Unit 2: Molecular Biology Flashcards

Question

Define metabolism

Answer 1

metabolism is all enzymatic reactions taking place in a living organism. it is the sum of all enzymatic reactions in a cell or organism. metabolism = anabolism + catabolism.

Answer 2

anabolism is synthesis or creation of complex molecules from simpler precursor molecules. it is the opposite of catabolism. it requires energy in the form of ATP. it includes the formation of macromolecules from monomers through condensation reactions(reaction where two small molecules combine to make a bigger one, with the formation of water or another simpler molecule occurring in the process).

Answer 3

catabolism is breaking down complex molecules into simpler ones. it includes hydrolysis of macromolecules into monomers(hydrolysis is breaking down chemical bonds by adding in water molecules). the breakdown of sugars (including the process of glycolysis) or fats in order to release energy, is an example of a catabolic reaction. energy is released during catabolism.

Answer 4

Hydrolysis reaction is the breaking of chemical bonds by the addition of water molecules.

Answer 5

Condensation reaction refers to the reaction in which two smaller organic molecules combine to form a larger molecule with the accompanied formation of water or some other simple molecule

Answer 6

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Answer 7

- naturally used to excrete amino acids from the body since it’s non-toxic and highly soluble - widely used to fertilize nitrogen, leading it to be artificially synthesized on a larger scale - was synthesized accidentally by German chemist Friedrich Wöhler in 1828. - demonstrated by-product of life could be artificially synthesized and that an organic compound could be synthesized from two inorganic molecules - provided evidence contradicting the theory of vitalism, allowing for it to be discredited.

Answer 8

theory of vitalism stated organic compounds could only be synthesized by living organisms, since they had an ‘element’ non-living things lacked. this element was referred to as the divine principle or life spark.

Answer 9

water has two hydrogen atoms and one oxygen atom joined by covalent bonds

Answer 10

- oxygen atoms are more electronegative than hydrogen atoms, meaning oxygen has more of a pull on the electrons that exist between atoms - because of this, oxygen gets a slightly negative charge and each hydrogen atom has a slightly positive charge(δ-/δ+). delta means partial change

Answer 11

water polarity is the main reason for the important properties like solvency, cohesion, and adhesion. they’re polar because they have both positive AND negative charges (oxygen is negative, hydrogen is positive).

Answer 12

- water allows hydrogen bonding, since the sides have different charges. positives and negatives attract, and negative oxygen is attracted to positive hydrogen, which make hydrogen bonding. this is why water molecules love to stick together. - hydrogen bonds are weak interactions between water molecules, and are responsible for many important properties like cohesion and adhesion

Answer 13

polarity of water molecules lets them attract other polar or charged compounds and form hydrogen bonds with them, meaning most polar or charged compounds can be dissolved in water. such compounds are hydrophilic. ex: sugars, salts, glucose, fructose. fats and oils and wax are non-polar, since they don’t have any attraction with water molecules. instead they repel each other. this is because they’re hydrophobic compounds.

Answer 14

- tendency of water molecules to stick to each other **due to the hydrogen bonding** between them - each can potentially form four hydrogen bonds with other water molecules in a tetrahedral arrangement - hydrogen bonds are weak but the presence of a large number of them in water gives cohesive forces great strength - lets insects to walk on water - lets water be pulled up from the roots to the leaves of plants - cohesion is responsible for the high surface tension of water, meaning that the surface behaves as a strong elastic membrane, allowing small organisms or some objects denser than water to float on the water surface. - surface tension is responsible for water droplets having a spherical shape and minimizing the ratio of area to volume

Answer 15

- interaction that water molecules have with other molecules - explains why water molecules stick to other polar compounds, by forming hydrogen bonds - responsible for capillary action which is the movement of water molecules and all the things dissolved in it within thin spaces without relying on gravity - adhesion lets water molecules be easily transported up the stems of plants - capillary action helps the pumping of the heart to help blood move through blood vessels - adhesion of water molecules to the cell wall of xylem vessels helps water move against gravity from the roots to the leaves

Answer 16

The movement of water molecules and all the things dissolved in it within thin spaces without relying on gravity

Answer 17

- Hydrogen bonds that hold water molecules together are responsible for thermal properties of water like the high specific heat capacity - to break down water’s hydrogen bonds, a lot of energy is needed - high specific heat capacity of water means that the temperature in aquatic ecosystems doesn’t change rapidly, making those ecosystems pretty stable - evaporation of sweat from body surfaces involves heat loss, which brings a cooling effect - **specific heat** is the amount of heat that must be absorbed or released for 1g of a substance to change it’s temperature by 1 degree Celsius - water is a great coolant. a lot of energy is needed to turn water into water vapour, meaning water has a **high latent heat of vaporisation** which is the amount of heat 1g of a liquid absorbs to change its state into a gas - specific heat capacity is the amount of energy needed to heat up 1g of water by 1 degree celsius. latent heat of vaporisation is amound of energy needed to change water liquid into water vapour.

