module 1; biological molecules Flashcards
Define the term Monomer
Monomers are smaller units from which larger molecules are made
Define the term Polymer
Polymers are molecules made from a large no.of monomers joined together in a chain
Give examples of Monomers
1. Glucose
2. Amino acids
3. Nucleotide**
Give examples of Polymers
1. Starch
2. Cellulose
3. Glycogen
4. Protein
5. DNA & RNA
What is a Condensation reaction?
It’s a reaction that joins 2 molecules, creating a chemical bond and forms water as a by-product
What is a Hydrolysis reaction?
Breaks a chemical bond between 2 molecules using water
give examples of monosaccharides
- glucose
- fructose
- galactose
give examples of disaccharides and their monomers
- sucrose = glucose + fructose
- maltose = glucose + glucose
- lactose = glucose + galactose
draw a an alpha~glucose & beta~glucose monomer
alpha - OH group on C1 is at the bottom
beta - OH group on C2 is at the top
define the term isomer
isomers are molecules with the same molecular formula but have different structures
give examples of polysaccharides and where they are found
- starch - found in plants (cells e.g. chloroplasts)
- cellulose - found in plants (cell wall)
- glycogen - found in animals (muscle & liver cells)
describe the structure & function of starch
starch forms both amylose & amylopectin
store of alpha~glucose
- amylose
1,4 glyco bonds
unbranched helix - is compact so can fit a lot of glucose in a small space - amylopectin
1,4 & 1,6 glyco bonds
branched molecule - increases SA for rapid hydrolysis back to glucose
both are insoluble = won’t affect water potential
describe the structure & function of cellulose
beta~glucose monomers
1,4 & 1,6 glyco bonds
structure strength for cell wall
polymer forms long, straight chains held in parallel by many H bonds forming microfibrils
many H bonds = collective strength
insoluble = won’t affect water potential
describe the structure & function of glycogen
alpha~glucose
1,4 glyco bonds
store of glucose
highly branched molecule
branched = increased SA for rapid hydrolysis back to glucose
insoluble = won’t affect water potential
how are triglycerides formed?
by a condensation reaction between 1 molecule of glycerol & 3 molecules of fatty acids
what is the difference between a saturated & unsaturated fatty acid
a saturated fatty acid only has single bonds between carbons whereas unsaturated fatty acids have at least 1 double bond between carbons
what are the properties of triglycerides?
- energy storage - large ratio of energy storing C-H bonds = lots of energy stored in molecule
- high ratio of H to O atoms - acts as metabolic water source = can release water when oxidised (essential for animals like camels)
- don’t affect water potentials & osmosis - as they are large & hydrophobic = so they are insoluble in water
- low mass - a lot can be stored without increasing mass & preventing movement
how are phospholipids formed?
by 2 condensation reactions, 2 fatty acids bond to a glycerol resulting in 2 ester bonds
what are the properties of phospholipids?
- hydrophobic head - due to -ve charge on phosphate group
- attracts water & repels fats - as it’s charged
- hydrophobic tail repels water & mixes with fats - as it’s not charged
- 2 charged regions = polar
how is the phospholipid bilayer formed?
in water phospholipids are positioned in a way that the heads are exposed but the tails are not which forms bilayer
what are the monomers that form proteins called?
amino acids
draw the structure of an amino acid
(NH3) - (R)-(C)-(H) - (O)=(C)-OH
what do 2 monomers of proteins form & name the reaction that occurs
a condensation reaction occurs which joins 2 amino acids to one another by forming a peptide bond
how are proteins formed?
a series of condensation reactions occur which form a peptide bond between each amino acid forming a chain
what is a primary structure?
It’s the order of amino acids in the polypeptide chain
what is a secondary structure?
the sequence of amino acids causes parts of a protein molecule to bend into an alpha~helix or fold into beta~pleated sheets - held by H bonds
what is a tertiary structure?
it’s the further folding of secondary structure to form unique 3D shape - held in place by ionic, H & disulphide bonds
what is a quaternary structure?
a protein made up of more than one polypeptide chain
what are enzymes?
enzymes are tertiary structure proteins which lower the activation energy of the reactions they catalyse
how does bonding affect the binding of enzyme & substrate?
the folding & bonding in the tertiary structure of a protein causes the active site to be specific & unique in shape so enzymes can only bind to substrates that are complementary in shape
describe the induced fit model
induced fit is where the enzyme active site slightly changes shape to mould around the substrate
how does the induced fit model explain how activation energy is lowered?
due to enzyme-substrate complex the enzyme moulding around the substrate puts a strain on the bonds - lowers activation energy
what are the factors that affect enzymes?
