Topic 1 Flashcards
what are monomers
smaller units from which larger molecules are made
what are polymers
molecules made from a large number of monomers joined together
examples of monomers
nucleotides
amino acids
monosaccharides
examples of polymers
DNA/RNA
protein
polysaccharides
whats a condensation reaction
the joining of two molecules forming a chemical bond with the removal of a water molecule
whats a hydrolysis reaction
breaking of a chemical bond between two molecules using a molecule of water
what are monosaccharides
monomers from which larger carbs are made
examples of monosaccharides
glucose galactose and fructose
what type of bond forms when a condensation reaction occurs between two monosaccharides
a glycosidic bond
a condensation reaction between two glucose molecules forms..
maltose
what is a disaccharide
two monosaccharides joined by a glycosidic bond
sucrose is formed from..
a glucose and fructose molecule
glucose + galactose =
lactose
what are the three types of glucose
starch, cellulose and glycogen
what are the two types of starch
amylose and amylopectin
what monomer of glucose is starch made from
alpha glucose
what is the function of starch
to store glucpse
where is starch usually found
in plants
describe the glycosidic bonds in amylose
1-4
describe the glycosidic bonds in amylopectin
1-4 and 1-6
describe the structure of amylose
alpha coiled helix structure
how does the structure of amylose relate to its function
coiled helix allows for compactness which allows for lots of glucose to be stored
what is the structure of amylopectin
branched molecule
how does the structure of amylopectin relate to its function
branches allow for larger surface area so rapid hydrolysis is enabled
which glucose monomer makes up cellulose
beta glucose
where is cellulose found
plants - cell walls
what is the function of cellulose
to provide structural support
describe the glycosidic bonds in cellulose
1-4
what is the structure of cellulose
straight branched chains with hydrogen bonds between them to form fibrils
how are fibrils formed
hydrogen bonds between straight chains
how does the structure of cellulose relate to its function
lots of hydrogen bonds allows for strength
what monomer of glucose makes up glycogen
alpha
describe the glycosidic bonds in glycogen
1-4, 1-6
where is glycogen found
animals
what is the function of glycogen
stores glucose
describe the strucutre of glycogen
highly branchedh
how does the structure of glycogen relate to its function
lots of branches allows for rapid hydrolysis of the molecule and effective release of glucose
what are the two types of lipids
triglycerides and phospholipids
describe the structure of a triglyceride
one glycerol molecule with 3 fatty acids
describe the structure of a phospholipid
a glycerol molecule with 2 fatty acids and one phosphate group attached
what type of reaction occurs between the glycerol and fatty acids to form a triglyceride/phospholipid
condensation reaction
what is the bond between a glycerol and fatty acid called
ester bond
what does it mean if a fatty acid is saturated
there are only single C-C bonds in the hydrocarbon chain
what does it mean if the fatty acid is unsaturated
there is at least one C=C in the hydrocarbon chain
why is a lot of energy stored in a triglyceride molecule
theres a large ratio of emergy storing carbon-hydrogen bonds compared to the number of carbon atoms > lots of energy is stored in the molecule
why are triglycerides a metabolic water source
high ratio of hydrogen to oxygen atoms so they can release water if oxidised
why do triglycerides not affect osmosis / water potential
they are large and hydrophobic > so insoluble in water
what is the effect of lipids having a relatively low mass
lots can be stored without increasing the mass and preventing movement
why does a phospholipid have a hydrophilic head
negative charge on the phosphate group > attracts water and repels fats
why does the fatty acid tail repel water
because it is not charged
what is the function of phospholipids
to form the phospholipid bilayer
how does the structure of a phospholipids help relate to its function
hydrophilic head > faces the water
hydrophobic tails > face eachother
from which monomers are proteins made
amino acids are the monomers from which proteins are made
describe the general structure of an amino acid
amine group - NH2
carboxyl group - COOH
central carbon with H and variable group
which bond forms when a condensation reaction occurs between two amino acids
peptide bonds
how are dipeptides formed
condensation reaction between two amino acids
how are polypeptide formed
condensation reaction of many amino acids
what are the levels of structure in a protein
primary
secondary
tertiary
quaternary
describe the primary structure
order of amino acids in polypeptide chain
describe the secondary structure of a protein
sequence of amino acids determines whether the protein bends into an alpha helix or beta pleated sheet
- held together by hydrogen bonds
describe the tertiary structure of a protein
secondary protein structure is further folded
- hydrogen, ionic and disulfide bridges are formed to hold the structure together
describe the quaternary structure of a protein
a protein made up of more than one polypeptide chain
what is the protein structure level of an enzyme
tertiary
how does the tertiary structure of an enzyme relate to its function
tertiary structure of protein allows for the unique and specific shape of the active site > so enzymes can only attach to complementary substrates
what is the function of an enzyme
to lower activation energy of reactions they catalyse
explain what the induced fit model states
the enzyme active site slightly changes shape and moulds around the substrate > causes strain on the bonds allowing for activation energy to be lowered
what are the factors affecting enzymes
temperature
pH
inhibitors
enzyme conc
substrate conc
how does a too low temperature affect enzyme activity
not enough kinetic energy for successful collisions between enzyme and substrates
what is the affect of a temperature being above the optimum on enzyme activity
enzymes active site will denature and change shapes so the substrates will no longer be complementary
how does a too low/high pH affect enzyme activity
the pH will interfere with the charges in the amino acids in the active site and cause bonds to break causing denaturing of the active site so substrates will no longer be complementary to the active site