Answer 18

- if a compound easily dissolves in water, it can normally be transported by blood. these compounds are transported in the blood plasms. - water-insoluble substances are absorbed and transported by the lymph vessels

Answer 19

biological molecules found in blood: - glucose - polar - soluble in water, so can be transported in blood - blood glucose concentration must be strictly maintained between certain levels due to its effect on osmotic potential - amino acids - both negatively and positively charged - most are soluble in water - solubility varies depending on size and R group. Amino acids with hydrophilic R group are easily dissolved in water and transported in blood. It amino acids have hydrophobic R group, they won’t be easily dissolved in water, and will be transported in lower concentrations in the blood - fat - nonpolar - transported in lipoproteins which are a single layer of phospholipids with proteins embedded among the molecules surrounding the fat - cholesterol - required for synthesis of many biologically important molecules - component of membranes - requires help of transport lipoproteins to be transported in blood - hydrophobic - oxygen - nonpolar - small size - soluble in water to a very limited extent, only because of its size - oxygen transported in blood is bound to hemoglobin, a protein - sodium chloride - ionic compound - transported in blood in the form of Na+ and Cl- ions, which are easily dissolved in water

Answer 20

Covalent compounds because they're made of atoms sharing electrons in covalent bonds

Answer 21

One carbon atom bonded with 4 hydrogen atoms

Answer 22

Water: Cohesive, adhesive, thermal, and solvent properties because it's polar and has hydrogen bonds

Answer 23

methane is a gas produced by anaerobic bacteria as a waste product. it’s also a greenhouse gas

Answer 24

Thermal properties. For example, water has a much higher boiling point than methane due to hydrogen bonding.

Answer 25

organic compounds = compounds made of carbon and other elements like oxygen and hydrogen. carbohydrates and lipids are organic compounds since they’re mostly made of carbon hydrogen and oxygen atoms

Answer 26

carbohydrates = carbon atoms and hydrates (hydrates are made from water and made of hydrogen and oxygen). they mainly provide energy in the form of sugars (i.e. glucose, fructose), but they also make up structures like cellulose which form the cell wall of plant cells

Answer 27

C*x*(H2O)*y*

Answer 28

Carbohydrates

Answer 29

condensation is a reaction where two smaller organic molecules combine to make a larger molecule and a molecule of water or a simple molecule is removed. the opposite reaction to condensation is hydrolysis where water is added to break down the bonds in a bigger compound.

Answer 30

Monosaccharides, disaccharides, polysaccharides

Answer 31

monosaccharides - considered sugar. single units of sugar. polar and soluble in water. simplest type. Number of carbon atoms ranges from 3 to 7. carbons are joined to hydroxyl group (-OH). monomers to make bigger carbohydrate molecules.

Answer 32

disaccharides - considered sugar. polar and soluble in water. 2 monosaccharide monomers are linked by a condensation reaction, forming a glycosidic bond, making a disaccharide and releasing one water molecule. examples: ribose, glucose, fructose, galactose.

Answer 33

polysaccharides - macromolecules that come from polymerisation (condensation) of sugars, and aren’t soluble in water. big molecules like cellulose, glycogen, and starch. cellulose is a polysaccharide in trees. glycogen is a storage substance in animals and fungi, while plants store starch in their roots and stems. Carbohydrates also make up the chitin exoskeleton of insects and crustaceans.

Answer 34

glucose exists in two forms: D-gluctose and L-gluctose. They have the same chemical formula but a slightly different atom arrangement. There are also two forms of D-Glucose, α-D-glucose and β-D-glucose. The OH group in carbon 1 is below in alpha and above in beta.

Answer 35

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Answer 36

Type: Disaccharide Monomers: Glucose, Fructose

Answer 37

Type: Disaccharide Monomers: Glucose, Glucose

Answer 38

Type: Disaccharide Monomers: Glucose, Galactose

Answer 39

Type: Polysaccharide Monomers: Glucose

Answer 40

Type: polysaccharide Monomers: Glucose

Answer 41

Type: Polysaccharide Monomers: Glucose

Answer 42

- polysaccharides have a giant role in supplying and storing energy. - in plants, starch is made up of a mixture of 70%-80% amylose, and the rest amylopectin. - in animals, glycogen is used to store energy - polysaccharides can also be used as a structural component - cellulose in plant cell walls give the walls more strength and protects them from bursting, and lets them store enough energy to be a source for biofuels

Answer 43

starch and cellulose are made of glucose but they have different arrangement of glucose molecules and position of the glycosidic bonds. within cellulose molecules, all glucose monomers are oriented in the same direction. in starch molecules the glucose monomers rotate 180 degrees around the backbone chain.

Answer 44

in starch, the arrangement of glucose molecules can be linear, which is called amylose, or they can be branched, which is called amylopectin.

Answer 45

hydrogen bonds between glucose subunits stabilise the structure of starch, cellulose, and glycogen.