- temperature:
temp too low = not enough KE for successful collisions
temp too high = active site changes shape - e/z complexes can’t form - pH:
too low/high pH = change in active site - charges change & bonds broken - enzyme denatures
different enzymes = different optimal pH - substrate conc:
insufficient substrate = reaction slower as fewer collisions between enz & sub - enzyme conc:
insufficient enzymes = enzyme active site will become saturated with subs & unable to work faster - enzyme inhibitors:
competitive = same shape at sub, binds to active site & prevents e/z complexes from forming
adding more substrate will outcompete the inhibitors knocking them out of active site
non-competitive = binds to allosteric site, causes active site to change shape
substrate can no longer bind to enzyme
what is the test for starch
- add iodine
- +ve test = solution turns from orange to blue/black
what is the test for reducing sugars?
- add benedict’s reagent & heat
- +ve test = solution turns from blue to green to yellow to orange or brick red (the more red = the higher conc of reducing sugars)
what is the test for non-reducing sugars?
- following benedict’s test where solution remained blue
- add acid & boil (acid hydrolysis)
- cool solution & add alkali to neutralise
- add benedict’s reagent & heat
- +ve test = solution turns from blue to orange or brick red
what is the test for proteins?
- add biuret
- +ve test = solution turns from blue to purple
what is the test for lipids
- dissolve sample in ethanol
- add distilled water
- +ve test = white emulsion forms
what is the monomer that forms DNA?
nucleotides
why is DNA important for proteins?
deoxyribonucleic acid (DNA) codes for sequence of amino acids in primary structure - determines final 3D structure & function
what does a DNA polymer form?
double helix
what are DNA’s monomers made up of?
deoxyribose (pentose sugar)
nitrogenous base - (guanine / cytosine / adenine / thymine)
phosphate group
how is a polynucleotide formed?
by a series of condensation reactions between deoxyribose sugar &phosphate group which forms phosphodiester bonds
how is a DNA polymer formed?
occurs in pairs joined by H bonds between bases (creates double helix 🧬) - H bonds can only form between complementary base pairs
what are the complementary base pairs in DNA?
cytosine + guanine
adenine + thymine
what is RNA & what is it made up of?
RNA is a polymer of a nucleotide formed of ribose, nitrogenous base & phosphate group
what are the complementary base pairs for RNA?
cytosine + guanine
adenine + uracil
what is the function of RNA?
its to transfer the genetic code from DNA in nucleus to the ribosomes.
some RNA (rRNA) is also combined with proteins to create ribosomes
name & explain the process of DNA replication called?
semi-conservative replication:
this is where one strand from the parental DNA & one strand that is newly synthesised forms a daughter strand
describe the process of semi-conservative replication
- DNA helicase breaks H bonds between complementary base pairs which causes DNA helix to unwind
- each of the separated parental DNA strand acts as a template. each of the free floating DNA nucleotides within the nucleus are attracted to their complementary bases on template strands of parental DNA
- the adjacent nucleotides are joined together (to form phospho bond) by condensation reaction. DNA polymerase catalyses the joining of adjacent nucleotides
- 2 sets of daughter DNA contains one strand of the parental DNA & one newly synthesised strand
give examples of evidence that supports semi-conservative replication
watson & crick discovered structure of DNA helped by rosalind franklin’s research on x-ray diffraction
meselson & stahl conducted experiment which proved that DNA replication is semi-conservative
what is ATP?
adenosine triphosphate (ATP) is a nucleotide derivative & an immediate source of energy for biological processes
why is ATP important for cells?
metabolic reactions in cells must have a constant & steady supply of ATP
how is ATP made?
made during respiration from ADP + Pi by a condensation reaction & using enzyme ATP synthase
how is energy released using ATP?
by hydrolysing ATP into ADP + Pi (by using ATP hydrolyse) small amounts of energy is released
what is phosphorylation & why is it important?
this is where an inorganic phosphate is released during hydrolysis of ATP can be bonded onto different compounds to make them more reactive. this is important for respiration as it happens to glucose at he start of respiration to make it more reactive
how does the bonds in water affect polarity?
the formation of these H bonds makes water dipolar
what are the key properties of water?
- its a metabolite (e.g. in condensation & hydrolysis reactions)
- important solvent in reactions
- has high heat capacity = buffers temp
4 .large latent heat of vaporisation = provides cooling effect with loss of water through evaporation - strong cohesion between water molecules = supports water columns & provides surface tension
where can inorganic ions be found?
they occur in solution in cytoplasms & body fluids of organisms varying in concs
give examples of inorganic ions & their roles
- H ions - lower pH of solutions & impact enzyme & haemoglobin function
- Fe ions - component of haemoglobin in transport of oxygen
- Na ions - involved in co-transport of glucose & amino acids in absorption or role in generating action potentials
- phosphate ions - component of DNA (forms phospho bonds with deoxyribose) & ATP (makes ADP more reactive)
