chemical elements and biological molecules Flashcards
ion definition
charged atom or molecule that has lost or gained electrons
inorganic meaning
doesn’t contain carbon atoms
magnesium function
Mg2+
- chlorophyll production
- lack = chlorosis
iron function
Fe2+
- part of haemoglobin
- lack = anaemia
calcium function
Ca2+
- component of bones, teeth
- strengthens tissues and plant cell walls
- form nerve signals
phosphate function
Po4 3-
- component of DNA, RNA
- forms ATP
water properties
- dipole
- polar
- universal solvent
- high specific heat capacity
- high latent heat of vaporisation
- high cohesion
- metabolite
- transparent
how is water a dipole
- has slightly +/- charged ends
- numerous hydrogen bonds between water molecules = strong
how is water polar
- 2 (+) charged H, 1 (-) charged O
- covalently bonded
- unequally charged
how is water a universal solvent
- water is a dipole so attracts charged molecules
- dissolves polar / charged molecules
- O2/CO2 can dissolve
- can act as a transport medium, water flows
- dissolves more than any other liquid
how does water have a high specific heat capacity
- many H bonds mean lots of energy is required to increase its temp
- reduces fluctuations = stable aquatic environments
how does water have a high latent heat of vaporisation
- lots of energy required to vaporise
- water in sweat absorbs heat energy as it evaporates = efficient cooling mechanism
how does water have high cohesion
- cohesion between water molecules, in lattice
- water molecules on surface pulled down = surface tension
- provides support and buoyancy
e.g. water pulled up xylem, pond skaters walk on water
water and its density
- liquid water is more dense than ice
- ice floats providing insulation beneath and water beneath doesn’t freeze
benefit of water being transparent
- allows photosynthesises
- light penetrates through
how is water a metabolite
- a reactant necessary to start a metabolic reaction (essential for life), and a by product
- reactant in photosynthesis and hydrolysis
- product of aerobic respiration and condensation
what is a carbohydrate
-organic molecule consisting of carbon, hydrogen, oxygen
what is a monosaccharide
- building blocks of complex carbs
- most basic monomers
- general formula: (CH2O)n
monosaccharide examples
- triose (3C) e.g. glyceraldehyde
- pentose (5C) e.g. ribose, deoxyribose
- hexose (6C) e.g. glucose, fructose, galactose
function of monosaccharides
- energy in respiration, bonds break releasing energy to make ATP
- building blocks
- intermediates in reactions e.g. triose in respiration
- nucleotides (DNA deoxyribose)
glycerol chemical formula
C3H8O3
what is a disaccharide
2 monosaccharides bonded by a glycosidic bond with the elimination of water in a condensation reaction
disaccharide general formula
C12H22O11
disaccharide examples
- maltose (glucose+glucose)
- sucrose (glucose+fructose)
- lactose (glucose+galactose)
maltose function
seed germination
sucrose function
phloem transport
lactose function
mammalian milk
what is a polysaccharide
large complex polymer
consist of monosaccharide units (the monomers) joined by glycosidic bonds
insoluble
polysaccharide examples
starch
glycogen
cellulose
chitin
why is glycogen more suitable than glucose in animals?
- it is insoluble = has no osmotic effect
- it can’t diffuse out cells
- it is compact = fit in small spaces
- carries lots of energy in its bonds
what is an isomer?
molecules with the same molecular formula but different arrangement of atoms
alpha vs beta glucose
alpha = OH group on bottom
beta = OH group on top
what is starch
the key energy store in plant
alpha glucose
amylopectin or amylase
amylase
- linear, unbranched
- alpha 1-4 glycosidic bonds
- coiled and compact = store lots of energy
- chain of a-glucose coiled into a helix
- glucose storage
amylopectin
- branched
- chains of glucose monomers with 1,4 glycosidic bonds. cross linked with a-1,6 glycosidic bonds between parallel chains.
- 1,6 bonds = side branches
- branches = rapidly digested by enzymes = quick energy release (quickly hydrolysed)
- water insoluble
glycogen
- energy storage molecule in animals
- insoluble
- molecules of a-glucose joined by 1,4 and 1,6 glycosidic bonds
- side branches = quick energy release
- large but compact, maximising energy store
cellulose
- in plant cell walls, structural role
- long chain of b-glucose units joined by b-1,4 glycosidic bonds
- straight, unbranched
- H (H+OH) bonds provide stability between parallel molecules
- tightly crosslinked by h bonds form microfibril held in bundles (fibres)
- permeable, allows water through cell membrane
- adjacent monomers twisted 180 to each other
chitin
- in exoskeleton of insects, fungal cell walls
- chains of b-glucose monomers with amino acid side chains
- b-glucose 1,4 glycosidic bonds
- strong, waterproof, lightweight
- each have an acetlyamine group
- polysaccharide
what are lipids?
