3.1 Biological Molecules💧 Flashcards

Question

Outline the characteristics of glycogen

Answer 1

• Polymer of alpha glucose • Used in animals to store glucose • Highly branched so has increased surface area for fast breakdown and enzyme action • 1,4-glycosidic bonds and 1,6-glycosidic bonds

Answer 2

• Polymer of alpha glucose • Used in plants to store glucose • Large molecule that cannot leave the cell • Insoluble in water (doesn’t affect water potential) • Found in two forms; amylose and amylopectin

Answer 3

• Large so it can’t cross the cell membrane • Insoluble in water so doesn’t affect water potential • Polymer of alpha glucose so provides glucose for respiration • Branched so it makes the molecule compact and can fit many molecules in a small area • Branched so has increased surface area for fast breakdown and enzyme action

Answer 4

• Carbon 1,4-glycosidic bonds • Compact helical structure to store lots of glucose in a small space • Hydrolysed into maltose by amylase enzyme

Answer 5

• Carbon 1,4 and 1,6-glycosidic bonds • Branched, so has increased surface area for enzyme action and releases glucose molecules faster than amylose

Answer 6

Iodine/potassium iodine test: - Add iodine solution, a positive result is a colour change from orange to blue-black

Answer 7

• Polymer of beta glucose • Provides structure and support in plant cell walls, preventing bursting under turgor pressure and holds the stem up • 1,4-glycosidic bonds • Alternating glycosidic bonds due to the differing -OH group placement in beta glucose than alpha glucose, so it’s found in long straight chains • These chains are joined together by hydrogen bonds to form bundles of cellulose fibres (microfibrils) that have high tensile strength

Answer 8

• Starch formed from alpha glucose, cellulose from beta glucose • Position of hydrogen and hydroxyl groups on Carbon atom one are inverted

Answer 9

Benedict’s solution test

Answer 10

• Add an equal volume of Benedict’s solution to a sample and heat in a water bath for 5 minutes • A positive results indicated by a colour change of the Benedict’s reagent from blue to brick red

Answer 11

An alkaline solution of Copper (II) sulphate

Answer 12

Semi-quantitative use can approximate the concentration of sugar present by the colour of the Benedict’s reagent

Answer 13

• They can’t be oxidised as they can’t donate electrons, so must be hydrolysed into monosaccharides by breaking any glycosidic bonds • Eg. Sucrose and all polysaccharides

Answer 14

• Negative Benedict’s test, reagent remains blue • Add dilute hydrochloric acid and heat in a water bath for 5 minutes and neutralise the solution with sodium hydrogen carbonate (NaHCO3) • Can use an indicator (eg red litmus paper to ensure neutralisation) • Carry out Benedict’s test as normal

Answer 15

• Make standard solutions with known concentrations, record absorbance or % transmission values • Plot calibration curve: absorbance or % transmission on the y-axis and concentration on the x-axis • Record absorbance or % transmission values of unknown samples. Use calibration curve to read off concentration

Answer 16

• Joined by ester bonds but don’t form polymers • Insoluble in water but soluble in organic solvents (eg. alcohols and acetone) • Found in two groups; triglycerides and phospholipids

Answer 17

• Source of energy: when oxidised they provide more than twice the energy as the same mass of carbon judges and release water • Waterproofing: lipids are insoluble in water and both pants and insects have waxy cuticles that conserve water while mammals produce an oily secretion from sebaceous glands • Insulation: slow conductors of heat that when stored beneath the body surface help retain body heat. They also act as electrical insulators around the myelin sheath and nerve cells • Protection; stored around the organs

Answer 18

Fats are solid at room temperature (10-20°C) while oils are liquid

Answer 19

• Formed by the condensation reaction of one molecule of glycerol and three molecules of fatty acid (RCOOH) forming an Ester bond • Contains an R-group of a fatty acid that may be saturated or unsaturated

Answer 20

• Saturated fatty acids mean the chain has no ‘carbon-carbon’ double bonds because all carbon atoms are linked with the maximum possible number of hydrogen atoms • Unsaturated fatty acids have one or more ‘carbon-carbon’ double bond and can be mono-unsaturated or poly-unsaturated

Answer 21

• High melting point; solid at room temperature • Energy dense animal fats • Long straight chains tightly packed together, so more energy’s required to move them (high melting point)

Answer 22

• Lower melting point • Plant fats • Not as tightly packed, so so are easier to move (lower melting point)

