3.1 biological molecules Flashcards
what is a monomer
small units from which larger molecules are made
what is a polymer
molecules made from a number of monomers joined together
what is a condensation reaction
a reaction which joins two molecules together forming a chemical bond, removing a molecule of water
what is a hydrolysis reaction
a reaction which breaks a a chemical bond with the addition of water
what are the uses of carbohydrates
energy source - respiration
energy store - starch and glycogen
structure - cellulose
what is the bond between 2 carbohydrates
glycosidic
what are the monomers of maltose
2 alpha glucose molecules
what are the monomers of lactose
glucose and galactose
what are the monomers of sucrose
glucose and fructose
what is the monomer of glycogen
alpha glucose
what is the monomer of starch
alpha glucose
what is the monomer of cellulose
beta glucose
how does the structure of glycogen relate to its function
long and highly branched chain of a-glucose, stored glucose can be released quickly for respiration for energy release.
very compact, alot can fit in a small place
insoluable, doesnt affect the water potential of cells
structure of amylose (starch)
long and unbranched chain of a-glucose with 1-4 glycosidic bonds giving it a coiled structure which is good for storage.
structure of amylopectin (starch)
long and branched chain of a-glucose with 1-4 and 1-6 bonds, branched structure allowing for release of glucose for production of energy.
structure of cellulose
b-glucose with straight unbranched chains. the chains run parallel linked by hydrogen bonds. the large number of h-bonds allows for strength in the structure. the chains form microfibrils.
similarities of starch and cellulose
both molecules are polymers, both contain glucose and glycosidic
differences of starch and cellulose
starch contains a-glucose, cellulose contains b-glucose
starch is coiled and branched, cellulose has parallel chains
test for reducing sugars
- add benedicts reagent and heat
- colour change from blue to brick red
what is the use of excess benedicts reagent
to ensure all the sugars have reacted.
test for non-reducing sugars
- add HCl and heat - this hydrolyses any glycosidic bonds-
- neutralise with an NaOH
- colour change from blue to brick red
test for starch
- add iodine
- colour change from brown to blue - black
structure of an ATP molecule
adenine bas, ribose sugar and 3 phosphate groups
what enzyme hydrolyses ATP
ATP hydrolase
hydrolysis reaction of ATP
ATP -> ADP and Pi
how is ADP and Pi resynthesised ( equation, reaction and enzyme)
ADP + Pi -> ATP
condensation reaction between ADP and Pi removing a molecule of water
3 ways ATP is used as an energy source
energy is released in small amounts so it is not wasted.
soluable so it is easily transported around the cell
energy is rapidly released as there is one reaction
why is ATP a better energy source than glucose
1 ATP molecule releases less energy than 1 glucose molecule so it is more manageable
energy is released quicker in the single step of the hydrolysis ATP compared to the long process of respiration
how can ATP make an enzyme - catalysed reaction take place often
ATP provides a phosphate which can attach to a molecule and make it more reactive, lowering its Ea
structure of water
one oxygen atom joined to 2 hydrogen atoms in a covalent bond. a water molecule is dipolar, hydrogen has a partial + charge and oxygen has a partial - charge. the partial charges allows molecules to bond to eachother
metabolite property of water
many metabollic reactions involve hydrolysis and condensation reactions which both involve water
high latent heat of vaporisation
alot of energy required to break the hydrogen bonds in water so when water vaporises the water loss is used as a cooling mechanism
high specific heat capacity
alot of energy required to heat up water by 1.c this means the temp of water doesnt change easily, maintaing a stable enviroment.
solvent property of water
as water is polar it dissolves other substances allowing for transport
cohesion property of water
water molecules are cohesive as they are polar, this allows for transpiration
use of iron ions in the body
Fe2+ found in the structure of haemoglobin, allows for O2 to bind to the ion and be transported around the body
use of phosphate ions in the body
Phosphate ions used in ATP and DNA, breaking bonds between phosphate ions releases energy
use hydrogen ions in the body
used to calculate pH, more H+, the more acidic the enviroment.
use of sodium ions in the body
allows for glucose and amino acids to be transported into a cell via co-transport
2 types of lipids
triglycerides and phospholipids
difference between triglycerides and phospholipids
triglycerides have one molecule of glycerol with 3 fatty acids attached
phospholipid has one molecule of glycerol, one phosphate and 2 fatty acids
bond between glycerol and fatty acid
ester bond
difference between saturated and unsaturated fatty acids
saturated only have single C-C bonds
unsaturated contain C-C and C=C bonds
why are lipids suitable for their role as energy storage molecules
they have long hydrocarbon chains which contain alot of chemical energy.
they are insoluble so dont affect the water potential of cells.
