2.2 Biological Molecules ✓

polymers of monosaccharides

2 molecules joined together w removal of water

2 molecules split apart w addition of water

weak interation which can occur where molecules contain slightly negatively charged atom bonded to slightly positively charged hydrogen atom

when 2 -OH groups react together

where 2 monomers join together

lots of monomers joined together

monosaccharides

polysaccharides

amino acids

polypeptides + proteins

nucleotides

DNA + RNA

the atom with greater no. of protons exerts stronger attraction for shared electrons, this makes that atom slightly negative and the other(s) slightly positive

weaker

hydrogen bonds due to polarity

low (flow easily)

-habitats
-major component of living tissues
-reaction medium
-effective transport medium

more

less due to polarity causing molecules to align in structure less dense than liquid water

-stable environment for aquatic life in winter
-bodies of water insulated against extreme cold

-polar meaning positive and negative parts of water attracted to positive and negative parts of solute
-water molecules cluster around charged parts seperating and keeping apart solute molecules (solute now dissolved)

-molecules/ ions move around and react together in water (eg cytoplasm)
-molecules and ions transported in living things

surface of water resists force applied to it

-water molecules at surface attracted to those beneath (hydrogen bonds)
-so more attracted to water than air causing surface to contract (molecules pulled inwards)

-columns of water in plant vascular tissue pulled up xylem from roots
-pond-skaters walk on water

molecules held together tightly by hydrogen bonds

water doesnt heat up or cool down easily

-living things need stable temp for enzyme controlled reactions
-aquatic organisms need stable environment

hydrogen bonds and means large amount of energy required to change state

can cool living things down eg sweat exaporating or transpiration in leaves of plants

important for digestion and synthesis of large biological molecules

C, H, O

bond formed between 2 monosaccharides by condensation reaction

-source of energy
-store of energy
-structural units

large number of carbon-hydrogen bonds

-soluble in water
-insoluble in non-polar solvents

straight chains or ring/ cyclic

how many carbons there are

straight chains

ring/ cyclic

non-reducing

reducing

reducing

2 monosaccharides joining

maltose

sucrose

lactose

cellobiose

$ C_6H_{12}O_6$

$ C_6H_{12}O_6$

$ C_5H_{10}O_5$

$ C_5H_{10}O_4$

-energy source
-component of starch + glycogen (energy stores)

-energy source
-component of cellulose (structural support cell walls)

component of ribonucleic acid (RNA), ATP and NAD

components of deoxyribonucleic acid (DNA)

hexose

hexose

pentose

pentose

polysaccharides made solely of one type of monosaccaride

source of energy

energy currency of the cell

join lots of them together into polysaccharides

amylose and amylopectin

in the form of large granules

do not oppucy a lot of space (dense granules)

easily 'snipped off' from end of chain by hydrolysis when required for respiration

yes

more compact but offer chance for lots of glucose molecules to be snipped off at the same time

as starch in chloroplasts and membrane-bound starch grains

as glycogen in cells of muscle and liver

linkage between carbon 1 of one glucose and carbon 4 of the other

amylase

glucosidase

if many glucose molecules dissolve in cytoplasm, water potential reduce so excess water would dissolve in disrupting cell function

size and that regions which could hydrogen bond with water are hidden away inside molecule

amylose

amylopectin and glycogen

double helix which presents hydrophobic external surface in contact with surrounding solution

between carbonds 1 and 4

long chain of a-glucose molecules

spiral shape with H bonds holding spiral in place

like amylose (glycosidic bond between C 1 + 4) BUT also has branches formed by glycosidic bonds between C 1 + 6

amylopectin also coils into a spiral held together with H bonds BUT branches emerging from spiral

glycogen (glycosidic bond between C1-4 + branches gormed by glycosidic bonds between C1-6)

