BIOLOGICAL MOLECULES Flashcards
TOPIC 1
MONOMERS
smaller units from which larger molecules are made
POLYMERS
Molecules made from large number of monomers joined together
CARBONHYDRATES
Monosaccharide
Polysaccharide
Carbon, hydrogen, oxygen
PROTEINS
monomer-Amino acid
polymer-Polypeptide
compounds-Carbon, hydrogen, oxygen, nitrogen, and sulphur
NUCLEIC ACID
monomer-Nucleotide
polymer-Polynucleotide
compounds-Carbon, hydrogen, oxygen, nitrogen, and phosphorus
WHY ARENT LIPIDS POLYMERS
macromolecules but are not polymers- because they are not made of repeating set of monomers, but number of molecules joined together in non-repeating pattern
CONDENSATION REACTION
remove a molecule of water from two monomers, forming chemical bond between them
HYDROLSIS REACTION
reaction that breaks a chemical bond
Between two molecules-Involves use of water molecule
GLYCOSIDIC BOND
C–O–C link
Between two sugar molecules
Formed by condensation reaction it is covalent bond
MONOSACHARIDES
monomers, single sugar units
DISACCHARIDES
two monosaccharides joined together, still generally sugars condensation reaction forms glycosidic bond
eg. maltose, sucrose,lactose
POLYSACHARIDES
polymer, lots of repeating units of monosaccharides condensation reaction forms glycosidic bond
eg.cellulose,starch,glycogen
GLUCOSE NOT ABLE TO BE STORED
cannot be stored within cells as it is soluble, it would dissolve in cytoplasm of cells, lowering its water potential, causing water to flow in cell, resulting in it bursting
STARCH + GLYCOGEN STORAGE
glucose in plants as starch and glycogen stores glucose in animal cells as glycogen- store excess glucose until organism requires energy from respiration
GLYCOGEN + STARCH STRUCTURE
polymer of a-glucose
insoluble-dont affect water potential
large-cant cross cell membrane
compact-store lots in cell
branched-provides lots of ends easily hydrolysed to release glucose used in respiration
AMYLOSE
Polysaccharide in starch
Made of α-glucose
Joined by 1,4-glycosidic bonds
Coils to form a helix
AMYLOPECTIN
Polysaccharide in starch
Made of α-glucose
Joined by 1,4 and 1,6-glycosidic bonds
Branched structure
CELLULOSE
straight chained polymer of β-glucose
very strong and rigid molecule which provided structural support in plant cell walls, preventing it from bursting when cell is filled w/water
Straight chains of cellulose interact w/each other w/hydrogen bonds forms structures known as microfibrils
microfibrils provide strength to cellulose structure
FIBRILS
Long, straight chains of β-glucose glucose
Held together by many hydrogen bonds
TESTING FOR CARBOHYDRATES-REDUCING SUGARS
1.Add excess Benedict’s to test solution
2.Boil mixture
3.If reducing sugar is present solution will change from blue to green/yellow/orange/brick-red
TESTING FOR CARBOHYDRATES-NON REDUCING SUGARS
1.Add Benedict’s reagent and heat, if it remains blue do following steps
2.Add hydrochloric acid and heat
3.Neutralise acid w/sodium hydroxide
4.Add Benedict’s reagent and boil
5.If solution now turns red then non-reducing sugar was initially present
WORKING OUT UNKNOWN CONCENTRATION
1.Create set of known concentrations of sugar solutions
2.Carry out Benedict’s test on each
3.Place solutions into colorimeter and measure absorbance OR filter precipitate, dry it and weigh mass
4.Plot these results onto a graph
5.Draw line of best fit
6.Carry out the benedict’s test on your unknown solution and measure its absorbance/mass of precipitate
7.Take absorbance/mass value of your unknown, read from line using graph to determine concentration
TESTING FOR STARCH
iodine dissolved incKI reacts with starch
colour change from orange to black
TRIGLYCERIDES
Formed by the condensation of one molecule of glycerol and three molecules of fatty acids
Forming 3 ester bonds
HOW DOES THE STRUCTURE OF TRIGLYCERIDES RELATE TO ITS FUNCTION