why do triglycerides form insoluble droplets
the fatty acid tails are hydrophobic so face inwards to shield themselves from water with the hydrophilic phosphate heads
how is the structure of phospholipids related to its function
hydrophilic phosphate head and hydrophobic fatty aid tail, double layer is formed with the heads facing outwards and tails facing inwards.
test for lipids
add ethanol and shake.
add water and observe milky emulsion
how are amino acids joined together
by condensation reactions between the carboxyl group of 1 amino acid and the amine group of another amino acid forming a peptide bond removing a water molecule
describe the primary structure of a protein
the sequence of amino acids in a polypeptide chain
describe the secondary structure of a protein
hydrogen bonds between amino acids in the polypeptide chain forming a coil into an alpha - helix or folded into a beta pleated sheet
describe the tertiary structure of a protein
the secondary structure being further coiled to form a 3D structure. ionic, covalent and hydrogen bonds are formed aswell as disulphide bridges
describe the quaternary structure of a protein
proteins made up of more than 1 polypeptide chain
what is a globular protein
soluble proteins with a specific 3D shape e.g. haemoglobin and enzymes
what is a fibrous protein
strong, insoluble proteins e.g. keratin and collagen
test for proteins
add biuret to sample, observe colour change from blue to lilac
4 functions of proteins
enzymes, antibodies, transport proteins and structural protiens
what is a catalyst
a substance which speeds up a reaction without being used up by lowering the activation energy
how are enzymes specific
they have a specific tertiary structure so have a specific active site
describe the induced fit model
complementary substrate binds to the active site of the enzyme, forming an enzyme substrate complex, the active site changes shape slightly
what are the 5 factors which affect rate of reaction
temp, pH, substrate conc, enzyme conc and conc of inhibitors
effects of substrate conc on enzyme activity
increase substrate conc, increase chance of successful collisions, increase chance of forming ES complex increasing rate of reaction.
this continues until all active sites are full reaching maximum rate of reaction
effect of enzyme conc on enzyme activity
increase enzyme conc, increase chance of successful collisions, increase chance of forming ES complex increasing rate of reaction.
this continues until all substrates have been used reaching maximum rate of reaction
effect of temp on enzyme activity (before optimum temp)
as temp increase kinetic energy increases, molecules move faster, increasing chance of successful collisions, increasing chance of ES complex until optimum temp is reached.
effect of temp on enzyme activity (after optimum temp)
bonds in tertiary structure break, active site denatures, ES complexes no longer form as substrate is no longer complementary.
effect of pH on enzyme activity
pH which is not optimum leads to the active site being denatured as ionic and hydrogen bonds in the tertiary structure break
competitive inhibitors
substance with a similar shape to the substrate and a complementary shape to the enzymes active site. causes fewer ES complexes to be made. over come by increasing substrate complex
non-competitive inhibitors
a substance which binds to an allosteric site on the enzyme. causes the active site to change shape so it is no longer complementary to the substrate. no ES complexes made
rate of reaction
volume of product produced / time
monomers of DNA/RNA
nucleotides
3 components on nucleotides
nitrogenous base, pentose sugar and a phosphate group
pentose sugar in DNA and RNA
DNA - deoxyribose
RNA - ribose
bases in DNA
adenine, thymine, cytosine and guanine
bases in RNA
adenine, uracil, cytosine and guanine
bond between 2 nucleotides
phosphodiester
structure of DNA
DNA is a polymer made up of nucleotides which are joined together in condensation reactions between a phosphate group of one nucleotide and the pentose sugar of another.
adjacent nucleotides are joined together by weak hydrogen bonds
A pairs with T
G pairs with C
the strands coil into a double helix
how is the structure of DNA related to its function
double stranded- strands act as templates in semi-conservative replication
double helix- compact
complementary base pairing- allows for accurate replication
structure of RNA
polymer made up of nucleotides, single stranded/ linear. a short polynucleotide. ribose pentose sugar
A pairs with U
G pairs with C
differences between DNA and RNA
DNA is double stranded and RNA is single stranded
DNA contains deoxyribose sugar and RNA contains ribose pentose sugar
DNA contains thymine and RNA contains uracil
why is DNA replication considered semi-conservative
half of the original DNA strand is part of the new DNA strand
evidence for semi-conservative replication
- 2 samples of bacterial DNA grown under 15N or 14N
- bacterial DNA grown under 15N is heavier
- as the DNA is grown under 14N it gets lighter
semi conservative replication
- DNA helicase breaks the hydrogen bonds between the double helix unzipping the 2 strands
- free DNA nucleotides are attracted to the template strands and line up along the complementary base A+T, C+G
- DNA polymerase joins the nucleotides together in condensation reactions in the 5’ to 3’ direction
- two double helix strands are made where one strand is the original template strand and the second is the newly synthesised strand