Answer 23

• High ratio of energy storing ‘C-H’ bonds to carbon atoms: excellent source of energy • Low mass to energy ratio: good storage molecules so much energy can be stored in a small volume • Large, non-polar, insoluble in water: storage doesn’t affect osmosis in cells or their water potential • High ratio of hydrogen to oxygen atoms: release water when oxidised, providing an important source of water

Answer 24

• Formed by the condensation reaction of two fatty acids with a molecule of glycerol and a phosphate molecule • Polar molecules: two poles that behave differently - hydrophilic phosphate head that interacts with water but not fat - hydrophobic fatty acid tail consisting of a large chain of hydrocarbons that repels water but mixes readily with fat

Answer 25

• Form a bilayer within cell-surface membranes, a hydrophobic barriers formed between inside and outside the cell • Hydrophilic phosphate head that helps to hold at the surface of the cell-surface membrane • Forms glycolipids by combining with carbohydrates within the cell-surface membrane which is important in cell recognition

Answer 26

Emulsion test

Answer 27

• Take a dry and grease free test tube for the sample • Add ethanol • Shake the test tube throughly to dissolve any lipids in the sample • Add water and shake gently • A milky white emulsion indicates the presence of lipids • As a control, repeat procedures using water instead of a sample and the final solution should be clear

Answer 28

Lipids in the sample are finely dispersed in the water to form an emulsion Light passing through this emulsions refracted as it passes from oil droplets to water droplets making it appear milky

Answer 29

• The monomers from which proteins are made that combine to form a polymer called a polypeptide • Consist of an amine group (NH2), carboxyl group (COOH), Central Carbon and variable ‘R’ group (side chain) • 20 amino acids are common in all organisms and differ only in their variable group.

Answer 30

A condensation reaction between two amino acids forms a peptide bond between the carbon atom from the carboxyl group of one amino acid and the nitrogen atom from the amine group of another amino acid

Answer 31

Can contain one or more polypeptide chains and is broken into primary, secondary, tertiary and quaternary structure

Answer 32

• The sequence of amino acids joined by peptide bonds • The sequence determines the shape and function of the protein, the shape is very specific to the function and any change in shape will affect its function • Determined by the sequence of DNA, and 20 different amino acids provide limitless number of possible combinations

Answer 33

• A basic level of protein folding caused by many weak hydrogen bonds between the carboxyl (-) and amine groups (+) • Forms either an alpha helix or beta sheet

Answer 34

• More complex, specific and unique 3D structure making each protein distinctive, allowing it to recognise and be recognised by other molecules • One polypeptide chain • Bonding between variable groups of amino acids including hydrogen bonds, ionic bonds and disulphide bridges • Can be globular (functional) proteins such as enzymes or Haemoglobin or fibrous (structural) proteins such as collagen, fibres or structural support proteins

Answer 35

• Large complex molecule with more than one polypeptide chain, potentially including a prosthetic (non amino acid) group • Eg. Haemoglobin/collagen

Answer 36

• A quaternary protein with 4 polypeptide chains, each associated with a ‘haem’ group containing a ferrous (Fe2+) ion • Haemoglobin transports oxygen and each Haemoglobin can carry four O2 molecules and therefore 8 oxygen atoms as each Fe2+ can combine with a single oxygen

Answer 37

• Has an unbranched primary structure and a tightly wound secondary structure. It’s tertiary structure is twisted into a second helix and it’s quaternary structure is made of three polypeptide chains wound together • Found in tendons (join muscle to bone)

Answer 38

Biuret test

Answer 39

• Place a sample of the solution in a test tube with an equal volume of sodium hydroxide solution at room temperature • Add a few drops of biuret reagent (very dilute (0.05%) Copper (II) sulphate solution) and mix gently • A colour change from blue to purple indicates the presence of peptide bonds and hence a protein

Answer 40

• Enzymes • Antibodies • Transport proteins • Structural proteins

Answer 41

• Protein with a 3D tertiary structure with an active site which has a specific shape that can only bind to a certain substrate • Enzymes speed up the rage of chemical reactions in organisms by acting as catalysts, and don’t get used up in reactions. Each enzyme lowers the activation energy of the reaction it catalyses as described by the induced fit model of enzyme action

Answer 42

• The active site of an enzyme changes shape as the substrate gets closer to become more complimentary • The active site moulds itself around the substrate to form an enzyme substrate complex (ESC) because the specific tertiary structure of its active site is complimentary to that substrate • The flexible active site puts strain on the bonds and lowers the activation energy, speeding up the rate of metabolic reactions • The products leave the active site which goes back to its original shape and the enzyme goes on to make more enzyme substrate complexes as it isn’t used up