-1-4 bonded chains tend to be smaller in glycogen, so less likely to coil
-glycogen has more branches, making it more compact and easier to remove monomer units (as there are more ends)

tough, insoluble and fibrous

homosaccharide

long chains of up to 15000 beta glucose molecules

condensation reactions to form glycosidic bonds

straight and lie side by side

spirals

-hydrogen and hydroxyl groups on C1 inverted in beta glucose meaning every other beta glucose molecule in chain rotated by 180 degrees
-hydrogen bonding between rotated beta glucose molecules in each chain gives strength (stopping spiralling)
-hydrogen bonding between rotated beta glucose molecules in different chains gives strength to whole structure

hydroxyl group on C2 sticks out

cellulose chains bound together

when microfibrils bundle together

macrofibrils embedded in pectins (like glue)

-microfibrils + macrofibrils have very high tensile strength
-macrofibrils run in all directions, criss-crossing wall for extra strength
-difficult to digest cellulose

glycosidic bonds between glucose molecules less easy to break

hydrogen bonds between chains + strength of glycosidic bonds

-strength to support whole plant (as plant has no rigid skeleton)
-space between macrofibrils
-high tensile strength
-macrofibril structure can be reinforced with other substances for extra support or to make walls waterproof

so water and mineral ions can pass on their way into and out of cell

No, fully permeable

protects delicate cell membrane + prevents cells from bursting when turgid, supporting whole plant (when turgid cells press against each other)

-cutin and suberin are waxes to block spaces in cell wall making it waterproof
-lignin performs same (as above) function for xylem

-cotton
-cellophane + celluloid (photographic film)
-a main component of paper
-rayon (semi-synthetic fibre)

a peptidoglycan

long polysaccharide chains which lie in parallel, cross-linked by short peptide chains (made of amino acids)

chitin

has acetylamino group (NH.OCCH3) rather than hydroxyl group on C2, which forms cross-links between long parallel chains of acetylglucosamine (like in cellulose)

large amounts of carbon and hydrogen, smaller amounts oxygen

not polar so dont attract water molecules

group of substances soluble in alcohol rather than water

very large, organic molecule

molecule consisting of glycerol, 2 fatty acids and 1 phosphate group

-triglycerides
-phospholipids
-steroids

no but they have different components bonded together

macromolecules

-triglycerides
-phospholipids
-glycolipids
-cholesterol

glycerol amd fatty acids

fatty acids that must be ingested ‘complete’

on one end, carboxyl group attached to hydrocarbon tail made only of H and C

1) H+ and -COO-
2) acid

no C=C bonds in molecule

double bond between carbon atoms meaning fewer hydrogen bonded to molecule

single C=C bond

more than one C=C bond

oleic acid

linoleic acid

kink where double bond is

kink pushes molecules apart slightly, making them more fluid

saturated

unsaturated

1 glycerol bonded to 3 fatty acids

condensation reaction between -COOH group (fatty acid) and -OH group (glycerol)

ester bond

no

more

-energy source
-energy store
-insulation
-buoyancy
-protection

-broken down in respiration to release energy and generate ATP
1) ester bond hydrolysed
2) glycerol and fatty acids broken down to CO2 and H2O

insoluble in water so stored without affecting water potential of cell

in adipose cells under skin

twice
-bcos lipids have higher proportion H than carbs and almost no O

-adipose tissue in whales (blubber) acts as heat insulator
-lipid in nerve cells act as electrical insulator
-animals store extra fat for hibernation

fat less dense than water so help aquatic animals stay afloat

fat around delicate organs like kidneys to act as shock absorber

peptidoglycan cell walk covered in lipid-rich outer coat

One of triglycerides fatty acid replaced by phosphate group

condensation reaction between OH group on phosphoric acid molecule (H3PO4) and 1 of 3 -OH groups on glycerol

