Biological Molecules Flashcards

Question

What happens to the Benedict’s reagent when it’s heated in a water bath with a reducing sugar?

Answer 1

Benedict’s reagent is an alkaline solution of copper (II) sulphate. When a reducing sugar is heated with the Benedict’s reagent it forms an insoluble red precipitate of copper (I) oxide. Electrons are donated from the reducing sugar to the Benedict’s reagent. Cu2+ + e- = Cu+

Answer 2

If the Benedict’s reagent stayed blue it’s a non-reducing sugar. - To make sucrose a reducing sugar you perform hydrolysis by adding hydrochloric acid and heating in a water bath for 5 mins. This should separate the disaccharide into two monosaccharides making two reducing sugars. - Then add neutraliser (sodium hydrogen carbonate) until it stops fizzing and is alkaline (or use litmus paper). - Retest the resulting solution by heating with 2cm3 of Benedict’s reagent in a water bath for 5 mins. If a non-reducing sugar as present in the original sample the Benedict’s will turn orange-brown. This is due to the reducing sugars that were produced from the hydrolysis of the non-reducing sugar.

Answer 3

Glucose + glucose = maltose Glucose + fructose = sucrose Glucose + galactose = lactose

Answer 4

- Polysaccharides are polymers formed by combining together many monosaccharides that are joined by glycosidic bonds through a condensation reaction. - Polysaccharides are insoluble as they’re very large molecules which make them suitable for storage. - When hydrolysed they break down into disaccharides or monosaccharides. - Starch is found in many parts of plants (in form of granules or grains) e.g. chloroplast. It’s formed by the joining of 200-100,000 alpha glucose molecules by glycosidic bonds in a series of condensation reactions. - Cellulose gives structural support to plant cells.

Answer 5

Starch is easily detectable as it changes the colour of iodine in potassium iodide from yellow to blue/black. - Put 2cm3 of the sample in a test tube or 2 drops into spotting tiles. - Add 2 drops of iodine solution + shake or stir. - Presence of starch = blue/black.

Answer 6

- Insoluble, doesn’t effect water potential, so water isn’t drawn into the cells by osmosis. - large and insoluble, doesn’t diffuse out of cells. - compact, so a lot of it can be stored in a small space. - When hydrolysed it forms alpha glucose which is both easily transported and readily used in respiration. - the branched form has many ends, each of which can be acted on by enzymes simultaneously meaning glucose monomers are released very rapidly.

Answer 7

Amylose and amylopectin

Answer 8

This and amylopectin make up starch - Formed by alpha glucose monomers. - alpha 1,4 glycosidic bonds between the monomers. - The chain forms a coiled shape.

Answer 9

This and amylose make up starch. - Formed from alpha glucose monomers. - alpha 1,4 and alpha 1,6 glycosidic bonding between the monomers. - Branch shape due to the extra alpha 1,6 glycosidic bonding. - More branches: more easily hydrolysed (because there’s more places where the enzyme can work) to glucose or maltose to provide energy when needed.

Answer 10

- Found in animal, fungi and bacterial cells. - Very similar structure to amylopectin. - formed from chains of monosaccharide alpha glucose but there’s less alpha 1-4 glycosidic bonds and more alpha 1,6 glycosidic bonds (because it’s highly branched so produces lots of glucose). - Main role: energy storage. - Also in small granules (like starch), found mainly in the muscles and liver. - Animals need more glucose than plants because they’re more active so they have more branches in glycogen than in starch.

Answer 11

-Joining of alpha glucose. Compact- so a lot can be stored in little space, due to their structure (coiled like a slinky). -Provide easy access to glucose (energy source)- glucose released by hydrolysis of glucose molecules from multiple ends (branches). -Large and insoluble so it doesn’t diffuse out of cells or affect the water potential.

Answer 12

- Cellulose molecules are made up of beta glucose and so form long straight, unbranched chains. - These cellulose molecular chains run parallel to each other and are crossed linked by weak hydrogen bonds which add collective strength. - These molecules are grouped to form microfibrils which in turn are grouped to form fibres all of which provide more strength. -By exerting an inward pressure that stops any further influx of water. As a result, living plant cells are turgid and push against one another, making non-woody parts of the plant semi-rigid. This is important in maintaining stems and leaves in a turgid state so they can provide the maximum surface area for photosynthesis.