Answer 46

- starch is a polymer made from glucose monomers. glucose monomers can make a long, unbranched chain known as amylose or a branched chain called amylopectin. a starch molecule consists of both forms: unbranched amylose and branched amylopectin. - amylopectin gives starch the stickiness which is useful in food, paper, and chemical industries, where it’s used to make paste, glue, or used as a lubricant - amylopectin makes up 80% of the starch content in potatoes. a genetically modified potato which predominantly produces amylopectin starches which is useful for adhesive making has been produced and approved for cultivation.

Answer 47

Monosaccharides - polar and soluble in water. glucose, ribose, fructose and galactose. fructose is a sugar found in fruits and honey. galactose is a sugar in milk

Answer 48

Disaccharides - polar and soluble in water.maltose, lactose, sucrose. maltose (glucose + glucose) is found in grains. sucrose (glucose + fructose) is found in sugar cane and sugar beets. lactose (glucose+galactose) is found in mammalian milk

Answer 49

Polysaccharides - not all are polar and soluble in water. glycogen, cellulose, starch. cellulose is structural component of plant cell walls. starch forms energy stores in plants. glycogen is the storage form of carbohydrate. it’s found in animals in the liver and muscles.

Answer 50

starch is a polymer made from glucose monomers. glucose monomers can make a long, unbranched chain known as amylose or a branched chain called amylopectin. a starch molecule consists of both forms: unbranched amylose and branched amylopectin.

Answer 51

- amylopectin gives starch the stickiness which is useful in food, paper, and chemical industries, where it’s used to make paste, glue, or used as a lubricant - amylopectin makes up 80% of the starch content in potatoes. a genetically modified potato which predominantly produces amylopectin starches which is useful for adhesive making has been produced and approved for cultivation.

Answer 52

carboxylic acids meaning they possess a COOH (carboxyl) function group which is attached to the head of a long hydrocarbon chain

Answer 53

Saturated and unsaturated. saturated has no double bonds between any of the carbon atoms in the hydrocarbon chain. unsaturated fatty acid can be monounsaturated if it has just one double bond. polyunsaturated fatty acid has 2+ double bonds in the hydrocarbon chain. can be either cis or trans isomers depending on position of the hydrogen atoms around the carbon-carbon double bond. Trans ones have a kink in them.

Answer 54

Cis: common in nature. the two hydrogen atoms are attached to the same side of the two carbon atoms. lipids/triglycerides formed from cis fatty acids have lower melting points (generally liquid at room temperature). healthier. promote good cholesterol. Trans: artificially produced when lipids made by polyunsaturated fatty acids from plants are ‘partially hydrogenated’ chemically. makes plant fatty acids more solid. the hydrogen atoms are on the opposite side of the two carbon atoms. lipids made from transfatty acids have higher melting points are generally solid at room temperature. dangerous for cardiovascular system. promote ‘bad cholesterol’.

Answer 55

its the type of fatty acids in fat that determines whether the fat is good or bad for our health. cis unsaturated fatty acids are good fatty acids and beneficial to our body

Answer 56

- little to no affinity to water - mostly hydrophobic or water-repellent - mainly consist of carbon, oxygen and hydrogen - can be simple like fats, oils, and waxes - non-polar and insoluble in water (hydrophobic), but soluble in organic solvents - main group of lipids is triglycerides - formed by condensation reactions between one glycerol and three fatty acids, making ester bonds - two types: fats and oils. fats are solid at room temperature while oils are liquid.

Answer 57

if a fatty acid in a triglyceride is replaced by a phosphate group (-PO4) it makes a phospholipid

Answer 58

steroids - are also lipids, but don’t resemble them since their structure consists of four fused rings. they’re still lipids though since they’re hydrophobic and insoluble in water. cholesterol and sex hormones are examples of steroids.

Answer 59

- lipids have a higher energy content than carbohydrates and can act as thermal insulators - carbohydrates energy storage: 17 kJ/g - Fats: 27 kJ/g - why lipids are better for long-term storage: - gram of lipid has 2x amount of energy as gram of glycogen - a gram of glycogen stored is associated with 2g of water, while lipids are stored in pure form. this and higher energy content of lipids means lipids contribute only 1/6 th as much to body mass as carbohydrates per unit of energy stored. therefore, using lipids as a long-term storage molecule means animals have a lighter body mass, which is essential for mobility.

Answer 60

glycogen is the carbohydrate used for energy storage in animals. It’s stored in the liver and muscles and can be easily broken down (compared to lipids) into glucose, which is a form in which it can be rapidly transported around the body for use in cellular respiration. Thus, energy stored in glycogen is more accessible than energy stored in fat.

Answer 61

- energy content - more energy per gram - density - less dense than water (proof: oil floats on water) - solubility - non-polar so will dissolve other non-polar compounds, but doesn’t affect movement of water - insulation - excellent heat insulation, like whale blubber - waterproof - lipids are water-insoluble and provide a waterproof layer in plants and animals

Answer 62

- saturated fats occur naturally in lots of food, but majority come from animal sources like meat and dairy products - trans fats are formed by the hydrogenation of vegetable oils by adding hydrogen to unsaturated fats under pressure. this increases spread ability of vegetable oils and extends shelf life of some food products.