Answer 43

• Enzyme concentration • Substrate concentration • Temperature • pH • Concentration of competitive and non-competitive inhibitors

Answer 44

As enzyme concentration increases: • Rate of reaction increases as there’s more active sites and enzyme substrate complexes • Substrate concentration becomes the limiting factor

Answer 45

As substrate concentration increases: • Rate of reaction increases as there’s more substrates attaching to active sites, more enzyme substrate complexes and more collisions • Enzyme concentration becomes the limiting factor

Answer 46

• As temperature increases rate of reaction increases due to more kinetic energy leading to more collisions and therefore enzyme substrate complexes • As temperature exceeds the optimum, bonds between amino acids change shape so the substrates no longer complimentary, so there’s fewer enzyme substrate complexes

Answer 47

• At optimum pH, enzymes are at maximum activity • A deviation will slow and eventually stop enzyme activity and can affect the shape of the substrate so enzymes and substrates are no longer complimentary, so less enzyme substrate complexes

Answer 48

• Competitive inhibitors compete with the substrate to occupy the active site of an enzyme without causing a reaction as they have a similar shape to the substrate molecule • reduces the amount of enzyme substrate complexes, decreasing rate of reaction

Answer 49

• Non-competitive inhibitors bind to a different site on the enzyme, changing the shape of the enzyme so that it cannot bind to the substrate effectively. • This slows down the reaction by making the enzyme less active.

Answer 50

• Made up of deoxyribose (pentose) sugar, a phosphate group and one of the organic bases, adenine, cytosine, guanine or thymine • The chain of sugars and phosphates are known as the sugar phosphate backbone • Double helix with two polynucleotide chains held together by weak hydrogen bonds between specific complementary base pairs (Cytosine/Guanine joined by 3 H-bonds and Adenine/Thymine joined by 2 H-bonds) • Antiparallel polynucleotide strands (running in opposite directions. As new DNA strands are produced, they can only be added in the 5’ to 3’ direction (carbon bonds 5 and 3) • The 5-prime Carbon atom has an attached phosphate group while the 3-prime has a hydroxyl group

Answer 51

Important information carrying molecule that holds genetic information

Answer 52

• Polymers of nucleotides; - A condensation reaction between two nucleotides forms a phosphodiester bond between the phosphate group of one nucleotide and the pentose sugar of another

Answer 53

• Stable structure - Passes from generation to generation, rarely mutating • Extremely large - Carries an immense amount of genetic information • Base pairing - DNA can replicate and transfer information as mRNA • Two strands joined only by hydrogen bonds - Allows them to separate during DNA replication and protein synthesis • Phosphodiester backbone - Protects the more chemically reactive organic bases inside the double helix from chemical and physical forces

Answer 54

• A relatively short (single stranded) polynucleotide chain • Components include a ribose sugar, a phosphate group and one of the organic bases adenine, cytosine, guanine or uracil • Formed by condensation reactions between nucleotides to form phosphodiester bonds • Important information carrying molecule that transfers genetic information from DNA to ribosomes

Answer 55

• Pentose sugar • Nitrogen-containing organic base • Phosphate group

Answer 56

• Both contain a phosphate group, nitrogenous base and pentose sugar • DNA is double stranded while RNA is single stranded • DNA contains deoxyribose while RNA contains ribose (pentose sugars) • DNA contains bases adenine, cytosine, guanine and thymine, whereas RNA contains uracil instead of thymine • DNA is self replicating while RNA is synthesised from DNA when required • DNA is located in the nucleus of a cell and mitochondria while RNA is located in the cytoplasm, nucleus and ribosomes

Answer 57

• DNA has to replicate itself every time a cell divides so both cells have identical copies of the entire genome to ensure genetic continuity between generations of cells • This method of replication’s called semi-conservative replication because one strand of each new DNA molecule has come from the double helix of the original molecule and conserved by the parent cell • The double helix structure of DNA and semi-conservative replication were discovered and proposed by James Watson and Francis Crick

Answer 58

• The double helix of the original DNA molecules are unwound by the enzyme DNA helicase • DNA helicase breaks hydrogen bonds between complimentary bases in the polynucleotide strands • Two template strands have been produced and free DNA nucleotides form hydrogen bonds by complimentary base pairing • The enzyme DNA polymerase catalyses the condensation reaction to join adjacent nucleotides by phosphodiester bonds • Two identical strands of DNA are formed, each containing half of the original DNA

Answer 59

• DNA helicase breaks hydrogen bonds between complementary nucleotides, it detaches from the lagging strand and has to go back • DNA polymerase catalyses the condensation reaction to join nucleotides between the leading and lagging strands by phosphodiester bonds by completing a chunk on the leading strand and then going back and repeating it on the lagging strand

