BIOLOGICAL MOLECULES - SECTION 1 Flashcards
(carbs, lipids, proteins, enzymes, nucleic acids, atp, water and inorganic ions.
1
Q
DEFINE MONOMERS AND POLYMERS?
A
MONOMERS ARE SMALLER UNITS (MOLECULES) WHICH MAKE UP THE LARGER MOLECULE, POLYMER. POLYMER IS A LARGE MOLECULE MADE UP OF MANY MONOMER UNITS (MOLECULES) JOINED TOGETHER.
2
Q
REACTION IN WHICH POLYMERS ARE MADE?
A
CONDENSATION REACTION TO FORM A CHAIN.
3
Q
WHAT ARE MONO, DI AND POLY SACCARIDES?
A
MONOSACC’S - SINGLE SUGAR MONOMER WHICH IS THE BUILDING BLOCK FOR POLYSACC’S (POLYMERS), THEY ARE A SOURCE OF ENERGY IN RESPIRATION. (ALL MONO SACC’S ARE REDUCING)
DISACC’S - 2 MONOSACC’S JOINED TOGETHER IN A CONDENSATION REACTION, VIA THE FORMATION OF A GLYCOSIDIC BOND. (LACTOSE IN MILK IS A DISACC FOR EG)
POLYSACC’S - MANY MONOSACC’S JOINED TOGETHER IN A CONDENSATION REACTION, VIA GLYCOSIDIC BONDS, TO FORM A LONG CHAIN.
4
Q
ARE LIPIDS POLYMERS? AND WHY?
A
NO, BECAUSE POLYMERS ARE MADE OF MANY OF THE SAME REPEATING UNIT (MONOMER), WHEREAS LIPIDS ARENT.
5
Q
HOW ARE REDUCING SUGARS DETECTED?
A
ADD BENEDICTS. HEAT THE MIXTURE. BRICK RED PPT FORMS IF REDUCING SUGAR PRESENT.
6
Q
IF UR A REDUCING SUGAR, IT MEANS U CAN DONATE ELECTRONS AND THEREFORE BE OXIDISED. (as ur an electron donor), hence why are some sugars classified as non -reducing? and therefore why cant u test them directly with benedicts)
A
cuz they cant donate electrons and therefore cannot be oxidised by benedicts, hence u cant test for their presence by adding benedicts to begin with.
7
Q
hence how do u detect non reducing sugars?
A
FIRST they need to be hydrolysed and broken down into their monosaccarides, so add dilute hcl, then neutralise. then heat with benedicts as normal.
8
Q
sucrose consists of ________ and ________. what glycosidic bonds are present in sucrose vs in maltose?
A
sucrose consists of beta fructose and alpha glucsose joined together in a condensation reaction, via 1,2 - glycosdic bond. in maltose a 1,4 - glycosdic bond is present.
9
Q
since sucrose is a non- reducing sugar and needs to be hydrolysed in order to add benedicts to it and test for it, where does the water in the hydrolysis of the glycodic bond in sucrose come from?
A
when sucrose is heated with hcl, this provides the h20
10
Q
DEFINE CHROMATOGRAPHY
A
technique to separate a mixture into its individual components.
11
Q
in paper chromatography, solutes with ____ solubility move further up the paper. and solute with _____ solubiltity move further down the paper. why?
A
high solubility, move further up the paper because they spend more time in the mobile phase. solutes with lower solubility move less further up, cuz they spend less time in the mobile phase.
12
Q
whats the mobile phase and stationary phase in paper chromatography?
A
mobile - solvent.
stationary - chromatography paper.
13
Q
why do mixtures containing coloured molecules ( ink present), not have to be stained prior to chromatography?
A
because they are already coloured.
14
Q
hence mixtures that have colourless molecules have to be ______?
A
stained
15
Q
use paper chromatography to separate a mix of monosacc’s ( give the procedure). and how can u identify the unkown monosacc sample?
A
a spot of the stained monoccaride sample mixture is placed on the line above the solvent. ( this spot contains the unknown monosacc)
spots of known standard solutions of monosacc’s are placed on the line beside the sample spot.
the chromatography paper is then suspended in a solvent.
as the solvent moves up the paper, the different monosacc’s within the mixture begin to separate at different distances from the line.
the unkown one can then be identified by comparing and matching them with the chromatograms (final outcome of spots) of the known standard solutions of different monosacc’s. (or by comparing rf values)
if a spot from the monosacc sample mixture is at the same distance from the line as a spot from one of the known standard solutions, then the mixture must contain this specific monosacc.
16
Q
WHY DOES STARCH TAKE LONGER TO DIGEST THAN GLUCOSE.
A
DUE TO THE MANY MONOMERS IN A STARCH MOLECULE.
17
Q
STARCH IS MADE UP OF AMYLOSE AND AMYLOPECTIN. ELABORATE AND EXPLAIN THE STRUCTURE OF BOTH THESE polysacc’s:
A
AMYLOSE : UNBRACHED HELIX- SHAPED CHAIN, CONSISTING OF MANY ALPHA GLUCOSE MOLECULES JOINED TOGETHER BY 1,4 - GLYCOSIDIC BONDS
ITS HELIX SHAPE ALLOWS FOR ITS COMPACTNESS WHICH, MAKES IT VERY RESISTANT TO DIGESTION. (AS WELL AS THE HIGH NUMBER OF MONOMERS PRESENT).
AMYLOPECTIN: BRANCHED MOLECULE CONSISTING OF MANY ALPHA GLUCOSE MOLECULES JOINED TOGETHER BY 1,4 GLYCOSIDIC BONDS AND 1,6 GLYCOSIDIC BONDS, ALLOWING IT TO BE CHAINED. THIS ALLOWS FOR MANY TERMINAL GLUCOSE ENDS TO BE PRESENT, HENCE MOLECULES CAN BE EASILY HYDROLYSED MORE RAPIDLY. (BRANCHED MEANS GLUCOSE CAN BE EASILY ADDED OR REMOVED)
18
Q
HOW DOES FAST HYDROLYSIS IN MOLECULES IN AMYLOPECTIN HELP?
A
USE IN REPIRATION OR ADDED TO FOR STORAGE
19
Q
WHY ARE STARCH AND GLYCOGEN STORAGE POLYSACCS?
A
THEY ARE COMPACT
THEY ARE INSOLUBLE IN WATER, HENCE DONT AFFECT THE WATER POTENTIAL (HAVE NO OSMOTIC EFFECT ON WATER)
20
Q
WHY DOES GLUCOSE HAVE AN OSMOTIC EFFECT ON WATER?
A
SINCE IT LOWERS THE WATER POTENTIAL, OF A CELL, CAUSING WATER TO MOVE INTO THE CELL, HENCE THESE PLANT CELLS WOULD THEN HAVE TO HAVE THICKER WALLS AND ANIMALS CELLS WOULD BURST UNDER INCREASED PRESSURE.
21
Q
ELABORATE AND EXPLAIN THE STRUCTURE OF GLYCOGEN? (WHY DO LIVER AND MUSCLE CELLS CONTAIN HIGH CONCS OF GLYCOGEN, glycogen being more branched than amylopectin means what?)
A
highly branched structure which isnt coiled. liver and muscle cells contain high concs of glycogen due to the high rate of respiration occuring in them. glycogen being more branched than amylopectin, makes it more compact, helping animals store more.the branching enables more free terminal glucose ends, where glucose can either be added or removed, (for use in respiration) allowing for condensation and hydrolysis reactions to happen more rapidly, hence the storage/release of glucose can suit the demand of the cell.