Answer 63

despite positive correlations, no relationship has been found. being overweight or obese increases risk of developing type 2 diabetes, coronary heart disease (CHD) and certain types of cancer. hypothesis is that trans fats and saturated fats contribute to formation of atherosclerotic plaques in arteries, which leads to heart attacks. This is supported by evidence obtained from patients who died from CHD that show high concentrations of trans fats are present in the fatty deposits in their diseased arteries

Answer 64

- BMI = weight (kg) / height (metres) squared - <18.5 means underweight, increased risk of health problems - 18.5-24.9 means normal weight, least risk of health problems - 25.0-29.9 is overweight, meaning increased risk of health problems - 30.0-34.9 is obese class I, meaning high risk - 35.0-39.9 is obese class II, meaning very high risk - ≥40 is obese class III, meaning extremely high risk

Answer 65

- proteins are workforce of nature - 16% of body is composed of proteins - estimated that human body can generate 2 million different types of proteins - all proteins are made of monomers called amino acids

Answer 66

Polypeptides: Amino Acids Linked by Condensation Reaction - polypeptides are a number of linked peptides - proteins and polypeptides are the same thing - basic unit is an amino acid which is a carbon-based compound with a carboxyl group (-COOH) and an amino group (-NH2) - initially, 2 amino acids bind in a condensation reaction to make a dipeptide. the carboxyl group and amino group give OH and H respectively. - bigger polypeptides are just more amino acids linked together. The biggest protein in the human body, titin, is 27,000 amino acids long.

Answer 67

- polypeptides are the same thing as proteins - peptides are smaller than proteins. they’re molecules that have between 2 and 05 amino acids. - proteins are polymers made up of 51 or more amino acids

Answer 68

Synthesis of polypeptides takes place on ribosomes, in a process known as translation

Answer 69

Genes = sections of DNA that contain instruction for all polypeptides (lots of which will be enzymes). normally code for one polypeptide which is a sequence of amino acids linked by peptide bonds. peptide bonds are the result of a condensation reaction.

Answer 70

the genetic material is transcribed into the ribonucleic acid (RNA) called mRNA (messenger RNA) which then carries instructions for the amino acid sequence to the ribosome which is found in the cytoplasm.

Answer 71

Polypeptides = many amino acids linked together. Order determines the shape and function of the protein.

Answer 72

amino acids differ by their R groups which determine the types of bonds and interactions with other molecules that they can make. this defines how polypeptide chain or chains fold up in the protein and so directly affect its three-dimensional structure, known as its conformation. a change in the order of amino acids changes the protein’s conformation, resulting in a change of shape or loss of function. Gene mutations can cause these changes as well.

Answer 73

- sequence of amino acids in protein is primary structure. it defines all aspects of the structure and function of a protein. - secondary structure is folding of chains on themselves to form pleated sheets or alpha helixes. - tertiary structure is when polypeptide folds and coils to form a complex three-dimensional shape - quaternary structure only occurs in proteins and are made of 2+ polypeptide chains and refers to the way the multiple subunits are held together in a multi-subunit complex

Answer 74

In sickle cell anemia, the glutamic acid is substituted by valine. this causes severe changes to the structure of hemoglobin

Answer 75

hemoglobin is an example of a protein with a quaternary structure. it has two alpha and two beta chains. with the heme group, hemoglobin makes a functional structure which can transport four molecules of oxygen.

Answer 76

- every organism has a complete and unique DNA content which is called a genome - every organism has a unique set of proteins coded by their genome. this is called a proteome, which is named from PROTE in and gen OME. - - proteome analysis has become a new tool in medical research and cancer treatment. to treat certain cancers, the proteome of a patient’s cancer cells is analysed to determine if a particular chemotherapy will be successful - you are a product of your genes and your environment and add proteome to that statement - proteomes of individuals even within a species can vary. each person can have a slightly different set of proteins because of differences in the amino acid sequence. - we can separate proteins using gel electrophoresis and analyse a proteome of the species.

Answer 77

- every organism has a complete and unique DNA content which is called a genome - every organism has a unique set of proteins coded by their genome. this is called a proteome, which is named from PROTE in and gen OME. - proteome analysis has become a new tool in medical research and cancer treatment. to treat certain cancers, the proteome of a patient’s cancer cells is analysed to determine if a particular chemotherapy will be successful - you are a product of your genes and your environment and add proteome to that statement - proteomes of individuals even within a species can vary. each person can have a slightly different set of proteins because of differences in the amino acid sequence. - we can separate proteins using gel electrophoresis and analyse a proteome of the species

Answer 78

- process where proteins lose secondary and tertiary structures and sometimes also quaternary - hydrogen bonds made between R-groups of amino acids and amino groups of different amino acids are disrupted - active sites lose their shape - whole enzyme loses enzymatic properties - two main ways to denature proteins: exposing to high temperatures and changing pH of a surrounding solution