- formed of C, H, O2 (little)
- non-polar compounds
- water insoluble
- soluble in organic compounds (alcohol)
what is a triglyceride composed of ?
- 1 glycerol molecule
- 3 fatty acid chains (carboxylic group and hydrogen chain)
- energy reserves in plant/animal cells
how are triglycerides formed?
in a condensation reaction
ester bonds is formed
3 water molecules removed
what are saturated fatty acids
contain no double bonds between 2 carbon atoms
- animal fats
- solid at room temp
what are unsaturated fatty acids
contain at least 1 double carbon-carbon bond
- poly = more than 1
- mono = 1
- plant fats
- liquid at room temp
why do unsaturated fatty acids have a lower melting point?
- more unsaturated bonds the weaker the intermolecular bonds
= lower m.p
(can’t align uniformly = doesn’t solidify readily)
triglyceride functions
- energy reserve: more C-H bonds than carbohydrates
- thermal insulation: stored under skin, insulates
- protection: fat stored round delicate organs, protect from physical damage
- producing metabolic water: water released from body’s chemical reactions
what are phospholipids comprised of
- 1 glycerol molecule
- 2 fatty acid tails
- 1 phosphate group
properties of a phospholipid
- phosphate head = hydrophilic = water soluble = attracts water = polar
- fatty acids = hydrophobic = repel water
phospholipid functions
- structural in biological membranes
- electrical insulation in myelin sheath
- waxes: waterproofing in exoskeletons and leaf cuticles
effects of saturated fats on health
- raises low density lipoprotein (LDL) cholesterol levels
- increases incidence of atheroma in coronary arteries
- LDL deposits in arteries = atherosclerosis (plaque build up)
- reduces blood supply to heart muscle
effects of unsaturated fats on health
- increase HDL
- carries fats to liver for disposal
amino acids
- form a polypeptide in a single chain
- 20 types (vary in R group)
- 2 = dipeptide
- join via a condensation reaction, forms peptide bond (+ water)
amino acid structure
- amine group - NH2
- carboxylic acid group - COOH
- variable group - R
what are proteins
polymers of amino acids
2+ polypeptide chains
protein primary structure
polypeptide chain / amino acid sequence
determined by gene coding for polypeptide
protein secondary strucutre
hydrogen bonding between amino acids
chain coils into a a-helix or b-pleated sheet
protein tertiary structure
globular or fibrous
further folding of secondary/chain = 3D
hydrogen bonds
interactions between amino acids - disulphide bridges, ionic bonds, hydrophobic interactions
protein quaternary strucutre
association of several polypeptide chain
some have prosthetic groups
what is protein function determined by
bonding within the protein affects the 3D structure
what are fibrous proteins
long strands
insoluble
structural role
e.g. keratin, collagen
collagen protein structure
in skin, teeth, bones, tendons
3 identical polypeptide chains wound into triple helix
what are globular proteins
sphere shaped
water soluble (hydrophobic and hydrophilic ends)
metabolic role
e.g. enzymes, haemoglobin
haemoglobin protein structure
4 polypeptides (2a, 2b)
4 haem groups
water soluble
iodine test for starch
- add 2 drops of iodine to test solution
- present = orange to blue-black colour change
(iodine in potassium-iodine solution)
biuret test for protein
- mix equal volumes of sample and Biurets reagent
- cover boiling tube and invert once
- present = blue to purple colour change
emulsion test for lipids
- mix sample with alcohol
- shake boiling tube
- pour mix into cold water
- present = cloudy white emulsion/precipitate
benedicts test for reducing sugars
- mix equal volumes of sample and benedicts reagent
- heat in water bath at 80c for 5 mins
- present = blue to brick red colour change
benedicts test for non-reducing sugars
- complete test for reducing and get negative result
- add hydrochloric acid to sample
- heat in water baths at 80c for 2 mins
- add sodium hydroxide
- add benedicts reagent
- heat in water bath at 80c for 5 mins
- present = blue to brick red colour change
examples of reducing sugars
- most monosaccharides and disaccharides
- glucose, fructose, lactose, maltose
example of non-reducing suagr
sucrose
how does water allow plants to grow under water?
water is transparent
allows light to penetrate for photosynthesis
CO2 can be absorbed for photosynthesis
why is sulphate needed?
for amino acid synthesis