Answer 60

• Grew bacteria in a culture containing Nitrogen 15 • Centrifuged it with a radioactive label • Put them in a culture containing nitrogen 14 allowed them to divide once and centrifuged again • Repeated with one more replication in Nitrogen 14 and centrifuged again

Answer 61

• Nucleotide derivative formed from a molecule of ribose, a molecule of adenine and three phosphate groups • Acts as an energy currency of cells

Answer 62

• Hydrolysis of ATP to adenosine diphosphate (ADP) and an inorganic phosphate group (Pi) is catalysed by the enzyme ATP hydrolase • Can be coupled to energy-requiring reactions within cells and the inorganic phosphate that’s released can be used to phosphorylate other compounds, often making them more reactive • Eg. To provide energy for other reactions (named process) or to add phosphate to other substances to make them more reactive or change their shape

Answer 63

• Condensation reaction of ADP and Pi catalysed by the enzyme ATP synthase, during photosynthesis of respiration • Eg. In chlorophyll during phosphorylation during photosynthesis • Eg. During oxidative phosphorylation in respiration

Answer 64

• ATP contains ribose sugar whereas DNA contains deoxyribose sugar • ATP has 3 phosphate groups whereas DNA contains only 1 phosphate group • ATP always contains the base adenine whereas the DNA base varies between adenine, cytosine, guanine and thymine

Answer 65

• Small and soluble, so it can be transported around the cell • ATP can’t pass out of the cell so cells always have an immediate supply of energy • Hydrolysis is a single reaction, so energy’s released quickly and it rapidly resynthesises • Low activation energy so it can release stored energy quickly • Stores and releases small amounts of energy at a time, so no energy’s wasted • Can transfer energy from one molecule to another by transferring one of its phosphate groups

Answer 66

• Metabolite in many reactions: - Required in hydrolysis and produced in condensation reactions • Important solvent: - In which metabolic reactions occur, and ionic compounds can dissolve in water because of its dipolarity (e.g. salt) • High specific heat capacity: - Buffers changes in temperature, making it a good habitat and helps organisms maintain a stable body temperature as temperature doesn’t rapidly change • Large latent heat of vaporisation: - Evaporates when hydrogen bonds are broken, which requires a relatively high amount of energy, so heat’s lost easily through evaporation which provides a cooling effect with little loss of water • Strong cohesion between water molecules because they’re polar and therefore flow easily: - Supports columns of water in tube-like transport cells of plants (xylem) - Produces surface tension where water meets air, allowing some organisms to ‘walk on water’.

Answer 67

• (H2O) Dipolar molecule containing a slightly negative oxygen atom and a slightly positive hydrogen atom bonded with a hydrogen bond • The body’s most critical nutrient where functional chemicals are dissolved and transported and chemical reactions take place • Makes up about 70% of adult body mass and is the largest component of cells, blood and fluid between cells • Helps regulate internal temperature • Protects and lubricators joints and other body structures

Answer 68

• SHC: The amount of energy required to raise the temperature of one kilogram of the substance by 1°C (4.2J raise 1 gram of water by 1°C - calorie) • LHV: The amount of energy that must be added to a liquid substance to transform it into a gas

Answer 69

• Atoms or molecules with an overall electric charge formed by the transfer of electrons, either positive (cations) or negative (anions) that don’t contain carbon • Inorganic ions occur in solution in the cytoplasm and body fluids of organisms and have specific roles dependent on their properties E.G: • Iron (Fe^2+) found in haemaglobin in red blood cells that bind to oxygen • Phosphate (Po4^3-) components of nucleic acids, ATP and phospholipids in the cell membrane • Sodium (Na+) involved in the co-transport of glucose and amino acids • Hydrogen (H+) maintain pH; the more H+, the lower the pH (more acidic)

Answer 70

• Oxygen is a key component of important chemical reactions (including ATP production). The brain’s sensitive to lack of oxygen due to its requirement for high, steady ATP production • Nutrients are substances in food and drink that are essential to human survival, they’re broken into water, macronutrients and micronutrients

Answer 71

Macronutrients are: • Energy yielding such as carbohydrates and lipids that are used in metabolic processes that convert them to ATP • Body building such as proteins that supply the amino acids that are the building blocks of the body

Answer 72

Vitamins and minerals, • Vitamins are organic substances • Minerals are inorganic compounds absorbed or consumed by animals

3.1 Biological Molecules💧 Flashcards

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