Answer 79

- when proteins lose their conformation, interactions between certain amino acids will be changed, so that quaternary and tertiary structures, and sometimes the secondary structures are irreversibly changed - this results in denatured proteins losing their form and function. should be noted peptide bonds holding adjacent amino acids don’t break during the denaturation process. therefore, primary structure of protein is not disrupted. - that’s why high fevers can be dangerous for humans. at temperatures above 40 degrees Celsius some proteins denature and enzymes don’t function properly. if it stays like that for too long the patient can die. not all proteins are easily denatured by temperature - certain enzymes that break down RNA and prion proteins are extremely stable and require long periods of high temperature before they denature

Answer 80

- pH can affect functionality of a protein - strong alkaline or acidic solutions can break bonds between non-adjacent amino acids or polypeptide chains of quaternary proteins - protein denatures and loses functionality

Answer 81

- process where proteins lose secondary and tertiary structures and sometimes also quaternary - hydrogen bonds made between R-groups of amino acids and amino groups of different amino acids are disrupted - active sites lose their shape - whole enzyme loses enzymatic properties - two main ways to denature proteins: exposing to high temperatures and changing pH of a surrounding solution

Answer 82

- when proteins lose their conformation, interactions between certain amino acids will be changed, so that quaternary and tertiary structures, and sometimes the secondary structures are irreversibly changed - this results in denatured proteins losing their form and function. should be noted peptide bonds holding adjacent amino acids don’t break during the denaturation process. therefore, primary structure of protein is not disrupted. - that’s why high fevers can be dangerous for humans. at temperatures above 40 degrees Celsius some proteins denature and enzymes don’t function properly. if it stays like that for too long the patient can die. not all proteins are easily denatured by temperature - certain enzymes that break down RNA and prion proteins are extremely stable and require long periods of high temperature before they denature

Answer 83

- pH can affect functionality of a protein - strong alkaline or acidic solutions can break bonds between non-adjacent amino acids or polypeptide chains of quaternary proteins - protein denatures and loses functionality

Answer 84

- enzymes are polypeptides with a tertiary or quaternary structure - catalytic reaction takes place on active site. only one type of substrate fits into the active site. this is what’s meant by enzyme-substrate specificity. - active site is result of folding of polypeptide chains. resulting shape formed by polypeptide chain forms the active site, which is where the substrate interacts with the enzyme.

Answer 85

- reaction that converts substrate into products occurs at active site of enzyme - substrate triggers change in shape of enzyme which allows a tighter fit - possible because of flexibility of protein molecules that make up the enzyme - when enzyme and substrate fit together tightly, the enzyme induces the weakening of bonds in the molecules of the substrate, thus reducing activation energy needed for reaction - when enzyme-catalysed reaction is finished, products are released from the enzyme - enzyme is globular protein acting as catalyst for biochemical reaction - an active site is the region of the enzyme to which substrates bind and where reactions are catalysed - enzymes are specific, they only catalyse one type of reactions

Answer 86

- can speed up reaction by lowering activation energy of the reaction - activation energy = minimum energy that reacting particles should possess for a reaction to occur - catalytic reaction is when enzyme converts substance into products - enzyme catalysis involves molecular motion and collision of substrates with the active sight. these reactions take place in watery environments. - catalysis of a reaction is only possible if the substrate and active sit happen to be properly aligned when they collide to allow binding to take place. - reaction where product formation is associated with release of energy is called an exothermic or exergonic reaction - reaction where product formation is associated with absorption of energy (normally heat) is called an endothermic or endergonic reaction.

Answer 87

- factors that generally affect the rate of reaction from enzymes: - substrate concentration - enzyme concentration

Answer 88

- enzymes are sensitive to temperature changes - in low temperature molecules move slowly and the chance of collision between substrate and enzyme molecules is also low - each enzyme has an optimum temperature where the rate of enzymatic reaction is highest - for human enzymes optimal temperature is about 37 degrees Celsius - for enzymes in the bacteria Thermus Thermophilus that lives in hot springs the optimal temperature is 65 degrees Celsius - if temperature is too high enzyme can be denatured so rate of reaction rapidly decreases - most enzymes have optimal temperature around 40 degrees celsius

Answer 89

- enzymes work in different environment - stomach has pH level 2 - small intestine has pH level 7.5 - change to pH from optimum affects enzymes and their activity. Extreme pH values can denature enzyme by altering structure of active site

Answer 90

- denaturation destroys tertiary or quaternary conformation of a protein - secondary structure can be altered in some cases - when there’s only a minor temperature increase or change in pH, it’s possible that the denaturation is still reversible and the protein can go back to its original and functional conformation - beta sheets and alpha helices lose their form and protein goes back to a primary conformation, meaning no more functional active site

Answer 91

immobilisation is a process of attaching an enzyme to a material so that its movements are restricted. enzymes sometimes need to be separated from substrate molecules to prevent reactions. in most cases, enzymes must be active in different temperatures and pH. to make them more stable and useful they need to be immobilised

Answer 92

- if enzymes arent immobilised, they’ll be present in the final product, which restricts concentration that can be used to process food for human consumption to avoid adverse effects - use of immobilised enzymes permits higher concentrations of enzymes to be used, allowing a faster rate of reaction - immobilisation of enzymes allows immediate separation of the enzymes from the reaction mixture, allowing them to be recycled, reducing production costs

Answer 93

- lactose - naturally occurring disaccharide present in mammalian milk and dairy products like cheese and yogurt - consists of two monosaccharides: glucose and galactose

Answer 94

lactase - enzyme that can break lactose down into monosaccharides. produced by cells in lining of small intestine.