22
Q
ELABORATE AND EXPLAIN THE STRUCTURE OF CELLULOSE?
A
CHAIN POLYMER CONSISTING OF CHAINS OF BETA GLUCOSE MOLECULES JOINED TOGETHER BY 1,4 GLYCOSIDIC BONDS. CUZ ITS FORMED FROM BETA GLUCOSE MOLECULES AND THESE GLUCOSE MOLECULES HAVE BEEN ROTATED BY 180*, MANY H2 CAN FORM BETWEEN THE LONG CHAIN GIVING CELLULOSE STRENGTH.
23
Q
WHY IS CELLULOSE USED AS A STRUCURAL COMPONENT?
A
THE PRESENCE OF MANY H2 BONDS THAT FORM BETWEEN THE LONG CHAINS OF BETA GLUCOSE MOLECULES (I.E, THE PARRALEL CHAINS OF MICROFIBRILS),
24
Q
GIVE THE FUNCTIONS OF CELLULOSE:
A
CELLULOSE FIBRES AND OTHER MOLECULES (LIKE LIGNIN),FOUND IN THE CELL WALL, FORM A MATRIX, STRENGTHENING THE CELL WALLS, HENCE PROVIDING SUPPORT TO THE PLANT.
USED AS A STRUCUTRAL COMPONENT IN CELLS WALLS DUE TO THE MANY H2 BONDS PRESENT BETWEEN THE PARALLEL CHAINS OF MICROFIBRILS.
THE HIGH TENSILE STENGTH OF CELLULOSE, ALLOWS IT TO BE STRETCHED WITHOUT BREAKING, MAKING IT POSSIBLE FOR CELL WALLS TO WITHSTAND TURGOUR PRESSURE.
CELLULOSE FIBRES ARE FREELY PERMEABLE, ALLOWING WATER AND SOLUTES TO ENTER AND REACH TH CELL SURFACE MEMBRANE.
few organism have enyme cellulase which hydrolyse cellulose, as its a source of fibre.
25
why is the benedicts test for reducing sugars a semi-quantitative?
cuz the degree of colour change shows how much conc of reducing sugar is present.
26
which sugar is non reducing and which are reducing
glucose, galactose,fructose, maltose are reducing. sucrose is non-reducing.
27
HOW DOES CELLULOSE GIVES THE PLANT FIBRE COTTON ITS STRENGTH?
THE MANY H2 BONDS PRESENT BETWEEN THE PARALLEL LONG CHAINS OF MICROFIBRILLS, PROVIDES STRENGTH.
CELLULOSE FIBRES AND MOLECULES LIKE LIGNIN, FOUND IN THE CELL WALL, FORM A MATRIX, PROVING STRENGTH TO THE CELL WALL, HENCE SUPPORTING THE CELL WALL.
28
2 SIMILARITIES AND 2 DIFFERENCES BETWEEN GLYCOGEN AND AMYLOPECTIN? (STRUCTURE WISE)
s: BOTH HAVE 1,4 AND 1,6 GLYCOSIDIC BONDS.
BOTH ARE MADE UP OF THE MONOMERS ALHPA GLUCOSE.
d: GLYCOGEN IS MORE HIGHLY BRANCHED THAN AMYLOPECTIN.
HENCE GLYCOGEN HAS MORE TERMINAL GLUCOSE ENDS THAN AMYLOPECTIN.
29
gLUCOSE IS CONVERTED INTO STARCH IN:
A CONDENSATIONR REACTION.
WHERES CHAINS ARE FORMED VIA 1,4 GLYCOSIDIC BONDS FORMING BETWEEN GLUCOSE MONOMERS.
AND BRANCHES ARE FORMED VIA 1,6 GLYCOSIDIC BONDS BETWEEN CHAINS.
WATER IS RELEASED/PRODUCED AS A BY-PRODUCT.
30
suggest why using a colorimeter to measure light absorbance would be favourable over a comparison done by eye?
it provides a quantitative measurement.
31
give 4 features of starch and explain how these features allow it to act as a storage substance. (8)
the helix-shaped chain in amylose, makes starch very compact, making it resistant to digestion.
starch is insoluble, hence doesnt affect the water potential.
amylopectin in starch makes it a branched molecule, making it more compact aswell as making it have many glucose terminal ends, for fast hydrolysis of glucose, allowing molecules to be added for storage.
long chain hence has many glucose molecules.
32
when asked about the description of how glucose is stored within the cell, what do u describe? (4)
I.E, u describe the structure of glycogen as:
condensationr reaction takes place where water is produced/released as a by product.
many alpha glucose monomers join together via 1,4 glycosidic bonds to form a long chain of alpha glucose molecules.
alpha 1,6 glycosidc bonds form between alpha glucose molecules to form branches of alhpa glucose molecules.
as a result glycogen forms which is an insoluble glucose store.
33
describe what appens when lacotse is broken down into its monomers.
enzyme lactase undergoes a hydrolysis reaction, and breaks the 1,4 glycosidic bond within lactose, using water.
34
state the role of cellulose in plant cell walls and explain how its structure is related to this role?
role: high tensile strength
the many h2 bonds present between unbranched parallel chains of glucose molecules, forming microfibrills.
35
HOW IS CONC CONTROLLED?
CONC IS CONTROLLED BY USING THE SAME STOCK SOLUTION.
36
DESCRIBE + EXPLAIN 3 FEATURES OF GLYCOGEN THAT MAKE IT WELL SUITED TO ITS ROLE AS AN ENERGY STORE?
INSOLUBLE HENCE DOESNT AFFECT THE WATER POTENTIAL.
COMPACT, HENCE CAN FIT INTO SMALL GRANULES.
CAN BE EASILY/RAPIDLY SYNTHESISED AND BROKEN DOWN. HENCE IT CAN RAPIDLY RESPOND TO HORMONES INSULIN + GLUCAGON.
37
2 SIMILARITIES AND 2 DIFFERENCES BETWEEN AMYLOSE AND AMYLOPECT (IN STARCH) AND EXPLAIN HOW THESE FEATURES RELATE TO THEIR FUNCTION.?
S: BOTH HAVE 1,4 GLYCOSIDIC BONDS, HENCE BOTH FORM CHAINS OF GLUCOSE MOLECULES, MEANING BOTH ARE COMAPCT.
BOTH ARE MADE UP OF ALPHA GLUCOSE MOLECULES AND HAVE MANY, SO LOTS OF RESPIRATION CAN TAKE PLACE.
D: AMYLOSE HAS A HELICAL SHAPE SO ITS COMPACT AND CAN RESIST DIGESTION, WHEREAS AMYLOPECTIN FORMS A BRANCHED MOLECULE, SO IT HAS MANY TERMINAL GLUCOSE MOLECULES, HENCE MANY CONDENSATION AND HYDROLYSIS REACTIONS CAN TAKE PLACE RAPIDLY.
THE IDEA OF AMYLOPECTIN HAVING 1,4 AND 1,6 GLYCOSIDIC BONDS MEANS IT CAN FORM A BRANCHED STRUCURE THAT ALLOWS FOLDING FOR EVEN MORE COMPACTNESS.
38
SUGGEST HOW STARCH IS ALTERED FOR USE AS A SOLUBLE LABORATORY REAGENT? (2)
STARCH IS HYDROLYSED PARTIALLY INTO SHORTER CHAINS OF ALPHA GLUCOSE. HELPING TO REDUCE THE SIZE OF THE STARCH POLYMER.
