Biological Molecules Flashcards
how do hydrogen bonds form between water molecules
water is polar-oxygen slightly - and hydrogen slightly +
intermolecular forces of attraction between oxygen and hydrogen on opposite molecule
state 5 properties of water
high specific latent heat of vaporisation
high specific heat capacity
cohesive
good solvent
lower density when solid
why does ice float and why is this important
ice is less dense as h bonds hold molecules in fixed positions further away
insulates water so aquatic organisms can survive
why is high surface tension important for organisms
slows water loss due to transpiration in plants
some insects can skim across water surface
why is water an important solvent for organisms
dissolves and transports charged particles involved in intra and extracellular reactions
why is high specific heat capacity important for organisms
hydrogen bonds can absorb a lot of energy and it takes a lot of energy to heat water
doesnt experience rapid temperature change so good habitat
why is high latent heat of vaporisation important for organisms
takes a lot of energy to break hydrogen bonds
good for cooling down organisms
what happens in a condensation reaction
chemical bonds formed and a molecule of water
what happens in a hydrolysis reaction
water molecule used to break chemical bonds between two molecules
name the elements found in carbohydrates and lipids
carbon, hydrogen, oxygen
name the elements found in proteins
carbon, hydrogen, oxygen, nitrogen, sulphur
name the elements found in nucleic acids
carbon, hydrogen, oxygen, nitrogen, phosphate
describe the properties of alpha glucose
small and water soluble-easily transported in bloodstream
complementary shape to enzymes for glycolosis- respiratory substrate
how is maltose formed
glucose+glucose
how is sucrose formed
glucose+fructose
how is lactose formed
glucose+galactose
describe the structure and function of starch
insoluble-water does not enter cells by osmosis
large-does not diffuse out of cells
made from amylose and amylopectin
describe the structure of amylose
long unbranched chain of alpha glucose
glycosidic bond so has a coiled structure
compact so good for storage
describe the structure of amylopectin
long branched chain of alpha glucose
side branches allow enzymes that break down molecules to get to glycosidic bonds
describe structure and functions of glycogen
main storage monomer of alpha glucose
1,4 and 1,6 glycosidic bonds
branched-many terminal ends for hydrolysis
compact-good for storage
describe structures and functions of cellulose
long unbranched chains of beta glucose-prevents bursting of plant
alternate glucose molecules rotate 180 degrees
h bonds crosslinks between parallel strands form microfibrils-high tensile strength
how do triglycerides form
condensation reaction between 1 molecule of glycerol and 3 fatty acids form ester bonds
contrast saturated and unsaturated fatty acids
saturated:
only single bonds
straight chain molecules
higher melting point-solid at room temp
in animal fats
unsaturated:
contain C=C double bonds
kinked molecules
lower melting point
in plant oils
describe the structure and function of phospholipids
centre of bilayer is hydrophobic so water soluble sentences cant easily pass through
describe the structure and function of triglycerides
mainly energy store
long hydrocarbon contains lots of chemical energy
insoluble so water doesnt enter cells by osmosis
describe the structure and function of cholesterol
helps strengthen cell membrane by interacting with phospholipid
small/flat so fit between molecules
bind to hydrophobic tails so membrane more rigid
what is the primary structure of a protein
sequence of amino acids
what is the secondary structure of a protein
alpha helix or beta pleated sheets
caused by hydrogen bonds forming between -NH and -CO groups of amino acids
what is the tertiary structure
bonds between parts of the chain
what are the types of bonds in the tertiary structure
ionic bonds-attractions between negatively charged and positive R groups
disulfide bonds
hydrophobic interactions-when hydrophobic R groups close together, hydrophilic more likely to be pushed to the outside
hydrogen bonds- weak bonds between slightly positive charged and slightly negative charged atoms
define quaternary structure of a protein
way polypeptides are assembled
describe structure and function of globular proteins
spherical and compact
hydrophilic R groups face outwards and hydrophobic R groups face inwards-water soluble
describe the structure of heamoglobin
globular conjugated proteins with prosthetic group
2 alpha chains and 2 beta chains
water soluble-dissolves in plasma
FE2+ haem groups
tertiary structures change so subsequent oxygen molecules bind
describe the structure and function of fibrous proteins
can form long chains or fibres
insoluble in water
useful for structure and support
what are the functions of collagen
component of bones, cartilage, connective tissues and tendons
what are the functions of elastin
provides elasticity to connective tissue
what are the functions of keratin
structural components of hair and nails
describe how to test for protein samples
biuret test
add equal volume of sodium hydroxide to sample
add drops of copper 2 sulfate-swirl to mix
positive result=colour change from blue to purple
negative result=solution stays blue
describe how to test for lipid samples
dissolve solid sample in ethanol
add an equal volume of water and shake
positive=milky white emulsion
describe how to test for reducing sugars
add bendicts reagent to sample and heat in water bath
positive=colour change (green, yellow, orange, brick red)
describe how to test for non-reducing sugars
negative=remains blue
add dilute hydrochloric acid and heat in water bath
neutralise with sodium hydrogencarbonate
carry out benedicts test
describe the test for starch
add iodine solution
positive=orange-blue black
outline the process for paper chromatography
use capillary tube to spot solution onto pencil line
place chromatography paper in solvent
allow solvent to run until almost touches other end of paper
