatty acid chain)
- string of C with H groups hanging off
- formed by dehydration of smaller molecules to form ester linkages
what are simple lipids
- triglycerides
- fatty acid: hydrocarbon chain with carboxyl group (COOH)
- waxes: long fatty acid / fatty alcohol chain (sebum, cerumen, vernix caisson - pregnancy)
what are fats
- glycerol molecule with 3 fatty acids = triglyceride
- C-H bonds = store energy, cushioning, insulation
what are the types of fats
saturated:
- maximum number of C-H bonds (single), straight fatty acid (solid at room temp, very dense)
- increase LDL: plaques, decrease artery size, connective tissue growth in cardiovascular system (decrease elasticity)
- HDL: bind to left over cholesterol, return it to liver
- hydrogenated oil: H added to unsaturated fat (peanut butter, margarine)
unsaturated:
- double bonds, kinks at double bonds, liquid at room temp, less dense (oil)
- take up larger volume
- polyunsaturated: more than one double bond
- ‘healthy’ fats
what are trans fats
- uncommon
- same molecular formula but different shape (hydrogenation)
- negative effects, straighter than -cis molecules
- risk of coronary heart disease due to increase LDL, removing double bond = susceptible to free radicals
what are other types of lipids
- phospholipid: glycerol backbone (3 C 3 OH), fatty acid chain (16-18 C, end with COOH), P group (hence amphipathic)
- isoprenoids: diverse (chemical signalling, light reception), vitamins A, E, K
- steroid: cholesterol, hormones (testosterone / oestrogen), co-factors (vitamin D)