ester bond

yes most do

yes

has negative charge, making it polar causing attraction

non-polar so repell water

hydrophillic

hydrophobic

both hydrophillic and hydrophobic

yes

no

-layer on surface if water with heads in water and tails sticking up ou of water
-micelles: tiny balls with tails tucked away inside and heads pointing outwards into water

form bilayer, w 2 rows of phospholipids (tails pointing in + heads pointing out to solution)

individual phospholipids free to move around in layer but not into position where tail exposed to water

membrane selctively permeable: only small and non polar molecules move through tails in bilayers (eg O and CO2)

steroid alcohol: type of lipid not made of glycerol or fatty acids

4 carbon-based rings or isoprene units

small + hydrophobic

regulates fluidity of membrane, preventing from becoming too stiff

liver

stigmasterol

stigmasterol has an extra double bond

testosterone, oestrogen + vit D

small enough

converted into animal hormones

monomers of all proteins that all have the same basic structure

bond formed when 2 amino scids join together

large polymers comprised of long chains of amino acids

-form structural components in animals
-act as enzymes, antibodies and hormones: tendency to adopt specific shapes
-act as carriers and pores for active transport across membranes and facilitated diffusion

amino acids animals must ingest

no, only some

yes

access to fixed nitrogen (eg nitrate)

carbon, nitrogen, hydrogen, oxygen (sometimes sulfur)

amino acids that are found in proteins

over 500

20

-amino group (-NH2)
-carboxyl group (-COOH)
-R group (different in each amino acid

-ine

exeptions: acidic R group

yes

-break peptide bonds during digestion
-break down protein hormones so effects arent permanent

dipeptide

longer chain of amino acids joined together

both

sequence of amino acids in molecule

protein structure where protein consists of more than one polypeptide chain

coiling or folding of amino acid chain, due to hydrogen bonding between different parts of chain (main forms are helix and pleated sheet)

overall 3d shape of protein molecule caused by hydrogen bonding, disulfide bridges, ionic bonds and hydrophobic interactions (of secondary structures)

at least 100 amino acids

yes

coiled chain of amino acids with 36 amino acids per 10 turns of helix

hydrogen bonds between -NH group of an amino acid and -CO group of another 4 places ahead in chain

amino acid chain with very slight zig zag structure

hydrogen bonds between -NH group of an amino acid with -CO group of another further down strand

many hydrogen bonds formed

no

no can be more than one eg different ends

very precise shape, held firmly in place

-supercoiled (eg fibrous proteins)
-spherical (globular proteins)

strong covalent peptide bonds

polar areas of R groups, hydroxyl, carboxyl and amino groups

carboxyl and amino groups of R groups

$ NH_3^+$

$COO^-$

strong covalent

between R groups of 2 cysteines

hydrophobic parts associate together in centre of polypeptide and opposite for hydrophillic parts

changes its shape

regular, repetitive relatively long thin structure, insoluble in water and metabolically inactive, structural role in organism

relatively spherical molecules, soluble in water often having metabolic roles in organism

non-protein component forming permanent part of functioning protein molecule

any hydrophobic R groups turned inward + hydrophilic groups outside so molecules easily cluster and bind to them

enzymes, hormones, haemoglobin

prevents artery bursting when withstanding high blood pressure

connect muscle to bones, allowing bones to be pulled

made from collagen and reinforced with calcium phosphate making them strong

cartilage, connective

finger nails, hair, claws, hoofs, horns etc

mechanical protection, impermeable barrier to infection, waterproof to prevents water-borne pollutants entering

cross-linking and coiling

skin streches around bones and muscle

allows inflation and deflation

expand to hold urine

stretch and recoil helping maintain pressure

4: 2 a-globin chains, 2 ß-globin chains

prosthetic group

protein associated with prosthetic group

purple red to bright red

2: A beginning with section of a-helix, B ending with section of ß-pleat

amino acids with hydrophollic R group

binds to glycoprotein receptors on outside of muscle and fat cells to increase uptake and consumption of glucose

enzyme that digests protein in stomach

single polypeptide chain

symmetrical tertiary structure

many acidic R groups so few can accept H+ ions which would otherwise affect enzyme structure

hydrogen bonds, 2 disulfide bridges

model built on physical and electrical properties of aroms in each amino acid in sequence providing multiple solutions to same sequence

other methods may be needed to reduce no. of solutions

protein threading which scans animo sequence against database of solved structure producing set of mtching possible models