Large ratio of energy-storing carbon-hydrogen bonds compared to number of carbon Atoms; lot of energy is stored in molecule
high ratio of hydrogen to oxygen atoms they Act as metabolic water source
Do not affect water potentials and osmosis
Have relatively low mass
PHOSPHOLIPIDS
Formed by the condensation of one molecule of glycerol and two molecules of fatty acid
Held by two ester bonds
Phosphate group is attached to glycerol
HOW DOES THE STRUCTURE OF PHOSPHOLIPIDS RELATE TO ITS FUNCTION
have two charged regions, so they are polar
In water, they are positioned so that heads are exposed to water and tails are not
This forms phospholipid bilayer which makes up plasma membrane around cells
SATURATED FATTY ACIDS VS UNSATURATED FATTY ACIDS
carbon-carbon single bonds vs carbon-carbon double bond
PHOSPHOLIPDIS VS TRIGLYCERIDES
.both have C,O,H
.both contain glycerol
.both contain ester bonds
.fatty acids can be saturated or unsaturated
.two fatty acid chains + phosphate group vs triglycerides’ three fatty acid chains .hydrophilic region as well as hydrophobic region vs entirely hydrophobic
.form micelles or bilayers when in solution vs don’t form micelles
TEST FOR LIPIDS
1.mix sample w/ethanol
2.add water
3.milk white emulsion will appear if result is positive
AMINO ACIDS
monomer that form protein polymers are 20 naturally occurring amino acids have an -NH2 and -COOH but have variable region which differs between each amino acid – this referred to as R group
PEPTIDE BONDS
Covalent bond joining amino acids together in proteins
C–N link between two amino acid molecules
Formed by condensation reaction
POLYPEPTIDE
polymer made up of many amino acid monomers joined together by peptide bonds
PROTEIN STRUCTURE
- P-sequence of amino acids on polypeptide chain
- S- folding or coiling create β pleated sheet or an α helix held in place by hydrogen bonds
- T-further folding- create unique 3D shape
held in place by hydrogen, ionic and disulphide bonds - Q-More than one polypeptide chain in protein
GLOBULAR PROTEIN
soluble proteins w/biochemical functions such as enzymes and hormones
FIBROUS PROTEIN
insoluble and have structural functions e.g. keratin in nails and hair
TEST FOR PROTEINS
Biuret solution is used to test for presence of a protein-added to sample and if solution changes from blue to lilac/purple then protein is present
ENZYMES
tertiary structured proteins
speed up rate of reaction – w/X getting used up themselves
specific to one type of reaction due to their specific tertiary shape
Enzymes bind to substrates-substrates bind to specifically shaped part of enzyme known as active site- active site is complementary to substrate
Once substrate has bound to enzyme an enzyme-substate complex is formed
HOW ENZYMES LOWER THE ACTIVATION ENERGY
1.Bending bonds in substrate, putting strain on bonds, and making them more likely to break
2.Bringing two molecules close together, overcoming natural repulsion between two molecules, making bond between two molecules more likely
INDUCED FIT MODEL
enzyme active site is not initially complementary to substrate
active site moulds around substrate-puts tension on bonds -lowers activation energy
LOCK + KEY MODEL
active site of an enzyme is structured to fit specifically shaped substrate
Once substrate binds to active site, enzyme will facilitate reaction and release products of reaction
EXPLAIN HOW ACTIVE SITE AN ENZYME CAUSES HIGH RATE OF REACTION (3)
.lowers activation energy
.induced fit causes active site to change shape
.enzyme-substrate compels cases bonds to form
HOW TEMPERATURE AFFECTS ENZYME ACTIVITY
At low temperatures, there is not enough kinetic energy for successful collisions between enzyme and substrate
At too high a temperature, enzymes denature, active site changes shape and enzyme- substrate complexes cannot form
HOW PH AFFECTS ENZYME ACTIVITY