Answer 13

- They contain carbon, hydrogen and oxygen. - The proportion of oxygen to carbon and hydrogen is smaller than in carbohydrates. - non-polar due to large % of Cs and Hs and so are Insoluble in water (hydrophobic). - Soluble in organic solvents such as alcohols and acetone.

Answer 14

- Phospholipids contribute to the flexibility of membranes and the transfer of lipid-soluble substances across them. - source of energy (when oxidised, lipids provide more than twice the energy as the same mass of carbohydrates + release valuable water. - Waterproofing (they’re insoluble in water + therefore good for waterproofing. Plants and insects have waxy lipid cuticles that conserve water while mammals produce an oily secretion from the sebaceous glands in the skin). - Insulation (fats are slow conductors of heat + when stored beneath body surface help to retain body heat. Also act as electrical insulators in the myelin sheath). - protection (fat is often stored around delicate organs such as the kidney).

Answer 15

E.g. meats, butter, dairy. - Contain only C-C bonds (no double bonds between carbon atoms because all the carbon atoms are linked to the maximum possible number of hydrogen atoms) so form linear hydrocarbon chains. - Fatty acids can pack closely together. Strong attraction between fatty acid chains. -High melting points -Solid at room temp.

Answer 16

E.g. vegetable oils - Contain one or more C=C double bond (causing hydrocarbon chains to bend). - Non-linear chains don’t allow fatty acid molecules to pack closely together. - Fewer interactions between fatty acid chains, so weaker attractions. - Low melting points - liquid at room temp

Answer 17

Three fatty acids combined with glycerol (glyceride). Each fatty acid forms an Ester bond with glycerol in a condensation reaction. Hydrolysis of a triglyceride produces glycerol and 3 fatty acids. The glycerol molecule is the same so the variations in properties of different fats and oils comes from variations in the fatty acids. All 70 fatty acids have a carboxyl (—COOH) group with a hydrocarbon chain attached. Saturated- chain has no C-C double bonds because all carbon atoms are saturated with hydrogen. Mono-unsaturated- single double bond. Polyunsaturated- more than one double bond. More double bonds, the lower the melting point.

Answer 18

- have a high ratio of energy- storing carbon- hydrogen bonds to carbon atoms and are therefore an excellent source of energy. - Low mass to energy ratio, making them good storage molecules because much energy can be stored in a small volume. This is especially beneficial to animals as it reduces the mass they have to carry as they move around. - Being large, non-polar molecules, triglycerides are insoluble in water. As a result their storage does not affect osmosis in cells or the water potential of them. - As they have high ratio of hydrogen to oxygen atoms, triglycerides release water when oxidised and therefore provide an important source of water, especially for organisms living in dry dessert.o

Answer 19

Phospholipids are similar to lipids except that one of the fatty acid molecules is replaced by a phosphate molecule. Fatty acid molecules repel water (are hydrophobic) while phosphate molecules attracts water (are hydrophilic). A phospholipid is therefore made up of two parts: A hydrophilic head: which interacts with water (attracted to it) but not with fat. A hydrophobic tail: which orients itself away from water but mixes readily with fat.

Answer 20

Because it’s a molecule that has two ends (poles) that behave differently: when they’re placed in water they position themselves so the hydrophilic head heads are as close to the water as possible and the hydrophobic tails are as far away from the water as possible.

Answer 21

- They’re polar molecules, having hydrophilic phosphate head and a hydrophobic tail of two fatty acids. This means in an aqueous environment, phospholipid molecules form a bilayer within cell surface membranes. As a result a hydrophobic barrier is formed between the inside and outside of a cell. - The hydrophilic phosphate heads of phospholipid molecules help to hold at the surface of the cell surface membrane. - The phospholipid structure allows them to form glycolipids by combining with carbohydrates within the cell surface membrane. These glycolipids are important in cell recognition.

Answer 22

Emulsion test: - Take a completely dry and grease free test tube. - Add 5cm3 of ethanol to 2cm3 of the sample being tested. - Shake tube thoroughly to dissolve any lipid in the sample. - Add 5cm3 of water and shake gently. - Milky white emulsion indicates presence of a lipid. - As a control, repeat the procedures using water instead of the sample, the final solution should remain clear. -The cloudy colour is due to lipid in the sample being finely dispersed in the water to form an emulsion. Light passing through this emulsion is refracted as it passes from oil droplets to water droplets, making it appear cloudy.