Ca 2+

-rigidity of bones, teeth and cartilage
-exoskeleton of crustaceans
-important in clotting blood
-important in muscle contraction
-activator for several enzymes
-regulates transmission of nerve impulses
-regulates permeability of cell membranes
-important for cell wall development in plants
-imporatant for formation of middle lamella between cell walls

Na +

-involved in regulating osmotic pressure
-involved in control of water levels in body
-involved in maintenance of pH
-affects absorption of carbohydrates in intestines
-affects absorbtion of water in the kidneys
-contributes to nervous transmission
-contributes to muscle contraction
-constituent of vacuole in plants

-lipase
-ATPase
-cholinesterase

K +

-involved in control of water levels in body fluid
-involved in maintenance of pH
-assists active transport across cell membrane
-involved in protein and glycogen synthesis
-involved in breakdown of glucose
-generates healthy leaves and flowers
-contrubutes to nervous transmission
-contributes to muscle contraction
-component of vacuole in plants

H +

-involved in photosynthesis and respiration
-involved in transport of oxygen and carbon dioxide in blood
-involved in regulation of blood pH

NH4 +

-component of amino acids, proteins, vitamins, chlorophyll
-hormones made of protein
-essential component of nucleic acids
-invlolved in maintenance of pH in body
-component of nitogen cycle

NO3 -

-component of amino acids, proteins, vitamins, chlorophyll
-essential component of nucleic acids
-hormones made of protein
-component of nitrogen cycle

HCO3 -

-involved in regulation of blood pH
-involved in transport of carbon dioxide into and out of blood

Cl -

-helps produce urine in kidney
-helps mintain water balance
-involved in transport of carbon dioxide into and out of blood
-regulates affinity of haemoglobin to oxygen through allosteric effects on haemoglobin molecule
-regulates blood pH
-produces hydrochloric acid in stomach

PO4 3-

- increases rigidity of bone teeth and cartilage
-component of exoskeletom of crustaceans
-component of phospholipids, ATP, nucleic acids, enzymes
-regulates blood pH
-helps plant root growth

OH -

regulates blood pH

ions required in large amounts

ions required in small amount

main elements

trace elements

iodine solution( in potassium iodide)

yellow-brown to blue-black

iodine forms triiodide ion (I3 -) when dissolved in potasium iodide which slips into middle of amylose helix

monosaccharides and some disaccarides

can reduce/ give elctrons to other molecules

benedicts solution

alkaline copper (II) sulfate

blue to green to yellow to orange-red

-Cu 2+ ion in benedicts solution reduced to Cu+ ions forming orange-red copper (I) oxide (Cu2O)
-this is a precipitate that is then suspended in mixture

80C for 3 min

concentration of sugar

comercially manufactured test strips

testing glucose in urine of diabetic person

hydrolyse the bond to ‘free up’ reducing groups

-test for reducing sugars to ensure none are there
-take seperate sample and boil with hydrochloric acid to hydrolyse sucrose into glucose and fructose
-cool solutiom and use sodium hydrogencarbonate solution to neutralise
-test for reducing sugars

-equal sized second sample tested for non reducing sugars will form precipitate with more mass than first sample
-check this by filtering precipitate

-mix sample thoroughly with ethanol
-filter
-pour solution into water in clean test tube

cloudy white emulsion made of lipid droplets that come out if solution when mixed with water

lipids are soluble in alcohol and not water

light blue to lilac

biuret A then biuret B

sodium hydroxide

copper sulfate