39
HOW DOES CELLULOSE HAVE THE ABILITY TO FORM STRONG, STRAIGHT FIBRES IN BIO TISSUES.
CELLULOSE HAS ALTERNATING GB'S THAT FORM ON OPPOSITE SIDES OF THE CHAIN.
DUE TO THE POSITION OF OH AND H GROUPS IN BETA GLUCOSE.
40
SIMILARITIES AND DIFFERENCES BETWEEN GLUCOSE AND FRUCTOSE?
S: BOTH ARE 6 CARBON SUGARS
D: GLUCOSE IS A 6 ATOM RING WHEREAS FRUCTOSE IS A 5 ATOM RING.
41
GIVE 2 METHODS IN WHICH THE GLYCOSIDIC BOND IN A DISACHARIDE CAN BE BROKEN?
ACID HYDROLYSIS:
BOIL A SAMPLE WITH DILUTE HCL
ENZYME HYDROLYSIS:
MIX THE DISACC WITH ENZYME AT OPTIMUM 40.
42
what are the 2 types of lipids?
triglycerides and phospholidips
43
triglycerides consist of what and is formed how?
3 fatty acids, and one glycerol molecule which are joined together in a condensation reaction, via the formation of 3 ester bonds, releasing 3h20 molecules. ( KNOWN AS ESTERIFICATION)
44
what are the 2 ways fatty acids can vary?
the length of the hydrocarbon chain
the fact that it may be saturated or unsaturated
45
unsaturated fatty acids can be _____ or _____
mono or poly
46
give all the functions of triglyerides?
the long hydrocarbon chain in Triglycerides contain many c-h bonds, which have little 02, so when triglycerides are oxidised during cellular respiration, the c-h bonds are broken, releasing energy used to produce ATP. hence triglycerides store lots of energy.
since T's are hydrophobic they dont cause osmotic water uptake in cells, hence more of it can be stored.
47
Why are plant-based triglycerides (oils) typically liquid at room temperature?
Plant-based triglycerides (oils) are liquid at room temperature because they contain double bonds in their fatty acid chains. These double bonds create kinks, preventing the molecules from packing closely together, which lowers their melting point and alters their properties.
48
the oxidation of c-h bonds in cellular respiration releases what? which can be used by what?
large numbers of h20 molecules which can be retained/used by desert animals where there is no liquid water to drink, (and can be used by birds and reptile embryos in their shells (also use this water released))
49
How do triglycerides function as insulation in the body?
Triglycerides help insulate the body in two ways:
They are part of the myelin sheath, which surrounds nerve fibres and increases the speed of nerve impulse transmission.
They are stored in adipose tissue beneath the skin (e.g., whale blubber), reducing heat loss and helping maintain body temperature.
50
How do triglycerides help animals float/ provide buoyancy?
The low density of triglyceride-rich fat tissue increases buoyancy, making it easier for animals to float in water.
51
How do stored triglycerides help protect organs in mammals?
Triglycerides are stored in adipose tissue, which acts as a cushion around organs, helping to protect and reduce the risk of damage.
52
phospholipids consist of?
2 fatty acids joined to a glycerol molecule via ester bonds in a condensation reaction, while having a phopshate group.
53
why are phospholipids soluble in water? and why are they hydrophobic at the same time?
phosphate group is polar, making phospholipids hydrophilic. the fatty acids tails are insoluble.
54
phospholipids are amphipathic (having both hydrophobic and philic parts). as a result of this they are able to do what?
form mono layers or bilayers in water.
55
main role of phospholipid?
it is the main component (building block) of cell membranes.
56
when a phospholipid bilayer forms, a hydrophobic core (part) is created. what stimulates that? and what does this bilayer act as?
the presence of hydrophobic fatty acid tails. this bilayer acts as a barrier for water-soluble molecules.
57
the hydrophilic phosphate head in phospholipids, forms hydrogen bonds with h20, allowing for what?
allowing the cell membrane to be used to compartmentalise, enabling the cells to organise specific roles into organelles helping with efficiency.
58
How do phospholipid fatty acid tails affect cell membrane fluidity?
Phospholipid composition influences membrane fluidity:
Saturated fatty acid tails pack tightly, making the membrane less fluid.
Unsaturated fatty acid tails have kinks that prevent tight packing, making the membrane more fluid.
59
How do phospholipids influence membrane protein orientation and movement?
Phospholipids control membrane protein orientation through weak hydrophobic interactions. These interactions hold proteins in place within the membrane while still allowing movement within the lipid bilayer.
60
what bonds are present in phospholipids?
2 ester bonds, and 1 phosphodiester bond. hence 3 h20 molecules are released when condensation reactions take place.
61
give the qualitative emulsion test for lipids?
add ethanol, then water, shake it (the mix).
white cloudy emulsion forms if lipid present.
62
in unsaturated fatty acids, there is atleast one single c=c double bond. what do these double bonds cause?
these double bonds cause the adding of kinks to the unsaturated fatty acid, causing the chain to bend slightly, hence preventing it from packing closely together, meaning they are not as straight as saturated fatty acids.
63
GIVE THE PROPERTIES OF TRIGLYERIDES AND EXPLAIN FOR EACH?
MaINLY Used as ENERGY STORAGE MOLECULES DUE TO THE LONG HYDROCARBON CHAIN WHICH CONTAINS LOTS OF CHEMICAL ENERGY WHICH IS RELEAED WHEN THE BONDS IN FATTY ACIDS ARE BROKEN (VIA OXIDATION IN CELLULAR RESPIRATION).
THEY ARE ALSO SUITED AS ENERGY STORAGE MOLECULES BECAUSE THEY ARE INSOLUBLE, HENCE THEY DONT AFFECT THE WATER POTENTIAL INSIDE THE CELLS.
INSIDE CELLS, TRIGLYCERIDES FORM INSOLUBLE DROPLETS, WITH THE HYDROHPHOBIC FATTY ACID TAILS IN THE INSIDE, AND THE HYDROPHILIC GLYERCOL HEAD ON THE OUTSIDE, preventing water soluble moleules (eg glucose) from passing through
64
GIVE THE PROPERTIES OF PHOSPHOLIPIDS?
phosholipids have a hydrophilic phosphate head, allowing a phospholipid bilayer to form which its centre being hydrophobic acting as a barrier, preventing water-soluble molecules from passing through, and controlling what substances enter and leave the cell.
65
why are phospho lipids suitable for making up cell membranes?
as they form a bilayer.
66
describe + explain a sample prep step that a scientist should take before performing the emulsion test on a sample of pasta?
crush the pasta (into a powder)
hence exposing the lipids in pasta to ethanol and water during the shaking process.
67
why use a rubber bung instead of just covering the test tube with a finger, during the shaking process in lipid emulsion test?
finger is a bio molecule, hence it may contain lipids, and therefore give a positive false result.,
68
give the structural feature that makes fatty acids to be solid at room temp?
long straight hydrocarbon chain present in fatty acids, allowing it to be very compact and tightly packed closely together.
69
what will happen to ph and why when more lipase is being added to break down lipids?
ph will decrease as lipase is added, as that means more lipids will be broken down into fatty acids and glycerol. hence more fatty acids are present, so its more acidic (lower ph)).
70
why does a solution go cloudy when h20 is added to triglycerides?
because triglycerides are non polar hydrophobic molecules, hence form micelles in water ( triglercides group up to minimise exposure to water), causing the clouds appearance.