Answer 23

Polypeptide (chain). | Polypeptides combine to make proteins.

Answer 24

Every amino acid has a central carbon atom to which four different chemical groups are attached: - amino group (—NH2)- a basic group from which the amino part of the name amino acid is derived. - carboxyl group (—COOH) - an acidic group which gives the amino acid the acid part of its name. - hydrogen atom (—H) - R (side) group- a variety of different chemical groups. Each amino acid has a different R group. These 20 naturally occurring amino acids differ only in their R (side) group.

Answer 25

Amino acid monomers combine to form a dipeptide in a condensation reaction. The water is made by combining an —OH from the carboxyl group of one amino acid with an —H from the amino group of another amino acid. The amino acids then become linked by a new peptide bond between the carbon atom of one amino acid and the nitrogen atom of the other. They can be broken by hydrolysis (addition of water) to give two amino acids.

Answer 26

Hundreds of amino acid monomers joined together through polymerisation is called a polypeptide chain (primary structure). The sequence of amino acids in a polypeptide chain forms the primary structure of any protein. (This sequence is determined by DNA). It’s the primary structure of a protein that determines its shape and therefore function so a change in a single amino acid in this primary sequence can lead to a change in the shape of the protein and therefore stop it carrying out its function. (Protein shape is specific to function). Normally, a protein is made up of a number of polypeptide chains though a simple protein can just consist of one. Formed between C-N Unbranched

Answer 27

The linked amino acids that make up polypeptide possess —NH and —C=O groups on either side of every peptide bond. The hydrogen of —NH has an overall positive charge while the oxygen of —C=O has an overall negative charge. These two groups therefore readily form weak hydrogen bonds which causes the long polypeptide chain to be twisted into a 3D shape e.g. the coil alpha helix. Beta sheet is also stabilised by hydrogen bonds.

Answer 28

The alpha helixes of the secondary protein structure twisted and folded to make the complex, 3D structure of each protein: tertiary structure. The 3D shape of a protein is important in how it functions and how it’s recognised by other molecules and therefore the specific way it interacts with them. Joined by dipeptide, ionic, hydrogen bonds and hydrophobic interactions between the R groups. Positive R groups attract negative R groups. The structure is maintained by these bonds: Disulfide bridges: fairly strong + not easily broken. Ionic bonds: formed between any carboxyl and amino groups that aren’t involved in forming peptide bonds. Weaker than disulfide bonds and easily broken by changes in PH. Hydrogen bonds: numerous but easily broken. Hydrophobic interactions

Answer 29

Large proteins often form complex molecules containing a number of individual polypeptide chains that are linked in various ways (Held together by the same 4 R group bonds as tertiary). There may also be non-protein groups associated with the protein, called prosthetic groups. E.g. haemoglobin. Haemo-prosthetic (non-protein) group. Globin-globular protein.

Answer 30

The Biuret test detects peptide bonds: - Place a sample of the solution to be tested in a test tube and add an equal volume of sodium hydroxide solution at room temp. - Add a few drops of very dilute (0.05%) copper (II) sulfate solution and mix gently. - A purple coloration indicates the presence of peptide bonds and hence a protein. If no protein is present, the solution remains blue.

Answer 31

- Spherical shape. - soluble in water because they have hydrophilic amino acids on their surface so hydrophilic R groups can interact with water mulecules while the hydrophobic amino acids are in the centre of the protein. - E.g. enzymes, (lysozyme) haemoglobin and insulin. - Carry out metabolic functions.

Answer 32

E.g. collagen (strengthens bones, cartilage, tendons, ligaments and skin), gluten They have structural functions.

Answer 33

- primary structure is an unbranched polypeptide chain. - in the secondary structure the polypeptide chain is very tightly wound . - lots of amino acid, glycine helps close packing. - in tertiary structure the chain is twisted into a second helix. - its quaternary structure is made up of 3 polypeptide chains wound together in the same way as individual fibres are wound together in a rope. - the individual collagen polypeptide chains in the fibres are held together by bonds between amino acids of adjacent chains. - the points where one collagen molecule ends and the next begins are spread throughout the fibre rather than all being in the same position along it.