Answer 95

- people that don’t have lactase are lactose-intolerant and can’t break down lactose - lack of lactase makes lactose build up and remain in digestive system, where it’s fermented by bacteria, causing gastric problems - advantages to production of lactose-free products: - no ill effects after consumption - quicker fermentation - sweeter tasting since glucose and galactose separately are sweeter than lactose - lactose-free products are made by adding enzyme lactase to milk. lactase breaks down the lactose. otherwise, lactase can be immobilized in alginate beads while milk is allowed to flow past so lactase doesn’t end up in the final product.

Answer 96

Nucleotides: Monomers that make up the basic structures of both DNA and RNA.

Answer 97

1. Pentose(5 carbon atoms) sugar 2. Phosphate Group 3. Nitrogenous base

Answer 98

- Bases - DNA has guanine, adenine, thymine, and cytosine - RNA has guanine, adenine, uracile, and cytosine - Pentose sugar - DNA has the sugar deoxyribose - RNA has the sugar ribose - Strands - DNA is double-stranded, forming a double helix - RNA is single-stranded

Answer 99

Polynucleotide: Nucleotide units link together through a phosphodiester bond, also known as a covalent bond, to make a single strand known as a polynucleotide.

Answer 100

Covalent/Phosphodiester bond: Formed between the phosphate group attached to the 5’ carbon of one sugar, and the hydroxyl OH group attached to the 3’ carbon of another sugar.

Answer 101

3’ and 5’ refer to the carbon position on the sugar in DNA. Carbon 1 is attached to the base and from there on carbon atoms are counted in a clockwise direction.

Answer 102

- Guanine always pairs with Cytosine - Adenine always pairs with Thymine - In order for bases to face each other, the two strands run in opposite directions, meaning they’re antiparallel (one strand runs from 3’ to 5’, and the other from 5’ to 3’).

Answer 103

Hydrogen Bonds: DNA strands are held together by hydrogen bonds. There are 3 hydrogen bonds between Guanine and Cytosine, and 2 hydrogen bonds between A and T.

Answer 104

Crick and Watson: They used information from DNA X-ray diffraction patterns produced by Rosalind Franklin and Maurice Wilkins to deduce that DNA molecules must have a regular double helix structure. They also integrated Chargaff’s base ratio, a finding showing that A is always equal to T and C is always equal to G in the DNA molecule to work out the complementary base pairing of A to T and C to G. They then built a 6 foot model out of a metal scrap and everything clicked into place.

Answer 105

Replication: The formation of a new DNA molecule. This occurs during the S phase of the cell cycle. In most cases, it results in identical copies of the DNA in the daughter cells. Chromosome number and genes stay unchanged during DNA replication, but the number of DNA molecules doubles after DNA replication. DNA Replication always occurs in 5’ to 3’ direction. Steps: 1. DNA Helicase unwinds the double helix and separates the two DNA strands by breaking the hydrogen bonds between bases. 2. DNA polymerase starts making new strands of DNA using the old parent strands as templates. DNA Polymerase proceeds in opposite directions during replication. On one strand it moves in the same direction as the replication fork (immediately behind the helicase enzyme) and it moves in the reverse direction on the other strand. Note: DNA Replication is semi-conservative because each daughter molecule formed contains one original strand from the old molecule and one newly synthesised strand.

Answer 106

Meselson and Stahl: Two scientists trying to figure out how replication of DNA worked in bacteria. They designed some elegant experiments that demonstrated that DNA replication is Semi-conservative. They cultured E.coli bacteria in the presence of a heavy, 15 nitrogen isotope. DNA has nitrogen in its nitrogenous bases so the radioactive 15 nitrogen would end up in the DNA. All of the bacteria had 15 N in the DNA. Then they transferred the bacterial culture into a fresh medium where the nitrogen was replaced by 14 nitrogen, a lighter isotope, and the bacteria could grow for several generations. Samples were then extracted from successive bacterial generations and subjected to caesium chloride equilibrium density gradient centrifugation, allowing DNA to move to different positions in the centrifuge tube based on density. All were light light or in the middle.

Answer 107

Coding information is copied or transcribed into messenger RNA. The DNA acts as a template, and the single-stranded mRNA molecule that’s made follows the complementary base pairing rules of DNA with uracil instead of thymine. Basically, the section of DNA that has the required gene is unwound and separated so that RNA polymerase enzymes can access DNA bases. The RNA polymerase then transcribes a sequence of DNA bases into mRNA.

