Chapter 1 - Biological Molecules Flashcards
what are carbohydrates
compounds comprising only of hydrogen carbon and oxygen units
what type of molecule is a carbohydrate
a polymer
characteristics of polymers
long complex molecules made of chains of monomers
examples of three monomers
monosaccharides
amino acids
nucleotides
what are the monomers of carbohydrates
monosaccharides
examples of monosaccharides 3
glucose fructose and galactose
what type of sugar is glucose and why
hexose sugar - it had 6 hydrogen atoms
glucose + glucose =
maltose
glucose + fructose =
sucrose
glucose + galactose =
lactose
what are the two types of glucose
alpha and beta glucose
what are isomers
molecules with the same molecular formula but the atoms are bonded in a different way
what is a condensation reaction
two monosaccharides join together to form a disaccharide and a molecule of water is produced
what bond is formed in a disaccharide
glycosidic
what can a hydrolysis reaction do
break apart polymers
how does a hydrolysis reaction work
it breaks the glycosidic bond in a disaccharide using a water molecule to form the original monosaccharides ut only under the correct conditions
what are reducing sugars
chemicals that readily reduce other when in solution
how to test for a reducing sugar
add 1cm3 sugar to test tube
add 1cm3 benedicts reagent
heat in a water bath at 70c for 4 minutes
positive result for benedicts test for reducing sugar
goes brick red if a lot of sugar is present
how to test for a non reducing sugar
add 1cm3 solution to test tube
add 1cm3 hydrochloric acid to hydrolyse the sugar
add sodium carbonate until universal indicator paper turns green
add 1cm3 benedicts solution
place in a water bath at 70c for 4 minutes
non reducing result for benedicts test for non reducing sugars
goes brick red
when are polysaccharides formed
when more than two monosaccharides join together in a condensation reaction
examples of polysaccharides 3
starch glycogen and cellulose
which monomers make up cellulose
beta glucose
structure of cellulose
straight unbranched chains of beta glucose run parallel to each other
hydrogen bonds form between the chains
this forms microfibrils which group to make fibres
function of cellulose
structural support
which monomers make up glycogen
alpha glucose
structure of glycogen
large branched chains of alpha glucose provide a large surface area for enzymes to act upon
function of glycogen
stores glucose to be released when we need it
how do you test for starch
add a solution of iodine dissolved in potassium iodide solution and it should change from brown to blue black
function of starch
plant store excess glucose as starch so it can be broken down into glucose when the plant needs energy
advantages of starch 2
large so can’t fit through cell membranes to upset osmotic potential
insoluble so doesn’t impact osmotic potential balance
which monomers make up starch
alpha glucose
structure of starch
made of two alpha glucose polysaccharides
amylose- long unbranched chains which coil up and make it very compact
amylopectin - long branched chain of glucose which provides a large surface area for enzymes to act on
what are triglycerides
one molecule of glycerol with three fatty acids tail
what are the fatty acids made from
hydrocarbons
are fatty acids tails hydrophilic or phobia
hydrophobic they repel water
how are triglycerides produced
a condensation reaction occurs between one fatty acid tail and the glycerol molecule forming an ester bond and a molecule of water
this happens three times
bonding in triglycerides
ester
how many molecules of water are released when a triglyceride is made
3
what are the two kinds of fatty acids
unsaturated and saturated
difference between saturated and unsaturated fatty acids
unsaturated fatty acids have double carbon bond which means that the maximum amount of hydrogen isn’t present
this also causes a characteristic kink
what are phospholipids
one molecule of glycerol
two fatty acid tails and one phosphate tails
is the phosphate tail hydrophilic or phobic
hydrophilic
how to test for lipids
use the emulsion tesy
take a completely dry and grease free test tube
add 2cm3 sample and 5cm3 ethanol
shake to dissolve any lipids
add 5cm3 water and shake again
if lipids are present a white precipitate will form
functions of phospholipids
make up a bilayer of cell membranes
why do phospholipids form a bilayer of cell membranes
the heads phosphate group are hydrophilic and interact with the water whilst the bodies fatty acids are hydrophobic so water substances can’t easily pass through
functions of triglycerides 2
heat insulation
energy storage molecules
why are triglycerides used as storage molecules
the hydrocarbon tails contain a lot of energy which is released when they are broken down
they are insoluble so they don’t affect the osmotic balance of the cell because of their hydrophobic tails and the glycerol heads act like a barrier
what are the monomers of proteins
amino acids
what is a polypeptide
when more than two amino acids join together
what is a dipeptide
when two amino acids join together
what are proteins made from
multiple polypeptides
what will all amino acids contain
an amine and a carboxyl group
what varies between amino acids
the r group
formula for amine group
NH2
Formula for carboxyl group
COOH
How are polypeptides formed
condensation reaction of amino acids
when does the reverse reaction for making proteins happen
digestion
what s the bond in polypeptides
peptide bond
how many molecules of water are released
1 molecule
what is the primary structure of a protein