Answer 34

This proposes that the active site forms as the enzyme and substrate interact (complimentary active site and substrate.) The enzyme is flexible and can mould itself around the substrate in the way that a glove moulds itself to a hand. The enzyme has a certain general shape but this alters in the presence of a substrate. Once the product(s) has been made, the enzyme molecule resumes its original shape. As it changes its shape, the enzyme puts a strain on the substrate molecule. This strain distorts a particular bond(s) in the substrate and therefore lowers the activation energy needed to break the bond.

Answer 35

Globular proteins that act as biological catalysts (have specific 3D shapes as a result of their sequence of amino acids). Catalysts alter the rate of chemical reactions without undergoing permanent changes themselves; they can be reused repeatedly and are therefore effective in small amounts.

Answer 36

- the sucrose and water molecule must collide with sufficient energy to alter the arrangement of their atoms to form glucose and fructose (in a hydrolysis reaction). - the free energy of the products (glucose and fructose) ,must be less than that of the substrates (sucrose and water). - many reactions require an activation energy (minimum amount of energy needed to activate the reaction).

Answer 37

Enzymes as catalysts lower the activation energy (make the hill or barrier lower) which must be initially overcome before the reaction can proceed. By the enzymes lowering the activation energy level, the enzymes allow reactions to take place at a lower temperature than normal. This enables some metabolic processes to occur rapidly at the human body temperature of 37 degrees (low in terms of chemical reactions). Without enzymes, these reactions would happen too slowly to sustain life as we know it.

Answer 38

Globular proteins that have a specific 3D shape as a result of their sequence of amino acids (amino acids joined with hydrogen bonds). The active site is made up of a relatively small number of amino acids and forms a small depression within the much larger enzyme molecule. The molecule that the enzyme acts on is called the substrate. This fits neatly into into the complimentary active site to form an enzyme-substrate complex. The substrate molecule is held in the active site by bonds that temporarily form between certain amino acids of the active site and groups on th substrate molecule.

Answer 39

In this model, the enzyme is suggested to be (like a lock) a rigid structure. However scientists observed that other molecules could bind to enzymes at sites other than the active site, altering the activity of the enzyme. This suggested that the enzymes shape was being altered by the binding molecule. It’s structure was therefore not rigid like this model suggests, but flexible (induced fit model).

Answer 40

Changes in PH changes the charges on the R groups in the active site and affects the binding of the substrate to the active site. Changes in PH changes the charges on the R groups in the protein and affects the hydrogen bonding and ionic bonds that stabilise the tertiary structure, leading to denaturation.

Answer 41

Resist changes in PH. Keep the PH of solution stable.

Answer 42

As the enzyme concentration increases, the rate of reaction increases. A high enzyme concentration increases the frequency of successful collisions. This leads to an increase in enzyme substrate complexes being formed. As a result there’s an increase in the rate of reaction.

Answer 43

It increases rapidly at first, but plateaus at the point of saturation where the increasing substrate concentration no longer affects rate of reaction. As substrate concentration increases the frequency of successful collisions also increases. This leads to an increase in the number of enzyme substrate complexes being formed. As a result there’s an increase in the rate of reaction. However when the substrate concentration becomes very high the enzyme becomes saturated with substrate. This means a further increase in substrate will not result in any more enzyme substrate complexes being formed. So the reaction proceeds at a maximum rate that can’t be increased unless more enzyme is added.

Answer 44

Inhibitors are substances that directly or indirectly interfere with the functioning of the active site of a specific enzyme and so decrease the rate of reaction.

Answer 45

-Have similar shape to the substrate which allows them to bind and occupy the active site. -Compete with substrate for active site. -Binding isn’t permanent so when it leaves the active site another molecule can enter (substrate or inhibitor). E.g. succinate and malonate in the Krebs cycle. The graph for substrate concentration to rate of reaction is less steep when an inhibitor is present because the rate of reaction is reduced as the active sites are occupied with inhibitor not allowing enzyme substrate complexes to form. Maximum rate can be achieved if the substrate levels are high enough.

Answer 46

-Attach to enzyme at the allosteric site. -Binding causes a change in the tertiary structure of the enzyme therefore also changing the shape of the active site. -This means the active site is no longer complimentary to the substrate so the substrate can no longer bind (so enzyme can’t catalyse the reaction). E.g. cyanide The graph stays flat because the active site is altered so the maximum rate can’t be achieved by raising the substrate levels.