71
how do phospholipids form a cell membrane?
hydrophilic polar phosphate head
forms hydrogen bonds with water
hydrophobic fatty acid non polar tails are located between the layers of phosphate heads, and therefore and away from water.
phospholipid then forms a bilayer.
72
the lipase (enzyme) had to be freshly prepared because _____
enzyme (solutions) can denature/lose activity if left in solution. (not fresh)
73
3 curves show a reduction of ph due to the hydrolysis of lipids into fatty acids? once curve uses a temp of 5, when uses a temp of 35 and one uses a temp of 55. explain whats happening in each?
at 5 degrees, it shows a smaller decrease in ph, and thats due to low molecular kinetic energy present.
at 35 degrees, it shows the fastest curve to reach a stable ph due to optimum temp.
at 55 degrees, it shows/remains the highest amount of ph level present, due to the denaturation of lipase hence not much product (fatty acids + gylcerol) is produced.
74
outline the 3 main biochemical outcomes for triglyercides that are ingested as part of an animal's diet?
triglercides are metabolised for:
converted to other fatty acids (for energy storage)
respired to generate energy
synthesis of new plasma membranes (as phospholipids)
75
describe how the amphipathic nature of a phospholipids structure allows phospholipids to perform their function?
phospholipid has a hydrophilic polar phosphate head, and a hydrophobic non-polar fatty acid tails.
the fatty acids repel and stay away from water, keeping them together, forming a hydrophobic core allowing for molescules to align in a bilayer.
to form a partially permeable membrane that forms as an effective boundary layer.
76
suggest which 2 features of the structure of cholesterol make it effective in performing its role in relation to membrane fluidity?
the hydrophilic and hydrophobic regions allow it to enter and remain in the bilayer.
the flat strucure allows is to sit easily between layers of the bilayer.
77
lipid compositon in RBC is 24% cholesterol. phagocytes (a WBC) contains around 11% cholesterol. explain why?
cholesterol increases the rigidity of the membrane (low cholesterol membranes are more flexible)
and bare in mind phagocytes substantially change shape as they engulf pathogens.
therefore because of this continuous changing of shape they need more fluidity, hence they need less and contain less cholesterol.
78
DEFINE PROTEINS?
polymers made up of the monomers amino acids which are joined together to form a long chain.
79
THE sequence, order and type of amino acids determines what?
the structure (shape) and hence the function of proteins.
80
whats a dipeptide and how is it formed?
2 amino acids joined together in a condensation reaction, via a peptide bond, releasing one molecule of h20.
81
whats a poly peptide? and can be broken down via what back into what>?
many amino acids (3 or more) joined together and can be broken back into amino acids via hydrolysis.
82
use paper chromatography to separate a mix of amino acids. elaborate on the process. (to identify unkown amino acids)
a sample mixture contain the unkown amino acids, is placed on the line above the solvent.
known standard solutions of different known amino acids are then placed beside it on the line.
the chromatography paper is then suspended in a solvent.
as the solvent moves up, the sample mixture as well as the known standard solutions begin to separate into different spots that have different distances from the line.
larger molecules will move slower down the paper than smaller ones
solutes with high solubility will move further up as they spend more time in the mobile phase (solvent), whereas solutes with lower solubility will spend less time in the mobile phase (solvent) and move less futher up.
a chromatogram is then produced but before comparisons between distances from the line of the known standard solutions of amino acids with the unknown sample mixture can be made, leave the paper to dry then spray the chromatography paper with ninhydrin solution. (or rf values)
if the sample mixture is at the same distance from the line as one of the other amino acids then it contains that amino acid.
83
whats the point of spraying the C paper with ninhydrin solution.
this chemical reacts with amino acids to produce an easily visible blue-violet colour.
84
DEFINE PRIMARY STRUCTURE
refers to the order/ sequence of amino acids, bonded by covalent peptide bonds, in a polypeptide chain.j
85
how does DNA determine the primary structure and fucntion of a protein?
instructs the cell by adding certain amino acids in specific quantities in a certain sequence. this affects the shape and therefore the function of the protein.
86
the primary structure is very specific for each protein. what does that mean?
1 alteration in the sequence of amino acids, can affect the overall function of the protein.
87
DEFINE SECONDARY STRUCTURE? and give the types.
COILING of the polypeptide chain that is held together by h2 bonds (that form between nh region of one end and the c=o region of another end), to form 2 shapes that can form due to the h2 bonds. alpha helix and beta pleated sheet.
the alpha helix forms when h2 bonds occur between every 4th peptide bond.
the beta pleated sheet occurs when the protein folds so that 2 parts of the polypeptide chain are parallel, allowing h2 bonds to form between folded layers.
88
define tertiary strucure?
further folding of secondary structure to form a 3d structure with additional bonds:
h2 bonds between R groups
ionic bonds between charged R groups
weak hydrophobic interactions between non-polar R groups
disuphide bonds between cycsteine molecules.
this strucutre is common in globular proteins
89
fibrous proteins are _____ whereas globular are__
F are secondary strucutred proteins, whereas G are tertiary structured proteins.
90
DEFINE QUATERNARY:
CONSISTS OF 2 OR MORE POLYPEPTIDE CHAINS BONDED TOGETHER BY THE SAME BONDS IN THE TERTIARY STRUCTURE.
91
EACH OF THE 20 AMINDO ACIDS THAT MAKE UP A PROTEIN EACH HAVE WHAT?, MAKING DIFF INTERACTIONS TO OCCUR
UNIQUE R GROUP, THEREFORE MANY DIFF INTERACTIONS CAN OCCUR.
92
ELABORATE ON DISULFIDE BONDS
STRONG COVALENT BOND THAT FORMS BETWEEN 2 CYCSTEIN MOLCULES. ITS THE STRONGEST BOND FOUND WITHIN THE PRTEIN BUT OCCUR LESS FREQUENT AND HELP STABILISE THE PROTEIN.
THEY CAN BE BROKEN DOWN BY REDUCTION.
93
give the protein test? and whats required for a positive result?
add biuret reagent.
solutions turns purple from blue if protein is present.
for a positive result there must be atleast 2 peptide bonds present, hence amino acids or a dipeptide will give a negative result.
94
buiret test is quanti or quali tative?
qualitative
95
elabotate on the entire structure of haemoglobin
haemoglobin is an oxygen-carrying pigment found in vast quantities in RBC's. it has a quaternary structure as it consists of 4 polypeptide chains joined together. each polypeptide chain (subunit) is a globin protein, there are 2 alpha globins and 2 beta globins. disulphide bridges are assembled between the subunits joining them together, to allow the arrangement of hydrophobic R groups to move inward, toward the centre of the protein, maintaining the 3d spherical shape, as well as allowing the hydrophilic polar R groups to move outwards, to maintain the proteins solubility.
The arrangement of R groups is vital in the structure and hence the function of haemoglobin. if any changes occur, this can affect the shape, properties and hence the function of haemoglobin. this is what happens to cause sickle cells anaemia where a base substion forms valine (non-polar) from glutamic acid (polar), making the protein way less soluble.
the prostheic haem groups in each of the subunits in haemoglobin contains fe2+, which can reversible combine (can bind and detach) to oxgyen, to form oxyhaemoglobin, making it easier for oxygen to transport around the body. there are 4 haem groups, which can bind to 4 oxygen molecules, hence 8 oxygen atoms.