Answer 108

RNA Polymerase: Responsible for separating the DNA strands of the double helix, as well as for joining the ribonucleotides together by phosphodiester bonds to form an mRNA strand.

Answer 109

Sense strand: The not transcribed DNA strand is called the sense strand, and has the same sequence of bases as the mRNA molecule except thymine being replaced by uracil.

Answer 110

Translation: Synthesis of polypeptides on ribosomes according to the genetic code in 5’ to 3’. After transcription, the mRNA leaves the nucleus and binds to one or several ribosomes, allowing translation process to begin. This happens with involvement of either free ribosomes in the cytoplasm or ribosomes on the rough endoplasmic reticulum. Each set of consecutive bases is known as a codon or triplet. Each codon is translated into one amino acid in a polypeptide chain. The sequence determines the amino acid sequence of the polypeptide. Any changes affecting the base sequence of the DNA can lead to the wrong amino acid being made.

Answer 111

Genetic code: Degenerate, meaning there are some amino acids encoded by more than one codon. It’s also universal.

Answer 112

mRNA: Length depends on the size of the gene it’s related to and the protein that’s made. Remember, three nucleotides are needed for the start codon, which codes for methionine, and three nucleotides are needed for the stop codon.

Answer 113

transfer RNA molecule brings an amino acid to the mRNA. tRNA molecules have an anticodon that pairs with a codon of the mRNA, making sure that the correct amino acid is added to the growing polypeptide chain. Common complementary base pairing rules apply.

Answer 114

Definition: Polymerase Chain Reaction. It’s used to amplify small fragments of DNA. It was developed by Kary Mullis in 1983. It is a technique that can make billions of copies of one DNA molecule by repeatedly copying a specific stretch of that DNA. It uses cyclic heating and cooling of a DNA sample in the presence of primers (small fragments of RNA), DNA nucleotides, and Taq polymerase to amplify DNA. It essentially allowing its rapid production of multiple copies of DNA by using Taq DNA polymerase.

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Taq polymerase: DNA isolated from a bacterium Thermus aquaticus. It lives in hot water springs at temperatures between 50 and 80 degrees C. Most of its proteins are thermostable, meaning they can operate at higher temperatures than other organisms. Since PCR uses high temperatures, it needs Taq polymerase.

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Transgenic organism: Results from placing a gene from one organism into a different organism. Transgenic microorganisms like bacteria are made by inserting a gene from another organism into the plasmid of their cell. The organism can then be used as a bio factory for many therapeutic drugs.

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Plasmids: Small circular DNA molecules in some prokaryotic cells that can be used as transfer molecules.

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Insulin: Insulin is a hormone produced by the beta cells of the pancreas. It regulates glucose uptake and the conversion of glucose to glycogen in the liver. Used to be extracted from the pancreas of farm animals because the structure of the hormone in them is similar to that in humans. However, the purification process was inefficient and some patients developed allergic reactions to animal insulin. In 1982, the human insulin gene was transferred to E. coli which resulted in the production of human insulin.

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Glucose: Preferred energy source for brain cells and is broken down in muscle cells for energy. It’s the most widely used source of energy in living organism.

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Cellular respiration: Gradual and controlled release of energy by breaking down organic compounds to produce ATP (Adenosine Tri Phosphate). It involves enzymes that control the process to make sure that energy is produced when required.

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Four main processes: Glycolysis, Krebs Cycle, the electron chain, and oxidative phosphorylation. All these processes generate energy in the form of ATP.

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Glycolysis: Takes place in the cytoplasm

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Mitochondria, in the mitochondrial matric

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Mitochondria on the inner membrane of the mitochondrial envelope

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ATP: Molecule that carries energy in the cell. Energy is produced when ATP is hydrolysed. It should be noted that it’s the same energy that was generated during respiration and stored in the energy-rich phosphate bond of ATP.

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Respiration: The breakdown of organic compounds and the production of ATP in the cell

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Definition: Cell respiration that occurs without oxygen. It only includes glycolysis.

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Location: The cell cytoplasm. It involves glycolysis

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Small amounts of ATP (2)

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Outputs: Smaller amounts of ATP (2) Types: Alcoholic and Lactic fermentation Alcoholic: Yeast respires anaerobically to make ethanol and carbon dioxide when fermenting raw ingredients to make beer, wine or bread. Carbon dioxide produced by yeast is used to make bread rise, while ethanol is evaporated away during baking. Therefore bread made without yeast would be very flat. Glucose → ethanol + carbon dioxide + 2 ATP molecules Lactic Fermentation: Although we breathe oxygen during strenuous exercise, muscle cells may use up all available oxygen. Then, the muscle cells begin to respire anaerobically and can produce a small amount of ATP this way, allowing the power of muscle contractions to be maximised without oxygen. During anaerobic respiration, animals produce lactate, also known as lactic acid. Glucose → lactate + 2 ATP molecules.