Answer 47

Allosteric enzymes can be used to control metabolic pathways using negative feedback. The end product binds to the first enzyme in the pathway and inhibit it if too much product is formed (supply and demand). Metabolic pathways are a sequence of chemical reactions where there are multiple steps and each step is catalysed by a different enzyme. Hundreds of metabolic pathways occur in every cell.

Answer 48

Pentose sugar (has 5 carbon atoms).(pentagon). A phosphate group (circle) A nitrogen containing organic base: cytosine, thymine, uracil, guanine. These are joined by condensation reactions to form mononucleotides.

Answer 49

Two mononucleotides (sugar, phosphate + base) can be joined in a condensation reaction between the deoxyribose sugar of one mononucleotide and the phosphate group of another. The bond formed is called a phosphodiester bond.

Answer 50

Dinucleotide.

Answer 51

Polynucleotide.

Answer 52

Single, relatively short polynucleotide chain in which the pentose sugar is always ribose and the organic bases are adenine, guanine, cytosine and uracil. One type of RNA transfers genetic info from DNA to the ribosomes (ribosomes are made from proteins and another type of RNA). Another type of RNA is involved in protein synthesis Messenger RNA Ribosomal RNA Transfer RNA.

Answer 53

Pentose sugar- deoxyribose. Organic bases- adenine, thymine, guanine and cytosine. DNA is made up of two long strands of nucleotides (polynucleotides) joined by hydrogen bonds between certain bases.

Answer 54

The bases are attached with hydrogen bonds. Adenine - thymine Guanine - cytosine These bases are complimentary to each other. The quantities of adenine and thymine in DNA are always the same and so are the quantities of guanine and cytosine. Though the ratio of a and d to g and c varies from species to species.

Answer 55

Polynucleotide chains are twisted around each other in a ladder like arrangement. I’m this way the uprights of phosphate and deoxyribose wind around eachother to form a double helix. They form the structural backbone of the DNA molecule.

Answer 56

- The phosphodiester backbone protects the more chemically reactive bases inside the double helix. - Hydrogen bonds link the organic base pairs forming bridges (rungs) between the phosphodiester uprights. - There are 3 hydrogen bonds between C and G so the higher the proportion of C-G pairings, the more stable the DNA molecule. - There are other interactive forces between the base pairings that hold the molecule together.

Answer 57

The hereditary material that passes genetic material through generations. There are around 3.2 million million base pairs of DNA in a mammalian cell meaning there’s almost an infinite variety of sequences of bases, providing genetic diversity within living organisms.

Answer 58

- The very stable structure passes from generation to generation without significant change, so most mutations are repaired and persistent mutations are rare. - Its two separate strands are only joined with hydrogen bonds which allows them to separate during DNA replication and protein synthesis (zip). - many hydrogen bonds joining the separate strands are strong together. - It’s an extremely large molecule and therefore carries an immense amount of genetic information. - By having the base pairs within the helical cylinder of the deoxyribose-phosphate backbone, genetic information is to some extent protected from being corrupted by outside chemical and physical forces. - Base pairing leads to DNA being able to replicate and to transfer information as mRNA. - The function of DNA depends on the sequence of base pairings that it possesses. This sequence is important to everything it does and to life itself. - Hydrophobic bases are protected on the inside of the hydrophilic backbone.

Answer 59

The DNA provided the bacteria with the genetic information needed to make the virus and can be passed from one bacterium to another. - the living harmful bacteria found in pneumonia mice were collected and various substances were isolated from these bacteria and purified. - each substance was added to suspensions of living safe bacteria to see whether it would transform them into the harmful form. - the only substance that produced this transformation was purified DNA and when an enzyme that breaks down DNA was added, the ability to carry out the transformation ceased.

Answer 60

The 5’ carbon has an attached phosphate group. The 3’ carbon has an attached hydroxyl group. When nucleotides are organised into the double strands of a DNA molecule, one strand runs in the 5’ to 3’ direction while the other runs in the 3’ to 5’direction. The two strands are therefore antiparallel. Nucleic acids can only be synthesised ‘in vivo’ in the 5’ to 3’ direction. This is because the enzyme DNA polymerase that assembles nucleotides into a DNA molecule can only attach nucleotides to the hydroxyl (OH) group on the 3’ carbon molecule.

Answer 61

Cytosine (3 H bonds) Guanine | Adenine (2 H bonds) Thymine

Answer 62

Proteins Carbon, hydrogen, oxygen, nitrogen, sulphur. Nucleic acids Carbon, hydrogen, oxygen, nitrogen, phosphorus.