96
function of haemoglobin
responsible for binding of 02 in the lund and transporting 02 around the body, to tissues, to be used in metabolic pathways. oxygen is not soluble and haemoglobin is hence the the binding makes it easier for o2 to be transported around the body when bound to haemoglobin.
the presence of the haem group and fe2+ makes it easier for o2 to be bound more easily as when each oxygen molecules binds subsequently (from 1st to 4th), it alters the tertiary strucutre, hence alters the quaternery structure of haemoglobin, making it easier to bind as haemoglobin then has a higher affinity for the subsequent oxygen molecule.
the existence of iron means o2 can reversibly bind.
97
intracellular enzymes vs extracellular?
intracellular enzymes are produced and function inside the cell,
extracellular enzymes are secreted by cells and catalyse reactions outisde the cell.
98
whats denaturation of an enzyme
extremes of heat or changes in ph can alter the shape of the active site, hence preventing substrate from binding. this is it.
99
the shape of the active site (and hence the specificity of the enzyme) is determined by what?
the teriary structure of the protein that makes up the enzyme.
100
enzyme reactions can either be cata or anabollic. how do the 2 differ?
catabollic involes the breakdown of complex molecules into more simpler products. this is what happens when a single substrate is drawn into the active site, and broken apart into 2 or more distinct molecules.
anabollic reactions involves the building up of a complex molecule from simpler ones. this is what happens when 2 or more substrates are drawn into the active site, and peptide bonds a formed between them, to release a single product..
101
enzymes speed up chemical reactions as they infuence the stability of bonds in the reactants (substtrates). the destabilisation of bonds in the substrate makes it more what?
reactive
102
whats the induced fit model
when the active site changes shape slightly to allow the substrate to be complementary to it so that E-s complex can form, maximising the enzymes ability to catalyse the reaction.
103
the progress of an enzyme catalysed reaction to measure enzyme activity can be investigated by:
measuring the rate of formation of a product using catalase.
measuring the rate of disappearance of a substrate (reactant) using amylase.
104
catalase breaks down hydrogen peroxide (toxic hence must be broken down quickly) into what? and whats measured to measure enzyme activity.
h20 and oxygen. the rate of oxgyen formation in a given time is measured to measure the activity of catalase.
105
whats the point of the measuring cylinder that collects o2 to be placed in a beaker of water.
the water surrounding it excludes air during o2 collection.
106
amylase breaks down starch into glucose. how is amylase activity measured.
using the time taken for starch to be broken down (disappear), which is measured.
107
How does a colourimeter measure the progress of an amylase-catalyzed starch breakdown reaction?
A colourimeter measures light absorbance or light transmission to track the breakdown of starch by amylase. As starch is broken down into maltose, the colour intensity decreases, leading to increased light transmission or decreased absorbance. This change can be used to determine the rate of the reaction.
108
Why is calibration important in a colourimetric investigation of amylase activity, and how is it done?
Calibration ensures accurate measurements by setting a reference point for 100% transmission. In this experiment, a weak iodine solution is used to calibrate the colourimeter, as it represents the end point when all starch is broken down. This allows accurate comparison of absorbance or transmission values during the reaction.
109
GIVE 6 LIMITING FACTORS WHICH AFFECT ENZYMES?
TEMP
PH
ENZYME CONC
SUBSTRATE CONC
PRESENCE OF INHIBITORS
INHIBITOR CONC
110
How does temperature affect enzyme activity, and why do high temperatures lead to enzyme denaturation?
At low temperatures, enzyme activity is slow because LOW KINETIC ENERGY IS PRESENT, HENCE molecules move less, leading to fewer successful collisions and less frequent enzyme-substrate complex formation.
At moderate/HIGH temperatures, molecules move faster AS HIGH KINETIC ENERGY IS PRESENT, increasing the frequency of successful collisions and enzyme-substrate complex formation, which speeds up the reaction.
However, at high temperatures, the enzyme denatures because hydrogen bonds break, altering the enzyme’s tertiary structure and changing the shape of the active site. This prevents the substrate from binding, stopping the reaction. Most human enzymes denature above 40–50°C.
111
how does PH affect enzyme activity?
Different enzymes have different optimum PH values.
enzymes are denatured at extreme PH values. h2 and ionic bonds are present in the tertiary structure of a protein holding it together. below and above the optimum ph of an enzyme, means that solutions with an excess of H+ and OH- ions will break these bonds present in the tertiary structure, hence altering the tertiary structure and therefore altering the shape of the active site, so subtrates can bind less easily, so less e-s complexes can form, eventualy not forming. causing the enzyme to denature.
112
how does enzyme conc affect enzyme activity/rate of reaction? and whats the limiting factor
the higher the enzyme conc, the more active sites available, hence the more e-s complexes form. as long as there is sufficient substrate available, the initial rate of reaction increases lineally with enzyme conc. if the amound of substrate is insufficient/limited in numers in a given time/period, then any further increase in enzyme conc, will have no effect and not increase the number of e-s complexes formed, hence wont increase the rate of reaction more. hence the substrate is the limiting factor. ( when in short supply, it affects the outcome)
113
how does substrate conc affect enzyme activity/rate of reaction?
the greater the substrate conc the more e-s complexes will form, and therefore the higher the rate of reaction. if the enzyme conc remains fixed at any certain point, and the substrate conc increases, all the active sites of the enzymes available will eventually become saturated/occupied and no more e-s complexes will form, hence the rate of the reaction will no longer increase. when the active sites of an enzyme are fully occupied, any substrate molecules have nowhere to bind to form e-s complexes.
114
what are comp and non-comp inhibitors?
comp inhibitors - inhibitors that have a similar shape to the substrate and compete with the substrate for the binding of the active site.
non-comp inhibitor - inhibitor that binds to an alternative site (allosteric site) on the active site, altering the shape of the active site so that it is no longer complementary to the substrate, hence no e-s complexes form.
115
How does end-product inhibition regulate metabolic pathways?
End-product inhibition is a form of reversible, non-competitive inhibition that prevents enzymes from overproducing a product. The final product of a metabolic pathway binds to an alternative site on the first enzyme, changing its active site and preventing further enzyme-substrate complex formation. When product levels drop, the inhibitor detaches, allowing the enzyme to become active again. This feedback loop ensures tight control of metabolic reactions, preventing excess product formation.
116
an enzyme activity can be reduced or stopped temporarily by what?
a reverse inhibitor. ( can bind and detach)
117
how does inhibitor conc affect enzme activity?
both types of inhibitors will slow down enzyme activity and so increasing the conc of inhibitors therefore reduces the rate of reaction, and eventuallyif inhibitor concs increases even more, the reaction will stop completely.
for comp inhibitors, the increase in comp inhibitors can be countered by increasing the conc of substrates so that more substrates are available for e-s complexes to from. but for non-comp inhibitors, this cant be countered even if u increase the conc of substrates cuz the binding of the non comp inhibitor to the alternative site, changes the shape of the active site so no e-s complexes can form.
118
while a comp inhibitor reduces the initial rate of reaction (by occupying some of the available active site), it eventually gets countered due to the increase in substrate conc, this means whats produced?
WHEREAS NON COMP INHIBITOR DOES WHAT TO THE INITIAL ASWELL AS MAXIMAL FINAL RATE?
eventually the same amount of product will be produced as would have been produced without a comp inhibitor. HENCE THE MAX RATE IS NOT ALTERED.