the sequence of multiple amino acids in a polypeptide chain
what is the secondary structure of protein
hydrogen bonds form between the amino acids in the polypeptide chain turning it into a beta pleated sheet or an alpha coil
what is the tertiary structure of a protein
the coiled chain of amino acids coils further. more bonds form between different parts of polypeptides
when will the tertiary structure of a protein be its final structure
when it is made form one single polypeptide chain
what are the three bonds in the tertiary structure of a protein
disulfide bridges
ionic bonds
hydrogen bonds
when will disulphide bonds form
between the sulphurs in the r group of two amino acids
what is the quaternary structure of a protein
numerous polypeptide chains are held together by bonds
when will the quaternary structure of a protein be its final structure
when it is made from multiple polypeptide chains
what is special about the quaternary structure of a protein
it may include a prosthetic group (a non protein group )
what are the four main jobs of proteins
antibodies
enzymes
transport proteins
structural proteins
characteristics of enzymes
they roughly spherical in shape because of the tight folding of the polypeptide chains
soluble
have roles in metabolism
characteristics of structural proteins
long polypeptide chains lying parallel to each other with crosslink between them
characteristics of antibodies
two short and two long polypeptide chains bonded together
characteristics of transport proteins
channel proteins found in cell membranes contain both hydrophobic and hydrophilic amino acids which cause the protein to fold up and form a channel along which substances can travel
what is the test for proteins
add sodium hydroxide solution to the sample to make it alkaline
add copper II sulphate solution
purple - protein
blue - no protein
what are enzymes
biological catalysts that lower the activation energy of a reaction without being affected themselves
how do enzymes lower the activation energy of a reaction
if a substrates are to be joined together being attached to the enzymes holds them close and overcomes any repulsion
if a substrate is to be broken down then fitting it into the active site puts a strain on the bonds so it easier to break
what is the lock and key model
the substrate fits into the active site in the same way a key does to a lock
what is the induced fit model of enzyme action
the active site can change to accommodate the substrate if they aren’t complimentary
why will enzymes only catalyse one reaction
every enzyme has a tertiary structure and a different shaped active site which can be impacted by pH or temperature
this means that only one substrate is complimentary and so will be broken down
what is the effect of temperature of enzymes
a rise in temperature increases the kinetic energy of the molecules which leads to an increase in more successful collisions and more enzyme substrate completed being completed
what happens when the temperature gets too high
the vibrating molecules break some of the bonds that hold the active site in shape so the enzyme substrate are no longer complimentary
the enzyme has denatures
what is the effect of pH on enzyme activity
at any other pH other than the optimum the OH- and H= ions mess up the hydrogen bonds in the proteins tertiary structure
this makes the active site change shape and the enzyme is denatured
how does the enzyme concentration affect the rate of reaction
the more enzyme molecules there are the more likely that an enzyme substrate complex will be formed. if the concentration is limited then it will have no further effect
how does substrate concentration affect the rate of reaction
the higher substrate concentration the higher the rate of reaction because collisions will be more likely
after saturation point through all the active sites are full and so an increase in substrate conenctration makes no difference
what are competitive inhibitors and how do they work
competitive inhibitors have a similar shape to the substrate so they directly compete for the active site
when they bind they block the active site so no enzyme substrate complexes can be formed
are competitive inhibitors affected by substrate concentrations
yes a higher concentration of substrate means that there is a lower chance of the inhibitor binding successfully to the active site
this increases the rate of reaction
what are non competitive inhibitors and how do they work
they bind to the allosteric site of the enzyme and cause the active site to change shape so the substrate can’t bind and create a complex
are non competitive inhibitors affected by substrate concentration
no they don’t compete with the substrate for the active site
what is covalent bondign
atoms share a pair of electrons in their outer shell
what is ionic bonding
ions with opposite charges attract each other electrostatic attractions
what is hydrogen bonding
the electrons in a bond aren’t very evenly spread between the two atoms
this forms a polar molecule because one region is more electronegative than another
what is metabolism
all the chemical reactions that take place in an organisms
what is a molar solution
a solution containing one mole of solute in each litre of solution
why do most molecules contain carbon
they form bonds readily so form a carbon backbone
why does benedicts reagent turn red when heated with a reducing sugar
the sugar donates electrons that turn the blue copper ii sulfate to red copper I oxide
what is produced when maltose is hydrolysed
glucose
what is produced when starch is hydrolysed
maltose