Too high or too low a pH will interfere w/ charges in amino acids in active site
breaks ionic and hydrogen bonds holding tertiary structure in place- active site changes shape and enzyme denatures
Different enzymes have different optimal pH
HOW SUBSTRATE CONCENTRATION AFFECTS ENZYME ACTIVITY
At low substrate concentrations, there will be fewer collisions between the enzyme and substrate
At high substrate concentrations, rate plateaus because all enzyme active sites are saturated
HOW ENZYME CONCENTRATION AFFECTS ENZYME ACTIVITY
At low enzyme concentrations, there will be fewer collisions between the enzyme and substrate
At high enzyme concentrations, rate plateaus because there are more enzymes than substrate, so many empty active sites
COMPETITIVE INHIBITOR
molecule that is same/similar shape as substrate-binds to active site
Prevents enzyme-substrate complexes from forming + reduces rate of reaction
NON-COMPETITIVE INHIBITOR
molecule that binds to an enzyme at allosteric site
Causing active site to change shape
Preventing enzyme-substrate complexes from forming
RP1: INVESTIGATING INTO EFFECT OF VARIABLE ON RATE OF ENZYME CONTROLLED REACTION
.Add 5cm3 of distilled water to 2cm potato cylinder-Crush to form smooth paste using pestle and mortar
.Label each of your test tubes w/dilution starting from 0.5M – 2.5M
.Starting w/2.5M tube, using syringe add 10cm3 of 2.5M H2O2 -Use stock solution and distilled water to make up other concentrations and add to appropriate labelled test tube
.Using forceps, dip filter paper disc into potato paste and tap off excess
.Starting w/2.5M solution, drop filter paper disc into hydrogen peroxide solution and measure time, to nearest second, that it takes from striking surface to sink, to float up surface again
.You will need to have your stopwatch ready as you drop disc in
.Make note of time
.Remove disc from the tube using forceps and discard it on your paper towel
.Repeat steps 3-5 for each solution
RP1: WHY SHOULD PASTE BE SMOOTH
Lumps would affect surface area and rate of enzyme-controlled reaction
RP1: WHY DID DISC RISE
Oxygen formed from breakdown of hydrogen peroxide would form on surface of paper disc-would become less dense causing it to rise
RP1: HOW WOULD YOU CALCULATE RATE FROM AN END POINT REACTION
1/Time taken
RP1: WHY SHOULD SMALLER INTERVALS BE USED
obtain more accurate optimum
RP1: WHY COMPLETE REPEATS
more reliable mean and allow identification of anomalies
RP1: WHY IS BUFFER SOLUTION USED
keep PH constant
see whether change in PH will affect enzyme controlled reaction
RP1: WHY WOULD A COLOUR STANDARD BE USED
rate is calculated by time of indicator to change colour
RP1: WHY ARE TEST TUBES KEFT IN WATER BATH BEFORE ADDING ENZYME TO SUBSTRATE
equilibrate
reach temperature of water bath
RP1: SUGGEST IMPROVEMENTS
use buffer solution to prevent changes in pH, use thermostatically controlled water bath
HOW TO WORK OUT CONCENTRATION OF NEWLY MADE SOLUTION OR SPECIFIC CONCENTRATION
C1=V1
C2=V2
C1=concentration of original stock solution
V1=volume of original solution to use
C2=concentration of new solution
V2=total volume of new concentration
PHOSPHDIESTER BOND
Condensation reactions join phosphate of one nucleotide to pentose sugar of another nucleotide
DNA STRUCTURE RELATED TO ITS FUNCTION
sugar - phosphate backbone-gives strength compact shape
sequence of bases-allows information to be stored
long molecule- stores large amount of information
information can be replicated-complementary base pairing
double helix- molecule stable prevents code being corrupted
chains held together by weak hydrogen bonds
chains can split for transcription
PROTEIN SYNTHESIS
contains genes which codes for order of amino acids in protein
RNA
single, relatively short, polynucleotide chain-used in production of proteins
MRNA