Answer 63

Monomers: nucleotides Polymers: nucleic acids Nucleic acids are information carrying polymers and are constructed by the condensation of nucleotide monomers. The enzyme that hydrolyses nucleic acids into nucleotides is nucleases

Answer 64

Pyrimidines: Cytosine, thymine, uracil. Single carbon-nitrogen ring with two nitrogen atoms Purines: Adenine, guanine. Double carbon-nitrogen ring with four nitrogen atoms Deoxyribose is ribose minus an oxygen atom, this makes it more stable and helps DNA maintain its integrity.

Answer 65

- The enzyme DNA helicase causes the DNA double helix to unwind and separate into two strands by breaking the hydrogen bonds between complimentary base pairs. - Each exposed strand then acts as a template for DNA replication to occur. Activated free nucleotides (nucleoplasm) are attracted to and hydrogen bond specifically to their complimentary bases on the exposed template strands by complimentary base pairing. - Once the newly added nucleotides have lined up they are then joined together by the enzyme DNA polymerase in the 5’ to 3’ direction, which catalyses the formation of phosphodiester bonds, forming a newly synthesised polynucleotide chain. - This results in two identical DNA molecules being produced, each of which contains one of the original DNA strands and one newly synthesised DNA strand. Semi-conservative replication.

Answer 66

Conservative: 2 lines found not valid Semi-conservative: one intermediate line Dispersive: one intermediate line. Second generation Dispersive: one intermediate line found not valid.

Answer 67

First generation Light 14N and dense 15N merge together in one intermediate line. Second generation Light 14N: top line Dense 15N: bottom line

Answer 68

N15- dense original DNA | N14- light new DNA

Answer 69

3 phosphates Ribose sugar- sugar molecule with 5 carbon ring structure (pentose sugar) which acts as a backbone that the other parts are attached to. Adenine- nitrogen containing organic base.

Answer 70

The bonds between the phosphate groups are unstable, so they have a low activation energy and are easily broken. When they do break, they release a considerable amount of energy. The third phosphate is removed. ATP + H2O = ADP + Pi + E Adenosine triphosphate + water = adenosine diphosphate + inorganic phosphate + energy. ATP is converted to ADP as water is added in a hydrolysis reaction. The reaction is catalysed by the enzyme ATP hydrolase.

Answer 71

The conversion of ATP to ADP is a reversible reaction and therefore energy can be used to add an inorganic phosphate to ADP to make ATP. The enzyme that catalyses this reaction is ATP synthase. ADP is converted back to ATP as water is removed in a condensation reaction.

Answer 72

- In chlorophyll-containing plant cells during photosynthesis (photophosphorylation). - In plant and animal cells during respiration (oxidative phosphorylation). - In plant and animal cells when phosphate groups are transferred from donor molecules to ADP (substrate-level phosphorylation).

Answer 73

The instability of ATP’s phosphate bonds makes it a good energy donor but a bad long-term energy store (fats and carbs serve this purpose better). It’s an immediate energy source of a cell so cells don’t store large large quantities but maintain a few seconds supply that can be rapidly re-formed from ADP and Pi.

Answer 74

- ATP molecules release less energy for reactions than glucose molecules in smaller, more manageable quantities rather than the bigger, less manageable quantities. - The hydrolysis of ATP to ADP is a single reaction that releases immediate energy. The breakdown of glucose is a long series of reactions so the energy release takes longer.

Answer 75

ATP can’t be stored so is continuously made within the mitochondria of cells that need it. - metabolic processes: ATP provides the energy needed to build up macromolecules from their basic units e.g. starch from glucose. - movement: ATP provides the energy for the filaments of muscle to slide past one another in muscle contractions and therefore shorten the overall length of a muscle fibre. - active transport: ATP provides the energy needed to change the shape of carrier proteins in plasma membranes. This allows molecules or ions to be moved against a concentration gradient. - secretion: ATP is needed to form the lysosomes necessary for the secretion of cell products. - activation of molecules: The inorganic phosphate released during the hydrolysis of ATP can be used to phosphorylate other compounds in order to make them more reactive, thus lowering the activation energy in enzyme-catalysed reactions. E.g. the addition of phosphate to glucose molecules at the start of glycolysis.