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Definition: Respiration that can yield more ATP, as it allows most of the energy in a glucose molecule to be harvested and converted to ATP, due to oxygen allowing all four steps of cellular respiration to be completed. This is because 6-carbon glucose is able to be systematically and gradually broken down into 6 CO2 molecules. Each step yields potential energy, which can be converted into ATP in the ETC. Location: Cytoplasm and mitochondria Equation: Glucose(C6H12O6) + Oxygen(6O2) → Carbon Dioxide(6CO2) + Water(6H20) + Energy

Answer 132

Definition: Apparatus that can measure the rate of respiration. In aerobic cellular respiration, we can use it to measure the consumption of oxygen as an indication of the respiration rate. Process: An organism in one tube respires, and consumes oxygen while producing carbon dioxide. The alkaline solution at the bottom of the tube absorbs the carbon dioxide. The second tube is a control, where no oxygen is used or carbon dioxide produced because no living organism is present. The connecting capillary is a manometer. The reduction in oxygen in the first tube reduces the pressure in tube A and moves the coloured liquid in the manometer towards tube A, providing an indirect measurement of the oxygen consumed. This allows the rate of oxygen consumption to be calculated. https://file.notion.so/f/f/e52fcf8a-d6ea-4a2d-a3c3-d8bce0c54560/b69a3a42-6f7b-4733-8dd9-e207a5d4a07e/Untitled.png?id=337b2ba6-c8d6-474f-bf5c-63e92852941c&table=block&spaceId=e52fcf8a-d6ea-4a2d-a3c3-d8bce0c54560&expirationTimestamp=1714780800000&signature=b4mX9yhAT5W79UUFrwUo6leXREqpg2iRsrLX-z0INVM&downloadName=Untitled.png

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Definition: The reaction of carbon dioxide and water using energy from light to produce carbohydrates and releasing oxygen as a waste product. Location: Chloroplasts, which are organelles in plant or algae cells where photons are captured. Type of reaction: Anabolic. Carbon dioxide and water are joined to form larger sugars.

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Pigments: Chloroplasts are green because chlorophyll a and chlorophyll b (pigments that capture photons) reflect green light and absorb most other wavelengths (red and blue the most effectively). Other involved pigments are xanthophyll and carotenoids which reflect yellow and orange light respectively. The colour of leaves of any plant is determined by the colour of light from the visible spectrum.

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Action Spectrum: Shows the efficiency of photosynthesis or the rate of photosynthesis achieved over various wavelengths of light from the visible spectrum

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Absorption spectrum: Shows which wavelength of visible light is absorbed by a particular photosynthetic pigment, like chlorophyll a or b. It’s measured by a spectrometer.

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Answer 138

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Answer 139

Definition: Photolysis is the stage of photosynthesis where water is split by using photon energy. Photolysis generates hydrogen ions, electrons, and oxygen. Formula: 2H2O+2(2 photons) → 4 electrons + 4 positive hydrogen ions + O2 Electrons are used to generate ATP. Both the ATP and the hydrogen ions are used in later stages, while oxygen becomes a waste product diffusing out of the plant.

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Calvin Cycle: Light-independent reactions. Consist of a cycle of chemical reactions where Carbon Dioxide is assimilated to make sugars. Occur in the stroma of chloroplasts. Involves carbon fixation to produce carbohydrates. Carbon dioxide + water → Carbohydrates + Oxygen

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Light-dependent reaction: Requires light. Occurs on the thylakoids of chloroplasts. This involves photolysis

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Light: When there is less light, the rate of photosynthesis slows down. When there is light, the rate of photosynthesis increases up to a certain point. Beyond that point, chemical reactions can’t go any faster, so any further increase does not increase the rate because photosynthesis operates via a certain number of photosystems that capture photons. Once they’re all occupied, it’s at the maximum rate. Carbon Dioxide: Raw material in the production of carbohydrates, which takes place in the light-independent reaction. Once all active sites of enzymes are occupied with a substrate, the graph levels off. Temperature: When temperature increases beyond optimum, enzymes start to denature.

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The earliest photosynthetic organisms were prokaryotes called cyanobacteria. They appeared on Earth around 3500 million years ago. It took several hundred millions of years before other photosynthetic organisms arrived. Initially the oxygen released from photosynthesis may have been used in oxidation of minerals like iron, and ended up in sediments and rocks. Around 2100 million years ago, eukaryotes appeared and then algae and other organisms in the ocean increased oxygen concentration aka partial pressure, in the water. Once oceans and deposits were saturated, the atmospheric oxygen started to build up.

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Definition: Technique used to separate mixtures of substances based on the movement of the different substances on a piece of paper by capillary action. Phases: Mobile and stationary. The paper is the stationary phase, while the solvent used to develop the chromatogram is the mobile phase. Ratio of distance moved by a pigment to the distance moved by the solvent is known as the retention factor. Rf=distance travelled by sample/distance travelled by solvent.