WHEREAS A NON COMP, REDUCES THE INITIAL AND MAXIMAL RATE OF REACTION (MEANING LOWER AMOUND OF PRODUCT PRODUCED THAN NORMALLY)
119
1 PIECE OF EVIDENCE TO SUPPORT INDUCED FIT
XRAY DIFFRACTION TECHNIQUES ALLOW FOR 3D PICTURES OF MOELCULES TO BE FORMED.
120
dipeptides are formed when what?
a peptide bond forms between 2 amino acids and joins them together.
a condesnation reaction takes place between nh2 and cooh of adjacent amino acids, releasing h20.
121
a polypeptide contains 288 peptide bonds. calc the total number of amino acids in this polypeptide. explain (3)
289
there must be atleast 1 more amindo acids then the total number of peptide bonds
as peptide bonds form between amino acids.
122
explain why most cellular enzymes like DNA polyperases are made predominantly from protein? (remember that enzymes like these substantially change in shape)
proteins shape is related the its function
and the folding of the primary structure into a teritary 3d structure is determined by the bonds (h2, ionic etc) present in the primary sequence.
if the order of amino acids is changed within the polypeptide, this affects the position of the bonds present that form between the acids in the structure, altering the shape of the protein.
123
its beneficial for washing powder to contain molecules that have the ability to break down protein because what?
it allows for the removal of protein stains.
124
explain how a polypeptides teriary strucutre is determined by bonds between amino acids? (4)
the proteins primary structure (bonds in the primary sequence) within the polypeptide chain determines how they fold to form a 3d tertiary structure.
bonds form between neighbouring amino acids on different parts of the chain.
the bonds themselves are dependent on which amino acids are brought close together.
disulfide bridges form between 2 cystein molecules.
125
explain how changes in the influenza HA gene segment would prevent human antibodies from binding to the influenza attachment protein? (5)
a change in the gene segment, means there is a change in the RNA base sequence of the HA gene segment.
this means there is a change in the sequence of amino acids.
this therefore alters the position of the bonds (H2, ionic, disulphide)
which alters the shape of the tertiary structure.
and so the specific antibodies are no longer complementary to the H.
126
explain why different solvents have to be used in each stage of some non-paper chromatography techniques (2-way thin layer chromatography)?
using 2 or more solvents gives better separation of each individual amino acids.
amino acids not separated by the first solvent will be separated by the 2nd solvet.
127
why would amino acids with the same rf values with a particular solvent not be separated by (2-way thin layer chromatography)
same rf values means that the spot would not separate. (remain on top of each other).
128
EXPLAIN how the secondary structure of a protein contributes to its overall 3D shape(4)?
due to the H-bonding
between the c=o and N-H group
the protein forms a alpha helix
and a beta pleated sheet forms due to the chain folding itself (in a ziz zag plane) , to form 2 chains parallel to each other (where h2 bonds form between these chains).
both help extend the proteins 3D shape.
129
dsecribe the quaternary structure of haemoglobin and explain how its structure is related to its function? (6)
consists of 4 polypeptide chains joined together. 2 alpha globins and 2 beta globins. disulphide brideges assemble between the polypeptide chains to help rearrange a strucutre in a way where the hydrophobic non-polar fatty acids are facing inwards, to maintain its spherical shape, and the hydrophilic polar parts facing outwards to maintain its solubility.
any change in the sequence of the R group would affect the structure and hence the function of haemoglobin.
haemoglobin contains globin each with a haem group which contains fe2+, allowing to reversibly bind with oxygen molecules, forming oxyhaemoglobin, making it easier for oxygen to transport around the body as haemoglobins primary function is to supply o2 around the body, so when o2 is bound to haemoglobin since its more soluble it makes it much easier.
the binding of oxygen increases haemoglobins affinity for oxygen as the quaternary structure is altered, making it easier for the binding with subsequent oxygen molecules. allowing haemoglobin to deliver oxygen readily to tissues that require it the most.
130
llamas and high soaring birds have an 18% diff in their amino acid sequence compared to humans. suggest and explain the diff between llama haemoglobin and human haemoglobin structure (4)?
llamas haemoglobin structure:
has a higher affinity for oxygen compared with humans
as it lives at higher altitudes where conc of oxygen is low.
and therefore each haem group in llamas haemoglobin binds more easily and quickly to oxygen
since the order of amino acids alters the tertiary structure differently compared to humans.
131
the component of cysteines structure that plays an important role in a proteins tertiary strucutre is:
sulfur atom
which forms disulfide bonds to other cysteine molecules
and disulfide bonds are strong, covalent links that strengthen a proteins overall structure.
132
suggest how the research scientist controlled the ph throughout the experiment?
used a buffer solution (which resists changes in PH)
and hence recorded the ph at regular time intervals.
133
attracting the enzymes to the beads is more efficient for using the enzyme lactase rather than directly adding it to the cows milk (through the jar). why? (4)
the cows milk (end product) will not contain lactase.
the enzymes in the beads can be used again as it doesnt end up in the end product.
its a continous process.
the enzymes are very stable ( due to the compactness of the beads, so less room to move around).
134
some enzymes used in experiements can often require storage in lab fridge. use ur knowledge of protein structure to explain why? (3)
enymes being stored in fridge, means enzyme is in a low temp environment.
so low kinetic energy is present
so less movement, hence less frequent successfull collision, so the bonds are less likely to break.
therefore this allows for the enzyme to remain stable.(less likely to denature).
135
an enzyme can only catalse 1 reaction, whereas a substrate can be hydrolysed by more than one enzyme? (4)
an enzyme can only catalyse 1 reaction because:
enzyme has an active site
only substrate can bind to the active site
a substrate can be hydrolysed by more than one enzymes because:
a substrate may have different parts to it
therefore specifc enzymes can only be complementary and have a specific shape to that specific part of the substrate.
136
scientists investigated the effect of PH on enzyme A. agar plates containing substrate were used. the scientists creared 4 wells of equal size in the agar of each plate. a drop of Enzyme A solution was added to each of the wels. the wells had 1 with :ph2, 1with: ph3, 1 with: ph4 and 1 with: ph5. describe and explain the results?
enzyme A works best at ph 5 as most substrate is broken down that well.
ata lower ph enzyme activity decreases, as the enzyme is denatured in acidic conditions.
137
explain why a small change in ph produces a large effect on the rate of reaction?
ph is a logarithmic scale, therefore a small change in ph value represents a large diff of H+ ions present.
138
suggest and explain 2 ways in which enzymes might reduce the activation energy (in the context of anabolic reacions)
by holding the 2 substrates closer together in the e-s complex, to make it easier for the substrates to collide.
by stressing the bonds in the substrate to make it easier to break.
139
give similarities and differences between comp and non-comp inhibitors? (6)
D: comp has a similar shape to the substrate, whereas non-comp doesnt.
non-comp binds to the allosteric site, whereas comp binds to the active site.
final product formation using comp is the same as the final product produced as the normal e-s complex without inhibitor, whereas non-comp produces less final product.
comp can be encountered by increasing the conc of substrate whereas non comp cant.
the rate of production formatiion is faster and higher than that of non-comp
non-comp changes the shape of the active site, comp doesnt and causes active site to be blocked (when bound).
S: both bind to the enzyme
both reduce the enzymes rate.
as inhibitor conc increases the rate of reaction decreases.
140
2 similarities and 2 differences in the features of a substrate and a comp inhibitor (4)?
sim: both have similar molecular shape
both bind to the active site of the enzyme.