what is the effect of insufficient substrate on enzyme activity
fewer collisions between enzyme and substrate so rare of reaction decreases
what is the effect of excessive amounts of substrates on enzyme activity
rate of reaction remains constant because theres not enough empty enzyme active sites for substrates to bind to
what is the effect of insufficient enzymes on enzyme activity
enzyme active sites become saturated with substrate and unable to work any faster
what is the effect of too many enzymes on enzyme activity
there isnt enough substrate to bind with the enzymes so rate will remain constant
what are the two types of inhibitors
competitive and non-competitive
where do competitive inhibitors bind
to the active site
why do competitive inhibitors affect enzyme activity
they prevent enzyme-substrate complexes
how can the effect of competitive inhibitors be counteracted
by adding more substrates so that the inhibitors can be knocked out
where do non-competitive inhibitors bind
not to the active site > allosteric site
explain how non-competitive inhibitors effect enzyme activity
they bind to the allosteric site which means that the active site shape changes so the substrate is no longer complementary to it so enzyme-substrate complexes cant be formned
what is the effect of adding lots of substrate to a reaction with an enzyme with a non-competitive inhibitor
no effect > substrate can no longer bind due to changed shape of active site
describe the test for starch
add iodine dissolved in potassium iodide
whats the observation for a positive test for presense of starch
orange/brown > blue/black
describe the test for reducing sugars
add Benedicts reagetn and heat
whats the observation for a positive test result of a reducing sugar
blue > green, yellow, orange or black
how can you determine the concentration of the reducing sugar if present
the redder the colour change, the higher the conc
describe the test for non-reducing sugars
if test for reducing sugars = negative (stays blue)
- add acid and boil (acid hydrolysis)
- cool and neutralise with alkali (sodium hydrogencarbonate)
- add Benedicts and heat
what is the observation for a positive result for presence of a non-reducing sugar
blue > orange/brick red
describe the test for proteins
add Biuret to sample
what is the observation for a positive test for proteins
blue > purple
describe the test for lipids
dissolve sample in ethaol and shake and add dsitilled water
what is the observation of a positive result for the prescence of lipids
milky emulsion forms
what is the function of DNA
codes for the sequence of amino acids in the primary structure of a protein
what is the monomer of DNA
DNA nucleotides
what is the structure of a DNA nucleotide
deoxyribose (pentose sugar), nitrogenous base, and one phosphate group
what are the nitrogenous bases for DNA
guanine, thymine, cytosine and adenine
what is the polymer of nucleotides called
polynucleotides
how are polynucleotides formed
condensarion reactions between nucleotides
what is the bond between nucleotides called when a condensation reaction occurs
phosphodiester bond
between what two parts of the nucleotides do phosphediester bonds form
the deoxyribose sugar and the phosphate group
how is the sugar phosphate backbone
condensation reactions between phosphate group and deoxyribose pentose sugar, forming phosphodiester bonds which are very strong
structure of RNA nucleotides
ribose sugar, phosphate group and nitrogenous bases
what are the nitrogenous bases for RNA nucleotides
guanine, thymine, cytosine and uracil
what are the key differences between RNA and DNA nucleotides
DNA:
- double stranded, ATCG, deoxyribose
RNA:
- single stranded, AUCG, ribose and shorter
what is the function of RNA
to transfer genetic code from DNA in the nucleus to the ribosomes
outline the steps of semi-conservative replication
- DNA Helicase breaks the hydrogen bonds between the complementary base pairs within the double helix
- Free DNA nucleotides match up to the complementary base pairs on the two template strands
- Condensation reactions occurs between the adjacent nucleotides to form phosphodiester bonds - catalysed by DNA Polymerase
- Two sets of daughter DNA contain one of the template strands and one newly synthesised strand
what evidence is there for semi-conservative replication
Mehelston and Stahl conducted experiments
what is ATP
adenosine triphosphate
describe the structure of ATP
adenine, ribose sugar and three phosphate groups
what is the function of ATP
to provide an immediate source of energy for metabolic processes
how is ATP made
condensation reaction between ADP and Pi during respiration using enzyme ATP synthase
how is energy released from ATP
it is hydroylsed into ADP + PI using ATP hydrolase
what is phosphorylation
when the Pi released during hydrolysis of ATP is bonded onto different compounds to make them more reactive
give an example of phosphorylation
glucose at the start of respiration
what type of bond forms between water molecules and where do they form
hydrogen bonds between the oxygen of one molecule and the hydrogen of another
why is water considered dipolar
hydrogen is slightly positive whilst the oxygen is slightly negative
what are the 5 properties of water
- metabolite
- solvent
- high specific heat capacity
- cohesion
- strong latent heat of vaporisation
explain why water is a metabolite
it is involved in reactions e.g. condensation, hydrolysis
explain why water is a good/important solvent
it is dipolar > can dissolve solutes and transport them
why is it a good thing that water has a high heat capacity
our bodys are mainly water, and it takes alot of energy to change the temperature of our bodys and therefore enables enzymes to not be denatured
advantage of large latent heat of vaporisation of water
provides a cooling effect when we sweat with loss of watter through evaporation
how is the cohesion property of water beneficial
enables for water columns and provides surface tension > transpiration stream
where do inorganic ions occur
in solution > cytoplasm and body fluids of organisms
whats the role of hydrogen ions
lower pH of solutions
impact enzyme function
haemoglobin function
role of iron ions
component of haemoglobin in the transport of oxygen
role of sodium ions
co transport of glucose and amino acids in absorption
role of phosphate ions
component of DNA > phosphodiester bonds
ATP > makes ADP more reactive