A single stranded straight chained molecule, made of bases which are read in triplets called codons
carry genetic code out of nucleus to ribosome for formation of 1 polypeptide
TRNA
single strand of RNA folded in many places forming complementary base pairs- shape is described as clover leaf
It has an amino acid binding site and triplet of bases called an anticodon
carry specific amino acids to mRNA at ribosomes for formation of polypeptide
RRNA
rRNA is found in cytoplasm
Along w/protein molecule, it forms ribosomes
DNA VS RNA
.Two strands vs One strand
.Very long vs Relatively short
.Adenine, thymine, guanine, and cytosine vs Adenine, uracil, guanine, and cytosine
.Stores genetic information vs Transfers genetic information in formation of proteins and helps form ribosomes
DESCRIBE STRUCTURE OF DNA
- Polymer of nucleotides
- Each nucleotide formed from deoxyribose, phosphate group and nitrogenous base
- Phosphodiester bonds between nucleotides
- Double helix held by hydrogen bonds
- Hydrogen bonds between adenine, thymine and cytosine, guanine
SEMI-CONSERVATIVE REPLICATION
DNA replication is semi- conservative replication
each new molecule of DNA contains one original strand and one new strand
DNA HELICASE
unwinds DNA and breaks hydrogen bonds between bases- allows nucleotides to attach to each strand and for each strand to act as template
DNA POLYMERASE
joins adjacent DNA nucleotides together- catalyse forming phosphodiester bonds in sugar-phosphate backbone
catalyses condensation reaction
ATP
nitrogen containing base – Adenine, pentose sugar – ribose and 3 phosphate groups
STAGES OF DNA REPLICATION
- DNA helicase separates DNA strands by breaking hydrogen bonds
- Each strand acts as template
- Free nucleotides attach to exposed bases by complementary base pairing
- adenine w/thymine and guanine w/ cytosine
- DNA polymerase joins nucleotides forming phosphodiester bond
MESELSON + STAHL EXPERIMENT
grew E Coli bacteria in broth containing Nitrogen- originally contained heavy isotope of Nitrogen (15N)- E Coli incorporated 15N into any newly made nucleotides
After while they transferred sample of E Coli from 15N broth into broth containing lighter isotope (14N) of Nitrogen – now any time E Coli made new nucleotides they would incorporate 14N making this DNA less dense DNA containing 15N
MESELSON + STAHL RESULTS
results proved that replication was semiconservative- first generation of DNA molecules contained both heavy and light DNA so ruled out conservative replication
second generative of DNA contained intermediate molecules and molecules which only contained light DNA, this ruled out dispersive, proving that semi-conservative was correct mode of DNA replication
Later generations have thicker bands of ‘light only DNA’ -shows there are more molecules of 14N only DNA with each generation
FUNCTION OF ATP
.storage and transfer of energy within cells- activation of enzymes and contraction of muscles
.releases energy in small amounts
.cannot leave cells through cell membrane
.involved in biosynthesis of macromolecules
ATP HYDROLASE
Enzyme that catalyses the hydrolysis of ATP into ADP +Pi
ATP SYTHASE
Enzyme that catalyses the synthesis of ATP from ADP + Pi
PROPERTIES OF WATER
.metabolite- condensation reaction
.solvent so metabolic reactions can occur
.high heat capacity-buffer changes in temperature
.large latent heat of vaporisation-provides a cooling effect
.cohesion-produces surface tension supporting organisms
.cohesion-supports column of water
INORGANIC IONS
Sodium- used in co-transport of glucose and amino acids in small intestine
Hydrogen-Changes pH of solutions by making it more acidic + create electrochemical gradients in production of ATP
Iron-component of haemoglobin in red blood cells oxygen ions transport around body
Phosphate-Important in production of ATP and nucleic acids