D: no product is formed from a comp inhibitor whereas a product is formed from a substrate.
a comp inhibitor may be irreversibly bound to the enzyme, whereas a product will always unbind/release from the enzyme when an e-s complex is formed prior using substrate.
141
DEFINE SPECIFICITY?
1 ENZYME HAS A SMALL NUMBER OF SUBSTRATES
DUE TO THE SPECIFIC COMPLEMENTARY SHAPE BERTWEEN THE SUBSTRATE AND THE ACTIVE SITE.
142
SUGGEST 2 SOURCES OF ERROR THAT COULD ARISE FROM AN EXPERIMENT TO MEASURE THE EFFECT OF TEMP ON THE RATE OF AN ENZYME-CONTROLLED REACTION?
GAS SYRINGE IS MORE PRECISE THAN MEASURING CYLINDER.
POOR CONTROL OF THE INDEPENDENT VARIABLE TEMP.
143
main function of dna?
hold or store genetic info, so gene can carry this to code for proteins.
144
whats the function of RNA?
carry the genetic code found in dna and transfer it out of the nucleus into the ribosomes in the cytoplasm.
145
both dna and rna are made up of many repeating units known as what?
nucleotides
146
structure of dna (nucleotide) consists of what? and rna consists (nucleotide) of what?
deoxyribose sugar (pentose sugar) , nitrogen-containing base , phosphate group.
rna - ribose sugar (pentose sugar), nitrogen-containing base, phosphate group.
147
what bases are present in dna vs in rna?
in dna, adenine, thymine, cytosine and guanine are present.
in rna, adenine, uracil, cytosine and guanine are present.
148
in the second position (carbon) in the pentose sugar in dna and rna, whats the difference between whats attached to it? and using this how does this link to dna being used as the storage molecule?
in dna at the position 2 carbon, a H group is attached, whereas in rna at the position 2 carbon, a OH group is attached.
the OH group attached to the position 2 carbon, makes and allows rna to be more susceptible to hydrolysis, hence this is why dna is the storage molecule, and RNA is the molecule with a shorter molecular lifespan.
149
the nitrogenous bases present in dna, (A, T,C,G), and rna (A,U,C,G), occur in 2 structural forms. give the names of these forms, and which bases belong to which form, also state why?
occur in 2 structural forms. pyrine and pyramidine.
the bases A and G are pyrines as they have a double ring structure.
the bases T, C, and U are pyrimidines as they have a single ring structure.
150
DNA IS _____ stranded, whereas RNA is ______ stranded?
dna is double standed (double helix), whereas rna is single stranded.
151
why are dna considered polymers?
because they consist of polynucleotides, which consist of many repeating units of nucleotide molecules.
152
how do the separate nucleotides in dna and rna join together?
via condensation reactions, where a phosphodiester bond forms between the pentose sugar of one nucleotides, and the phosphate group of another.
153
whats the sugar-phosphate backbone (of dna or rna)?
the chain of alternating phosphate groups of pentose sugars produced as a result of many phosphodiester bonds forming. this is known as the sugar-phoshate backbone.
154
elaborate on the complete structure of dna?
SAME APPLIES WITH RNA IN TERMS OF SUGAR PHOSPHATE BACKBONE STUFF (EXLUDE H2 BONDS AND 2 POLYNUCLEOTIDES)
consists of 2 polynucleotide stands that form in opposite directions making them antiparallel. hence one forms 3' to 5' end and the other forms 5' to 3' end.
the alternating phoshpate groups and deoxyribose sugars, joined together by phosphodiester bond form a sugar phosphate backbone. within the same nucleotide and phosphodiester bond forms between the 5th carbon atom and the phosphate group to join them together, and so that phophate group is bonded to another phospodiester bond which is bonded to the 3rd carbon in the following deoxyribose sugar, joining the 2 nucleotides together.
these antiparallel polynucleotides join together via Hygrogen bonds forming between dna base pairs, forming complementary base pairing. the purine base Adenine pairs with the pyrimidine base thymine, and so 2 hydrogen bonds are formed between them. the purine base cytosine always pairs with the pyrimidine base guanine, and 3 h2 bonds are formed between them.
155
unlike dna, rna only has one _____, and what affect does that have on it size?
rna only has 1 polynucleotide strand (they are single standed), hence rna polynucleotide chains are relatively shorter compared to dna.
156
WHAT ARE RIBOSOMES, what are they formed from. and whats the specifc type of rna that forms it?
small organelles that are free in the cytoplasm of all cells or are attached to the rough endoplasmic reticulum. they are the site of protein synthesis.
they are formed from RNA and proteins. the specific type of RNA that makes up a part of ribosomes is ribosomal RNA(rRNA). each ribosome is a mixture of rRNA and proteins.
157
what ribosomes are found in eurkaryotic cells and what ribosomes are formed in prokaryotic cells?
80S ribosomes are found in eu, and 70S are found in pro, as well as in chloroplasts and mitochondria of eukaryotic cells.
158
ribosomes are not surrounded by what>
a membrane.
159
whats the reason as to why early scientists doubted whether DNA had the genetic code or not?
due to the simplicity of DNA's strucutre as it was only made of repeating nucleotides.
160
purpose of semi-conservative replication?
before a cell (parental) divides it needs to copy the dna within it, this is to ensure that the 2 new daughter cells produced received and have this parental DNA (full copies).
161
why is semi conservative classified as semi conservative?
as for each new dna molecule (daughter cell) produced, one of the dna polynucleotide strands from the o.g. dna molecule (parental cell), is being copied. the other polynucleotide dna strand (i.e the other half of the new dna molecule), has to be newly created by the cell. hence overall the new dna molecule has conserved half of the og dna and then used this copy to create a new stand.
162
whats the importance about conserving one original dna strand?
ensures genetic continuoity between generations of cells, meaning for each new daughter cells (the pair) produced during cell division, they inherit all their genes from their parent cells. this is vital as in the body cells are replaced regularly, hence u need new cells to do the same as old ones.
163
give the process of semi-conservative replication?
enzyme dna helicase unwinds the double helix of the dna molecule, by breaking the h2 bonds between the nitrogenous base pairs of the antiparralel polynucleotide strands, forming 2 single dna polynucleotide strands, each of them having exposed bases.
each of these single polynucleotide strands acts as a template for the formation of a new stand, where free nucleotides are attacted to the exposed dna bases due to bases pairing.
dna polymerase joins these free nucleotides together and catalyses the condensation reactions to form the new strand.
the 2 new stands are then joined together via h2 bonds between the complementary base pairs, to form the new dna molecule.
164
dna polymerase breaks the 2 additional phosphate groups (from nucleoside triphosphates), and uses what to do what?
and using the energy released, to form phospodiester bonds to joint the adjacent nucleotides together. h2 bonds then form between complementary base pairs of the template and new dna strands.
165
define nucleoside triphosphate? and what do the extra phosphates do?
in the nucleus there are free nucleotides that contain 3 phosphate groups, this is nucleoside triphosphate. the extra phosphate groups active the nucleotide, allowing the dna to take part in replication.
166
in terms of calcs when bases are said to be complementary to one another, what does this mean?
meaning the frequency of the number of base=complementary base. eg, a=t, c=g
167
How did Meselson and Stahl’s experiment demonstrate that DNA replication is semi-conservative?
Meselson and Stahl grew bacteria in a 15N (heavy nitrogen) broth, allowing their DNA to incorporate the heavier isotope. The bacteria were then transferred to a 14N (light nitrogen) broth and allowed to replicate once. After centrifugation, the DNA settled in the middle of the tube, indicating that each DNA molecule contained one heavy strand and one light strand. This confirmed semi-conservative replication, where each new DNA molecule consists of one old and one new strand.
168
What result would Meselson and Stahl have seen if DNA replication were conservative instead of semi-conservative?
If conservative replication had occurred, the original 15N DNA would have remained intact and settled at the bottom of the centrifuge tube, while newly synthesized 14N DNA would have settled at the top. However, they observed DNA in the middle, proving that replication is semi-conservative, where each new DNA molecule contains one old (15N) strand and one new (14N) strand.
169
atp stands for what? and adenosine can be combined with what to give what? and atp is a type of what?
adenosine triphosphate. (adenosine = base adenine attached to a pentose sugar). the adenosine can be combined with 1 phosphate to give adenosine monophosphate (AMP), with 2 to give ADP and with 3 to give atp.
ATP IS A TYPE OF NUCLEIC ACID.
170
DIFF BETWEEN ADENINE AND ADENOSINE?
ADENINE = NITROGENOUS BASE, WHEREAS adenosine is a nucleoside, hence a pentose sugar attached to a nitrogenous base adenine.
171
atp is small, soluble and what?
reversibly stable at cellular ph levels.
172
hydrolysis of atp explain. (energy released in this reaction can be used in what?)
atp is hydrolysed into adp +pi, via enzyme atp hydrolase, using water. the energy released in this exp can be used in:
the active transport of ions up the conc gradient.
enzyme controlled reactions that require energy
MUSCLE CONTRACTION AND MUSCLE FIBRE MOVEMENT.
173
GIVE 5 FEATURES OF ATP AND GIVE THEIR BENEFIT?
RELEASES a small amount, but sufficient amout of energy enough to drive important metabollic reactions while keeping energy wastage low.
exists as a stable molecule - it doesnt breakdown unless a catalsyst (atp hydrolase) is used so energy wont be wasted
CAN BE RECYCLED - HYDROLYSIS OF ATP IS A REVERSIBLE REACTION, HENCE ATP CAN BE REFORMED FROM ADP AND PI. (SO THE SAME MOLECULE CAN BE USED ELSEWHERE IN THE CELL FOR DIFF REACTIONS)
HYDROLYSIS IS QUICK AND EZ - ALLOW CELLS TO RESPOND TO A SUDDEN INCREASE IN ENERGY DEMAND.
SOLUBLE AND MOVE EZILY WITHIN CELS - HENCE CAN TRANSPORT ENERGY TO DIFF PARTS/AREAS OF THE CELL.
174
synthesis of atp.
atp can be synthesised, where adp reacts with pi to form atp + water in a condensation reaction, via enzyme atp synthase. atp synthase needs energy.
175
why do h2 bonds form betweeen water molecules?
due to the polarity of the water molecule that is caused by their being one negatively charged region and one more positively charged region, hence h2 bonds form between these regios across adjacent h20 molecules.
176
h2 bonds contribute to which properties in water?
adhesion and cohesion
acts as a good universal solvent
high shc
high latent heat of vaporisation
acts as a reagent
high surface tension
177
shc is the amount of energy needed to raise the temp of 1 kg of a substance by 1 degree celsius. explain why water has high shc, and how is this beneficial?
water has a high shc due to the many h2 bonds, hence large amounts of energy are needed to break and make these bonds. water having a high shc is very vital as it means it can absorb lots of heat energy without experiencing big changes in temps or changing. this is important in living organisms as suitable habitats are hence able to be provided due to the maintenance of temp. water absorbing heat energy without changing in temp also plays a huge role in maintaining that temp for optimal enzyme environment temp to maximise its activity. water in blood plasma is also important in tranferring heat around the body helping to maintain temp.
178
latent heat of vaporisiation is the amount of energy needed to change state from liquid to gas. water has a high latent heat of vaporisation, meaning large amounts of energy (thermal) must be absorbed by water in order to break h2 bonds to evaporate. how is this advantageous?
this is advantageous for living organisms as this means that only little amount of water is required to evaporate (absorb heat energy), for the organism to lose a great amount of heat, providing a cooling effect for living organisms. (e.g. transpiration from leaves or evaportion of water in sweat on skin).
179
WATER BEING A SOLVENT, HAVING A HIGH SHS AND HIGH LATENT HEAT OF VAPORISATION. GIVE THESE properties' role in living organisms and give the reason?
Property: Solvent
Role in living organisms: Allows chemical reactions to occur, Transport medium
Reason: Polarity of water
Property: High specific heat capacity
Role in living organisms:
Allows water to be a suitable habitat
Optimal temperature maintained within cells and bodies (enzyme activity)
Reason: Presence of many hydrogen bonds
Property: High latent heat of vaporization
Role in living organisms: Coolant
Reason: Presence of many hydrogen bonds
180
How do hydrogen bonds contribute to water’s cohesive and adhesive properties?
Hydrogen bonds between water molecules create strong cohesion, allowing water to move in continuous columns through the xylem in plants and blood vessels in animals. Cohesion also creates surface tension, forming a film on water that enables insects like pond skaters to float. Water also exhibits adhesion, allowing it to bond with other molecules like cellulose, which helps water move up the xylem during transpiration.
181
Why is cohesion important for water transport in plants?
Cohesion allows water molecules to stick together, forming continuous columns that move up the xylem in plants. This ensures an uninterrupted flow of water from the roots to the leaves, driven by transpiration. Without cohesion, the water column would break, disrupting water transport and affecting plant survival.
182
How do hydrogen ions (H⁺) influence pH and enzyme activity?
The concentration of H⁺ ions determines the pH of a solution—more H⁺ ions result in a lower pH (acidic), while fewer H⁺ ions lead to a higher pH (alkaline). Enzyme activity depends on pH, as abnormal H⁺ levels can alter enzyme structure by affecting amino acid side chains, potentially leading to denaturation.
183
Why are iron ions (Fe²⁺) essential in the body?
Iron ions in the Fe²⁺ form are a key component of haemoglobin, allowing red blood cells to bind and transport oxygen. They also play a role in electron transport chains during respiration and photosynthesis, switching between Fe²⁺ and Fe³⁺ to transfer electrons and generate energy.
184
What is the role of sodium ions (Na⁺) in glucose and amino acid transport?
Sodium ions enable co-transport of glucose and amino acids across epithelial cell membranes in the small intestine. Na⁺ is first actively transported out, creating a concentration gradient. Na⁺ then re-enters via co-transport proteins, bringing glucose or amino acids with it into the cell. Na⁺ also plays a role in nerve impulse transmission.
185
How do phosphate ions (PO₄³⁻) contribute to cellular functions?
Phosphate ions form phosphate groups, which are essential in DNA, RNA, ATP, and phospholipids. In DNA and RNA, they help link nucleotides together. In ATP, the high-energy bonds between phosphate groups store and release energy for cellular processes. Phosphates also help form the phospholipid bilayer in cell membranes.
186
What are the key roles of calcium ions (Ca²⁺) in the body?
Ca²⁺ is crucial for muscle contraction, as it binds to troponin C, exposing binding sites for actin-myosin interaction. It also regulates nerve impulse transmission at synapses, affects membrane permeability, and activates enzymes. Additionally, Ca²⁺ is a clotting factor, necessary for blood clot formation.
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